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BACKGROUND: Recent studies have shown that the occurrence and prevention of osteoporosis often focus on the cellular molecular level, and the mechanism of related signaling pathways is an important way to further understand osteoporosis. At present, traditional Chinese medicine has been proved to play a significant role in alleviating osteoporosis. Kaempferol as an emerging Chinese herbal extract has become the focus of clinical and basic research due to its antiosteoporosis effectiveness and mechanism of action. OBJECTIVE: To further understand the mechanism underlying the anti-osteoporosis effect of kaempferol active monomer through regulation of related signaling pathways by analyzing and collating domestic and foreign literature. METHODS: “Kaempferol, osteoporosis, osteoblasts, osteoclasts, bone marrow mesenchymal stem cells, signaling pathways” were used as Chinese and English search terms to search CNKI, WanFang, VIP, PubMed, Web of Science and Embase databases for relevant literature published from database inception to February 2023. RESULTS AND CONCLUSION: Kaempferol affects the occurrence and progression of osteoporosis to varying degrees by participating in the regulation of differentiation, proliferation and apoptosis of bone marrow mesenchymal stem cells, osteoblasts and osteoclasts. Kaempferol can prevent and treat osteoporosis by regulating various signaling pathways. Kaempferol can promote the proliferation and differentiation of osteoblasts and inhibit the formation of osteoclasts by interfering with the Wnt/β-catenin signaling pathway to regulate β-catenin protein counting and the formation of β-catenin-TCf/LEF complex. Kaempferol interferes with the RANK/RANKL pathway to maintain the dynamic balance of osteoclasts and bone homeostasis. Kaempferol can promote bone formation by intervening with the PI3K/Akt signaling pathway to upregulate the levels of related osteogenic factors Runx2 and Osterix and promote bone cell calcification. Kaempferol interferes with osteoclast differentiation and inhibits reactive oxygen species activity by regulating the ER/ERK pathway. Kaempferol inhibits the expression of ERK, JNK, p38/MAPK and decreases reactive oxygen species production by interfering with the MAPK pathway, thus protecting osteogenesis. Kaempferol enhances the expression of osteogenic factors, bone morphogenetic protein-2, p-Smad1/5/8, β-catenin and Runx2, inhibits the expression of Peroxisome proliferation-activated receptor, and promotes the differentiation and proliferation of osteoblasts through the BMP/Smad pathway. [ABSTRACT FROM AUTHOR]

BACKGROUND: Upregulation of hedgehog protein signaling can increase the expression of osteoarthritis markers, Runx2, a disintegrin and metalloproteinase with thrombospondin motifs, collagen type X alpha 1, and matrix metalloproteinase 13, while inhibition of hedgehog proteins attenuates the severity of osteoarthritis. It is speculated that osteoarthritic chondrocytes can influence bone formation by affecting osteoblasts through the Indian hedgehog protein (IHH) signaling pathway. OBJECTIVE: To investigate the effect of human osteoarthritic chondrocytes on subchondral osteoblasts. METHODS: Tibial plateau specimens from patients with osteoarthritis were collected. Chondrocytes were extracted using enzymatic digestion, and osteoblasts were extracted using enzymatic pre-digestion + bone block method. Chondrocytes were identified by toluidine blue staining and immunofluorescence and osteoblasts were identified by alkaline phosphatase staining and immunofluorescence. Chondrocytes were cultured in sodium alginate beads to maintain chondrocyte phenotype and co-cultured with osteoblasts. The co-culture system was added with IHH signaling pathway inhibitor (cyclopamine, 10 nmol/L) and activator (purmorphamine, 10 nmol/L) separately. After 48 hours of co-culture, osteoblasts from each group were collected, mRNA expressions of Gli1, osteoprotegerin, Runx2, parathyroid hormone-related peptide, alkaline phosphatase, receptor activator of nuclear factor-kB ligand (RANKL) and osteocalcin were detected by qRT-PCR, and protein expressions of GLi1, oseoprotegerin and RANKL in osteoblasts were detected by western blot. RESULTS AND CONCLUSION: The mRNA expression levels of GLi1, osteoprotegerin and RUNX2 in osteoblasts were significantly increased, while the mRNA expression levels of parathyroid hormone-related peptide were decreased (P < 0.05) when co-cultured with human osteoarthritic chondrocytes. The mRNA and protein levels of Gli1 were significantly decreased after the addition of IHH signaling pathway inhibitor (cyclopamine) (P < 0.05), and the mRNA and protein levels of Gli1 were significantly increased after the addition of IHH signaling pathway activator (purmorphamine) (P < 0.05). Osteoprotegerin showed the same trend as Gli1 in the experiment. The osteoprotegerin/RANKL ratio followed the same trend as osteoprotegerin. To conclude, human osteoarthritic chondrocytes can promote the expression of Gli1, osteoprotegerin, Runx2 and other proteins in osteoblasts. The upregulation of osteoprotegerin is related to the IHH signaling pathway. Osteoarthritic chondrocytes can up-regulate the expression of osteoprotegerin in osteoblasts through the IHH signaling pathway and thus up-regulate the osteoprotegerin/RANKL ratio, which will contribute to bone formation in subchondral bone. [ABSTRACT FROM AUTHOR]

BACKGROUND: Punicalagin has a wide range of effects and high safety, but its effect on osteoblasts and postmenopausal osteoporosis is unknown. OBJECTIVE: To investigate the effect of punicalagin on osteoblasts and postmenopausal osteoporosis. METHODS: The effect of punicalagin on the proliferation of MC3T3-E1 cells was detected. Punicalagin was added to the osteogenic induction medium to detect its effect on osteogenic differentiation. Punicalagin was used to treat ovariectomized rats and Micro CT scan and serum procollagen type 1 N-terminal propeptide test were performed after 3 months to detect the therapeutic effect. RESULTS AND CONCLUSION: Cell counting kit-8 assay showed that punicalagin could promote the proliferation of osteoblasts (P < 0.05). The results of qRTPCR and western blot showed that punicalagin could promote the mRNA and protein expressions of alkaline phosphatase and Runx2 in osteoblasts (P < 0.05). The results of Micro CT scan and serological test showed that punicalagin could improve bone mineral density, bone volume fraction, trabecular thickness, trabecular number and procollagen type 1 N-terminal propeptide level of ovariectomized rats. To conclude, punicalagin can promote osteoblast proliferation and differentiation, and have therapeutic effects in postmenopausal osteoporosis rats [ABSTRACT FROM AUTHOR]

Oxytocin (OT) is a posterior pituitary hormone that, in addition to its role in regulating childbirth and lactation, also exerts direct regulatory effects on the skeleton through peripheral OT and oxytocin receptor (OTR). Bone marrow mesenchymal stem cells (BMSCs), osteoblasts (OB), osteoclasts (OC), chondrocytes, and adipocytes all express OT and OTR. OT upregulates RUNX2, BMP2, ALP, and OCN, thereby enhancing the activity of BMSCs and promoting their differentiation towards OB rather than adipocytes. OT also directly regulates OPG/RANKL to inhibit adipocyte generation, increase the expression of SOX9 and COMP, and enhance chondrocyte differentiation. OB can secrete OT, exerting influence on the surrounding environment through autocrine and paracrine mechanisms. OT directly increases OC formation through the NκB/MAP kinase signaling pathway, inhibits osteoclast proliferation by triggering cytoplasmic Ca2+ release and nitric oxide synthesis, and has a dual regulatory effect on OCs. Under the stimulation of estrogen, OB synthesizes OT, amplifying the biological effects of estrogen and OT. Mediated by estrogen, the OT/OTR forms a feedforward loop with OB. Apart from estrogen, OT also interacts with arginine vasopressin (AVP), prostaglandins (PGE2), leptin, and adiponectin to regulate bone metabolism. This review summarizes recent research on the regulation of bone metabolism by OT and OTR, aiming to provide insights into their clinical applications and further research. [ABSTRACT FROM AUTHOR]

BACKGROUND: Heterotopic ossification of skeletal muscle is a clinically serious complication. For heterotopic ossification of skeletal muscles, the cells involved in the process of heterotopic ossification remain unclear. OBJECTIVE: To investigate the involvement of myocytes, fascia cells, and endothelial cells in the process of heterotopic ossification in skeletal muscle and to observe the cell origin of heterotopic ossification in skeletal muscle induced by bone morphogenetic protein 4. METHODS: Both C2C12 cells and the myotubes formed by the C2C12 cells in the induction medium were cultured, and 500 ng/mL bone morphogenetic protein 4 was added to the medium respectively, and whether the C2C12 cells and myotubes continued to proliferate within 10 days under the treatment were observed under a microscope. Myogenic cells (L6, derived from rats) and fibroblast-derived cells (derived from human) were co-cultured. After treatment with 500 ng/mL bone morphogenetic protein 4 and 10 ng/mL transforming growth factor-β, osteogenic and chondrogenic differentiation potential within 21 days were observed using Safranine O staining and Alcian blue staining. Using transgenic animal FVB/N-TgN (TIE2-LacZ) 182Sato mice, 15 μL of adeno-associated virus-bone morphogenetic protein 4 (5 × 1010 PFU/mL) were implanted in the thigh muscle space of genetic mice for 10 and 14 days. X-gal staining was used to observe the formation of new blood vessel endothelium in the differentiated bone. RESULTS AND CONCLUSION: (1) Bone morphogenetic protein 4 caused myotube breakdown and increased C2C12 cell proliferation. Compared with other groups, the pure fibroblast-derived cell group had a higher area of positive alcian blue and safarin O staining (P < 0.05) and a lower area of alkaline phosphatase staining (P < 0.05), while the pure L6 group had a bigger area of alkaline phosphatase staining (P < 0.05) but a smaller area of positive alcian blue and safarin O staining (P < 0.05). (2) Transplantation of adeno-associated virus-bone morphogenetic protein 4-adsorbed gelatin sponge into FVB/N-TgN (TIE2-LacZ)182Sato mice resulted in heterotopic ossification. (3) X-gal staining results demonstrated that there was no obvious staining in chondrocytes and differentiated bones and Tie2+ endothelial cells did not participate in the formation of the alienated bone. (4) These findings verify that fibroblasts are the primary source of osteoblasts during the adeno-associated virus-bone morphogenetic protein 4-induced ectopic endochondral ossification in skeletal muscle, but myogenic cells are the main source of osteoblasts. Tie2+ endothelial cells might not be the cell source for cartilage and bone. [ABSTRACT FROM AUTHOR]

