Activation of cannabinoid receptor 2 enhances osteogenic differentiation of bone marrow derived mesenchymal stem cells

Abstract

Bone marrow derived mesenchymal stem cells (BM-MSCs) are considered as the most promising cells source for bone engineering. Cannabinoid (CB) receptors play important roles in bone mass turnover. The aim of this study is to test if activation of CBreceptor by chemical agonist could enhance the osteogenic differentiation and mineralization in bone BM-MSCs. Alkaline phosphatase (ALP) activity staining and real time PCR were performed to test the osteogenic differentiation. Alizarin red staining was carried out to examine the mineralization. Small interference RNA (siRNA) was used to study the role of CBreceptor in osteogenic differentiation. Results showed activation of CBreceptor increased ALP activity, promoted expression of osteogenic genes, and enhanced deposition of calcium in extracellular matrix. Knockdown of CBreceptor by siRNA inhibited ALP activity and mineralization. Results of immunofluorescent staining showed that phosphorylation of p38 MAP kinase is reduced by knocking down of CBreceptor. Finally, bone marrow samples demonstrated that expression of CBreceptor is much lower in osteoporotic patients than in healthy donors. Taken together, data from this study suggested that activation of CBreceptor plays important role in osteogenic differentiation of BM-MSCs. Lack of CBreceptor may be related to osteoporosis.