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Osteoarthritis is a highly prevalent progressive joint disease that still requires an optimal therapeutic approach. Intermittent fasting is an attractive dieting strategy for improving health. Here this study shows that intermittent fasting potently relieves medial meniscus (DMM)‐ or natural aging‐induced osteoarthritic phenotypes. Osteocytes, the most abundant bone cells, secrete excess neuropeptide Y (NPY) during osteoarthritis, and this alteration can be altered by intermittent fasting. Both NPY and the NPY‐abundant culture medium of osteocytes (OCY‐CM) from osteoarthritic mice possess pro‐inflammatory, pro‐osteoclastic, and pro‐neurite outgrowth effects, while OCY‐CM from the intermittent fasting‐treated osteoarthritic mice fails to induce significant stimulatory effects on inflammation, osteoclast formation, and neurite outgrowth. Depletion of osteocyte NPY significantly attenuates DMM‐induced osteoarthritis and abolishes the benefits of intermittent fasting on osteoarthritis. This study suggests that osteocyte NPY is a key contributing factor in the pathogenesis of osteoarthritis and intermittent fasting represents a promising nonpharmacological antiosteoarthritis method by targeting osteocyte NPY. [ABSTRACT FROM AUTHOR]

Both Alzheimer's disease (AD) and osteoporosis (OP) are common age‐associated degenerative diseases and are strongly correlated with clinical epidemiology. However, there is a lack of clear pathological relationship between the brain and bone in the current understanding. Here, it is found that young osteocyte, the most abundant cells in bone, secretes extracellular vesicles (OCYYoung‐EVs) to ameliorate cognitive impairment and the pathogenesis of AD in APP/PS1 mice and model cells. These benefits of OCYYoung‐EVs are diminished in aged osteocyte‐derived EVs (OCYAged‐EVs). Based on the self‐constructed OCY‐EVs tracer transgenic mouse models and the in vivo fluorescent imaging system, OCY‐EVs have been observed to be transported to the brain under physiological and pathological conditions. In the hippocampal administration of Aβ40 induced young AD model mice, the intramedullary injection of Rab27a‐shRNA adenovirus inhibits OCYYoung‐EVs secretion from bone and aggravates cognitive impairment. Proteomic quantitative analysis reveals that OCYYoung‐EVs, compared to OCYAged‐EVs, enrich multiple protective factors of AD pathway. The study uncovers the role of OCY‐EV as a regulator of brain health, suggesting a novel mechanism in bone‐brain communication. [ABSTRACT FROM AUTHOR]

A differentiation switch of bone marrow mesenchymal stem/stromal cells (BMSCs) from osteoblasts to adipocytes contributes to age‐ and menopause‐associated bone loss and marrow adiposity. Here it is found that osteocytes, the most abundant bone cells, promote adipogenesis and inhibit osteogenesis of BMSCs by secreting neuropeptide Y (NPY), whose expression increases with aging and osteoporosis. Deletion of NPY in osteocytes generates a high bone mass phenotype, and attenuates aging‐ and ovariectomy (OVX)‐induced bone‐fat imbalance in mice. Osteocyte NPY production is under the control of autonomic nervous system (ANS) and osteocyte NPY deletion blocks the ANS‐induced regulation of BMSC fate and bone‐fat balance. γ‐Oryzanol, a clinically used ANS regulator, significantly increases bone formation and reverses aging‐ and OVX‐induced osteocyte NPY overproduction and marrow adiposity in control mice, but not in mice lacking osteocyte NPY. The study suggests a new mode of neuronal control of bone metabolism through the ANS‐induced regulation of osteocyte NPY. [ABSTRACT FROM AUTHOR]