A major fraction of loci identified by genome-wide association studies (GWASs) mediate alternative splicing, but mechanistic interpretation is hindered by the technical limitations of short-read RNA sequencing (RNA-seq), which cannot directly link splicing events to full-length protein isoforms. Long-read RNA-seq represents a powerful tool to characterize transcript isoforms, and recently, infer protein isoform existence. Here, we present an approach that integrates information from GWASs, splicing quantitative trait loci (sQTLs), and PacBio long-read RNA-seq in a disease-relevant model to infer the effects of sQTLs on the ultimate protein isoform products they encode. We demonstrate the utility of our approach using bone mineral density (BMD) GWAS data. We identified 1,863 sQTLs from the Genotype-Tissue Expression (GTEx) project in 732 protein-coding genes that colocalized with BMD associations (H4PP ≥ 0.75). We generated PacBio Iso-Seq data (N = ∼22 million full-length reads) on human osteoblasts, identifying 68,326 protein-coding isoforms, of which 17,375 (25%) were unannotated. By casting the sQTLs onto protein isoforms, we connected 809 sQTLs to 2,029 protein isoforms from 441 genes expressed in osteoblasts. Overall, we found that 74 sQTLs influenced isoforms likely impacted by nonsense-mediated decay and 190 that potentially resulted in the expression of unannotated protein isoforms. Finally, we functionally validated colocalizing sQTLs in TPM2 , in which siRNA-mediated knockdown in osteoblasts showed two TPM2 isoforms with opposing effects on mineralization but exhibited no effect upon knockdown of the entire gene. Our approach should be to generalize across diverse clinical traits and to provide insights into protein isoform activities modulated by GWAS loci. Many GWAS loci are associated with alternative splicing, but the identities and functions of most protein isoform effectors are unknown. We demonstrate how the integration of splicing QTLs (sQTLs) and PacBio long-read RNA-seq data enables the prediction, characterization, and functional prioritization of protein isoforms associated with complex human disease. [ABSTRACT FROM AUTHOR]

Transposable elements (TEs) are mobile genetic modules of viral derivation that have been co-opted to become modulators of mammalian gene expression. TEs are a major source of endogenous dsRNAs, signaling molecules able to coordinate inflammatory responses in various physiological processes. Here, we provide evidence for a positive involvement of TEs in inflammation-driven bone repair and mineralization. In newly fractured mice bone, we observed an early transient upregulation of repeats occurring concurrently with the initiation of the inflammatory stage. In human bone biopsies, analysis revealed a significant correlation between repeats expression, mechanical stress and bone mineral density. We investigated a potential link between LINE-1 (L1) expression and bone mineralization by delivering a synthetic L1 RNA to osteoporotic patient-derived mesenchymal stem cells and observed a dsRNA-triggered protein kinase (PKR)-mediated stress response that led to strongly increased mineralization. This response was associated with a strong and transient inflammation, accompanied by a global translation attenuation induced by eIF2α phosphorylation. We demonstrated that L1 transfection reshaped the secretory profile of osteoblasts, triggering a paracrine activity that stimulated the mineralization of recipient cells. Synopsis: Transposable elements (TEs) are selfish genetic modules that have, in certain contexts, evolved into modulators of mammalian gene expression. This study provides evidence for a role of TEs in promoting an inflammatory response that is required for bone repair and mineralization via dsRNA sensing-dependent PKR activation. In mice, TE expression is transiently upregulated shortly after a bone fracture concurrently with the onset of the inflammatory process. In humans, mechanically loaded bones upregulate TE expression, which correlates with local bone mineral density. Transfection with LINE-1 (L1) TE RNA stimulates mineralization activity in human osteoblasts in vitro. Cytoplasmic L1 RNA accumulation in differentiating osteoblasts triggers PKR-dependent translational shutdown, inflammation, and reshaping of the secretome. The secretome of L1 RNA-primed osteoblasts induces the mineralization activity of recipient osteoblasts. Bone fracture is associated with upregulation of transient transposable element RNA expression triggering bone mineralization via a paracrine, secretome mediated process. [ABSTRACT FROM AUTHOR]

Background: Here, we evaluated whether the histone lysine demethylase 5B (JARID1B), is involved in osteogenic phenotype commitment of periodontal ligament cells (PDLCs), by considering their heterogeneity for osteoblast differentiation. Materials and Methods: Epigenetic, transcriptional, and protein levels of a gene set, involved in the osteogenesis, were investigated by performing genome‐wide DNA (hydroxy)methylation, mRNA expression, and western blotting analysis at basal (without osteogenic induction), and at the 3rd and 10th days of osteogenic stimulus, in vitro, using PDLCs with low (l) and high (h) osteogenic potential as biological models. Results: h‐PDLCs showed reduced levels of JARID1B, compared to l‐PDLCs, with significant inversely proportional correlations between RUNX2 and RUNX2/p57. Epigenetically, a significant reduction in the global H3K4me3 content was observed only in h‐PDLCs. Immunoblotting data reveal a significant reduction in the global H3K4me3 content, at 3 days of induction only in h‐PDLCs, while an increase in the global H3K4me3 content was observed at 10 days for both PDLCs. Additionally, positive correlations were found between global H3K4me3 levels and JARID1B gene expression. Conclusions: Altogether, our results show the crucial role of JARID1B in repressing PDLCs osteogenic phenotype and this claims to pre‐clinical protocols proposing JARID1B as a potential therapeutic target. [ABSTRACT FROM AUTHOR]

Diet‐induced obesity is associated with enhanced systemic inflammation that limits bone regeneration. HDAC inhibitors are currently being explored as anti‐inflammatory agents. Prior reports show that myeloid progenitor‐directed Hdac3 ablation enhances intramembranous bone healing in female mice. In this study, we determined if Hdac3 ablation increased intramembranous bone regeneration in mice fed a high‐fat/high‐sugar (HFD) diet. Micro‐CT analyses demonstrated that HFD‐feeding enhanced the formation of periosteal reaction tissue of control littermates, reflective of suboptimal bone healing. We confirmed enhanced bone volume within the defect of Hdac3‐ablated females and showed that Hdac3 ablation reduced the amount of periosteal reaction tissue following HFD feeding. Osteoblasts cultured in a conditioned medium derived from Hdac3‐ablated cells exhibited a four‐fold increase in mineralization and enhanced osteogenic gene expression. We found that Hdac3 ablation elevated the secretion of several chemokines, including CCL2. We then confirmed that Hdac3 deficiency increased the expression of Ccl2. Lastly, we show that the proportion of CCL2‐positve cells within bone defects was significantly higher in Hdac3‐deficient mice and was further enhanced by HFD. Overall, our studies demonstrate that Hdac3 deletion enhances intramembranous bone healing in a setting of diet‐induced obesity, possibly through increased production of CCL2 by macrophages within the defect. [ABSTRACT FROM AUTHOR]

BACKGROUND: Interleukin-8 is an important cytokine that has been found to play an important role in bone regeneration through multiple pathways. OBJECTIVE: To comprehensively review the action mechanism of interleukin-8 effects on bone regeneration to provide ideas for the following studies on interleukin-8. METHODS: By searching the China National Knowledge Infrastructure database for articles published from January 1999 to February 2023 and PubMed database for articles published from January 1985 to February 2023 reporting the role of interleukin-8 in bone-associated cells and vascularisation. Chinese and English search terms were "interleukin-8, bone repair, bone metabolism, mesenchymal stem cells, osteoblasts, osteoclasts, vascularization". The initial review yielded 508 articles in English and Chinese, and a total of 51 articles were included for review and analysis according to the inclusion and exclusion criteria. RESULTS AND CONCLUSION: According to the existing research, interleukin-8 can promote bone cell regeneration and assist bone healing through multiple pathways, which is mainly divided into three aspects: (1) Promote the proliferation and differentiation of bone cells such as mesenchymal stem cells and osteoblasts, and promote the development of cells in the direction of promoting bone healing; (2) interleukin-8 can promote angiogenesis and provide sufficient nutrition and oxygen for bone tissue, thus further improving the quality and stability of bone healing. (3) The appearance of interleukin-8 facilitates the expression of hypoxia-inducible factor-1α, vascular endothelial growth factor, and matrix metalloproteinase, which can create a microenvironment conducive to bone regeneration, thus promoting the regeneration and repair of bone tissue. In summary, interleukin-8 plays an important role in bone healing by promoting osteoblast proliferation and differentiation, facilitating angiogenesis and improving the mechanical properties of bone regeneration, as well as influencing bone metabolism through osteoclasts, mesenchymal stem cells, and other action sites. [ABSTRACT FROM AUTHOR]

Genetic mutations in the b-globin gene lead to a decrease or removal of the bglobin chain, causing the build-up of unstable alpha-hemoglobin. This condition is referred to as beta-thalassemia (BT). The present treatment strategies primarily target the correction of defective erythropoiesis, with a particular emphasis on gene therapy and hematopoietic stem cell transplantation. However, the presence of inefficient erythropoiesis in BT bone marrow (BM) is likely to disturb the previously functioning BM microenvironment. This includes accumulation of various macromolecules, damage to hematopoietic function, destruction of bone cell production and damage to osteoblast(OBs), and so on. In addition, the changes of BT BM microenvironment may have a certain correlation with the occurrence of hematological malignancies. Correction of the microenvironment can be achieved through treatments such as iron chelation, antioxidants, hypoglycemia, and biologics. Hence, This review describes damage in the BT BM microenvironment and some potential remedies. [ABSTRACT FROM AUTHOR]

BACKGROUND: Steroid-induced osteonecrosis of the femoral head is a refractory disease in the field of orthopedics. There is no definitive idea to fully explain its pathogenesis. With the increased research on the active ingredients of Panax notoginseng interfering with the signaling pathways related to various diseases, the active ingredients of Panax notoginseng that treat steroid-induced necrosis of the femoral head via the regulation of relevant signaling pathways have gradually become a hot research topic. OBJECTIVE: To systematically summarize the literature on the pathological mechanism of steroid-induced osteonecrosis of the femoral head and the regulation of signaling pathways by the active ingredients of Panax notoginseng in recent years, thereby providing a reference for the follow-up study on the active ingredients of Panax notoginseng in the treatment of this disease. METHODS: CNKI, WanFang, and PubMed were searched for relevant literature with the key words of “glucocorticoid, steroid-induced osteonecrosis of the femoral head, pathological mechanism, signaling pathway, Panax notoginseng, active ingredient” in Chinese and English. Documents related to the pathological mechanism of steroid-induced osteonecrosis of the femoral head as well as related to the intervention of active ingredients of Panax notoginseng on the signaling pathway of steroid-induced osteonecrosis of the femoral head were retrieved. A total of 63 documents were finally included according to the inclusion and exclusion criteria. RESULTS AND CONCLUSION: The main ingredients of Panax notoginseng include Panax notoginseng saponins, ginsenoside, Panax notoginseng saponins, quercetin, kaempferol, etc. Panax notoginseng saponins, ginsenoside Rb1 and quercetin can promote bone repair and angiogenesis by acting on the transforming growth factor-β/bone morphogenetic protein pathway. Panax notoginseng saponins, ginsenoside CK and kaempferol can promote osteogenic differentiation and lipid metabolism by acting on the Wnt/β-catenin pathway. Panax notoginseng saponins and Panax notoginseng saponins R1/R2 act on the MAPK pathway to inhibit osteoclastogenesis and promote bone repair. Panax notoginseng saponins, ginsenoside Rb2 and quercetin can inhibit osteoclast proliferation and promote osteoblastic differentiation by acting on the RANKL/RANK/OPG pathway. Panax notoginseng saponins, quercetin and kaempferol can repair vascular injury and promote osteogenesis by acting on the hypoxia-inducible factor-1α pathway. Panax notoginseng saponins R1, quercetin combined with hydroxyapatite nanoparticles, Panax notoginseng saponins combined with polyethylene-L-lactic acid and other biomaterials have good research prospects in the treatment of steroid-induced osteonecrosis of the femoral head. The active ingredients of Panax notoginseng can regulate the signaling pathways related to steroid-induced osteonecrosis of the femoral head through various mechanisms, and play an active intervention role in the disease. However, the depth and breadth of relevant research are insufficient at present, and the future research should be based on the existing mechanism to explore the specific mechanism of Panax notoginseng regulating different pathways and the interaction between pathways, which will be beneficial to the multi-development of the active ingredients of Panax notoginseng in the treatment of steroid-induced osteonecrosis of the femoral head. [ABSTRACT FROM AUTHOR]

