In vitro models of ageing have been developed for several cell types including fibroblasts, endothelial cells, keratinocytes and lymphocytes. However, very little is known about senescence of human peritoneal mesothelial cells (HPMC) that form the largest cell population in the peritoneal cavity and play a crucial role in intraperitoneal homeostasis and, host defense.
In this study we have attempted to characterize HPMC ageing in vitro using a new model of replicative senescence. HPMC were isolated from the pieces of omentum obtained during elective abdominal surgery. The age of the donors ranged from 24 to 77 years of age. Cells were serially passaged at 3 day intervals at a constant seeding density of 30 000 cells/cm2 and irrespectively of whether they reached confluence or not. The cells were propagated up to the point at which the number of cells was not enough to plate them again at a density required. Cells were compared after their first and last passages. The data were analyzed using the Wilcoxon test for paired non-parametric data and expressed as means ± SD.
HPMC could be passaged effectively 5 to 10 times. There was no correlation between the number of population doublings achieved and the age of the donor. While early passage HPMC easily formed monolayers within 72 h after plating, cells from later passages were gradually losing this ability. This effect was reflected by a significant increase in population doubling time (from 48.7±6.9 to 2004.0±2927.0 hours, n=24, p
These results demonstrate that a modified model of HPMC replicative senescence may a convenient experimental tool for cytogerontological studies.