Morphometric assessment of the dermal microcirculation in patients with chronic venous insufficiency

Ultrastructural assessments of the dermal microcirculation in patients with chronic venous insufficiency have been limited to qualitative morphologic descriptions of venous ulcer edges or venous stasis dermatitis. The purpose of this investigation was to quantify differences in endothelial cell structure and local cell type with emphasis on leukocytes and their relationship to arterioles, capillaries, and postcapillary venules (PCVs).

Two 4.0 mm punch biopsies were obtained from areas of dermal stasis skin changes in the gaiter region of the leg, as well as from noninvolved areas of skin in the ipsilateral thigh, from 35 patients: CEAP class 4 (11 patients), class 5 (9 patients), class 6 (10 patients), and five normal skin biopsies from patients without chronic venous insufficiency. Electron microscopy was performed on sections at 6700x and 23,800x magnification. At 6700x endothelial cell thickness was determined, and the number of fibroblasts, leukocytes, and mast cells were recorded relative to their proximity to arterioles, capillaries, and PCVs. Similarly, at 23,800x endothelial cell vesicle density, interendothelial junctional widths, and basal lamina thickness (cuff width) were measured. Preliminary evaluation for the presence of transforming growth factor-beta 1 (TGF-beta 1) was performed on three patients using reverse transcriptase-polymerase chain reaction (RT-PCR).

Quantitative measurements demonstrated increased mast cell content for class 4 and 5 patients around arterioles and PCVs and increased macrophage numbers for class 6 patients around PCVs (p < 0.05). Fibroblasts were the most common cells observed; however, no differences were demonstrated between groups. No differences were observed in interendothelial junctional widths or vesicle densities in arterioles, capillaries, or PCVs. Basal lamina thickness was increased only at the capillary level (p < 0.05). The results of RT-PCR for TGF-beta 1 messenger RNA were positive in the three patients studied.

Our data suggest that (1) mast cells play a role in the pathogenesis of chronic venous insufficiency; (2) the effects of mast cells, macrophages, or both may be mediated in part by TGF-beta 1; and (3) capillary cuff formation is not associated with widened interendothelial gap junctions, but may be a result of enhanced vesicular transport rate or conformational changes in the interendothelial glycocalyx.