BACKGROUND: Osteoporosis has a high incidence, leading to fracture and other complications. However, existing drugs have great side effects and are difficult to meet the clinical application. OBJECTIVE: To explore the effect and potential mechanism of fucoxanthin on osteoporosis induced by glucocorticoid. METHODS: Primary rat osteoblasts were inoculated in 6-well plates. When the cell fusion reached 80%, the cells were divided into four groups: the control group was cultured alone for 24 hours, the glucocorticoid group was intervened with dexamethasone for 24 hours, the fucoxanthin group was intervened with fucoxanthin for 24 hours, and the glucocorticoid + fucoxanthin group was intervened with dexamethasone and fucoxanthin at the same time for 24 hours. After intervention, cell proliferation, apoptosis, intracellular reactive oxygen species level, and protein expression of apoptosis-related proteins, bone formationrelated proteins, and nuclear factor erythroid-2-related factor 2 were detected. RESULTS AND CONCLUSION: Cell counting kit-8 results showed that the cell viability was decreased in the glucocorticoid group compared with the control group (P < 0.05) but increased in the glucocorticoid+fucoxanthin group compared with the glucocorticoid group (P < 0.05). JC-1 mitochondrial membrane potential staining and flow cytometry assay showed that the percentage of apoptosis increased in the glucocorticoid group compared with the control group (P < 0.05) but decreased in the glucocorticoid+fucoxanthin group compared with the glucocorticoid group (P < 0.05). Western blot assay showed that compared with the control group, the protein expression of BAX and cleaved poly (ADP-ribose) polymerase was elevated in the glucocorticoid group (P < 0.05), and the protein expression of BCL2, type I collagen α1 peptide chain, alkaline phosphatase, osteocalcin, and RUNX2 was decreased in the glucocorticoid group (P < 0.05). Compared with the glucocorticoid group, the protein expression of BAX and cleaved poly (ADP-ribose) polymerase was decreased (P < 0.05), and the protein expression of BCL2, type I collagen α1 peptide chain, alkaline phosphatase, osteocalcin, and RUNX2 was elevated (P < 0.05) in the glucocorticoid+fucoxanthin group. Fluorescent probe assay showed an increase in reactive oxygen species level in the glucocorticoid group compared with the control group (P < 0.05) and a decrease in reactive oxygen species level in the glucocorticoid+fucoxanthin group compared with the glucocorticoid group (P < 0.05). Immunofluorescence staining and western blot assay showed that the protein expression of nuclear factor erythroid-2-related factor 2 in the glucocorticoid group was decreased compared with that in the control group (P < 0.05); and the protein expression of nuclear factor erythroid-2-related factor 2 in the glucocorticoid+fucoxanthin group was elevated compared with that in the glucocorticoid group (P < 0.05). To conclude, fucoxanthin can improve glucocorticoid-induced osteoblast apoptosis and the expression of bone formation-related molecules by activating nuclear factor erythroid-2-related factor 2. [ABSTRACT FROM AUTHOR]

CKLF-like MARVEL transmembrane domain-containing 3 (CMTM3), a member of the CMTM family that is closely related to tumor occurrence and progression, plays crucial roles in the immune system, cardiovascular system, and male reproductive system. Recently, CMTM3 has emerged as a potential target for treating diseases related to bone formation. However, additional studies are needed to understand the mechanisms by which CMTM3 regulates the process of osteogenic differentiation. In this study, we observed a significant downregulation of Cmtm3 expression during the transdifferentiation of C2C12 myoblasts into osteoblasts induced by BMP4. Cmtm3 overexpression suppressed proliferation and osteogenic differentiation in BMP4-induced C2C12 cells, whereas its knockdown conversely facilitated the process. Mechanistically, Cmtm3 overexpression upregulated both the protein and mRNA levels of p53 and p21. Conversely, Cmtm3 knockdown exerted the opposite effects. Additionally, we found that Cmtm3 interacts with p53 and increases protein stability by inhibiting proteasome-mediated ubiquitination and degradation. Notably, Trp53 downregulation abrogated the inhibitory effect of Cmtm3 on BMP4-induced proliferation and osteogenic differentiation of C2C12 myoblasts. Collectively, our findings provide key insights into the role of CMTM3 in regulating myoblast proliferation and transdifferentiation into osteoblasts, highlighting its significance in osteogenesis research. [ABSTRACT FROM AUTHOR]

The onset of osteonecrosis of the femoral head (ONFH) is intimately associated with the extensive administration of glucocorticoids (GCs). Long‐term stimulation of GCs can induce oxidative stress in both osteoclasts (OCs) and osteoblasts (OBs), resulting in the disturbance of bone remodelling. An alkaloid named crebanine (CN) demonstrates pharmacological properties including anti‐inflammation and reactive oxygen species (ROS) modulation. Our objective is to assess the therapeutic potential of CN in treating ONFH and elucidate the associated underlying mechanisms. The network pharmacology analysis uncovered that CN played a role in regulating ROS metabolism. In vitro, CN demonstrated its ability to reduce the dexamethasone (DEX)‐stimulated generation of OCs and suppress their resorptive function by downregulating the level of osteoclast marker genes. Concurrently, CN also mitigated DEX‐induced damage to OBs, facilitating the restoration of osteoblast marker gene expression, cellular differentiation and function. These effects were achieved by CN augmenting the antioxidant system to reduce intracellular ROS levels. Furthermore, in vitro results were corroborated by micro‐CT and histological data, which also showed that CN attenuated MPS‐induced ONFH in mice. This study highlights the therapeutic potential of CN in counteracting GCs‐induced ONFH. [ABSTRACT FROM AUTHOR]

Teriparatide is a peptide derived from a parathyroid hormone (PTH) and an osteoporosis therapeutic drug with potent bone formation‐promoting activity. To identify novel druggable genes that act downstream of PTH signaling and are potentially involved in bone formation, we screened PTH target genes in mouse osteoblast‐like MC3T3‐E1 cells. Here we show that Gprc5a, encoding an orphan G protein‐coupled receptor, is a novel PTH‐inducible gene and negatively regulates osteoblast proliferation and differentiation. PTH treatment induced Gprc5a expression in MC3T3‐E1 cells, rat osteosarcoma ROS17/2.8 cells, and mouse femurs. Induction of Gprc5a expression by PTH occurred in the absence of protein synthesis and was mediated primarily via the cAMP pathway, suggesting that Gprc5a is a direct target of PTH signaling. Interestingly, Gprc5a expression was induced additively by co‐treatment with PTH and 1α, 25‐dihydroxyvitamin D3 (calcitriol), or retinoic acid in MC3T3‐E1 cells. Reporter analysis of a 1 kb fragment of human GPRC5A promoter revealed that the promoter fragment showed responsiveness to PTH via the cAMP response element, suggesting that GPRC5A is also a PTH‐inducible gene in humans. Gprc5a knockdown promoted cell viability and proliferation, as demonstrated by MTT and BrdU assays. Gprc5a knockdown also promoted osteoblast differentiation, as indicated by gene expression analysis and mineralization assay. Mechanistic studies showed that Gprc5a interacted with BMPR1A and suppressed BMP signaling induced by BMP‐2 and constitutively active BMP receptors, ALK2 (ACVR1) Q207D and ALK3 (BMPR1A) Q233D. Thus, our results suggest that Gprc5a is a novel gene induced by PTH that acts in an inhibitory manner on both cell proliferation and osteoblast differentiation and is a candidate for drug targets for osteoporosis. [ABSTRACT FROM AUTHOR]

Introduction: Avascular Necrosis (AVN) of the femoral head, a condition characterized by the interruption of blood supply leading to bone tissue death, presents significant therapeutic challenges. Recent advancements in orthobiologics, including the use of Autologous Adult Live-Cultured Osteoblasts (AALCO), combined with core decompression, offer a novel approach for managing AVN. This study assesses the efficacy of this treatment modality in improving functional outcomes and hindering disease progression. Materials and methods: This retrospective observational study encompassed 30 patients treated between 2020 and 2023 for idiopathic AVN of the femoral head, grades I to III, who had not responded to conservative treatment. Patients were excluded based on specific criteria including age, secondary AVN causes, and certain health conditions. The treatment involved a two-stage surgical procedure under spinal anesthesia with OSSGROW® for AALCO generation. Post-operative care emphasized early mobilization, DVT prevention, and avoidance of NSAIDs. Outcome measures were evaluated using the Visual Analog Scale (VAS) for pain, modified Harris Hip Score, and annual MRI imaging for up to 36 months. Results: Among 26 patients (41 hips) completing the study, statistically significant improvements in pain and hip functionality were documented, alongside positive radiological signs of osteogenesis in the majority of cases. However, four instances required advancement to total hip replacement due to disease progression. Conclusion: The combination of core decompression and AALCO implantation shows promise as an effective treatment for AVN of the femoral head, with notable improvements in functional and radiological outcomes. This study supports the potential of orthobiologic approaches in AVN treatment, warranting further investigation through comprehensive randomized controlled trials. [ABSTRACT FROM AUTHOR]

Bone is one of the most prevalent sites of metastases in various epithelial malignancies, including breast cancer and this metastasis to bone often leads to severe skeletal complications in women due to its osteolytic nature. To address this, we devised a novel drug delivery approach using an Alendronate (ALN) functionalized self-assembled porous crystalsomes for concurrent targeting of Oleanolic acid (OA) and ALN (ALN + OA@NCs) to bone metastasis. Initially, the conjugation of both PEG-OA and OA-PEG-ALN with ALN and OA was achieved, and this conjugation was then self-assembled into porous crystalsomes (ALN + OA@NCs) by nanoemulsion crystallization. The reconstruction of a 3D single particle using transmission electron microscopy ensured the crystalline porous structure of ALN + OA@NCs, was well aligned with characteristic nanoparticle attributes including size distribution, polydispersity, and zeta potential. Further, ALN + OA@NCs showed enhanced efficacy in comparison to OA@NCs suggesting the cytotoxic roles of ALN towards cancer cells, followed by augmentation ROS generation (40.81%), mitochondrial membrane depolarization (57.20%), and induction of apoptosis (40.43%). We found that ALN + OA@NCs facilitated inhibiting osteoclastogenesis and bone resorption followed by inhibited osteolysis. In vivo activity of ALN + OA@NCs in the 4 T1 cell-induced tibia model rendered a reduced bone loss in the treated mice followed by restoring bone morphometric markers which were further corroborated bone–targeting effects of ALN + OA@NCs to reduce RANKL-stimulated osteoclastogenesis. Further, In vivo intravenous pharmacokinetics showed the improved therapeutic profile of the ALN + OA@NCs in comparison to the free drug, prolonging the levels of the drug in the systemic compartment by reducing the clearance culminating the higher accumulation at the tumor site. Our finding proposed that ALN + OA@NCs can effectively target and treat breast cancer metastasis to bone and its associated complications. [Display omitted] [ABSTRACT FROM AUTHOR]

