miR-23a/b regulates the balance between osteoblast and adipocyte differentiation in bone marrow mesenchymal stem cells

Age-related osteoporosis is associated with the reduced capacity of bone marrow mesenchymal stem cells （BMSCs） to differentiate into osteoblasts instead of adipocytes. However, the molecular mechanisms that decide the fate of BMSCs remain unclear. In our study, microRNA-23a, and microRNA-23b （miR-23a/b） were found to be markedly downregulated in BMSCs of aged mice and humans. The overexpression of miR-23a/b in BMSCs promoted osteogenic differentiation, whereas the inhibition of miR-23a/b increased adipogenic differentiation. Transmembrane protein 64 （Tmem64）, which has expression levels inversely related to those of miR-23a/b in aged and young mice, was identified as a major target of miR-23a/b during BMSC differentiation. In conclusion, our study suggests that miR-23a/b has a critical role in the regulation of mesenchymal lineage differentiation through the suppression of Tmem64.

Total knee arthroplasty in Ranawat Ⅱ valgus deformity with enlarged femoral valgus cut angle:A new technique to achieve balanced gap

BACKGROUND Nearly 10%of patients undergoing primary total knee arthroplasty(TKA)have valgus deformity(VD)of the knee.For severe VD of the knee,a more lateral structural release is needed to achieve balance between medial and lateral space and neutral femorotibial mechanical axis(FTMA),which is challenging and technical.AIM To introduce a new surgical technique of resection,soft tissue release,and FTMA for Ranawat type-Ⅱ VD with a 5-year follow-up.METHODS A retrospective study was conducted on patients who underwent TKA from December 2011 to December 2014.Hip-knee-ankle(HKA),range of motion(ROM),Oxford knee score(OKS),and knee society score(KSS)were used to assess the joint activity of patients in the new theory TKA group(NT-TKA)and were compared with those of the conventional TKA group(C-TKA).RESULTS A total of 103 people(103 knees)were included in this study,including 42 patients with an average follow-up period of 83 mo in the C-TKA group and 61 patients with an average follow-up period of 76 mo in the NT-TKA group.Six patients had constrained prosthesis,one had common peroneal nerve injury,and two had joint instability in the C-TKA group,but none of these occurred in the NT-TKA group.There were significant statistical differences in constrained prosthesis usage and complications between the groups(P=0.002 and P=0.034,respectively).The KSS at 1 mo post-operation for the C-TKA and NT-TKA groups were 11.2±3.8 and 13.3±2.9,respectively,with a significant difference(P=0.007).However,the data of HKA,ROM,OKS KSS,and prosthesis survival rate were insignificant(P>0.05)in both the preoperative and follow-up periods.CONCLUSION Adopting 5°-7°valgus cut angle for VD and sacrificing 2°neutral FTMA for severe VD which cannot be completely corrected during TKA can reduce the need for soft tissue release,maintain early joint stability,reduce the use of constrained prostheses,and minimize postoperative complications.