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In this work, a tumor microenvironment (TME)-responsive biodegradable MnSiO3@Fe3O4 nanoplatform for dual-mode magnetic resonance imaging (MRI)-guided combinatorial cancer therapy was constructed. Fe3O4 nanoparticles decorated on the surface of MnSiO3 could effectively obstruct the pores of MnSiO3 and reduce the leakage of anticancer drugs under physiological conditions. The structure of the nanoplatform was broken under the weakly acidic and high-concentration glutathione conditions in the TME, resulting in the separation of the Fe3O4 nanoparticles from the nanoplatform and rapid drug release. In addition, the exfoliated Fe3O4 and released Mn2+ can help reduce the interference between their T1 and T2 contrast abilities, resulting in dual-mode MRI contrast enhancement. Furthermore, during the exfoliation process of the Fe3O4 nanocrystals, the catalytic activity of the Fe3O4 nanocrystals toward a Fenton-like reaction within cancer cells could be improved because of the increase in specific surface area, which led to the generation of highly toxic hydroxyl radicals and induced HeLa cell apoptosis. The nanoplatform also displayed excellent T1-T2 dual-mode MRI contrast enhancement and anticancer activity in vivo with reduced systemic toxicity. Thus, this multifunctional nanoplatform could be a potential nanotheranostic for dual-mode MRI-guided combinatorial cancer therapy.

The recapitulation of cartilage/bone formation via guiding induced pluripotent stem cells (iPSCs) differentiation toward chondrogenic mesoderm lineage is an ideal approach to investigate cartilage/bone development and also for cartilage/bone regeneration. However, current induction protocols are time-consuming and complicated to follow. Here, we established a rapid and efficient approach that directly induce iPSCs differentiation toward chondrogenic mesoderm lineage by regulating the crucial Bmp-4 and FGF-2 signaling pathways using a 3D rotary suspension culture system. The mechanical stimulation from 3D rotary suspension accelerates iPSCs differentiation toward mesodermal and subsequent chondrogenic lineage via the Bmp-4-Smad1 and Tgf-β-Smad2/3 signaling pathways, respectively. The scaffold-free homogenous cartilaginous pellets or hypertrophic cartilaginous pellets derived from iPSCs within 28 days were capable of articular cartilage regeneration or vascularized bone regeneration via endochondral ossification in vivo, respectively. This biomimetic culture approach will contribute to research related to cartilage/bone development, regeneration, and hence to therapeutic applications in cartilage-/bone-related diseases.

Segmental bone regeneration remains a considerable challenge due to the associated low degree of vascularization. To solve this problem, in this study, hollow-pipe-packed silicate bioceramic (BRT-H) scaffolds are fabricated using a coaxial three-dimensional (3D) printing technique. Based on a modified core/shell printer nozzle and a modulated viscoelastic bioceramic paste, hollow struts with an external diameter of 1 mm and internal dimeter of 500 μm can be directly printed, yielding a compressive strength of the BRT-H scaffolds as high as 26 MPa. Apart from the effects on osteogenesis, the bioactive ions released from the BRT scaffolds can also facilitate angiogenesis via inducing endothelial cell migration. More importantly, the hollow pipes not only significantly promote the rapid infiltration of host blood vessels into the channels but also exhibit great advantages for the delivery of stem cells and growth factors to further enhance tissue regeneration. When used for the regeneration of rabbit radius segmental defects, radiological and histological findings indicate that the BRT-H scaffolds can enhance early vascularization and later bone regeneration and remodeling. Taken together, the hollow pipes and the ionic products from BRT-H scaffolds have a synergistic effect on enhancing vascularized bone regeneration.

In this work, a tumor microenvironment (TME)-responsive biodegradable MnSiO

Chemodynamic therapy (CDT) was widely exploited for cancer therapy and expected to replace traditional anticancer drug therapies. Generally, CDT needs to combine with extra therapeutic methods for obtaining the optimal therapeutic efficacy of cancer. Herein, a multifunctional theranostic platform combing CDT with limotherapy was developed via nanoselenium (nano-Se)-coated manganese carbonate-deposited iron oxide nanoparticle (MCDION-Se). MCDION-Se could release abundant of Mn2+ ions that catalyzed H2O2 into hydroxyl radicals (·OH) via a Fenton-like reaction, effectively inducing the apoptosis of cancer cells. Besides, nano-Se coated onto MCDION-Se also dramatically activated superoxide dismutase (SOD) and promoted the generation of superoxide anion radicals (SOARs) in tumor tissue. Subsequently, a high content of H2O2 was produced via SOD catalysis of SOARs, further enhancing CDT efficiency. Meanwhile, the nano-Se and Mn2+ ions inhibited the generation of adenosine triphosphate (ATP), thus starving cancer cells. In addition, in vitro and in vivo experiments showed that MCDION-Se could effectively enhance the contrast of tumor tissue and improve the quality of magnetic resonance imaging (MRI). Overall, this work provided a nanoplatform that combined CDT with limotherapy for cancer therapy and simultaneously utilized MRI for monitoring the treatment of tumors.