(1) Background: Methylphenidate (MP) and amphetamine (AMP) are psychostimulants that are widely prescribed to treat Attention Deficit Hyperactivity Disorder (ADHD) and narcolepsy. In recent years, 6.1 million children received an ADHD diagnosis, and nearly 2/3 of these children were prescribed psychostimulants for treatment. The purpose of this review is to summarize the current literature on psychostimulant use and the resulting effects on bone homeostasis, biomechanical properties, and functional integrity. (2) Methods: Literature searches were conducted from Medline/PubMed electronic databases utilizing the search terms "methylphenidate" OR "amphetamine" OR "methylphenidate" AND "bone health" AND "bone remodeling" AND "osteoclast" AND "osteoblast" AND "dopamine" from 01/1985 to 04/2023. (3) Results: Of the 550 publications found, 44 met the inclusion criteria. Data from identified studies demonstrate that the use of MP and AMP results in decreases in specific bone properties and biomechanical integrity via downstream effects on osteoblasts and osteoclast-related genes. (4) Conclusions: The chronic use of psychostimulants negatively affects bone integrity and strength as a result of increased osteoclast activity. These data support the need to take this into consideration when planning the treatment type and duration for bone fractures. [ABSTRACT FROM AUTHOR]

Osteoporosis, a metabolic bone disorder characterized by decreased bone mass per unit volume, poses a significant global health burden due to its association with heightened fracture risk and adverse impacts on patients' quality of life. This review synthesizes the current understanding of the pathophysiological mechanisms underlying osteoporosis, with a focus on key regulatory pathways governing osteoblast and osteoclast activities. These pathways include RANK/RANKL/OPG, Wingless-int (Wnt)/β-catenin, and Jagged1/Notch1 signaling, alongside the involvement of parathyroid hormone (PTH) signaling, cytokine networks, and kynurenine in bone remodeling. Pharmacotherapeutic interventions targeting these pathways play a pivotal role in osteoporosis management. Anti-resorptive agents, such as bisphosphonates, estrogen replacement therapy/hormone replacement therapy (ERT/HRT), selective estrogen receptor modulators (SERMs), calcitonin, anti-RANKL antibodies, and cathepsin K inhibitors, aim to mitigate bone resorption. Conversely, anabolic agents, including PTH and anti-sclerostin drugs, stimulate bone formation. In addition to pharmacotherapy, nutritional supplementation with calcium, vitamin D, and vitamin K2 holds promise for osteoporosis prevention. However, despite the availability of therapeutic options, a substantial proportion of osteoporotic patients remain untreated, highlighting the need for improved clinical management strategies. This comprehensive review aims to provide clinicians and researchers with a mechanistic understanding of osteoporosis pathogenesis and the therapeutic mechanisms of existing medications. By elucidating these insights, this review seeks to inform evidence-based decision-making and optimize therapeutic outcomes for patients with osteoporosis. [ABSTRACT FROM AUTHOR]

BACKGROUND: Bone formation is the process by which osteoblasts synthesize and secrete osteoid and promote its mineralization, which generally involves mechanical signal transduction. Osteoblasts are primarily regulated by mechanical factors such as gravity, compressive stress, tensile stress, fluid shear stress, and hydrostatic pressure in vivo, and different mechanical stimuli modulate the proliferation, differentiation, and apoptosis of osteoblasts through various mechanisms, including hormones, cytoskeletal proteins, and microRNAs. By clarifying the effects of biomechanical forces on osteoblasts, it provides ideas and a reference basis for the treatment of osteometabolic diseases involving osteoblasts. OBJECTIVE: To review the effects of different biomechanical forces on the biological characteristics of osteoblasts. METHODS: We conducted a literature search using PubMed, Web of Science, FMRS, CNKI, and WanFang databases for relevant publications published from 2000 to 2023, covering basic research and tissue engineering studies related to the effects of biomechanical forces on osteoblasts. Ultimately, a total of 70 articles were reviewed. RESULTS AND CONCLUSION: Different biomechanical forces have an impact on the biological characteristics of osteoblasts, including proliferation, differentiation, and apoptosis, and these effects are dependent on the intensity and duration of the applied force. Specifically, the effects are as follows: (1) Under microgravity conditions, osteoblast proliferation and differentiation are inhibited, resulting in a decrease in bone density and the development of osteoporosis. (2) Compared to microgravity, hypergravity has a promoting effect on osteoblast proliferation. (3) The effects of compressive stress on osteoblasts are dependent on the loading intensity and time. Appropriate compressive stress can promote osteoblast proliferation and differentiation, which is beneficial for bone tissue formation and repair, while excessive compressive stress can cause osteoblast apoptosis and bone tissue destruction. (4) The biological effects of different types of tensile stress on osteoblasts differ. Studies have shown that a strain rate within the range of 0-12% has a promoting effect on osteoblast proliferation. (5) Fluid shear stress can promote osteoblast proliferation and differentiation and enhance the bone-inducing effect of biomaterials. (6) Static hydrostatic pressure can affect the biological behavior of osteoblasts, including proliferation, differentiation, and apoptosis, and these effects are closely related to the time and intensity of the pressure. Understanding the effects of different biomechanical forces on osteoblasts is of great significance for a deeper understanding of bone growth and maintenance mechanisms. [ABSTRACT FROM AUTHOR]

BACKGROUND: Tumor necrosis factor-α is a broadly acting inflammatory cytokine that plays an important role in the immune inflammatory response of the body. The current study concluded that tumor necrosis factor-α has significant biological effects on a variety of bone tissue cells. OBJECTIVE: To summarize the expression and action pathways of tumor necrosis factor-α in osteoblastic and osteoclastic cells to further elucidate the regulatory role of tumor necrosis factor-α on bone tissue cells. METHODS: PubMed and CNKI were searched until March 2023, and the Chinese search terms included “tumor necrosis factor α, osteoblast, osteoclast, osteoclast, osteoprogenitor”; the English search terms included “TNF-α, osteoblast, osteoclast, osteocyte, osteoprogenitor cell”. The corresponding criteria were established according to the research needs, and the final literature was screened. Finally, 77 articles were included for review. RESULTS AND CONCLUSION: (1) Tumor necrosis factor-α is participating in regulating the recruitment, appreciation, and differentiation of osteoprogenitor cells, but leads to osteoprogenitor cell stripping and death under specific environments. It also participates in bone resorption directly or indirectly through secreted enzymes. (2) Tumor necrosis factor-α can increase the level of inflammatory factors in the environment by activating relevant signaling pathways in osteoclast lineage cells or directly induce the generation of osteoclasts in specific environments. (3) Tumor necrosis factor-α can inhibit osteogenic differentiation by activating nuclear factor-κB signaling pathway, inhibiting the expression of transcription factors such as RUNX2 and Osterix, and inducing apoptosis and necrotizing apoptosis in osteoblasts. (4) Tumor necrosis factor-α inhibits osteogenesis and promotes osteoclastogenesis by activating the nuclear factor-κB signaling pathway in osteocytes and inducing cytokines such as RANKL, SOST, and DKK1, while enhancing apoptosis of the osteocytes, as well as bone resorption around the apoptotic bone tissue. (5) Taken together, the effect of tumor necrosis factor-α in bone tissue is mainly to inhibit osteogenesis and promote osteoclastosis. The biological effect of tumor necrosis factor-α in bone tissue cells is usually dependent on the activation of tumor necrosis factor receptor and nuclear factor-κB signaling pathways. (6) The interaction of tumor necrosis factor-α with other tissue cell types surrounding bone tissue and its role in bone immune regulation still deserve attention in future studies. [ABSTRACT FROM AUTHOR]

BACKGROUND: Studies have shown that imbalance of bone metabolism during glucocorticoid-induced osteonecrosis of the femoral head necrosis is closely related to oxidative stress. OBJECTIVE: To investigate the pathological mechanism by which oxidative stress-induced ferroptosis promote apoptosis in osteoblasts involved in steroidinduced osteonecrosis of the femoral head. METHODS: General data and serum specimens were collected from 47 patients with steroid-induced osteonecrosis of the femoral head. In addition, six femoral head specimens were collected from these patients. According to the Association Research Circulation Osseous (ARCO) staging system, serum specimens were grouped into ARCO II, III, and IV, while femoral head specimens were classified into ARCO III and IV. Serum levels of malondialdehyde and superoxide dismutase 1 were measured. The protein expression of superoxide dismutase 1, glutathione peroxidase 4, Bcl-2 in the femoral head was detected and verified by Data independent acquisition (DIA) for quantitative sequencing, western blot and alkaline phosphate detection. RESULTS AND CONCLUSION: The ARCO stage of patients with steroid-induced osteonecrosis of the femoral head was independent of age, sex and necrotic side. The serum levels of malondialdehyde and superoxide dismutase 1 were higher in patients with ARCO stage III compared with those with ARCO stage II and IV. The results of DIA protein quantification showed that the function of differential proteins was mainly related to redox. The levels of superoxide dismutase 1, glutathione peroxidase 4, and Bcl-2 in the necrotic region were lower than in the normal region, as well as lower in ARCO stage IV than in ARCO stage III. Western blot verified the results of DIA protein quantification. The alkaline phosphatase activity was lower in the necrotic region than in the normal region, as well as lower in ARCO stage IV than in ARCO stage III. In the necrotic and sclerotic regions, the function of differential proteins was also related to redox, and superoxide dismutase 1, glutathione peroxidase 4, Bcl-2 protein expression and alkaline phosphatase activity were lower in the necrotic area than in the sclerotic region, as well as lower in ARCO stage IV than in ARCO stage III. To conclude, glucocorticoids can influence the progression of steroid-induced osteonecrosis of the femoral head by upregulating oxidative stress levels, inducing osteoblast ferroptosis, and inhibiting osteogenic function. [ABSTRACT FROM AUTHOR]

Objective: The present study aimed to investigate the underlying mechanism of mechanical stimulation in regulating osteogenic differentiation. Materials and methods: Osteoblasts were exposed to compressive force (0–4 g/cm2) for 1–3 days or CGRP for 1 or 3 days. Expression of receptor activity modifying protein 1 (RAMP1), the transcription factor RUNX2, osteocalcin, p38 and p-p38 were analyzed by western blotting. Calcium mineralization was analyzed by alizarin red straining. Results: Using compressive force treatments, low magnitudes (1 and 2 g/cm2) of compressive force for 24 h promoted osteoblast differentiation and mineral deposition whereas higher magnitudes (3 and 4 g/cm2) did not produce osteogenic effect. Through western blot assay, we observed that the receptor activity-modifying protein 1 (RAMP1) expression was upregulated, and p38 mitogen-activated protein kinase (MAPK) was phosphorylated during low magnitudes compressive force-promoted osteoblast differentiation. Further investigation of a calcitonin gene-related peptide (CGRP) peptide incubation, a ligand for RAMP1, showed that CGRP at concentration of 25 and 50 ng/ml could increase expression levels of RUNX2 and osteocalcin, and percentage of mineralization, suggesting its osteogenic potential. In addition, with the same conditions, CGRP also significantly upregulated RAMP1 and phosphorylated p38 expression levels. Also, the combination of compressive forces (1 and 2 g/cm2) with 50 ng/ml CGRP trended to increase RAMP1 expression, p38 activity, and osteogenic marker RUNX2 levels, as well as percentage of mineralization compared to compressive force alone. This suggest that RAMP1 possibly acts as an upstream regulator of p38 signaling during osteogenic differentiation. Conclusion: These findings suggest that CGRP-RAMP1/p38MAPK signaling implicates in osteoblast differentiation in response to optimal magnitude of compressive force. This study helps to define the underlying mechanism of compressive stimulation and may also enhance the application of compressive stimulation or CGRP peptide as an alternative approach for accelerating tooth movement in orthodontic treatment. [ABSTRACT FROM AUTHOR]

