Comparative analysis of effects of cyclic uniaxial and equiaxial stretches on gene expression of human umbilical vein endothelial cells.

It has been well established that biomechanical environment can influence functionality of biological cells. There are evidences that show mechanical cyclic stretch can promote smooth muscle cell (SMC) markers in endothelial cells (ECs). The objective of this study was to determine whether mechanical stimuli in the forms of uniaxial and equiaxial cyclic stretches (UNCS and EQCS) can affect endothelial and smooth muscle gene expressions in mRNA level of human umbilical vein endothelial cells (HUVECs). For this purpose, 10% uniaxial UNCS and EQCS (60 cycles/min for 24 h) were applied on HUVECs, and using real-time PCR expressions of three EC specific markers, vascular endothelial growth factor receptor-2 (VEGFR-2, also known as FLK-1), von Willebrand Factor (vWF) and vascular endothelial-cadherin (VE-cadherin) and two SMC specific genes, α-smooth muscle actin (α-SMA) and smooth muscle myosin heavy chain (SMMHC) were quantified. Moreover, alterations in cell height were analyzed by atomic force microscopy (AFM). Results showed that cyclic UNCS for 24 h downregulated the expression of all EC markers and upregulated the expression of all SMC markers while low effects on HUVECs height were observed. Cyclic EQCS in the same conditions resulted in minor effect on SMC gene expression in HUVECs, while led to strong reduction in vWF with no significant change in other two endothelial genes. Cyclic EQCS considerably elevated cell height. Results proposed that ECs can transdifferentiate to SMC phenotype under specific microenvironmental conditions.