Senile osteoporosis (OP) is often concomitant with decreased autophagic activity. OPTN (optineurin), a macroautophagy/autophagy (hereinafter referred to as autophagy) receptor, is found to play a pivotal role in selective autophagy, coupling autophagy with bone metabolism. However, its role in osteogenesis is still mysterious. Herein, we identified Optn as a critical molecule of cell fate decision for bone marrow mesenchymal stem cells (MSCs), whose expression decreased in aged mice. Aged mice revealed osteoporotic bone loss, elevated senescence of MSCs, decreased osteogenesis, and enhanced adipogenesis, as well as optn–/ – mice. Importantly, restoring Optn by transplanting wild-type MSCs to optn–/ – mice or infecting optn–/ – mice with Optn-containing lentivirus rescued bone loss. The introduction of a loss-of-function mutant of OptnK193R failed to reestablish a bone-fat balance. We further identified FABP3 (fatty acid binding protein 3, muscle and heart) as a novel selective autophagy substrate of OPTN. FABP3 promoted adipogenesis and inhibited osteogenesis of MSCs. Knockdown of FABP3 alleviated bone loss in optn–/ – mice and aged mice. Our study revealed that reduced OPTN expression during aging might lead to OP due to a lack of FABP3 degradation via selective autophagy. FABP3 accumulation impaired osteogenesis of MSCs, leading to the occurrence of OP. Thus, reactivating OPTN or inhibiting FABP3 would open a new avenue to treat senile OP. Abbreviations: ADIPOQ: adiponectin, C1Q and collagen domain containing; ALPL: alkaline phosphatase, liver/bone/kidney; BGLAP/OC/osteocalcin: bone gamma carboxyglutamate protein; BFR/BS: bone formation rate/bone surface; CALCOCO2/NDP52: calcium binding and coiled-coil domain 2; CDKN1A/p21: cyclin-dependent kinase inhibitor 1A; CDKN2A/p16: cyclin dependent kinase inhibitor 2A; CDKN2B/p15: cyclin dependent kinase inhibitor 2B; CEBPA: CCAAT/enhancer binding protein (C/EBP), alpha; COL1A1: collagen, type I, alpha 1; Ct. BV/TV: cortical bone volume fraction; Ct. Th: cortical thickness; Es. Pm: endocortical perimeter; FABP4/Ap2: fatty acid binding protein 4, adipocyte; H2AX: H2A.X variant histone; HE: hematoxylin and eosin; MAP1LC3B: microtubule-associated protein 1 light chain 3 beta; MAR: mineral apposition rate; MSCs: bone marrow mesenchymal stem cells; NBR1: NBR1, autophagy cargo receptor; OP: osteoporosis; OPTN: optineurin; PDB: Paget disease of bone; PPARG: peroxisome proliferator activated receptor gamma; Ps. Pm: periosteal perimeter; qRT-PCR: quantitative real-time PCR; γH2AX: Phosphorylation of the Serine residue of H2AX; ROS: reactive oxygen species; RUNX2: runt related transcription factor 2; SA-GLB1: senescence-associated (SA)-GLB1 (galactosidase, beta 1); SP7/Osx/Osterix: Sp7 transcription factor 7; SQSTM1/p62: sequestosome 1; TAX1BP1: Tax1 (human T cell leukemia virus type I) binding protein 1; Tb. BV/TV: trabecular bone volume fraction; Tb. N: trabecular number; Tb. Sp: trabecular separation; Tb. Th: trabecular thickness; μCT: micro computed tomography. [ABSTRACT FROM AUTHOR]

Recently, the gut microbiota (GM) has been shown to be a regulator of bone homeostasis and the mechanisms by which GM modulates bone mass are still being investigated. Here, it is found that colonization with GM from children (CGM) but not from the elderly (EGM) prevents decreases in bone mass and bone strength in conventionally raised, ovariectomy (OVX)‐induced osteoporotic mice. 16S rRNA gene sequencing reveals that CGM reverses the OVX‐induced reduction of Akkermansia muciniphila (Akk). Direct replenishment of Akk is sufficient to correct the OVX‐induced imbalanced bone metabolism and protect against osteoporosis. Mechanistic studies show that the secretion of extracellular vesicles (EVs) is required for the CGM‐ and Akk‐induced bone protective effects and these nanovesicles can enter and accumulate into bone tissues to attenuate the OVX‐induced osteoporotic phenotypes by augmenting osteogenic activity and inhibiting osteoclast formation. The study identifies that gut bacterium Akk mediates the CGM‐induced anti‐osteoporotic effects and presents a novel mechanism underlying the exchange of signals between GM and host bone. [ABSTRACT FROM AUTHOR]