Simple Summary: Therapies to prevent osteoporosis are relevant since it is one of the most common non-communicable human diseases in the world and the most prevalent bone disorder in adults. Jaboticaba is a small, round fruit with white pulp and purple peel that concentrates compounds that may have therapeutic applications. Since jaboticaba peel extract (JPE) enhances the activity of osteoblasts (the cells that form bone) under osteoporotic conditions, we hypothesized that JPE prevents the development of osteoporosis induced by the removal of the ovaries. Ovariectomized rats were treated with either JPE (30 mg/kg of body weight) or its vehicle for 90 days, starting 7 days after the ovariectomy. JPE attenuated ovariectomy-induced bone loss due to its ability to prevent the imbalance between osteoblast and adipocyte (the cells that produce bone and fat, respectively) differentiation. These data indicate the potential therapeutic use of JPE to prevent osteoporosis. Therapies to prevent osteoporosis are relevant since it is one of the most common non-communicable human diseases in the world and the most prevalent bone disorder in adults. Since jaboticaba peel extract (JPE) added to the culture medium enhanced the osteogenic potential of mesenchymal stem cells (MSCs) derived from osteoporotic rats, we hypothesized that JPE prevents the development of ovariectomy-induced osteoporosis. Ovariectomized rats were treated with either JPE (30 mg/kg of body weight) or its vehicle for 90 days, starting 7 days after the ovariectomy. Then, the femurs were subjected to microcomputed tomography and histological analyses, and the osteoblast and adipocyte differentiation of MSCs was evaluated. JPE attenuated ovariectomy-induced bone loss, as evidenced by higher bone volume/total volume and trabecular number, along with lower trabecular separation and bone marrow adiposity. These protective effects of JPE on bone tissue are due to its ability to prevent the imbalance between osteoblast and adipocyte differentiation of MSCs, since, compared with MSCs derived from ovariectomized rats treated with vehicle, MSCs treated with JPE exhibited higher gene and protein expression of osteogenic markers and extracellular matrix mineralization, as well as lower gene expression of adipogenic markers. These data highlight the potential therapeutic use of JPE to prevent osteoporosis. [ABSTRACT FROM AUTHOR]

Objective To investigate the molecular mechanisms by which silencing of the Periostin gene affects the expression of Runx2, receptor activator of nuclear factor kappa B ligand (RANKL), and osteoprotegerin (OPG) in murine osteoblasts and its impact on bone resorption activity. Methods Murine osteoblast cell line MC3T3-El was divided into an experimental group and a control group. The experimental group was transfected with LVpFU - GW 016PSC66473-1 virus, while the control group received pFU-GW-016PSC53349-1 virus to ensure equivalent cellular conditions. The efficiency of gene silencing was assessed using MDC method, and the protein expression of Runx2, RANKL, and OPG in both groups was evaluated by Western blotting. Results Following Periostin silencing, the experimental group showed significantly enhanced fluorescence expression compared to the control group (P<0.01). Protein expression of Runx2 and RANKL was significantly decreased (P<0.05), whereas OPG expression was markedly in- creased (P<0.05) in the experimental group compared to the control group. Conclusion Silencing of Periostin alters RANKL and OPG expression in murine osteoblasts, potentially influencing the Runx2 gene via the nuclear factor kappa B (NF-kB) signaling pathway. This enhancement of osteoblast function may contribute to the inhibition of bone resorption. [ABSTRACT FROM AUTHOR]

Objective To investigate the effect of recombinant human lactoferrin (rhLF) on fracture healing in rat models with femur fracture and the proliferation of rat primary osteoblasts. Methods Male rats were randomly di- vided into 3 groups; simple fracture group (SF group), collagen film-treated group (CF group) and rhLF-com- pound collagen lamination film-treated group (CLF group). The fracture healing was observed by X-my image and histological microscopy with HE and Masson staining. The newborn SD rats with osteoblasts were treated with differ- ent concentrations of rhLF, and osteoblast proliferation was detected by MTT method. Results The bone scabs in the CLF group were significantly larger than those in the SF and CF groups at 1, 2, and 3 weeks postoperatively (P<0.05). There was no difference in the comparison between the groups at 4th week. The proliferation of cartilag- inous and sclerotic bone scabs in the CLF group was more pronounced and showed the appearance of mature trabec- ulae and lamellar bone with a high degree of maturation of the bone scabs. The groups with 100 mg/L and 500 mg/L rhLF showed a significant decrease in A value for rat primary osteoblasts cultured in vitro as compared with the control group (P<0.05). The A value increased significantly at the first day (P<0.05). The concentration of rhLF increased at the fifth and tenth days. Conclusions rhLF has an accelerating effect on fracture healing which is manifested by fast seab formation, large volume and high maturity. The rhLF can promote the proliferation of os- teoblasts cultured in vitro, and the effect is mainly manifested in the rapid proliferation stage of osteoblasts. [ABSTRACT FROM AUTHOR]

Objectives: Periodontitis is induced by the imbalance between osteoblast and osteoclast activity, which leads to periodontal tissue destruction. Macrophages play a vital role in periodontitis. However, the hypoxic periodontal environment will also induce macrophage apoptosis within a short time. Apoptotic bodies (ABs) are the major products generated from apoptotic cells, but whether macrophage‐derived ABs play a regulatory role as their mother cells in periodontitis remains unknown. In the present study, we aimed to investigate the effects of ABs on osteoblasts. Method: ABs derived from hypoxia‐induced macrophages were co‐cultured with osteoblasts and the impact of ABs on osteoblast differentiation in vitro was assessed. In vivo, periodontitis model was established and macrophages‐derived ABs were injected into the gingival sulcus. The effects of ABs on periodontal bone resorption were determined. Results: The results showed that ABs significantly inhibit osteoblast differentiation and promoted alveolar bone resorption in periodontitis. MicroRNA (miRNAs) array analysis was performed and revealed that miR‐483‐5p is the key miRNA in ABs. Dual luciferase reporter assays were performed and confirmed that miR‐483‐5p targeted Col1A1 mRNA and attenuated its expression. Conclusion: Macrophage‐derived ABs inhibit osteoblast differentiation via the transfer of miR‐483‐5p, which downregulates Col1A1 expression and finally suppresses osteogenic activity. [ABSTRACT FROM AUTHOR]

Perimenopausal period causes a significant amount of bone loss, which results in primary osteoporosis (OP). The Periostin (Postn) may play important roles in the pathogenesis of OP after ovariectomized (OVX) rats. To identify the roles of Postn in the bone marrow mesenchymal stem cell derived osteoblasts (BMSC-OB) in OVX rats, we investigated the expression of Wnt/β-catenin signaling pathways in BMSC-OB and the effects of Postn on bone formation by development of BMSC-OB cultures. Twenty-four female Sprague–Dawley rats at 6 months were randomized into 3 groups: sham-operated (SHAM) group, OVX group and OVX+Postn group. The rats were killed after 3 months, and their bilateral femora and tibiae were collected for BMSC-OB culture, Micro-CT Analysis, Bone Histomorphometric Measurement, Transmission Electron Microscopy and Immunohistochemistry Staining. The dose/time-dependent effects of Postn on the proliferation, differentiation and mineralization of BMSC-OB and the expression of osteoblastic markers were measured in in vitro experiments. We found increased Postn increased bone mass, promoted bone formation of trabeculae, Wnt signaling and the osteogenic activity in osteoblasts in sublesional femur. Postn have the function to enhance cell proliferation, differentiation and mineralization at a proper concentration and incubation time. Interestingly, in BMSC-OB from OVX rats treated with the different dose of Postn, the osteoblastic markers expression and Wnt/β-catenin signaling pathways were significantly promoted. The direct effect of Postn may lead to inhibit excessive bone resorption and increase bone formation through the Wnt/β-catenin signaling pathways after OVX. Postn may play a very important role in the pathogenesis of OP after OVX. [ABSTRACT FROM AUTHOR]

Background: Understanding human stem cell differentiation into osteoblasts and osteoclasts is crucial for bone regeneration and disease modeling. Numerous morphological techniques have been employed to assess this differentiation, but a comprehensive review of their application and effectiveness is lacking. Methods: Guided by the PRISMA framework, we conducted a rigorous search through the PubMed, Web of Science and Scopus databases, analyzing 254 articles. Each article was scrutinized against pre-defined inclusion criteria, yielding a refined selection of 14 studies worthy of in-depth analysis. Results: The trends in using morphological approaches were identified for analyzing osteoblast and osteoclast differentiation. The three most used techniques for osteoblasts were Alizarin Red S (mineralization; six articles), von Kossa (mineralization; three articles) and alkaline phosphatase (ALP; two articles) followed by one article on Giemsa staining (cell morphology) and finally immunochemistry (three articles involved Vinculin, F-actin and Col1 biomarkers). For osteoclasts, tartrate-resistant acid phosphatase (TRAP staining) has the highest number of articles (six articles), followed by two articles on DAPI staining (cell morphology), and immunochemistry (two articles with VNR, Cathepsin K and TROP2. The study involved four stem cell types: peripheral blood monocyte, mesenchymal, dental pulp, and periodontal ligament. Conclusion: This review offers a valuable resource for researchers, with Alizarin Red S and TRAP staining being the most utilized morphological procedures for osteoblasts and osteoclasts, respectively. This understanding provides a foundation for future research in this rapidly changing field. [ABSTRACT FROM AUTHOR]

Evidences shows that T helper 17 (Th17) and regulatory T (Treg) cells imbalance plays a critical role in bone lesions of MM patients. Therefore, regulating the Th17/Treg imbalance may be beneficial for bone lesions in MM. Ten MM mice complicated with bone lesions were established and divided into the halofuginone (HF) group and the PBS group. After treatment, tibia and fibula from both groups were scanned by micro-CT. Osteoclasts and osteoblasts were validated by histochemical staining and ELISA. Th17 and Treg cells were tested by flow cytometry. The correlations between Th17/Treg cell ratio and osteoclasts, osteoblasts and bone remodeling were analyzed using the Spearman relative analysis. After treatment, mice in the HF group had an increase in trabecular bone volume fraction and thickened cortex, but a decrease in trabecular separation compared to mice in the PBS group.Tartrate-resistant acid phosphase (TRAP) + osteoclasts and its biomarker TRACP5b in serum were reduced, while alkaline phosphatase (ALP) + osteoblasts and its biomarker N-terminal propeptide of type 1precollagen (P1NP) in serum were accreted in the HF group. Th17/Treg cell ratio in halofuginone-treated mice was 0.85 ± 0.05, and was significantly lower than that in PBS-treated mice, which was 1.51 ± 0.03. In addition, it showed that the Th17/Treg cell ratio was significantly and positively associated with osteoclasts, but was significantly and negatively associated with osteoblasts and bone remodeling. Halofuginone plays a critical role in the amelioration bone lesions in MM, as it can inhibit osteoclastogenesis and enhance osteoblastogenesis by regulating the Th17/Treg cell balance. [ABSTRACT FROM AUTHOR]

