ANTIPROLIFERATIVE EFFECT OF ELEVATED GLUCOSE IN HUMAN MICROVASCULAR ENDOTHELIAL-CELLS

Diabetic microangiopathy has been implicated as a fundamental feature of the pathological complications of diabetes including retinopathy, n europathy, and diabetic foot ulceration. However, previous studies dev oted to examining the deleterious effects of elevated glucose on the e ndothelium have been performed largely in primary cultured cells of ma crovessel origin. Difficulty in the harvesting and maintenance of micr ovascular endothelial cells in culture have hindered the study of this relevant population. Therefore, the objective of this study was to ch aracterize the effect of elevated glucose on the proliferation and inv olved signaling pathways of an immortalized human dermal microvascular endothelial cell line (HMEC-1) that possess similar characteristics t o their in vivo counterparts. Human dermal microvascular endothelial c ells (HMEC-1) were grown in the presence of normal (5 mM) or high D-gl ucose (20 mM) for 14 days. The proliferative response of HMEC-1 was co mpared under these conditions as well as the cAMP and PKC pathways by in vitro assays. Elevated glucose significantly inhibited (P < 0.05) H MEC-1 proliferation after 7, 10, and 14 days. This effect was not mimi cked by 20 mM mannitol. The antiproliferative effect was more pronounc ed with longer exposure (1-14 days) to elevated glucose and was irreve rsible 4 days after a 10-day exposure. The antiproliferative effect wa s partially reversed in the presence of a PKA inhibitor, Rp-cAMP (10-5 0 mu M), and/or a PKC inhibitor, Calphostin C (10 nM). HMEC-1 exposed to elevated glucose (20 mM) for 14 days caused an increase in cyclic A MP accumulation, PKA, and PKC activity but was not associated with the activation of downstream events such as CRE and AP-1 binding activity . These data support the hypothesis that HMEC-1 is a suitable model to study the deleterious effects of elevated glucose on microvascular en dothelial cells. Continued studies with HMEC-1 may prove advantageous in delineation of the molecular pathophysiology associated with diabet ic microangiopathy. (C) 1998 Wiley-Liss, Inc.