Maclurin Promotes the Chondrogenic Differentiation of Bone Marrow Mesenchymal Stem Cells by Regulating miR-203a-3p/Smad1.

Bone marrow mesenchymal stem cells (BMSCs) differentiate into chondrocytes under appropriate conditions, providing a method for the treatment of bone- and joint-related diseases. Previously, we found that mulberry ( Morus nigra ) promoted the chondrogenic differentiation of BMSCs. Although the mechanism of action and active ingredients remain unknown, several studies describe the involvement of micro-RNAs. We obtained BMSCs from the bone marrow of Sprague Dawley rats. Cell Counting Kit-8 assays showed that maclurin (25 μg/mL) treatment was not toxic to BMSCs, and compared with untreated controls, maclurin upregulated Sox9 and Col2a expression. Quantitative-PCR revealed that miR-203a-3p levels decreased significantly during chondrogenic differentiation of BMSCs promoted by maclurin. Compared with treatment with an miR-203a-3p inhibitor, miR-203a-3p mimic inhibited expression of Sox9 and Col2a as evidenced by immunofluorescence staining and Western blotting. Smad1 was identified as a key target gene of miR-203a-3p according to biological-prediction software, and miR-203a-3p negatively regulated its transcription and translation in the dual-luciferase reporter gene assay and Western blotting. Sox9 and Col2a expression was downregulated following transfection of short interfering Smad1 (siSmad1) plasmids into BMSCs. We elucidated how maclurin promotes the chondrogenic differentiation of BMSCs by regulating miR-203a-3p/Smad1, which provides a strategy for future exploration of osteoarthritis therapy through cell transplantation.