Osteoporosis (OP) is a highly prevalent disorder characterized by low bone mass that severely reduces patient quality of life. Although numerous treatments for OP have been introduced in clinic, many have side effects and high costs. Therefore, there is still an unmet need for optimal solutions. Here, raw signal analysis was used to identify potential high-risk factors for OP, and the biological functions and possible mechanisms of action (MOAs) of these factors were explored via gene set enrichment analysis (GSEA). Subsequently, molecular biological experiments were performed to verify and analyze the discovered risk factors in vitro and in vivo. PMAIP1 was identified as a potential risk factor for OP and significantly suppressed autophagy in osteoblasts via the AMPK/mTOR pathway, thereby inhibiting the proliferation and differentiation of osteoblasts. Furthermore, we constructed an ovariectomy (OVX) model of OP in rats and simultaneously applied si-PMAIP1 for in vivo interference. si-PMAIP1 upregulated the expression of LC3B and p-AMPK and downregulated the expression of p-mTOR, and these effects were reversed by the autophagy inhibitor. Micro-CT revealed that, si-PMAIP1 significantly inhibited the development of osteoporosis in OVX model rats, and this therapeutic effect was attenuated by treatment with an autophagy inhibitor. This study explored the role and mechanism of PMAIP1 in OP and demonstrated that PMAIP1 may serve as a novel target for OP treatment. [ABSTRACT FROM AUTHOR]

Cortactin (CTTN), a cytoskeletal protein and substrate of Src kinase, is implicated in tumor aggressiveness. However, its role in bone cell differentiation remains unknown. The current study revealed that CTTN was upregulated during osteoblast and adipocyte differentiation. Functional experiments demonstrated that CTTN promoted the in vitro differentiation of mesenchymal stem/progenitor cells into osteogenic and adipogenic lineages. Mechanistically, CTTN was able to stabilize the protein level of mechanistic target of rapamycin kinase (mTOR), leading to the activation of mTOR signaling. In-depth investigation revealed that CTTN could bind with casitas B lineage lymphoma-c (c-CBL) and counteract the function of c-CBL, a known E3 ubiquitin ligase responsible for the proteasomal degradation of mTOR. Silencing c-Cbl alleviated the impaired differentiation of osteoblasts and adipocytes caused by CTTN siRNA, while silencing mTOR mitigated the stimulation of osteoblast and adipocyte differentiation induced by CTTN overexpression. Notably, transplantation of CTTN-silenced bone marrow stromal cells (BMSCs) into the marrow of mice led to a reduction in trabecular bone mass, accompanied by a decrease in osteoblasts and an increase in osteoclasts. Furthermore, CTTN-silenced BMSCs expressed higher levels of receptor activator of nuclear factor κB ligand (RANKL) than control BMSCs did and promoted osteoclast differentiation when cocultured with bone marrow-derived osteoclast precursor cells. This study provides evidence that CTTN favors osteoblast differentiation by counteracting the c-CBL-induced degradation of mTOR and inhibits osteoclast differentiation by downregulating the expression of RANKL. It also suggests that maintaining an appropriate level of CTTN expression may be advantageous for maintaining bone homeostasis. [ABSTRACT FROM AUTHOR]

Glass ionomer cement (GIC) is composed of anionic polyacrylic acid and a silica-based inorganic powder. GIC is used as a filling material in the decayed cavity of the tooth; therefore, compatibility with the tooth tissue is essential. In the present study, we aimed to improve the histocompatibility of GIC by introducing nano-hydroxyapatite (nHA), a component of teeth, into a silica-based inorganic powder. CFAS-nHA was prepared by chemically bonding nanorod hydroxyapatite (nHA) to the surface of calciumfluoroaluminosilicate (CFAS). The synthesis of CFAS-nHA was confirmed using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The prepared CFAS-nHA was mixed with polyacrylic acid and cured to prepare GIC containing nHA (GIC-nHA). Cytocompatibility tests of GIC-nHA and GIC were performed using osteoblasts. Osteoblast activity and bone formation ability were superior after GIC-nHA treatment than after control GIC treatment. This enhanced histocompatibility is believed to be due to the improvement of the biological activity of osteoblasts induced by the HA introduced into the GIC. Therefore, to enhance its compatibility with dental tissues, GIC could be manufactured by chemically bonding nHA to the surface of GI inorganic powder. [ABSTRACT FROM AUTHOR]

Glucocorticoid-induced bone loss is a severe and toxic effect of long-term therapy with glucocorticoids, which are currently prescribed for millions of people worldwide. Previous studies have uncovered that glucocorticoids reciprocally converted osteoblast lineage cells into endothelial-like cells to cause bone loss and showed that the modulations of Foxc2 and Osterix were the causative factors that drove this harmful transition of osteoblast lineage cells. Here, we find that the inhibition of aurora kinase A halts this transition and prevents glucocorticoid-induced bone loss. We find that aurora A interacts with the glucocorticoid receptor and show that this interaction is required for glucocorticoids to modulate Foxc2 and Osterix. Together, we identify a new potential approach to counteracting unwanted transitions of osteoblast lineage cells in glucocorticoid treatment and may provide a novel strategy for ameliorating glucocorticoid-induced bone loss.

Abstract Osteoblasts and osteoclasts play an important role in maintaining the structural integrity of bone tissue, in which osteoclasts degrade bone structure and osteoblasts restore bone tissue. The imbalance of osteoblast and osteoclast function can lead to many bone-related diseases, such as osteoporosis and inflammatory osteolysis. The drug that can both promote bone formation and inhibit bone loss will be able to treat those diseases. In this study, it was found that LMK-235, an selective HDAC4/5 inhibitor, inhibited the differentiation and maturation of osteoclasts by regulating NF-κB and p-Smad2/3 signaling pathways via inhibition of HDAC4. At the same time, we found that LMK-235 promoted osteoblast mineralization by upregulating Runx2 expression via inhibition of HDAC4. In vivo, LMK-235 was able to alleviate lipopolysaccharide (LPS)-induced calvarial osteolysis and promote the repair of bone defects. Taken together, LMK-235 suppresses osteoclast differentiation and promotes osteoblast formation by inhibiting HDAC4. This may provide a valuable treatment for bone diseases caused by abnormal osteoclast bone resorption and osteoblast bone regeneration.

Abstract Objective Delayed fracture healing is a common complication of fractures that significantly impacts human health. This study aimed to explore the role of LINC00339 (lncRNA) in delayed fracture healing to provide new directions for its treatment. Methods This study included 82 patients with fractures healing in a normal manner and 90 patients experiencing delayed fracture healing. Levels of LINC00339, miR-16-5p, and osteogenic marker-related mRNAs were measured using RT-qPCR. The predictive potential of LINC00339 for delayed fracture healing was validated using ROC curve analysis. The interaction between LINC00339 and miR-16-5p was validated using dual-luciferase reporter assays and RIP experiments. CCK-8 was used to assess cell proliferation, and apoptosis rates were measured by flow cytometry. Results LINC00339 was significantly upregulated in delayed fracture healing patients and exhibited strong predictive ability for this condition. Overexpression of LINC00339 inhibited osteoblast proliferation, promoted apoptosis, and reduced mRNA levels of osteogenic markers (P

Ting Liu,1,2 Luxu Wang,1– 3 Tuo Shi,4 Hongrui Liu,1,2 Bo Liu,5 Jie Guo,1,2 Minqi Li1,2,5 1Department of Bone Metabolism, School and Hospital of Stomatology, Cheeloo College of Medicine, Shandong University & Shandong Key Laboratory of Oral Tissue Regeneration & Shandong Engineering Research Center of Dental Materials and Oral Tissue Regeneration & Shandong Provincial Clinical Research Center for Oral Diseases, Jinan, People’s Republic of China; 2Center of Osteoporosis and Bone Mineral Research, Shandong University, Jinan, People’s Republic of China; 3School of Stomatology, Jinzhou Medical University, Jinzhou, People’s Republic of China; 4School of Traditional Chinese Medicine, Beijing University of Chinese Medicine, Beijing, People’s Republic of China; 5School of Clinical Medicine, Jining Medical University, Jining, People’s Republic of ChinaCorrespondence: Bo Liu, School of Clinical Medicine, Jining Medical University, Jining, 272067, People’s Republic of China, Tel +86-0537-6051782, Email liubo7230@mail.jnmc.edu.cn Jie Guo, Department of Bone Metabolism, School and Hospital of Stomatology, Cheeloo College of Medicine, Shandong University & Shandong Key Laboratory of Oral Tissue Regeneration & Shandong Engineering Research Center of Dental Materials and Oral Tissue Regeneration & Shandong Provincial Clinical Research Center for Oral Diseases, Jinan, Shandong, 250012, People’s Republic of China, Tel +86-0531-88382923, Email kqgj@sdu.edu.cnPurpose: Bone loss is a common complication of type 2 diabetes mellitus (T2DM). Circadian rhythms play a significant role in T2DM and bone remodeling. Eldecalcitol (ED-71), a novel active vitamin D analog, has shown promise in ameliorating T2DM. We aimed to investigate whether the circadian rhythm coregulator BMAL1 mediates the anti-osteoporotic effect of ED-71 in T2DM and its associated mechanisms.Methods: A T2DM mouse model was established using high-fat diet (HDF) and streptozotocin (STZ) injection, and blood glucose levels were monitored weekly. HE staining, Masson staining, and Micro-CT were performed to assess the changes in bone mass. IHC staining and IF staining were used to detect osteoblast status and BMAL1 expression and RT-qPCR was applied to detect the change of oxidative stress factors. In vitro, high glucose (HG) stimulation was used to simulate the cell environment in T2DM. RT-qPCR, Western blot, IF, ALP staining and AR staining were used to detect osteogenic differentiation and SIRT1/GSK3β signaling pathway. DCFH-DA staining was used to detect reactive oxygen species (ROS) levels.Results: ED-71 increased bone mass and promoted osteogenesis in T2DM mice. Moreover, ED-71 inhibited oxidative stress and promoted BMAL1 expression in osteoblasts The addition of STL1267, an agonist of the BMAL1 transcriptional repressor protein REV-ERB, reversed the inhibitory effect of ED-71 on oxidative stress and the promotional effect on osteogenic differentiation. In addition, ED-71 facilitated SIRT1 expression and reduced GSK3β activity. The inhibition of SIRT1 with EX527 partially attenuated ED-71’s effects, whereas the GSK3β inhibitor LiCl further enhanced ED-71’s positive effects on BMAL1 expression.Conclusion: ED-71 ameliorates bone loss in T2DM by upregulating the circadian rhythm coregulator BMAL1 and promoting osteogenesis through inhibition of oxidative stress. The SIRT1/GSK3β signaling pathway is involved in the regulation of BMAL1.Keywords: eldecalcitol, type 2 diabetic mellitus, osteoblast, BMAL1, SIRT1/GSK3β signaling pathway