Objectives: We aimed to investigate whether skeletal‐specific H‐type blood vessels exist in alveolar bone and how they function in alveolar bone remodeling. Materials and Methods: H‐type vessels with high expression of CD31 and Endomucin (CD31hiEmcnhi) were immunostained in alveolar bone. Abundance and age‐related changes in CD31hiEmcnhi endothelial cells (H‐ECs) were detected by flow cytometry. Osteoprogenitors association with H‐type vessels and bone mass were detected in tooth extraction model of alveolar bone remodeling by immunohistofluorescence and micro‐CT, respectively. Transcription and expression of H‐EC feature genes during in vitro Notch inhibition were measured by RT‐qPCR and immunocytofluorescence. Results: We verified that H‐type vessels existed in alveolar bone, the abundance of which was highest at infancy age, then decreased but maintained a constant level during aging. In tooth extraction model, H‐ECs significantly increased with concomitant perivascular accumulation of Runx2+ osteoprogenitors and gradually augmentation of bone mass. Notch inhibition of in vitro cultured H‐ECs resulted in decreased expression levels of Emcn and hes1, but not Pecam1 or Kdr genes, with decreased expression levels of H‐EC numbers, accordingly. Conclusions: The present study suggests that H‐type vessels promote osteogenesis during alveolar bone remodeling. Notch signaling pathway regulates expression of Emcn and possibly determines fate and functions of alveolar H‐ECs. [ABSTRACT FROM AUTHOR]

Background/Aims: Recently, we and others showed that the relative abundance of a specific vessel subtype, strongly positive for CD31 and Endomucin (CD31hiEmcnhi), is associated with bone formation and bone loss, and platelet-derived growth factor-BB (PDGF-BB) secreted by preosteoclasts induces the formation of the specific vessels and thereby stimulates osteogenesis. Inhibition of Src homology 2 domain-containing protein tyrosine phosphatase-2 (SHP-2) has been shown to block the fusion of preosteoclasts into mature osteoclasts. However, it is unclear whether inhibition of SHP-2 could promote preosteoclast-induced angiogenesis and then enhance bone formation. This study aimed to determine the effects of a specific SHP-2 inhibitor (NSC-87877) on CD31 hiEmcnhi vessel and bone formation. Methods: 3-month-old C57BL/6 mice were subjected to either ovariectomy (OVX) or sham operation. OVX mice were intraperitoneally injected with NSC-87877 and the control (sham) mice were treated with an equal volume of diluents (PBS). Two months later, bone samples from mice were collected for µCT, histological, immunohistochemical and immunofluorescent analyses to assess bone mass, osteogenic and osteoclastic acitivities, as well as the densities of CD31hiEmcnhi vessels. A series of angiogenesis- related assays were performed to test the effects of NSC-87877 on the pro-angiogenic activities of preosteoclasts in vitro. Results: We found that NSC-87877 is sufficient to induce bone-sparing effects in OVX-induced osteoporotic mouse model. We also found that NSC-87877 induces higher numbers of preosteoclasts and CD31hiEmcnhi vessels and higher levels of PDGF-BB in bone marrow of osteoporotic mice. In vitro assays showed that NSC-87877 prevents preosteoclast fusion, increases PDGF-BB production, and augments the pro-angiogenic abilities of preosteoclasts. Conclusion: Our results suggest that NSC-87877 can be used as a promising therapeutic agent for osteoporosis by inhibiting osteoclast formation and promoting preosteoclast-induced angiogenesis. [ABSTRACT FROM AUTHOR]

Cancer incidence is rising, and the efficacy of current available anticancer agents is limited by severe dose‐limiting toxicities and drug resistance problems. Nanoparticles are heralded as the next frontier in cancer treatment. Here, a pure physical method is used to efficiently fabricate very small silver particles even approaching the Ångstrom (Ång) dimension. Fructose is used as a dispersant and stabilizer to coat the Ång‐scale silver particles (AgÅPs). Functional and mechanistic studies demonstrate that fructose‐coated AgÅPs (F‐AgÅPs) can enter and accumulate in multiple cultured cancer cell lines to induce apoptotic death, whereas most normal cells are resistant to the efficacious dose of F‐AgÅPs; in vivo, intravenous administration of F‐AgÅPs potently inhibits the growth of pancreatic and lung cancer xenografts in nude mice, without inducing notable toxic effects on the healthy tissues. The results suggest the promising potential of F‐AgÅPs as a potent, safe, and broad‐spectrum agent for the cancer treatment. [ABSTRACT FROM AUTHOR]

