EFFECTS OF STRETCHED VASCULAR ENDOTHELIAL CELLS AND SMOOTH MUSCLE CELLS ON DIFFERENTIATION OF ENDOTHELIAL PROGENITOR CELLS

Differentiation of endothelial progenitor cells (EPCs) plays important roles in endothelial repair after vessel injury. Endothelial cells (ECs), vascular smooth muscle cells (VSMCs), and mechanical forces, including cyclic strain and shear stress, synergistically form the microenvironment of EPCs. However, the synergistic effect of cyclic strain, ECs, and VSMCs on the differentiation of EPCs remains unclear. In the present study, EPCs were indirectly co-cultured with stretched ECs or VSMCs that were subjected to 5%, 1.25-Hz cyclic strain by using FX-4000T Strain Unit. Then, Western blot and real-time PCR were used to examine expressions of EC marker, i.e., vascular cell adhesion molecule (VCAM), CD31, von Willebrand factor (vWF); VSMC markers, i.e., α-actin, Calponin, and SM22α; and signaling molecules, i.e., p-Akt and p-ERK. In static, co-cultured ECs increased expression of VCAM and phosphorylation of Akt and ERK in EPCs compared to that in EPCs cultured alone. In EPCs, co-cultured VSMCs decreased expre...