Objective To investigate the effects of new and traditional non-steroidal anti-inflammatory drugs (NSAIDs) on the proliferation, morphology, adhesion, activity and expression of osteoblast related genes of MG-63 osteoblasts by establishing a osteogenic model of implants. Methods MG-63 cells were implanted on sand-blasted, largegrit, acid-etched titanium plates surface (SLA) to establish a model of osseointegration between implant surface and osteoblasts. The experiments included NO-flurbiprofen group, flurbiprofen group and the control group. Cell proliferation was detected by CCK-8 assay, cell morphology was observed by scanning electron microscopy (SEM), cell adhesion was detected by MTT assay, alkaline phosphatase (ALP) activity was detected by chemical method, calcified nodules was observed after Alizarin red staining, and the expression of bone formation related genes ALP, OCN, Runx-2 was detected by RT-qPCR. Results CCK-8 assay showed that statistical difference was observed in cell proliferation among the groups treated with different drug concentrations (P < 0.01). Cell proliferation was higher in the NO-flurbiprofen group and the flurbiprofen group than the control group, and in the NO-flurbiprofen group than the flurbiprofen group (P < 0.01). SEM displayed that the cells from the NO-flurbiprofen group grew to multiple lays first. Cell adhesion results showed that the number of cell adhesion was lower in the NO-flurbiprofen group than the flurbiprofen group and the control group (P < 0.01). ALP activity of drug groups was lower than the control group (P < 0.01). No typical red deeply stained calcified nodules were observed in neither NO-flurbiprofen group nor flurbiprofen group during the observation period. RT-qPCR indicated that the mRNA expression of OCN in the NO-flurbiprofen group and Runx-2 in the flurbiprofen group was higher than those of the control group, while the mRNA level of ALP was lower than that of the control group (P < 0.01). Conclusion Both NO-flurbiprofen and flurbiprofen effectively promote the proliferation of osteoblasts on the surface of titanium plates and the expression of some osteogenic related genes. The promotion effect of NO-flurbiprofen is more significant.

Objective To investigate the effect of recombinant human lactoferrin (rhLF) on fracture healing in rat models with femur fracture and the proliferation of rat primary osteoblasts. Methods Male rats were randomly divided into 3 groups: simple fracture group (SF group), collagen film-treated group (CF group) and rhLF-compound collagen lamination film-treated group (CLF group). The fracture healing was observed by X-ray image and histological microscopy with HE and Masson staining. The newborn SD rats with osteoblasts were treated with different concentrations of rhLF, and osteoblast proliferation was detected by MTT method. Results The bone scabs in the CLF group were significantly larger than those in the SF and CF groups at 1, 2, and 3 weeks postoperatively (P＜0.05). There was no difference in the comparison between the groups at 4th week. The proliferation of cartilaginous and sclerotic bone scabs in the CLF group was more pronounced and showed the appearance of mature trabeculae and lamellar bone with a high degree of maturation of the bone scabs. The groups with 100 mg/L and 500 mg/L rhLF showed a significant decrease in A value for rat primary osteoblasts cultured in vitro as compared with the control group(P＜0.05). The A value increased significantly at the first day (P＜0.05). The concentration of rhLF increased at the fifth and tenth days. Conclusions rhLF has an accelerating effect on fracture healing which is manifested by fast scab formation, large volume and high maturity. The rhLF can promote the proliferation of osteoblasts cultured in vitro, and the effect is mainly manifested in the rapid proliferation stage of osteoblasts.

Copper is an essential trace element for the human body. Abnormalities in copper metabolism can lead to bone defects, mainly by directly affecting the viability of osteoblasts and osteoclasts and their bone remodeling function, or indirectly regulating bone metabolism by influencing enzyme activities as cofactors. Copper ions released from biological materials can affect osteoblasts and osteoclasts, either directly or indirectly by modulating the inflammatory response, oxidative stress, and rapamycin signaling. This review presents an overview of recent progress in the impact of copper on bone metabolism.Translational potential of this article: The impact of copper on bone metabolism can provide insights into clinical application of copper-containing supplements and biomaterials.

Glucocorticoid-induced bone loss is a toxic effect of long-term therapy with glucocorticoids resulting in a significant increase in the risk of fracture. Here, we find that glucocorticoids reciprocally convert osteoblast-lineage cells into endothelial-like cells. This is confirmed by lineage tracing showing the induction of endothelial markers in osteoblast-lineage cells following glucocorticoid treatment. Functional studies show that osteoblast-lineage cells isolated from glucocorticoid-treated mice lose their capacity for bone formation but simultaneously improve vascular repair. We find that the glucocorticoid receptor directly targets Foxc2 and Osterix, and the modulations of Foxc2 and Osterix drive the transition of osteoblast-lineage cells to endothelial-like cells. Together, the results suggest that glucocorticoids suppress osteogenic capacity and cause bone loss at least in part through previously unrecognized osteoblast-endothelial transitions.

BACKGROUND: It has been found that vascular endothelial growth factor 165 and bone morphogenetic proteins interact with each other during hypoxiareoxygenation and are involved in the repair process of osteoblast injury by regulating the activation of intracellular signaling pathways. OBJECTIVE: To further investigate the relationship between vascular endothelial growth factor 165/bone morphogenetic protein and hypoxic-reoxygenated osteoblast injury. METHODS: Osteoblasts were selected and the hypoxic-reoxygenated injury model was established. Vascular endothelial growth factor 165 and bone morphogenetic protein expressions at mRNA and protein levels were detected by real-time PCR and western blot before and after modeling. After modeling, osteoblasts were given different concentrations of vascular endothelial growth factor 165 and bone morphogenetic protein 2 (10, 20, 40 ng/mL). Cell proliferation was detected by cell counting kit-8 method and apoptosis was detected by DAPI at 12, 24, 36, 48, and 72 hours after treatment. RESULTS AND CONCLUSION: Compared with before modeling, the mRNA and protein expressions of vascular endothelial growth factor 165 and bone morphogenetic protein 2 in osteoblasts after modeling were significantly decreased (P < 0.05). The proliferation rate of osteoblasts was significantly increased with the increase of vascular endothelial growth factor 165 concentration (P < 0.05), while the apoptosis rate of osteoblasts decreased significantly with the increase of vascular endothelial growth factor 165 concentration (P < 0.05). The proliferation rate of osteoblast was significantly increased with the increase of bone morphogenetic protein 2 concentration (P < 0.05), while the apoptosis rate of osteoblast decreased significantly with the increase of bone morphogenetic protein 2 concentration (P < 0.05). To conclude, vascular endothelial growth factor 165 and bone morphogenetic protein are lowly expressed in hypoxicreoxygenated osteoblast injury, and treatment with vascular endothelial growth factor 165 and bone morphogenetic protein can reduce the injury of hypoxicreoxygenated osteoblast in a concentration-dependent manner, suggesting that vascular endothelial growth factor 165 and bone morphogenetic protein have a significant protective effect against the injury of hypoxic-reoxygenated osteoblasts. [ABSTRACT FROM AUTHOR]

BACKGROUND: Sepsis-induced systemic inflammation leads to rapid bone mass loss; however, there is a lack of effective treatments. Ulinastatin is an antiinflammatory drug, but its protective effect and mechanism on bone under sepsis-induced systemic inflammation are still unclear. OBJECTIVE: To explore whether ulinastatin can relieve acute bone loss caused by lipopolysaccharide. METHODS: (1) Animal experiment. Thirty male C57BL/6 mice were randomly divided into three groups (n=10 per group): control group, model group and experimental group. The control group was injected intraperitoneally with normal saline, the model group was injected intraperitoneally with lipopolysaccharide, and the experimental group was injected intraperitoneally with lipopolysaccharide and ulinastatin. In the experimental group, ulinastatin was injected continuously for 3 days. After intraperitoneal injection of ulinastatin for 14 days, femoral tissues were taken for CT scanning and pathological observation. (2) Cell experiment. C57BL/6 mouse primary osteoblasts were isolated and divided into three groups: the control group was routinely cultured, lipopolysaccharide was added to the model group, and lipopolysaccharide with ulinastatin was added to the experimental group. Cell proliferation and osteogenic differentiation were detected. C57BL/6 mouse bone marrow mononuclear cells were isolated and divided into three groups: the control group was routinely cultured, lipopolysaccharide was added to the model group, and lipopolysaccharide and ulinastatin were added to the experimental group. Osteoclast differentiation was detected. RESULTS AND CONCLUSION: (1) Animal experiment. CT scanning and hematoxylin-eosin staining showed that bone mass in lipopolysaccharide-treated mice was reduced but increased after treatment with ulinastatin. Tartrate resistant acid phosphatase staining showed that the number of osteoclasts in bone tissue increased in the model group, but significantly decreased in the experimental group compared with the model group. (2) Cell experiment. Cell counting kit-8 assay showed that lipopolysaccharide treatment inhibited the proliferation of osteoblasts, and ulinastatin elevated the proliferation of osteoblasts after lipopolysaccharide treatment. Alkaline phosphatase staining, alizarin red staining and osteogenesis-related gene (alkaline phosphatase, Runx2, osteocalcin, osteoblastin, nuclear factor κB receptor-activating factor ligand, osteoprotegerin) detection showed that lipopolysaccharide treatment inhibited osteogenic differentiation of osteoblasts and elevated the nuclear factor κB receptor-activating factor ligand/osteoprotegerin ratio; ulinastatin did not have any significant effect on the reduction of osteoblast function induced by lipopolysaccharide but decreased the nuclear factor κB receptor-activating factor ligand/osteoprotegerin ratio. Tartrate resistant acid phosphatase staining and osteoclast-related gene (tartrate resistant acid phosphatase and matrix metalloproteinase 9) detection showed that lipopolysaccharide treatment could promote osteoclast differentiation of bone marrow monocytes, while ulinastatin could inhibit lipopolysaccharide-induced osteoclast differentiation of bone marrow monocytes. (3) Overall, ulinastatin can significantly inhibit lipopolysaccharide-induced bone loss, mainly through promoting osteoblast proliferation and directly or indirectly inhibiting osteoclast differentiation to alleviate bone loss and achieve osteoprotective effects. [ABSTRACT FROM AUTHOR]