Osteonecrosis of the femoral head (ONFH) commonly occurs after glucocorticoid (GC) therapy. The gut microbiota (GM) participates in regulating host health, and its composition can be altered by GC. Here, this study demonstrates that cohousing with healthy mice or colonization with GM from normal mice attenuates GC-induced ONFH. 16 S rRNA gene sequencing shows that cohousing with healthy mice rescues the GC-induced reduction of gut Lactobacillus animalis . Oral supplementation of L. animalis mitigates GC-induced ONFH by increasing angiogenesis, augmenting osteogenesis, and reducing cell apoptosis. Extracellular vesicles from L. animalis ( L. animalis -EVs) contain abundant functional proteins and can enter the femoral head to exert proangiogenic, pro-osteogenic, and antiapoptotic effects, while its abundance is reduced after exposure to GC. Our study suggests that the GM is involved in protecting the femoral head by transferring bacterial EVs, and that loss of L. animalis and its EVs is associated with the development of GC-induced ONFH.

Serious infection caused by multi-drug-resistant bacteria is a major threat to human health. Bacteria can invade the host tissue and produce various toxins to damage or kill host cells, which may induce life-threatening sepsis. Here, we aimed to explore whether fructose-coated Ångstrom-scale silver particles (F-AgÅPs), which were prepared by our self-developed evaporation-condensation system and optimized coating approach, could kill bacteria and sequester bacterial toxins to attenuate fatal bacterial infections. Methods: A series of in vitro assays were conducted to test the anti-bacterial efficacy of F-AgÅPs, and to investigate whether F-AgÅPs could protect against multi-drug resistant Staphylococcus aureus ( S. aureus )- and Escherichia coli ( E. coli )-induced cell death, and suppress their toxins ( S. aureus hemolysin and E. coli lipopolysaccharide)-induced cell injury or inflammation. The mouse models of cecal ligation and puncture (CLP)- or E. coli bloodstream infection-induced lethal sepsis were established to assess whether the intravenous administration of F-AgÅPs could decrease bacterial burden, inhibit inflammation, and improve the survival rates of mice. The levels of silver in urine and feces of mice were examined to evaluate the excretion of F-AgÅPs. Results: F-AgÅPs efficiently killed various bacteria that can cause lethal infections and also competed with host cells to bind with S. aureus α-hemolysin, thus blocking its cytotoxic activity. F-AgÅPs inhibited E. coli lipopolysaccharide-induced endothelial injury and macrophage inflammation, but not by directly binding to lipopolysaccharide. F-AgÅPs potently reduced bacterial burden, reversed dysregulated inflammation, and enhanced survival in mice with CLP- or E. coli bloodstream infection-induced sepsis, either alone or combined with antibiotic therapy. After three times injections within 48 h, 79.18% of F-AgÅPs were excreted via feces at the end of the 14-day observation period. Conclusion: This study suggests the prospect of F-AgÅPs as a promising intravenous agent for treating severe bacterial infections., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)

Alzheimer's disease (AD) is currently ranked as the third leading cause of death for eldly people, just behind heart disease and cancer. Autophagy is declined with aging. Our study determined the biphasic changes of miR-331-3p and miR-9-5p associated with AD progression in APPswe/PS1dE9 mouse model and demonstrated inhibiting miR-331-3p and miR-9-5p treatment prevented AD progression by promoting the autophagic clearance of amyloid beta (Aβ). Methods: The biphasic changes of microRNAs were obtained from RNA-seq data and verified by qRT-PCR in early-stage (6 months) and late-stage (12 months) APPswe/PS1dE9 mice (hereinafter referred to as AD mice). The AD progression was determined by analyzing Aβ levels, neuron numbers (MAP2 + ) and activated microglia (CD68 + IBA1 + ) in brain tissues using immunohistological and immunofluorescent staining. MRNA and protein levels of autophagic-associated genes ( Becn1, Sqstm1, LC3b ) were tested to determine the autophagic activity. Morris water maze and object location test were employed to evaluate the memory and learning after antagomirs treatments in AD mice and the Aβ in the brain tissues were determined. Results: MiR-331-3p and miR-9-5p are down-regulated in early-stage of AD mice, whereas up-regulated in late-stage of AD mice. We demonstrated that miR-331-3p and miR-9-5p target autophagy receptors Sequestosome 1 ( Sqstm1 ) and Optineurin ( Optn ), respectively. Overexpression of miR-331-3p and miR-9-5p in SH-SY5Y cell line impaired autophagic activity and promoted amyloid plaques formation. Moreover, AD mice had enhanced Aβ clearance, improved cognition and mobility when treated with miR-331-3p and miR-9-5p antagomirs at late-stage. Conclusion: Our study suggests that using miR-331-3p and miR-9-5p, along with autophagic activity and amyloid plaques may distinguish early versus late stage of AD for more accurate and timely diagnosis. Additionally, we further provide a possible new therapeutic strategy for AD patients by inhibiting miR-331-3p and miR-9-5p and enhancing autophagy., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)

