A study of endothelium-dependent proliferation of pulmonary smooth muscle cells in vitro

Summary

The direct effect of hypoxia and the effect of hypoxic endothelial cells conditioned medium on cultured pulmonary arterial smooth muscle cells in vitro were studied with phase contrast microscopy,³H-thymidine labelled technique and flow cytometric measurements. The results showed that direct hypoxia inhibited proliferation of pulmonary arterial smooth muscle cells, retained pulmonary arterial smooth muscle cells in the Go/G₁ phase and decreased³H-thymidine incorporation into pulmonary arterial smooth muscle cells and that hypoxic endothelial cells conditioned medium stimulated proliferation of pulmonary arterial smooth muscle cells, promoted pulmonary arterial smooth muscle cells from G₀/G₁ phase to S phase and increased³H-thymidine incorporation into pulmonary arterial smooth muscle cells. It was reasonable to believe that hypoxia might enable pulmonary arterial endothelial cells to secrete some growth factors which could stimulate proliferation of pulmonary arterial smooth muscle cells, thereby playing an important role in structural remodeling of the pulmonary arteries and in the development of hypoxic pulmonary hypertension.