May 2019 — Vol 139 No 5

Fli1 ECKO mice (middle panels) and control litter mates (left panels) were administered six courses of cyclophosphamide biweekly. Two weeks after the final administration, vascular structure was visualized by FITC-dextran injection (n = 5 per group). A right upper panel depicted arteriolar stenosis (shown with arrows), which corresponds to the area surrounded with a dotted square. AU, arbitrary unit; Fli1 ECKO, endothelial cell-specific Fli1 knockout; PBS, phosphate buffered saline. Scale bar = 100 microns.

Targeted inactivation of the gene encoding the transcription factor Fli1 in mouseendothelial cells causes a vasculopathy that mimics important features ofvasculopathy in systemic sclerosis patients. Yamashita used this mouse model(Fli1 ECKO mice) to assess effects of cyclophosphamide treatment on vascularstructure and function. Repeated administration of cyclophosphamide to Fli1ECKO mice attenuated arteriolar stenosis and other vessel structural abnormalities. See page 1150 for details..