Cytogenetic evaluation of human endothelial cell cultures

Cytogenetic evaluation of serially subcultivated human endothelial cells revealed significant differences between cultures derived from fetal umbilical cords and cultures derived from various vessel sites in adults. A rapid increase in the prevalence of polyploid cells, to levels of 100% in many cases, was detected in human umbilical vein endothelial cell cultures but not in endothelial cell cultures from adult vessels. Because the development of polyploidy has been viewed as one signpost of in vitro senescence, it may be that these in vitro observations of high levels of polyploidy are a reflection of the fact that umbilical tissue is at the end of its in vivo developmental lifespan when studied. Consistent karyotypic alterations also were observed in two clones from adult human abdominal aorta, even though these cultures exhibited low percentages of polyploid cells. Cultures of one clone exhibited a trisomy of chromosome 11, on which there are at least three onc gene loci, and a deletion of chromosome 13 through band q14. A loss of band 13q14 is a prezygotic chromosomal lesion known to predispose to retinoblastoma. In the other clone, two cell populations were observed, and each displayed a chromosomal abnormality. A trisomy of the long arm of chromosome 2 was noted in one cell population via a marker chromosome involving 2 and 14. The other cell population exhibited an abnormality of chromosome 2. Neither of these karyotypic alterations was detected in the parent culture from which the clones were derived. The results reported in this study have both practical and theoretical implications. The high incidence of polyploidy in serially cultivated umbilical cultures as well as the occurrence of chromosomal changes in umbilical and aortic cultures testify to the need for cytogenetic monitoring of cell cultures even though they are derived from presumably normal tissue. Cytogenetic changes in the endothelium may be important in atherogenesis and other pathologic states. The conversion of diploid endothelial cells into polyploid endothelial cells may provide a convenient model cell system for studying mechanisms of the development of polyploidy in cells and their relationship to in vitro senescence.