Background: The therapeutic potential of exosomes derived from stem cells has attracted increasing interest recently, because they can exert similar paracrine functions of stem cells and overcome the limitations of stem cells transplantation. Exosomes derived from bone mesenchymal stem cells (BMSC-Exos) have been confirmed to promote osteogenesis and angiogenesis. The magnetic nanoparticles (eg. Fe₃O₄, γ-Fe₂O₃) combined with a static magnetic field (SMF) has been commonly used to increase wound healing and bone regeneration. Hence, this study aims to evaluate whether exosomes derived from BMSCs preconditioned with a low dose of Fe₃O₄ nanoparticles with or without the SMF, exert superior pro-osteogenic and pro-angiogenic activities in bone regeneration and the underlying mechanisms involved. Methods: Two novel types of exosomes derived from preconditioned BMSCs that fabricated by regulating the contents with the stimulation of magnetic nanoparticles and/or a SMF. Then, the new exosomes were isolated by ultracentrifugation and characterized. Afterwards, we conducted in vitro experiments in which we measured osteogenic differentiation, cell proliferation, cell migration, and tube formation, then established an in vivo critical-sized calvarial defect rat model. The miRNA expression profiles were compared among the exosomes to detect the potential mechanism of improving osteogenesis and angiogenesis. At last, the function of exosomal miRNA during bone regeneration was confirmed by utilizing a series of gain- and loss-of-function experiments in vitro. Results: 50 µg/mL Fe₃O₄ nanoparticles and a 100 mT SMF were chosen as the optimum magnetic conditions to fabricate two new exosomes, named BMSC-Fe₃O₄-Exos and BMSC-Fe₃O₄-SMF-Exos. They were both confirmed to enhance osteogenesis and angiogenesis in vitro and in vivo compared with BMSC-Exos, and BMSC-Fe₃O₄-SMF-Exos had the most marked effect. The promotion effect was found to be related to the highly riched miR-1260a in BMSC-Fe₃O₄-SMF-Exos. Furthermore, miR-1260a was verified to enhance osteogenesis and angiogenesis through inhibition of HDAC7 and COL4A2, respectively. Conclusion: These results suggest that low doses of Fe₃O₄ nanoparticles combined with a SMF trigger exosomes to exert enhanced osteogenesis and angiogenesis and that targeting of HDAC7 and COL4A2 by exosomal miR-1260a plays a crucial role in this process. This work could provide a new protocol to promote bone regeneration for tissue engineering in the future. Graphical

Background: Both magnetic nanoparticles (MNPs) and exosomes derived from bone mesenchymal stem cells (BMSC-Exos) have been reported to improve wound healing. In this study, novel exosomes (mag-BMSC-Exos) would be fabricated from BMSCs with the stimulation of MNPs and a static magnetic field (SMF) to further enhance wound repair. Methods: Mag-BMSC-Exos, namely, exosomes derived from BMSCs preconditioned with Fe₃O₄ nanoparticles and a SMF, together with BMSC-Exos were both first isolated by ultracentrifugation, respectively. Afterwards, we conducted in vitro experiments, including scratch wound assays, transwell assays, and tube formation assays, and established an in vivo wound healing model. The miRNA expression profiles were compared between BMSC-Exos and mag-BMSC-Exos to detect the potential mechanism of improving wound healing. At last, the function of exosomal miR-21-5p during wound healing was confirmed by utilizing a series of gain- and loss-of-function experiments in vitro. Results: The optimal working magnetic condition was 50 μg/mL Fe₃O₄ nanoparticles combined with 100 mT SMF. In vitro, mag-BMSC-Exo administration promoted proliferation, migration and angiogenesis to a greater extent than BMSC-Exo administration. Local transplantation of mag-BMSC-Exos into rat skin wounds resulted in accelerated wound closure, narrower scar widths and enhanced angiogenesis compared with BMSC-Exo transplantation. Notably, miR-21-5p was found to be highly enriched in mag-BMSC-Exos and served as a critical mediator in mag-BMSC-Exo-induced regulatory effects through inhibition of SPRY2 and activation of the PI3K/AKT and ERK1/2 signaling pathways. Conclusion: Mag-BMSC-Exos can further enhance wound healing than BMSC-Exos by improving angiogenesis and fibroblast function, and miR-21-5p upregulation in mag-BMSC-Exos might be the potential mechanism. This work offers an effective and promising protocol to improve wound healing in clinic.

