دانلود رایگان مقاله کرنش چرخه ای ترویج نژاد تفکیک استئوژنیک از یک سلول استرومایی استخوان مغز

Abstract

Mechanical stimuli and neovascularization are closely coupled to osteogenic differentiation and new bone formation. The purpose of present study was to detect the effect of cyclic mechanical strain on a co-culture system of bone marrow stromal cells (BMSCs) and vascular endothelial cells (VECs) and to clarify the related mechanisms. Primary BMSCs and VECs were isolated from Sprague-Dawley rats and co-cultured at various ratios (1:0, 1:2, 1:4, 4:1, 2:1, 1:1, and 0:1). To determine optimized loading conditions, the cells were then subjected to various cyclic tensile strains (0%, 3%, 6% and 9%) using a Flexcell 5000 mechanical loading system. A protocol of 6% strain on the co-cultured cells at a 1:1 ratio was selected as the optimized culture conditions based on the best osteogenic effects, which included increased ALP activity, matrix mineralization and the expressions of VEGF, Runx-2 and Col-1. The VEGF-R inhibitor tivozanib was used to analyze the paracrine role of VEGF, and the osteogenesis-promoting effects of 6% tensile strain were abrogated in the co-cultured cells treated with tivozanib. These results demonstrate that cyclic tensile strain promotes osteogenic differentiation in BMSC/VEC co-culture systems, possibly via a VEC-mediated paracrine effect of VEGF on BMSCs.

5. Conclusions

Cumulatively, our study established a regimen comprising the combined treatment of mechanical stimuli and BMSC/VEC 2D coculture for optimal osteogenesis in vitro. The VEGF released by BMSCs was potentiated by the combined treatment of cyclic tensile strain and co-cultured VECs and, in turn, activated VECs to facilitate BMSC osteogenesis via paracrine signaling. These results provide new insight into the regulatory mechanism of bone repair under dynamic environments and will aid in the development of new strategies for bone tissue engineering via the combination of in vitro pre-vascularization and mechanical simulations.