[Cyclic tensile strain promotes osteogenic differentiation and angiogenic activity of mouse pericytes].

PURPOSE: To evaluate the effects of cyclic tensile strain on osteogenic differentiation and angiogenic activity of mouse pericytes (PCs).

METHODS

Primary mouse brain microvascular PCs were isolated and cultured, and the membranous markers were detected by flow cytometry. Flexcell loading system was used to apply 6% cyclic tensile strain to the cells. Mouse bone marrow mesenchymal stem cells (BMSCs) were used as a positive control. Alkaline phosphatase (ALP) assay, alizarin red (AR) staining and Matrigel angiogenesis test were used to evaluate the effects of mechanical strain on the osteogenic differentiation and angiogenic activity of PCs. The expression levels of osteogenic and angiogenic genes were determined by qRT-PCR.

RESULTS

The PCs expressed the characteristic mouse stem cell surface proteins CD29+CD44+CD45-CD31- and highly expressed PDGFRβ. Under 6% cyclic strain, the ALP activity of PCs increased by 1.6-fold and the AR activity by 2.9-fold. Similarly, the ALP and AR activities of BMSCs were increased by 1.5 and 3.9 times, respectively. Matrigel angiogenesis assay showed that the angiogenic activity of human umbilical vein endothelial cells (HUVECs) was induced by conditioned medium from PCs and BMSCs under mechanical strain. qRT-PCR showed that the expressions of RUNX2, OCN and IBSP were higher in PCs under mechanical strain, and the expressions of VEGF and VEGFR1 were higher in BMSCs.

CONCLUSIONS

Cyclic tensile strain promotes osteogenic differentiation and angiogenic activity of PCs.