Augmentation of endothelin-1, prostacyclin and thromboxane A 2 secretion associated with in vitro ageing in cultured human umbilical vein endothelial cells

Abstract

Differences in the secretion of the vascular regulators endothelin-1 (ET-1, prostacyclin (PGI 2) and thromboxane A 2 (TXA 2) associated with ageing were investigated in cultured endothelial cells isolated from normal human umbilical veins (HUVECS). HUVECS at different population doubling levels (PDLs) were cultured in medium MCDB-104 supplemented with FBS and ECGF. Cell saturation density was determined by a Coulter counter, and concentrations of ET-1, PGI 2 and TXA 2 in the media were determined by radioimmunoassay. The cellular and nuclear size of HUVECS increased with advancing age, and the dividing ability decreased. Cell saturation density of HUVECS decreased 5-fold between PDLs 7 and 67 ( P < 0.01). The secretiion of ET-1 by HUVECS at a young stage of growth (PDL 7.6) increased linearly between 0 and 36 h of incubation ( P < 0.01). ET-1 secretion increased approximately 3-fold between PDLs and 67 ( P < 0.01). PGI 2 secretion increased 6-fold between PLDs 7 and 67 ( P <0.01), and TXA 2 secretion increased 18-fold between PDLs 7 and 67 ( P < 0.01). The ratio of PGI 2 to TXA 2 secretion decreased 3-fold between PDLs 78 and 40 ( P < 0.01), and remained at the lower ratio between PDLs 40 and 67. This data indicates that the anti-thrombotic or anti-vasoconstrictive role of endothelial cells may decrease during in vitro ageing.