The regeneration capacity of the osteoporotic bones is generally lower than that of the normal bones. Current methods of bone defect treatment for osteoporosis are not always satisfactory. Recent studies have shown that the silicate based biomaterials can stimulate osteogenesis and angiogenesis due to the silicon (Si) ions released from the materials, and enhance bone regeneration in vivo. Other studies showed that strontium (Sr) plays a distinct role on inhibiting bone resorption. Based on the hypothesis that the combination of Si and Sr may have synergetic effects on osteoporotic bone regeneration, the porous Sr-substituted calcium silicate (SrCS) ceramic scaffolds combining the functions of Sr and Si elements were developed with the goals to promote osteoporotic bone defect repair. The effects of the ionic extract from SrCS on osteogenic differentiation of bone marrow mesenchymal stem cells derived from ovariectomized rats (rBMSCs-OVX), angiogenic differentiation of human umbilical vein endothelial cells (HUVECs) were investigated. The in vitro results showed that Sr and Si ions released from SrCS enhanced cell viability, alkaline phosphatase (ALP) activity, and mRNA expression levels of osteoblast-related genes of rBMSCs-OVX and expression of vascular endothelial growth factor (VEGF) without addition of extra osteogenic and angiogenic reagents. The activation in extracellular signal-related kinases (ERK) and p38 signaling pathways were observed in rBMSCs-OVX cultured in the extract of SrCS, and these effects could be blocked by ERK inhibitor PD98059, and P38 inhibitor SB203580, respectively. Furthermore, the ionic extract of SrCS stimulated HUVECs proliferation, differentiation and angiogenesis process. The in vivo experiments revealed that SrCS dramatically stimulated bone regeneration and angiogenesis in a critical sized OVX calvarial defect model, and the enhanced bone regeneration might be attributed to the modulation of osteogenic differentiation of endogenous mesenchymal stem cells (MSCs) and the inhibition of osteoclastogenesis, accompanying with the promotion of the angiogenic activity of endothelial cells (ECs).

Tissue engineering combined with gene therapy represents a promising approach for bone regeneration. The Hypoxia-inducible factor-1α (HIF-1α) gene is a pivotal regulator of vascular reactivity and angiogenesis. Our recent study has showed that HIF-1α could promote osteogenesis of bone mesenchymal stem cells (BMSCs) using a gene point mutant technique. To optimize the function of HIF-1α on inducing stem cells, another constitutively active form of HIF-1α (CA5) was constructed with truncation mutant method and its therapeutic potential on critical-sized bone defects was evaluated with calcium-magnesium phosphate cement (CMPC) scaffold in a rat model. BMSCs were treated with Lenti (lentivirus) -CA5, Lenti-WT (wild-type HIF-1α), and Lenti-LacZ. These genetically modified BMSCs were then combined with CMPC scaffolds to repair critical-sized calvarial defects in rats. The results showed that the overexpression of HIF-1α obviously enhanced the mRNA and protein expression of osteogenic markers in vitro and robust new bone formation with the higher local bone mineral density (BMD) was found in vivo in the CA5 and WT groups. Furthermore, CA5 showed significantly greater stability and osteogenic activity in BMSCs compared with WT. These data suggest that BMSCs transduced with truncation mutanted HIF-1α gene can promote the overexpression of osteogenic markers. CMPC could serve as a potential substrate for HIF-1α gene modified tissue engineered bone to repair critical sized bony defects.

Premineralized silk fibroin protein scaffolds (mSS) were prepared to combine the osteoconductive properties of biological apatite with aqueous-derived silk scaffold (SS) as a composite scaffold for bone regeneration. The aim of present study was to evaluate the effect of premineralized silk scaffolds combined with bone morphogenetic protein-2 (BMP-2) modified bone marrow stromal cells (bMSCs) to repair mandibular bony defects in a rat model. bMSCs were expanded and transduced with adenovirus AdBMP-2, AdLacZ gene in vitro. These genetically modified bMSCs were then combined with premineralized silk scaffolds to form tissue-engineered bone. Mandibular repairs with AdBMP-2 transduced bMSCs/mSS constructs were compared with those treated with AdLacZ-transduced bMSCs/mSS constructs, native (nontransduced) bMSCs/mSS constructs and mSS alone. Eight weeks after post-operation, the mandibles were explanted and evaluated by radiographic observation, micro-CT, histological analysis and immunohistochemistry. The presence of BMP-2 gene enhanced tissue-engineered bone in terms of the most new bone formed and the highest local bone mineral densities (BMD) found. These results demonstrated that premineralized silk scaffold could serve as a potential substrate for bMSCs to construct tissue-engineered bone for mandibular bony defects. BMP-2 gene therapy and tissue engineering techniques could be used in mandibular repair and bone regeneration.