Poor wound healing after diabetes or extensive burn remains a challenging problem. Recently, we presented a physical approach to fabricate ultrasmall silver particles from Ångstrom scale to nanoscale and determined the antitumor efficacy of Ångstrom-scale silver particles (AgÅPs) in the smallest size range. Here we used the medium-sized AgÅPs (65.9 ± 31.6 Å) to prepare carbomer gel incorporated with these larger AgÅPs (L-AgÅPs-gel) and demonstrated the potent broad-spectrum antibacterial activity of L-AgÅPs-gel without obvious toxicity on wound healing-related cells. Induction of reactive oxygen species contributed to L-AgÅPs-gel-induced bacterial death. Topical application of L-AgÅPs-gel to mouse skin triggered much stronger effects than the commercial silver nanoparticles (AgNPs)-gel to prevent bacterial colonization, reduce inflammation, and accelerate diabetic and burn wound healing. L-AgÅPs were distributed locally in skin without inducing systemic toxicities. This study suggests that L-AgÅPs-gel represents an effective and safe antibacterial and anti-inflammatory material for wound therapy., (Copyright © 2020 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC).)

Osteosarcoma is a common malignant bone cancer easily to metastasize. Much safer and more efficient strategies are still needed to suppress osteosarcoma growth and lung metastasis. We recently presented a pure physical method to fabricate Ångstrom-scale silver particles (AgÅPs) and determined the anti-tumor efficacy of fructose-coated AgÅPs (F-AgÅPs) against lung and pancreatic cancer. Our study utilized an optimized method to obtain smaller F-AgÅPs and aimed to assess whether F-AgÅPs can be used as an efficient and safe agent for osteosarcoma therapy. We also investigated whether the induction of apoptosis by altering glucose metabolic phenotype contributes to the F-AgÅPs-induced anti-osteosarcoma effects. Methods: A modified method was developed to prepare smaller F-AgÅPs. The anti-tumor, anti-metastatic and pro-survival efficacy of F-AgÅPs and their toxicities on healthy tissues were compared with that of cisplatin (a first-line chemotherapeutic drug for osteosarcoma therapy) in subcutaneous or orthotopic osteosarcoma-bearing nude mice. The pharmacokinetics, biodistribution and excretion of F-AgÅPs were evaluated by testing the levels of silver in serum, tissues, urine and feces of mice. A series of assays in vitro were conducted to assess whether the induction of apoptosis mediates the killing effects of F-AgÅPs on osteosarcoma cells and whether the alteration of glucose metabolic phenotype contributes to F-AgÅPs-induced apoptosis. Results: The newly obtained F-AgÅPs (9.38 ± 4.11 nm) had good stability in different biological media or aqueous solutions and were more effective than cisplatin in inhibiting tumor growth, improving survival, attenuating osteolysis and preventing lung metastasis in osteosarcoma-bearing nude mice after intravenous injection, but were well tolerated in normal tissues. One week after injection, about 68% of F-AgÅPs were excreted through feces. F-AgÅPs induced reactive oxygen species (ROS)-dependent apoptosis of osteosarcoma cells but not normal cells, owing to their ability to selectively shift glucose metabolism of osteosarcoma cells from glycolysis to mitochondrial oxidation by inhibiting pyruvate dehydrogenase kinase (PDK). Conclusion: Our study suggests the promising prospect of F-AgÅPs as a powerful selective anticancer agent for osteosarcoma therapy., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)