BACKGROUND: Recent studies have shown that research on naringin anti-osteoporosis mostly stays in in vitro and in vivo experiments. Understanding the mechanism of related signaling pathways and the expression of related proteins and some specific genes is an important way to deeply understand naringin anti-osteoporosis. At present, traditional Chinese medicine has been confirmed to have a significant role in anti-osteoporosis. Naringin is one of the main active ingredients in Rhizoma Drynariae. Its effectiveness and mechanism of action against osteoporosis have been gradually recognized by scholars, and its clinical and basic research has been gradually emphasized. OBJECTIVE: To analyze and summarize the research progress of naringin in anti-osteoporosis in vitro and in vivo, thereby providing some ideas for the next step to study its related mechanism of action. METHODS: The relevant literatures included in CNKI and PubMed database were searched with the Chinese search terms of “naringin, osteoporosis, traditional Chinese medicine compound, pathogenesis, signaling pathway, bone marrow mesenchymal stem cells, osteoblasts, osteoclasts” in Chinese and English, respectively. The corresponding criteria were established according to the research needs, and finally 69 articles were included for review. RESULTS AND CONCLUSION: Naringin blocks the increase in the number of osteoclasts and adipocytes, the decrease in the number of osteocytes and osteocalcin (+) cells induced by fructose-rich diet, and promotes the secretion of Sema3A from osteoblasts and osteocytes, thereby enhancing local bone formation and inhibiting osteoclast production by activating the Wnt/β-catenin pathway. Naringin is an important way to induce autophagy of osteoblasts, but autophagy-related proteins participate in osteoblast differentiation and bone formation. Lack of autophagy in osteoblasts reduces mineralization and leads to an imbalance in the number of osteoblasts and osteoclasts, which results in bone loss and decreased bone density. The composite scaffold loaded with naringin can be used as a necessary carrier for bone defect repair and has excellent bone repair properties. Naringin can also accelerate the growth of new bone tissue by increasing the local contents of bone morphogenetic protein 2 and vascular endothelial growth factor. Naringin can regulate bone metabolism and inhibit oxidative stress via ERK, PI3K/Akt and Wnt signaling pathways to improve osteoporosis, which can play a good role in preventing and controlling the disease. However, the depth and breadth of the relevant research is insufficient. Based on the mechanism of the current study, we should investigate the specific mechanisms by which naringin regulates different pathways and inter-pathway interactions in the future, which will be beneficial to the multifaceted development of naringin used in the treatment of osteoporosis.. [ABSTRACT FROM AUTHOR]

BACKGROUND: Fluid shear stress plays an important role in osteoblast proliferation and apoptosis. However, whether Caveolin-1 is involved in the process of fluid shear stress-induced proliferation and apoptosis in osteoblasts is unknown. OBJECTIVE: To explore the role of Caveolin-1 in fluid shear stress-regulated osteoblast proliferation and apoptosis. METHODS: The MC3T3-E1 osteoblasts in good growth status were selected and loaded with fluid shear stress at an intensity of 1.2 Pa for different times (0, 30, 60, 90 minutes). The expression of Caveolin-1 protein was observed and conditions with a time of 60 minutes were screened for the experiment. MC3T3-E1 cells were divided into control group, fluid shear stress group, fluid shear stress+pcDNA 3.1 group (control), fluid shear stress+pcDNA Cav-1 group (plasmid overexpression), and intervened with fluid shear stress and overexpression of Cav-1, respectively. The expression of molecules related to proliferation and apoptosis in MC3T3-E1 cells was detected by qRT-PCR and western blot. In addition, the proliferative activity of MC3T3-E1 cells was detected by cell counting kit-8 and EdU assay; and cell apoptosis was detected by Hoechst 33258 and flow cytometry. RESULTS AND CONCLUSION: The expression of Caveolin-1 in MC3T3-E1 cells was significantly down-regulated after loading fluid shear stress, and the expression level was lowest after 60 minutes. Overexpression of Caveolin-1 attenuated the proliferation-promoting and apoptosis-suppressing effects of fluid shear stress in MC3T3-E1 cells. In conclusion, Caveolin-1 has a vital role in fluid shear stress-regulated osteoblast proliferation and apoptosis, which may offer a potential therapeutic strategy for osteoporosis. [ABSTRACT FROM AUTHOR]

Lead (Pb(II)) is a pervasive heavy metal toxin with many well-established negative effects on human health. Lead toxicity arises from cumulative, repeated environmental exposures. Thus, prophylactic strategies to protect against the bioaccumulation of lead could reduce lead-associated human pathologies. Here we show that DNA and RNA aptamers protect C. elegans from toxic phenotypes caused by lead. Reproductive toxicity, as measured by brood size assays, is prevented by co-feeding of animals with DNA or RNA aptamers. Similarly, lead-induced neurotoxicity, measured by behavioral assays, are also normalized by aptamer feeding. Further, cultured human HEK293 and primary murine osteoblasts are protected from lead toxicity by transfection with DNA aptamers. The osteogenic development, which is decreased by lead exposure, is maintained by prior transfection of lead-binding DNA aptamers. Aptamers may be an effective strategy for the protection of human health in the face of increasing environmental toxicants. • Lead toxicity remains a pervasive public health problem, with limited interventions available. • Aptamers are short single-stranded nucleic acids that bind targets including proteins, small molecules, and ions. • Lead-binding aptamers applied to C. elegans protect the animals from lead-induced reproductive toxicity and neurotoxicity. • Upon transfection, DNA aptamers protect primary osteoblasts from lead toxicity. • The study represents the first demonstration of the use of an aptamer as a prophylactic to an environmental pollutant. [ABSTRACT FROM AUTHOR]

BACKGROUND: Careful regulation of bone immune response during repair of bone scaffold is important for bone regeneration. OBJECTIVE: To review the influence of bone immune response on bone repair and the design of bone tissue engineering scaffold with regulating bone immune function and its application in bone repair. METHODS: Relevant articles published from 1973 to 2023 were retrieved from Science Direct, PubMed, Web of Science, and CNKI databases. English search terms were “osteoimmunology, macrophages, bone repair materials, bone scaffold, bone defects, bone regeneration”. Chinese search terms were “bone immunity, macrophages, bone repair material, bone stent, bone defect, bone regeneration”. Totally 80 articles of the latest research progress in this field were summarized and analyzed. RESULTS AND CONCLUSION: (1) A detailed review was conducted on the important time points in the origin and development process of bone immunity, and it was explained that macrophages, as important members of the bone immune regulatory system, can be divided into two phenotypes: M1 (pro-inflammatory) and M2 (anti-inflammatory), and play a key role in different stages of bone regeneration. During the inflammatory phase, M1 type macrophages can activate osteoclasts, initiate tissue repair processes, and participate in the reconstruction of bone microvascular networks. On the other hand, during the bone tissue regeneration process in the later stages of inflammation, sustained high expression of M1 type macrophages can hinder the formation of new bones. During the repair phase, M2 macrophages can secrete osteogenic cytokines, stimulate osteogenic differentiation and mineralization of bone marrow mesenchymal stem cells, and promote bone formation. On the other hand, long-term activation of M2 macrophages can increase the secretion of fibrogenic molecules, leading to excessive formation of scar tissue and delaying the healing process. Therefore, regulating macrophages to undergo phenotype transformation at appropriate stages and constructing an immune microenvironment beneficial for osteogenesis has great significance for bone regeneration. (2) In the process of designing bone scaffolds with bone immune regulation characteristics, the physical and chemical properties such as scaffold roughness, pore structure, stiffness, hydrophilicity, surface charge, and surface functional groups can be changed to affect non-specific protein and cell adhesion, thereby affecting the interaction between bone scaffolds and the immune system. By designing surface functional coatings of bioactive substances such as hydroxyapatite, bioactive glass, metal ions, extracellular matrix, drugs, cytokines, and exosomes, the immune microenvironment can be actively regulated by releasing bioactive substances after implantation into the body, affecting macrophage polarization and crosstalk between macrophages and bone cells, and promoting more M2 polarization of macrophages, so as to build a bone immune microenvironment that is conducive to bone regeneration. (3) Based on the research and development of bone tissue engineering scaffolds, in addition to focusing on the direct regulatory factors of stem cell osteogenic differentiation, this article also proposes that attention should be paid to the management of the immune microenvironment of stem cell differentiation. By regulating the appropriate bone immune microenvironment, more stem cell osteogenic differentiation can be induced; the osteogenic efficiency of the scaffold can be enhanced, and the concept of “bone immune regulatory characteristics” can be condensed; deeply elucidated the multi-directional regulatory role of the bone immune microenvironment and introduced the existing strategies for changing the physicochemical properties and surface functional coating of scaffolds to endow them with bone immune regulatory potential, providing new ideas for guiding the development of a new generation of bone tissue engineering scaffolds with bone immune regulatory characteristics. However, the bone immune microenvironment is a dynamic equilibrium state, and most of the existing regulatory strategies do not consider the dynamic matching of regulation. Therefore, the research and development of intelligent bone immune regulatory scaffolds with efficient and targeted regulation of the immune microenvironment will be a key focus of attention for scholars in future. [ABSTRACT FROM AUTHOR]

BACKGROUND: The pathogenesis of osteoporosis is complex, and its essence is the weakening of bone formation and the enhancement of bone absorption caused by various reasons, resulting in the imbalance of bone metabolism. In recent years, N6-methyladenosine has been found (N6-methyladenosine, m6A) methylation can prevent and treat osteoporosis by regulating bone metabolism. OBJECTIVE: Taking the regulation of bone metabolism by m6A methylation as an entry point, to systematically sort out and summarize the research progress of m6A methylation in osteoporosis, so as to provide certain theoretical reference bases for the search of new therapeutic targets for osteoporosis. METHODS: CNKI, WanFang, VIP, PubMed, MEDLINE, Nature, and Cochrane databases were retrieved for relevant literature published from database inception to 2023. The keywords were “osteoporosis, m6A methylation, bone metabolism, bone marrow mesenchymal stem cells, osteoblasts, osteoclasts” in Chinese and English. Duplicates and obsolete non-referenced documents were excluded, and a total of 73 standard papers were included for further review. RESULTS AND CONCLUSION: m6A methylation can affect the activity and differentiation of bone marrow mesenchymal stem cells, osteoblasts, and osteoclasts through various pathways to regulate bone metabolism and prevent osteoporosis. The regulatory process of m6A methylation is extremely complex, and its related proteins play different roles in different cells. Even in the same kind of cells, the same type of proteins may have radically different roles, regulating different physiological and pathological processes. [ABSTRACT FROM AUTHOR]

Purpose: To compare the osteoblastic activity around dental implants placed via adaptive osteotomy and osseodensification techniques using bone scintigraphy in human subjects. Materials and Methods: A single-blinded, split-mouth design was conducted on two sites in each of the 10 subjects, with the adaptive osteotomy (n = 10) and osseodensification (n = 10) techniques for implant placement performed on either side of the D3-type bone in the posterior mandible. All participants were subjected to a multiphase bone scintigraphy test on the 15th, 45th, and 90th days after implant placement to evaluate the osteoblastic activity. Results: The mean values obtained on the 15th, 45th, and 90th days in the adaptive osteotomy group were 51.14% ± 3.93%, 51.40% ± 3.41%, and 50.73% ± 1.51%, respectively, while the osseodensification group values were 48.88% ± 3.94%, 48.78% ± 3.38%, and 49.29% ± 1.56%, respectively. The intragroup and intergroup analyses revealed no significant difference between the mean values of the adaptive osteotomy and osseodensification groups on the tested days (P > .05). Conclusions: Osseodensification and adaptive osteotomy techniques improved primary stability of D3-type bone and accelerated the osteoblastic activity after implant placement, with no superiority of one method over the other. [ABSTRACT FROM AUTHOR]