Mesangial cell migration precedes proliferation in Habu snake venom-induced glomerular injury.

Background: Mesangial cells migrate in response to platelet released products in vitro (Am J Pathol 1991;138:859). Cell migration, in addition to proliferation might play a role in cell remodeling during the course of proliferative glomerular disease.

Experimental Design: In this study, we examined mesangial cell migration in vivo in a platelet-dependent model of proliferative glomerulonephritis induced by Habu snake venom. Mesangial cell migration was assessed by phenotypic identification and temporal location of mesangial cells within glomerular lesions in serial time studies from 8 to 48 hours after Habu snake venom. Autoradiography of [3H]thymidine incorporation into cells was employed to identify and temporally separate cell division and proliferation from cell motility and other related events.

Results: Early (8-hour) lesions consisted of microaneurysms devoid of mesangial cells. By 24 hours, glomeruli showed mesangial cells at the margins of lesions adjacent to intact glomerular tufts, followed by the presence of clusters of cells at 30 and 36 hours. By 48 hours, most lesions were filled with proliferating mesangial cells. Cells containing [3H]thymidine were rarely observed until 30 hours, at which point they were found in advanced lesions. Marginating cells did not contain [3H]thymidine, suggesting that the location of these cells was not related to cell division but rather to migration. Platelet depletion eliminated platelets from lesions and substantially retarded mesangial cell migration into glomerular lesions indicating mesangial cell migration is, in part, dependent on platelets or their secretory products.

Conclusions: These studies show that mesangial cells can migrate in vivo and suggest that cell migration is an important early step in cell redistribution and remodeling during glomerular injury in this model of proliferative glomerulonephritis.