Abstract: Objective:?To Explore the function and mutual regulatory mechanism of miR-615-3p and its target gene fibronectin 1 (FBLN1) in osteogenic differentiation of adipose derived stem cells (ADSCs). Methods：Using lentivirus transfection to obtain miR-615-3p knockdown ADSCs and FBLN1 overexpressing ADSCs, qRT-PCR and Western blot were used to detect the knockdown efficiency of miR-615-3p and FBLN1 overexpression efficiency, as well as the expression of FBLN1 after knocking down miR-615-3p. The effects of knocking down miR-615-3p and overexpressing FBLN1 on the osteogenic differentiation ability of ADSCs were evaluated by alkaline phosphatase (ALP) activity assay and alizarin Red staining. Detection of gene expression of osteogenic cell specific transcription factors Osterix (OSX), dentin sialoprotein (DSPP), and dentin matrix protein-1 (DMP1) in knocking down miR-615-3p and overexpressing FBLN1 ADSCs by qRT-PCR. The expression changes of DMP1 and DSPP were detected by Western blot in knocking down miR-615-3p and overexpression of FBLN1. Results：After knocking down miR-615-3p in ADSCs, miR-615-3p gene expression decreased, ALP activity increased (P>0.05), mineralized nodules increased, OSX, DMP1, DSPP gene expression levels increased (P>0.05), and DMP1 and DSPP protein expression increased. The expression of FBLN1 was increased in ADSCs with low expression of miR-615-3p. After overexpression of FBLN1, the expression of FBLN1 gene increased, ALP activity increased (P>0.05), mineralized nodules increased, and the expression levels of osteogenic related indicators such as OSX, DMP1, DSPP increased (P>0.05). Conclusions：miR-615-3p inhibits osteogenic differentiation of ADSCs by downregulating FBLN1.

Key words: miR-615-3p, fibulin 1, adipose derived stem cells, osteogenic differentiation