Linc-ROR promotes mesenchymal stem cells chondrogenesis and cartilage formation via regulating SOX9 expression

The present study is to characterize the role of long intergenic non-coding RNA, regulator of reprogramming (linc-ROR) in bone marrow mesenchymal stem cell (BMSCs) chondrogenesis, cartilage formation and OA development.

Linc-ROR expression pattern in articular cartilage tissue sample from OA patients were studied by real-time PCR. Linc-ROR lentivirus mediated BMSCs were constructed. In vitro micromass cultured BMSCs chondrogenesis or in vivo MeHA hydrogel encapsulated BMSCs cartilage formation activity were studied. Linc-ROR associating miRNAs which repressed SOX9 expression were characterized by luciferase assay, real-time PCR and Western blot. Linc-ROR was co-transfected with miRNAs into BMSCs to study its rescue effect on SOX9 expression and chondrogenesis activity.

Linc-ROR was down-regulated in articular cartilage tissue from OA patients and was positively correlated with the expression level of SOX9 (R² = 0.43). Linc-ROR expression was upregulated during BMSCs chondrogenesis. Linc-ROR ectopic expression significantly promoted in vitro BMSCs chondrogenesis and in vivo cartilage formation activities as revealed by safranin O, alcian blue and COL II staining. The mRNA expression level of chondrogenesis markers including COL II, SOX9 and ACAN were increased, and the hypertrophy markers MMP13 and COL X were decreased upon linc-ROR overexpression in BMSCs. Linc-ROR functioned as a miRNA sponge for miR-138 and miR-145. Both miR-138 and miR-145 suppressed BMSCs chondrogenesis activity and SOX9 expression, while co-expression of linc-ROR displayed a rescuing effect.

Taken together, linc-ROR modulated BMSCs chondrogenesis differentiation and cartilage formation by acting as a competing endogenous RNA for miR-138 and miR-145 and activating SOX9 expression. Linc-ROR could be considered as a new diagnostic and therapeutic target for OA treatment.