Co-Culture of Bone Marrow Mesenchymal Stem Cell (BMSC) and Osteoclasts Regulates Cell Differentiation and Alleviates Osteoporosis by Up-Regulating miR-211

Bone marrow mesenchymal stem cells (BMSCs) can release a large amount of exosomes (EXO) during bone remodeling by osteoclasts. EXO contains miRNA-211, which has a variety of biological effects. However, little is known about whether miR-211 from BMSC-EXO affects the surrounding cells. Therefore, we aim to study the role of miRNA-211 derived from BMSC-EXO in regulating osteoclasts differentiation. Macrophage colony stimulating factor (M-CSF) and nuclear factor kappa B receptor activator (RANKL) were used to stimulate bone marrow macrophages (BMM) to obtain osteoclasts, which were treated with BMSC-EXO or LPS followed by analysis of osteoclast-related genes expression by PCR, ROS release by flow cytometry, actin ring formation by immunofluorescence, and osteoclast differentiation by anti-tartrate acid phosphatase (TRAP) staining. Finally, an in vivo experiment was conducted to verify BMSC-EXO’s effect on osteoporosis. BMSC-EXO significantly inhibited RNAKL-induced osteoclast differentiation of BMMs. During osteoclasts formation, BMSC-EXO inhibited ROS production induced by RANKL and the subsequent activation of NF-κB signaling pathway induced by ROS. In addition, BMSC-EXO significantly down-regulated the osteoclast genes including nuclear factor, cytoplasmic 1 (NFATc1), C-fos, tartrate-resistant acid phosphatase (TRAP) and osteoclast-associated immunoglobulin-like receptor (OSCAR) in activated T cells. BMSC-EXO inhibited ROS release by promoting miR-211 expression, thereby inhibiting the NF-κB signaling and ultimately participating in osteoclasts differentiation. In LPS-induced mouse osteoporosis models, BMSC-EXO inhibited LPS-induced bone loss and exerted a protective effect. In conclusion, microRNA-211 derived from BMSC-EXO can regulate osteoclasts differentiation, suggesting that it might be used as a potential approach for treating osteoporosis.

Second Generation Needling Techniques for the Treatment of Chondral Defects in Animal Model

Purpose To compare the macroscopic, histological, and immunohistochemical characteristics of the repair tissue of chondral defects treated with microfracture and nanofracture in an ovine model. Methods Full-thickness chondral lesions were created in the medial femoral condyle of both knees in four adult sheep and were treated with microfracture on one side and with nanofracture on the contralateral side. Chondral repair was assessed after 12 months by macroscopic, histological, and immunohistochemical analyses. Results Histological cartilage repair significantly improved in the samples treated with nanofracture for cellular morphological characteristics and cartilage architecture. The immunohistochemical analysis showed a significantly higher immunoreactivity to type II collagen in the defects treated with nanofracture. Conclusion Nanofracture provided better repair tissue than microfracture, with a more satisfactory cartilage architecture renovation and tissue having greater type II collagen content. Clinical Relevance Mesenchymal stem cell stimulation is the most frequently used primary cartilage repair procedure. Nanofracture represents a novel technique to stimulate bone marrow that results into a successful repair of chondral defects.

Erythropoietin Gene Expression in the Stromal Cell Increased by Silica to Induce Erythrocyte Differentiation

Silica containing materials are often applied in bone tissue engineering, which may contact with bone marrow cells. However, the biological effects have not always been observed in studies of bone marrow cells exposed to silica. In this experiment, the relevant biological effects were evaluated. Bone marrow cells and stromal cells treated with silica particles (0.5-10 μm) were applied to investigate the possible interaction mechanism. HEL-92 cells were culture with the condition medium of stromal cells treated with or without silica particles. The erythrogenesis of bone marrow cells treated with silica particles was increased significantly. The expression level of glycophorin A the erythroid marker in HEL-92 cells treated by condition medium was higher than control group. The silica particles could also up-regulate the erythropoietin gene expression of stromal cells. The results indicate that bone marrow cells can be stimulated by silica particles to differentiate into erythrocytes. Our results suggest that silica particles can stimulate bone marrow cells to differentiate erythrocytes possibly via enhancing gene expression of erythropoietin.