Vascular wall von Willebrand factor in human diabetic retinopathy.

Purpose. To reconstruct the role played by vascular endothelium in the elevation of circulatingvon Willebrand factor (vWf) in diabetic patients with microangiopathy and, specifically, todetermine whether storage and synthesis o isf altere vWfd in diabetic retinal vessels.Methods. Trypsin digests were prepared form retinas obtained post mortem from 11 patients(age 62 ± 9 years, mean ± SD) with 9 ± 5 years of diabetes and 12 nondiabetic control subjectsmatched for age and sex. Trypsin digests were inspected for the presenc lesione of s of diabeticretinopathy; vWf protein was localized by indirect immunofluorescence; and vWf mRNA levelswere studied by in situ hybridization.Results. vWf immunofluorescence was present in vessels al ofl sizes. The granular fluorescencewas localized to the endothelial cell cytoplasm. Pattern and intensity of staining in diabeticmicrovessels and large vessels were similar to those observed in the vessels of nondiabeticsubjects. The amount of vWf mRNA detected by in situ hybridization in retinal endothelialcells was similar in diabetic (0.92 ± 0.32 grains/cell) and control (0.91 ± 0.42 grains/cell)microvessels. Likewise, no differences were observed in vWf mRNA levels in the large vesselsof diabetic (0.073 ± 0.034% grain area) and control (0.069 ± 0.018 grain area) subjects.Conclusions. These observations are compatible with the occurrence in diabetes of the slowrelease of endothelial vWf through the pathway of vWf secretion not linked to synthesis, ie, theregulated pathway. Invest Ophthalmol Vis Sci. 1994;35:600-607.Several features of diabetic microangiopathy indicateor suggest that vascular endothelium is affected in dia-betes mellitus,