Response of the human peritoneal mesothelial cell to injury: An in vitro model of peritoneal wound healing

Abstract

The denudation of the peritoneal mesothelium and damage to the underlying interstitium is a frequent finding in patients receiving continuous ambulatory peritoneal dialysis as a treatment for end-stage renal failure. The response of the mesothelium to injury from repeated episodes of infection or from exposure to dialysis fluids has not been extensively studied. The present study describes a simple and reproducible method with which to investigate the response of human mesothelial cells to injury. The model of peritoneal injury consists of mechanically wounding a monolayer of human peritoneal mesothelial cells with a glass probe and following the repopulation of the denuded area by time-lapse photomicroscopy. In addition immunohistochemistry was used to follow the response of marker proteins for stress fibers and focal adhesions as well as macromolecules associated with the extracellular matrix. Under serum-free conditions the wound (0.58 +/- 0.094 mm; mean +/- SD; N = 20) closed within 72 +/- 5 hours (N = 8). This rate of healing was enhanced by fetal calf serum, by human serum (10%) and by undiluted spent non-infected dialysate. The repair process over the first 48 hours was the result of cell migration, was independent of cell proliferation and involved the de novo synthesis of several different extracellular matrix components. An early event in the healing process was the rapid reorganization of intracellular stress fibers together with the formation of associated focal adhesions in cells at the wound edge. This in vitro model should prove invaluable in characterizing the process of wound healing within the peritoneal cavity, thus allowing a better understanding of the response to infection as well as any effect of dialysis fluids in this pattern of cell behavior.