With the ability to produce components with complex and precise structures, additive manufacturing or 3D printing techniques are now widely applied in both industry and consumer markets. The emergence of tissue engineering has facilitated the application of 3D printing in the field of biomedical implants. 3D printed implants with proper structural design can not only eliminate the stress shielding effect but also improve in vivo biocompatibility and functionality. By combining medical images derived from technologies such as X-ray scanning, CT, MRI, or ultrasonic scanning, 3D printing can be used to create patient-specific implants with almost the same anatomical structures as the injured tissues. Numerous clinical trials have already been conducted with customized implants. However, the limited availability of raw materials for printing and a lack of guidance from related regulations or laws may impede the development of 3D printing in medical implants. This review provides information on the current state of 3D printing techniques in orthopedic implant applications. The current challenges and future perspectives are also included.

Background: Increasing evidence has proven that rheumatoid arthritis (RA) can aggravate atherosclerosis (AS), and we aimed to explore potential diagnostic genes for patients with AS and RA.Methods: We obtained the data from public databases, including Gene Expression Omnibus (GEO) and STRING, and obtained the differentially expressed genes (DEGs) and module genes with Limma and weighted gene co-expression network analysis (WGCNA). Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) enrichment analysis, the protein–protein interaction (PPI) network, and machine learning algorithms [least absolute shrinkage and selection operator (LASSO) regression and random forest] were performed to explore the immune-related hub genes. We used a nomogram and receiver operating characteristic (ROC) curve to assess the diagnostic efficacy, which has been validated with GSE55235 and GSE57691. Finally, immune infiltration was developed in AS.Results: The AS dataset included 5,322 DEGs, while there were 1,439 DEGs and 206 module genes in RA. The intersection of DEGs for AS and crucial genes for RA was 53, which were involved in immunity. After the PPI network and machine learning construction, six hub genes were used for the construction of a nomogram and for diagnostic efficacy assessment, which showed great diagnostic value (area under the curve from 0.723 to 1). Immune infiltration also revealed the disorder of immunocytes.Conclusion: Six immune-related hub genes (NFIL3, EED, GRK2, MAP3K11, RMI1, and TPST1) were recognized, and the nomogram was developed for AS with RA diagnosis.

The reconstruction of large bone defects remains a significant challenge for orthopedists. Three‐dimensional–printed (3DP) scaffold is considered a promising repair material. Static magnetic field (SMF) treatment is an effective and noninvasive therapeutic method to improve bone regeneration. However, the osteogenic effect of SMF on human bone–derived mesenchymal stem cells (hBMSCs) in 3DP scaffolds, as well as its potential mechanism, are unclear. In this study, the osteogenic effect of SMF on hBMSCs in a 3DP scaffold was investigated in vitro and in vivo . In addition, the potential mechanism for promoting osteogenesis was investigated by proteomic analysis. The results showed that SMF promoted osteogenic differentiation of hBMSCs in vitro . A total of 185 differential proteins were identified under SMF conditions by proteomic analysis. The osteogenic effect might be associated with bone morphogenetic protein‐Smad1/5/8–signaling pathway and increased transport of phosphorylated Smad1/5/8 and phosphorylated Smad2/3 to the nucleus by up‐regulating Smad4 under SMF conditions. The in vivo experiment showed that bone regeneration and osseointegration was enhanced by SMF in the rat model of bone defect. In conclusion, moderate SMF was a safe and effective method for enhancing osteogenesis in 3DP scaffolds in vitro and in vivo .—He, Y., Yu, L., Liu, J., Li, Y., Wu, Y., Huang, Z., Wu, D., Wang, H., Wu, Z., Qiu, G. Enhanced osteogenic differentiation of human bone–derived mesenchymal stem cells in 3‐dimensional printed porous titanium scaffolds by static magnetic field through up‐regulating Smad4. FASEB J. 33, 6069–6081 (2019). www.fasebj.org