Cyclic tensile strain promotes the osteogenic differentiation of a bone marrow stromal cell and vascular endothelial cell co-culture system

• Published in: Archives of biochemistry and biophysics Vol. 607; pp. 37 - 43
• Main Authors: Jiang, Yunan, Wang, Yu, Tang, Guohua
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01-10-2016
• Subjects: Alkaline Phosphatase - metabolism; Animals; Anthraquinones - chemistry; BMSC; Cell Differentiation; Cells, Cultured; Co-culture; Coculture Techniques; Collagen Type I - metabolism; Core Binding Factor Alpha 1 Subunit - metabolism; Cyclic tensile strain; Endothelial Cells - cytology; Enzyme-Linked Immunosorbent Assay; Male; Mesenchymal Stromal Cells - cytology; Osteogenesis - physiology; Osteogenic differentiation; Phenylurea Compounds - therapeutic use; Quinolines - therapeutic use; Rats; Rats, Sprague-Dawley; Receptors, Vascular Endothelial Growth Factor - metabolism; Stress, Mechanical; Tensile Strength; Vascular endothelial cell; Vascular Endothelial Growth Factor A - metabolism; VEGF; Vascular endothelial cell; Cyclic tensile strain; BMSC; Co-culture; Osteogenic differentiation; VEGF
• ISSN: 0003-9861; 1096-0384
• DOI: 10.1016/j.abb.2016.08.015

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.
•Optimization of BMSC/VEC co-culture ratios and cyclic tensile loading conditions for best osteogenic effect.•Reveal the synergic effect of cyclic tensile strain and co-cultured VECs on BMSC osteogenic differentiation.•The combined effect of tensile strain and VECs on BMSC osteogenesis relies on VEGF paracrine signaling pathway.