The α-calcitonin gene-related peptide (α-CGRP) regulates bone metabolism and has potential applications in enhancing bone remodeling in vivo. However, α-CGRP's role in bone marrow mesenchymal stem cells (BMSCs) osteogenic differentiation remain
unclear. Rat BMSCs were separated into control group, α-CGRP group and α-CGRP siRNA group, in which BMSCs were transfected with α-CGRP plasmid and α-CGRP siRNA respectively followed by analysis of α-CGRP level by real time PCR
and ELISA, cell proliferation by MTT assay, Caspase 3 activity, ALP activity, formation of calcified nodules by alizarin red staining, Smad1 and Smad7 level by Western blot and Runx2 by real time PCR. αCGRP transfection into BMSCs significantly up-regulated CGRP, which could promote
cell proliferation, inhibit Caspase 3 activity, promote ALP activity, increase calcified nodules formation and upregulate Smad1, Smad7 and Runx2 compared to control (P < 0.05); transfection of αCGRP siRNA significantly down-regulated CGRP in BMSCs, inhibited cell proliferation,
promoted Caspase 3 activity, inhibited ALP activity, inhibited calcified nodules formation and downregulate Smad1, Smad7 and Runx2 (P < 0.05). αCGRP overexpression promotes the Smad/Runx2 signaling, which in turn promotes BMSCs proliferation and osteogenesis. Decreased
αCGRP level inhibits Smad/Runx2 signaling, promotes BMSCs apoptosis, inhibits proliferation and osteogenic differentiation.