Healing of the chronic diabetic ulceration and large burns remains a clinical challenge. Therapeutic fasting has been shown to improve health. Our study tested whether fasting facilitates diabetic and burn wound healing and explored the underlying mechanism. Methods: The effects of fasting on diabetic and burn wound healing were evaluated by analyzing the rates of wound closure, re-epithelialization, scar formation, collagen deposition, skin cell proliferation and neovascularization using histological analyses and immunostaining. In vitro functional assays were conducted to assess fasting and refeeding on the angiogenic activities of endothelial cells. Transcriptome sequencing was employed to identify the differentially expressed genes in endothelial cells after fasting treatment and the role of the candidate genes in the fasting-induced promotion of angiogenesis was demonstrated. Results: Two times of 24-h fasting in a week after but especially before wound injury efficiently induced faster wound closure, better epidermal and dermal regeneration, less scar formation and higher level of angiogenesis in mice with diabetic or burn wounds. In vitro , fasting alone by serum deprivation did not increase, but rather reduced the abilities of endothelial cell to proliferate, migrate and form vessel-like tubes. However, subsequent refeeding did not merely rescue, but further augmented the angiogenic activities of endothelial cells. Transcriptome sequencing revealed that fasting itself, but not the following refeeding, induced a prominent upregulation of a variety of pro-angiogenic genes, including SMOC1 (SPARC related modular calcium binding 1) and SCG2 (secretogranin II). Immunofluorescent staining confirmed the increase of SMOC1 and SCG2 expression in both diabetic and burn wounds after fasting treatment. When the expression of SMOC1 or SCG2 was down-regulated, the fasting/refeeding-induced pro-angiogenic effects were markedly attenuated. Conclusion: This study suggests that fasting combined with refeeding, but not fasting solely, enhance endothelial angiogenesis through the activation of SMOC1 and SCG2, thus facilitating neovascularization and rapid wound healing., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)

Osteoporosis and osteoporotic fractures severely compromise quality of life in elderly people and lead to early death. Human umbilical cord mesenchymal stromal cell (MSC)-derived extracellular vesicles (hucMSC-EVs) possess considerable therapeutic effects in tissue repair and regeneration. Thus, in the present study, we investigated the effects of hucMSC-EVs on primary and secondary osteoporosis and explored the underlying mechanisms. Methods : hucMSCs were isolated and cultured. EVs were obtained from the conditioned medium of hucMSCs and determined by using transmission electron microscopy, dynamic light scattering and Western Blot analyses. The effects of hucMSC-EVs on ovariectomy-induced postmenopausal osteoporosis and tail suspension-induced hindlimb disuse osteoporosis in mouse models were assessed by using microcomputed tomography, biomechanical, histochemical and immunohistochemical, as well as histomorphometric analyses. Proteomic analysis was applied between hucMSC-EVs and hucMSCs to screen the candidate proteins that mediate hucMSC-EVs function. The effects of hucMSC-EVs on osteogenic and adipogenic differentiation of bone marrow mesenchymal stromal cells (BMSCs), and osteoclastogenesis of the macrophage cell line RAW264.7 in vitro were determined by using cytochemical staining and quantitative real-time PCR analysis. Subsequently, the roles of the key protein in hucMSC-EVs-induced regulation on BMSCs and RAW264.7 cells were evaluated. Results: hucMSCs were able to differentiate into osteoblasts, adipocytes or chondrocytes and positively expressed CD29, CD44, CD73 and CD90, but negatively expressed CD34 and CD45. The morphological assessment revealed the typical cup- or sphere-shaped morphology of hucMSC-EVs with diameters predominantly ranging from 60 nm to 150 nm and expressed CD9, CD63, CD81 and TSG101. The systemic administration of hucMSC-EVs prevented bone loss and maintained bone strength in osteoporotic mice by enhancing bone formation, reducing marrow fat accumulation and decreasing bone resorption. Proteomic analysis showed that the potently pro-osteogenic protein, CLEC11A (C-type lectin domain family 11, member A) was very highly enriched in hucMSC-EVs. In addition, hucMSC-EVs enhanced the shift from adipogenic to osteogenic differentiation of BMSCs via delivering CLEC11A in vitro . Moreover, CLEC11A was required for the inhibitory effects of hucMSC-EVs on osteoclast formation. Conclusion: Our results suggest that hucMSC-EVs serve as a critical regulator of bone metabolism by transferring CLEC11A and may represent a potential agent for prevention and treatment of osteoporosis., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)