Sonication-induced silk hydrogels were previously prepared as an injectable bone replacement biomaterial, with a need to improve osteogenic features. Vascular endothelial growth factor (VEGF(165)) and bone morphogenic protein-2 (BMP-2) are key regulators of angiogenesis and osteogenesis, respectively, during bone regeneration. Therefore, the present study aimed at evaluating in situ forming silk hydrogels as a vehicle to encapsulate dual factors for rabbit maxillary sinus floor augmentation. Sonication-induced silk hydrogels were prepared in vitro and the slow release of VEGF(165) and BMP-2 from these silk gels was evaluated by ELISA. For in vivo studies for each time point (4 and 12 weeks), 24 sinus floors elevation surgeries were made bilaterally in 12 rabbits for the following four treatment groups: silk gel (group Silk gel), silk gel/VEGF(165) (group VEGF), silk gel/BMP-2 (group BMP-2), silk gel/VEGF(165)/BMP-2 (group V + B) (n = 6 per group). Sequential florescent labeling and radiographic observations were used to record new bone formation and mineralization, along with histological and histomorphometric analysis. At week 4, VEGF(165) promoted more tissue infiltration into the gel and accelerated the degradation of the gel material. At this time point, the bone area in group V + B was significantly larger than those in the other three groups. At week 12, elevated sinus floor heights of groups BMP-2 and V + B were larger than those of the Silk gel and VEGF groups, and the V + B group had the largest new bone area among all groups. In addition, a larger blood vessel area formed in the remaining gel areas in groups VEGF and V + B. In conclusion, VEGF(165) and BMP-2 released from injectable and biodegradable silk gels promoted angiogenesis and new bone formation, with the two factors demonstrating an additive effect on bone regeneration. These results indicate that silk hydrogels can be used as an injectable vehicle to deliver multiple growth factors in a minimally invasive approach to regenerate irregular bony cavities.

Cryopreserved bone-derived osteoblasts (CBOs) have been considered as a promising cell source for bone regeneration. Previous studies have demonstrated that CBOs had good proliferation and osteogenicity. However, the long-term outcome of CBOs in vivo still remains unknown. In this experiment, we applied CBOs combined with calcium phosphate cement (CPC) to augment maxillary sinus in canine, computer tomography, polychrome labeling, biomechanical tests, fluorescent immunohistochemistry staining and histological analysis were used to analyze the property and mineralization process of the tissue-engineered bone preclinical application. Our results showed that CBOs combined with CPC could promote bone regeneration, dramatically maintain the height, volume and biomechanical property of augmented maxillary sinus. Furthermore, the tissue-engineered bone was more mature than scaffold alone or autogenous bone, and bone formation and remodeling were still apparent 20 months postoperatively. Additionally, 4 months after surgery might be the suitable time point for implants placement in the regenerated bone. These results also indicate that cryopreserved bone may be a potential source of osteoblasts for maxillary sinus augmentation.

The emerging fields of tissue engineering and regenerative medicine require large numbers of cells for therapy. Although the properties of cells obtained from a variety of fresh tissues have been delineated, the knowledge regarding cryopreserved grafts-derived cells remains elusive. Previous studies have shown that living cells could be isolated from cryopreserved bone grafts. However, whether cryopreserved bone-derived cells can be applied in regenerative medicine is largely unknown. The present study was to evaluate the potential application of cryopreserved grafts-derived cells for tissue regeneration. We showed that cells derived from cryopreserved bone grafts could maintain good proliferation activity and osteogenic phenotype. The biological phenotype of these cells could be well preserved. The transplantation of cryopreserved bone-derived cells on scaffold could promote new bone formation in nude mice and enhance the osteointegration for dental implants in canine, which confirmed their osteogenic capacity, and showed that cells derived from cryopreserved bone were comparable to that of fresh bone in terms of the ability to promote osteogenesis in vivo. This work demonstrates that cryopreserved bone grafts may represent a novel, accessible source of cells for tissue regeneration therapy, and the results of our study may also stimulate the development of other cryopreservation techniques in basic and clinical studies.

A tissue-engineered bone has become a viable alternative to autologous bone for bone augmentation in atrophy alveolar ridge. The aim of the present study was to evaluate porous beta-tricalcium phosphate (beta-TCP) combined with autologous osteoblasts to augment edentulous alveolar ridge in a canine model. Autologous osteoblasts were expanded and combined with beta-TCP scaffold to fabricate a tissue-engineered bone. 12 bilateral alveolar ridge augmentation surgeries were carried out in 6 beagle dogs with the following 3 groups: beta-TCP/osteoblasts, beta-TCP alone and autogenous iliac bone control (n=4 per group). Sequential fluorescent labeling and radiographs were used to compare new bone formation and mineralization in each group. 24 weeks later, animals were sacrificed and non-decalcified and decalcified sections were evaluated histologically and histomorphometrically. Results indicated that the tissue-engineered bone dramatically enhanced new bone formation and mineralization, increase the new bone area, and maintain the height and thickness of the augmented alveolar ridge when compared with beta-TCP alone group. More importantly, the tissue-engineered bone achieved an elevated bone height and thickness comparable to that of autogenous iliac bone graft. This study demonstrated the potential of porous beta-TCP as a substrate for autogenous osteoblasts in bone tissue engineering for alveolar ridge augmentation.