Focal adhesion kinase promotes BMP2-induced osteogenic differentiation of human urinary stem cells via AMPK and Wnt signaling pathways

Human urine-derived stem cells (hUSCs) serve as favorable candidates for bone transplants due to their efficient proliferative and multipotent differentiation abilities, as well as the capacity to secrete a variety of vasoactive agents to facilitate tissue engineering. The present study aimed to explore the role of focal adhesion kinase (FAK) in bone morphogenetic protein 2 (BMP2)-induced osteogenic differentiation of hUSCs and to investigate the underlying mechanism. The degree of osteogenic differentiation and the correlated signals, following BMP2 overexpression and siRNA-mediated silencing of FAK, were determined in vitro. Moreover, hUSCs induced bone formation in a rat model with cranial defects, in vivo. Our findings revealed that alkaline phosphatase production, calcium deposits, osteocalcin and osteopontin expression, and bone formation were upregulated in vitro and in vivo following BMP2-induced osteogenic differentiation, and AMPK and Wnt signaling pathway activation by FAK could effectively regulate BMP2-enhanced osteogenic differentiation of hUSCs. Taken together, these findings indicated that FAK could mediate BMP2-enhanced osteogenic differentiation of hUSCs through activating adenosine 5'-monophosphate-activated protein kinase and Wnt signaling pathways.