Objectives: 

Mechanical strain induces cardiovascular differentiation of mouse embryonic stem (ES) cells. In the present study the signaling cascades underlying the stimulation of vasculogenesis was investigated.

Methods and results: 

Treatment of embryoid bodies derived from ES cells with 10% static mechanical strain using a Flexercell strain system significantly increased CD31-positive vascular structures following 4 days of post-incubation. Vasculogenesis was paralleled by upregulation of the angiogenesis guidance molecules plexinB1, ephrinB2, NRP1 and the angiogenic growth factors vascular endothelial growth factor (VEGF), fibroblast growth factor-2 (FGF-2) and platelet-derived growth factor-BB (PDGF-BB) as evaluated by western blot. Mechanical strain application resulted in increase in intracellular calcium as well as intracellular reactive oxygen species (ROS) and nitric oxide (NO). Furthermore, activation of ERK1,2 and PI3 kinase (PI3K) was observed. Mechanical strain-induced vasculogenesis was abolished in the presence of the PI3K inhibitor LY294002, the flk-1 antagonist SU5614 as well as upon chelation of intracellular calcium by BAPTA. BAPTA treatment likewise blunted the strain-induced expression of VEGF, FGF-2 and PDGF-BB, the increase in NO generation as well as the expression of angiogenesis guidance molecules.

Conclusions: 

Mechanical strain stimulates vasculogenesis of ES cells by the intracellular messengers ROS, NO and calcium as well as by upregulation of the angiogenic growth factors VEGF, FGF-2 and PDGF-BB.