Enhanced expression of fibronectin during in vivo cellular aging of human vascular endothelial cells and skin fibroblasts.

Vascular endothelial cells are thought to play an important role in human aging as their senescence and/or detachment from vascular wall contribute to arteriosclerosis and high blood pressure in elderly persons. Since fibronectin is necessary for cell attachment and spreading and its increased expression has been reported in aging fibroblasts, we checked its expression in aortic endothelial cells aged in vivo. We found that the steady-state level of fibronectin expression increases with increasing donor age, while the labeling index of cultured cells decreases with age. The increased level of fibronectin expression correlated well with an increase in cell area. To explore whether these changes were a reflection of exhaustion of proliferation potential in vivo, we examined fibronectin expression in human umbilical vein endothelial cells aging in vitro. Very similar results were obtained, supporting the idea that vascular endothelial cells age in vivo by using up division potential. When we examined the expression of fibronectin in human skin fibroblasts aged in vivo and fetal lung fibroblasts aged in vitro, we obtained similar results. In conclusion, the level of expression of fibronectin and cell size increase during in vivo and in vitro aging of both endothelial cells and fibroblasts in a coordinate manner.