AGE-DEPENDENT INJURY IN HUMAN UMBILICAL VEIN ENDOTHELIAL-CELLS - RELATIONSHIP TO APOPTOSIS AND CORRELATION WITH A LACK OF A20 EXPRESSION

BACKGROUND: It has recently been shown that human umbilical vein endot helial cells (HUVEC) become increasingly sensitive to growth factor de privation, resulting in cell death, as a function of age in culture. T he overall goal of the present study was to investigate the mechanism of lethal injury in these cells and to compare the injury process to o ther known mechanisms of injury in the same cells. EXPERIMENTAL DESIGN : HUVEC were established in culture and maintained for four passages. Injury to first-passage cells and fourth-passage cells was compared. F ourth-passage cells were examined for injury in the presence of agents that are known to confer resistance to apoptosis. Ultrastructural fea tures of injury and DNA fragmentation patterns were assessed. Expressi on of factors that are known to be associated with resistance to apopt osis in other models was assessed. RESULTS: Fourth-passage HUVEC under going injury exhibited morphologic features characteristic of apoptosi s and DNA fragmentation. Agents known to inhibit apoptotic cell injury in other models inhibited injury. A20 expression was correlated with resistance to injury in fourth-passage HUVEC, but there was no correla tion between Bcl-2 and Bcl-x expression and resistance to injury. CONC LUSIONS: HUVEC injury resulting from growth factor deprivation increas es as a function of age in vitro and appears to be a form of apoptosis . A20 expression may confer resistance to cell injury through this pat hway.