Study on the Osteogenic Differentiation of hUCMSCs in Silk Fibroin/Polycaprolactone Membrane Under the Intervention of Photobiomodulation

Abstract

Fractures, as the most common traumatic injuries, were a significant health problem worldwide. Presently, the application of tissue engineering in the treatment of bone defects has received massive attention. Herein, we verified that photobiomodulation (PBM) could accelerate the osteogenic differentiation of human umbilical cord mesenchymal stem cells (hUCMSCs) on the silk fibroin/polycaprolactone (SF/PCL) membrane, providing a new insight into tissue engineering. HUCMSCs were divided into non-irradiated group and experimental groups. The laser of 635 and 808 nm were emerged in this study. The output energy density and power density of the laser were settled as 1-12 J/cm² and 10, 20 and 40 mW/cm², respectively. Dexamethasone acted as an inducer for osteogenic differentiation. Alkaline phosphatase (ALP) activity was detected by ALP detection kit. Runt-related transcription factor 2 (Runx2), ALP and osteocalcin (OCN) gene expressions were determined by RT-PCR. Cytokines bone morphogenetic protein 2 (BMP-2), collagen-1 (COL-1) and OCN were measured by ELISA. It was demonstrated that PBM efficiently promoted the proliferation and differentiation of hUCMSCs. When hUCMSCs were inoculated on SF/PCL membrane and treated with PBM, the activity of ALP significantly increased, and the expression levels of osteogenic-related genes Runx2, ALP, OCN and osteogenic related cytokines such as BMP-2, Col-1 and OCN all presented massive increasing with dose-dependent. Notably, the effect of PBM in promoting osteogenic differentiation would also be inhibited when the energy density exceeded the threshold.