Down-regulation of exosomal microRNA-224-3p derived from bone marrow-derived mesenchymal stem cells potentiates angiogenesis in traumatic osteonecrosis of the femoral head.

Traumatic osteonecrosis of the femoral head (ONFH) is a condition leading to the collapse of the femoral head, and the primary treatment is a total hip replacement, which has a poor prognosis. The current study was conducted with the aim of investigating the role of exosomes from bone marrow-derived mesenchymal stem cells (BM-MSCs) carrying microRNA-224-3p (miR-224-3p) in traumatic ONFH. Initially, a microarray analysis was performed to screen the differentially expressed genes and miRs associated with traumatic ONFH. Patients with traumatic and nontraumatic ONFH were enrolled, and HUVECs were obtained. The BM-MSCs-derived exosomes were purified and characterized, after which HUVECs were cocultured with exosomes. The functional role of miR-224-3p in traumatic ONFH was determined using ectopic expression, depletion, and reporter assay experiments. Endothelial cell proliferation, migration, invasion abilities, and angiogenesis were evaluated. Based on microarray analysis, miR-224-3p was found to be down-regulated, whereas focal adhesion kinase family interacting protein of 200 kDa (FIP200) was up-regulated in ONFH. Traumatic ONFH exosomes resulted in the up-regulation of FIP200 and down-regulation of miR-224-3p. FIP200 was confirmed to be a target gene of miR-224-3p. Exosomes were internalized by vascular endothelial cells. The down-regulation of exosomal miR-224-3p was observed to promote endothelial cell proliferation, migration, invasion abilities, angiogenesis, and FIP200 expression. In addition, FIP200 overexpression promoted angiogenesis. In summary, the results highly indicated that lower miR-224-3p levels in exosomes derived from BM-MSCs promote angiogenesis of traumatic ONFH by up-regulating FIP200. The present study provides a potential strategy for the treatment of traumatic ONFH.-Xu, H.-J., Liao, W., Liu, X.-Z., Hu, J., Zou, W.-Z., Ning, Y., Yang, Y., Li, Z.-H. Down-regulation of exosomal microRNA-224-3p derived from bone marrow-derived mesenchymal stem cells potentiates angiogenesis in traumatic osteonecrosis of the femoral head.

BMSC-derived exosomes carrying microRNA-122-5p promote proliferation of osteoblasts in osteonecrosis of the femoral head.

Mesenchymal stem cells (MSCs) with multipotential differentiation capacity can differentiate into bone cells under specific conditions and can be used to treat osteonecrosis (ON) of the femoral head (ONFH) through cell transplantation. The current study aims to explore the role of bone marrow (BM) MSCs (BMSCs)-derived exosomes carrying microRNA-122-5p (miR-122-5p) in ONFH rabbit models.First, rabbit models with ONFH were established. ONFH-related miRNAs were screened using the Gene Expression Omnibus (GEO) database. A gain-of-function study was performed to investigate the effect of miR-122-5p on osteoblasts and BMSCs and effects of exosomes carrying miR-122-5p on ONFH. Co-culture experiments for osteoblasts and BMSCs were performed to examine the role of exosomal miR-122-5p in osteoblast proliferation and osteogenesis. The target relationship between miR-122-5p and Sprouty2 (SPRY2) was tested.MiR-122, significantly decreased in ONFH in the GSE89587 expression profile, was screened. MiR-122-5p negatively regulated SPRY2 and elevated the activity of receptor tyrosine kinase (RTK), thereby promoting the proliferation and differentiation of osteoblasts. In vivo experiments indicated that bone mineral density (BMD), trabecular bone volume (TBV), and mean trabecular plate thickness (MTPT) of femoral head were increased after over-expressing miR-122-5p in exosomes. Significant healing of necrotic femoral head was also observed.Exosomes carrying over-expressed miR-122-5p attenuated ONFH development by down-regulating SPRY2 via the RTK/Ras/mitogen-activated protein kinase (MAPK) signaling pathway. Findings in the present study may provide miR-122-5p as a novel biomarker for ONFH treatment.

Overexpressing Runx2 of BMSCs Improves the Repairment of knee Cartilage Defects.

BACKGROUND: Recruitment of gene modifying bone marrow mesenchymal stem cells (BMSCs) has been considered an alternative to single-cell injection in articular cartilage repair. PURPOSE: This study aimed to investigate whether the effect of runt-related transcription factor 2(Runx2) overexpression bone marrow mesenchymal stem cells in vivo could improve the quality of repaired tissue of a knee cartilage defect in a rabbit model. METHODS: Thirty-two New Zealand rabbits were randomly divided into four groups. The blank group (Con) did not receive anything, the model group (Mo) was administered saline, the simple stem cell group (MSCs) received MSCs injection, and the Runx2 transfection group (R-MSCs) received Runx2 overexpression MSCs injection. After adapting to the environment for a week, a 5 mm diameter cylindrical osteochondral defect was created in the center of the medial femoral condyle. Cell and saline injections were performed in the first and third weeks after surgery. The cartilage repair was evaluated by macroscopically and microscopically at 4 and 8 weeks. RESULTS: Macroscopically, defects were filled and surfaces were smoother in the MSCs groups than in the Mo group at 4th week. Microscopically, the R-MSCs group showed coloration similar to surrounding normal articular cartilage tissue at 8 weeks in masson trichrome staining. The COL-II, SOX9, and Aggrecan mRNA expressions of MSCs were enhanced at 4 weeks compared with R-MSCs, then the expression reduced at 8 weeks, but was still higher than Mo group level (P<0.05). The western blot examination revealed that the COL-IIand SOX9 expression of MSCs was higher than R-MSCs at 4 weeks, then the expression reduced at 8 weeks, but was still higher than the Mo level (P<0.05). The IL-1ß content in the joint fluid also revealed that cartilage repair with R-MSCs was better than that with MSCs at 8 weeks (P<0.05). CONCLUSION: The R-MSCs group showed cellular morphology and arrangement similar to surrounding normal articular cartilage tissue, and Runx2 overexpression of MSCs resulted in overall superior cartilage repair as compared with MSCs at 8 weeks.