Endothelial cell renewal in skin of patients with progressive systemic sclerosis (PSS): an in vitro autoradiographic study.

The labelling index of endothelial cells of the dermal microvessels was studied by in vitro autoradiography with [3H] thymidine. 14 patients with PSS were compared with 7 control subjects, by sampling the upper-third of the forearm skin. One patient had a second biopsy in this area, on a telangiectasis. Microvessels from patients showed a significant increase in endothelial cell labelling. Within the PSS group, no difference was found between the indurated and the non-indurated skin. There was no correlation between the labelling index and the duration of the disease. A very high uptake was found in the telangiectasis. Such an increased labelling index in PSS is consistent with a response to the endothelial cell destruction as described in electron microscopy and in cultures with patient's serum.