Effects of the medium conditioned by endothelial cells under hypoxic condition on the phenotype of porcine pulmonary arterial smooth muscle cells.

The effects of the medium conditioned by endothelial cells under hypoxic condition on the phenotype modulation of pulmonary artery smooth muscle cells (PASMCs) were investigated by using cell culture and morphometrical analysis. The results showed that the number of diploid cells and alpha-sm-actin of PASMCs in the hypoxic endothelial cell conditioned medium group (HECCM) was lower and the myofibrilles were even less than that in normal endothelial cell conditioned medium group (NECCM). On the contrary, the volume density of rough endoplasmic reticulum (RER) and mitochondria of PASMCs in the HECCM group was higher than that in the NECCM group, i.e. altering from a contractile type to a synthetic type. However, under direct hypoxic condition for 24 h, the phenotype of cultured PASMCs remained unchanged, i.e. retained contractile type. It suggests that the HECCM can induce phenotype modulation of PASMCs, may be mediated by the pulmonary artery endothelial cells (PAECs) which can secrete some cytokins affecting the PASMCs.