Poor wound healing affects millions of people worldwide each year and needs better therapeutic strategies. Synechococcus elongatus PCC 7942 is a naturally occurring photoautotrophic cyanobacterium that can be easily obtained and large-scale expanded. Here, we investigated the therapeutic efficacy of this cyanobacterium in a mouse model of acute burn injury and whether the secretion of extracellular vesicles (EVs), important mediators of cell paracrine activity, is a key mechanism of the cyanobacterium-induced regulation of wound healing. Methods : The effects of Synechococcus elongatus PCC 7942 on burn wound healing in mice under light or dark conditions were evaluated by measuring wound closure rates, histological and immunofluorescence analyses. A series of assays in vivo and in vitro were conducted to assess the impact of the cyanobacterium on angiogenesis. GW4869 was used to interfere with the secretion of EVs by the cyanobacterium and the abilities of the GW4869-pretreated and untreated Synechococcus elongatus PCC 7942 to regulate endothelial angiogenesis were compared. The direct effects of the cyanobacterium-derived EVs ( S. elongatus -EVs) on angiogenesis, wound healing and expressions of a class of pro-inflammatory factors that have regulatory roles in wound healing were also examined. Results : Synechococcus elongatus PCC 7942 treatment under light and dark conditions both significantly promoted angiogenesis and burn wound repair in mice. In vitro , the cyanobacterium enhanced angiogenic activities of endothelial cells, but the effects were markedly blocked by GW4869 pretreatment. S. elongatus -EVs were capable of augmenting endothelial angiogenesis in vitro , and stimulating new blood vessel formation and burn wound healing in mice. The expression of interleukin 6 (IL-6), which has an essential role in angiogenesis during skin wound repair, was induced in wound tissues and wound healing-related cells by S. elongatus -EVs and Synechococcus elongatus PCC 7942. Conclusion : Synechococcus elongatus PCC 7942 has the potential as a promising strategy for therapeutic angiogenesis and wound healing primarily by the delivery of functional EVs, not by its photosynthetic activity. The promotion of IL-6 expression may be a mechanism of the cyanobacterium and its EVs-induced pro-angiogenic and -wound healing effects., Competing Interests: Competing Interests: The authors have declared that no competing interest exists.

Recently, researchers identified a distinct vessel subtype called type H vessels that couple angiogenesis and osteogenesis. We previously found that type H vessels are reduced in ovariectomy (OVX)-induced osteoporotic mice, and preosteoclasts are able to secrete platelet-derived growth factor-BB (PDGF-BB) to stimulate type H vessel formation and thereby to promote osteogenesis. This study aimed to explore whether harmine, a β-carboline alkaloid, is capable of preventing bone loss in OVX mice by promoting preosteoclast PDGF-BB-induced type H vessel formation., Methods: The impact of harmine on osteoclastogenesis of RANKL-stimulated RAW264.7 cells was verified by gene expression analysis and tartrate-resistant acid phosphatase (TRAP) staining. Enzyme-linked immunosorbent assay (ELISA) was conducted to test PDGF-BB production by preosteoclasts. A series of angiogenesis-related assays in vitro were performed to assess the pro-angiogenic effects of the conditioned media from RANKL-stimulated RAW264.7 cells treated with or without harmine. Meanwhile, the role of PDGF-BB in this process was determined. In vivo , OVX mice were intragastrically administrated with harmine emulsion or an equal volume of vehicle. 2 months later, bone samples were collected for µCT, histological, immunohistochemical and immunofluorescent analyses to evaluate bone mass, osteogenic and osteoclastic activities, as well as the numbers of type H vessels. Bone marrow PDGF-BB concentrations were assessed by ELISA., Results: Exposure of RANKL-stimulated RAW264.7 cells to harmine enhanced the formation of preosteoclasts and the production of PDGF-BB. Harmine augmented the ability of RANKL-stimulated RAW264.7 cells to promote angiogenesis of endothelial cells, whereas the effect was blocked by PDGF-BB inhibition. In vivo , the oral administration of harmine emulsion to OVX mice resulted in enhanced trabecular bone mass and osteogenic responses, increased numbers of preosteoclasts, as well as reduced numbers of osteoclasts and fat cells. Moreover, OVX mice treated with harmine exhibited higher levels of bone marrow PDGF-BB and much more type H vessels in bone., Conclusion: Harmine may exert bone-sparing effects by suppression of osteoclast formation and promotion of preosteoclast PDGF-BB-induced angiogenesis., Competing Interests: Competing Interests: The authors have declared that no competing interest exists.

