rno‐miR‐90 promotes chondrogenic differentiation of bone marrow mesenchymal stem cells by targeting SPARC‐related modular calcium binding 2

AbstractBone marrow mesenchymal stem cells (BMSCs) have the ability to differentiate into chondrocytes. In the differentiation of BMSCs into chondrocytes, micro‐RNAs (miRNAs) play an important role. rno‐miR‐90 is a new miRNA discovered by our research team, and its role in chondrogenic differentiation of BMSCs is unknown. This study aimed to investigate whether rno‐miR‐90 could promote chondrogenic differentiation of BMSCs by regulating secreted protein acidic and rich in cysteine‐related modular calcium binding 2 (Smoc2). First, BMSCs chondroblast differentiation was successfully induced in vitro by classical induction method of transforming growth factor (TGF)‐β3. On this basis, we transfected rno‐miR‐90 mimic and inhibitor, and confirmed that rno‐miR‐90 mimic could promote the differentiation of BMSCs into chondrocytes by real‐time reverse transcription‐quantitative polymerase chain reaction (RT‐qPCR) and western blotting. In addition, we demonstrated that Smoc2 was a target gene of rno‐miR‐90 by dual‐luciferase reporter assay, and confirmed that rno‐miR‐90 mimic could inhibit the expression of Smoc2 by RT‐qPCR and western blotting. In order to further prove the targeting relationship between rno‐miR‐90 and Smoc2, we constructed three interfering fragments of Smoc2, and proved that silencing Smoc2 could promote the differentiation of BMSCs into chondrocytes at the transcriptional and protein levels. Finally, we constructed a carrier scaffold for ectopic chondrogenic differentiation in vivo, and confirmed that rno‐miR‐90 mimic and siSmoc2 could promote chondrogenic differentiation of BMSCs by Alcian blue staining and immunohistochemistry. In summary, our results suggested that rno‐miR‐90 could promote chondrogenic differentiation of BMSCs by down‐regulating the expression of Smoc2. rno‐miR‐90 mimic and Smoc2 may be therapeutic targets of osteoarthritis.