Chronic non-healing wounds represent one of the most common complications of diabetes and need advanced treatment strategies. Exosomes are key mediators of cell paracrine action and can be directly utilized as therapeutic agents for tissue repair and regeneration. Here, we explored the effects of exosomes from human urine-derived stem cells (USC-Exos) on diabetic wound healing and the underlying mechanism. Methods: USCs were characterized by flow cytometry and multipotent differentiation potential analyses. USC-Exos were isolated from the conditioned media of USCs and identified by transmission electron microscopy and flow cytometry. A series of functional assays in vitro were performed to assess the effects of USC-Exos on the activities of wound healing-related cells. Protein profiles in USC-Exos and USCs were examined to screen the candidate molecules that mediate USC-Exos function. The effects of USC-Exos on wound healing in streptozotocin-induced diabetic mice were tested by measuring wound closure rates, histological and immunofluorescence analyses. Meanwhile, the role of the candidate protein in USC-Exos-induced regulation of angiogenic activities of endothelial cells and diabetic wound healing was assessed. Results: USCs were positive for CD29, CD44, CD73 and CD90, but negative for CD34 and CD45. USCs were able to differentiate into osteoblasts, adipocytes and chondrocytes. USC-Exos exhibited a cup- or sphere-shaped morphology with a mean diameter of 51.57 ± 2.93 nm and positive for CD63 and TSG101. USC-Exos could augment the functional properties of wound healing-related cells including the angiogenic activities of endothelial cells. USC-Exos were enriched in the proteins that are involved in regulation of wound healing-related biological processes. Particularly, a pro-angiogenic protein called deleted in malignant brain tumors 1 (DMBT1) was highly expressed in USC-Exos. Further functional assays showed that DMBT1 protein was required for USC-Exos-induced promotion of angiogenic responses of cultured endothelial cells, as well as angiogenesis and wound healing in diabetic mice. Conclusion: Our findings suggest that USC-Exos may represent a promising strategy for diabetic soft tissue wound healing by promoting angiogenesis via transferring DMBT1 protein., Competing Interests: Competing Interests: The authors have declared that no competing interest exists.

The application of blood plasma for soft tissue wound healing is receiving much more attention recently. Exosomes are critical paracrine mediators that can be obtained from biological fluids including plasma and be able to induce regenerative effects by transferring bioactive molecules such as microRNAs (miRNAs). This study aimed to investigate the effects of exosomes from human umbilical cord blood plasma (UCB-Exos) on wound healing and to elucidate the underlying mechanism. Methods: UCB-Exos were isolated by ultracentrifugation and subcutaneously injected into full-thickness skin wounds in mice. The efficacy of UCB-Exos on wound healing was evaluated by measuring wound closure rates, histological analysis and immunofluorescence examinations. In vitro , quantitative real-time PCR (qRT-PCR) analysis was performed to detect the expression levels of a class of miRNAs that have positive roles in regulating wound healing. The scratch wound assay, transwell assay and cell counting kit-8 analysis were conducted to assess the effects of UCB-Exos on migration and proliferation of human skin fibroblasts and endothelial cells. Tube formation assay was carried out to test the impact of UCB-Exos on angiogenic tube formation ability of endothelial cells. Meanwhile, by using specific RNA inhibitors or siRNAs, the roles of the candidate miRNA and its target genes in UCB-Exos-induced regulation of function of fibroblasts and endothelial cells were assessed. Results: The local transplantation of UCB-Exos into mouse skin wounds resulted in accelerated re-epithelialization, reduced scar widths, and enhanced angiogenesis. In vitro , UCB-Exos could promote the proliferation and migration of fibroblasts, and enhance the angiogenic activities of endothelial cells. Notably, miR-21-3p was found to be highly enriched in UCB-Exos and served as a critical mediator in UCB-Exos -induced regulatory effects through inhibition of phosphatase and tensin homolog (PTEN) and sprouty homolog 1 (SPRY1). Conclusion: Our results suggest that UCB-Exos are important effectors of plasma activity and can be used as a novel promising strategy for soft tissue wound healing., Competing Interests: Competing Interests: The authors have declared that no competing interest exists.