Cultured fibroblasts from chronic diabetic wounds on the lower extremity (non-insulin-dependent diabetes mellitus) show disturbed proliferation

Patients with diabetes mellitus experience impaired wound healing often res ulting in chronic foot ulcers. Hospital discharge data indicate that 6-20% of all diabetic individuals hospitalized (mostly with type 2 diabetes) have a lower extremity ulcer. Maintaining glucose levels at acceptable levels ( below 10 mmol/l) is considered to be an important part of the clinical trea tment, but the exact mechanism by which diabetes delays wound repair is not yet known. We studied this phenomenon by determining the potential of fibr oblasts isolated from the ulcer sites of four patients with non-insulin-dep endent diabetes mellitus to proliferate in vitro, Controls were fibroblasts isolated from normal skin of the upper leg of five healthy age-matched vol unteers and of six non-insulin-dependent diabetes patients. Proliferative c apacity was analysed by evaluation of plates after trypsinization and [H-3] thymidine incorporation. Fibroblast morphology was studied by light and tra nsmission electron microscopy, Diabetic ulcer fibroblasts, measured by [H-3 ]thymidine incorporation, proliferated significantly more slowly than the n onlesional control fibroblasts (P < 0.00047) and age-matched control fibrob lasts (P < 0.00003), After culturing the fibroblasts for a prolonged period in high-glucose (27.5 mM) and low-glucose (5.5 mM, i.e. physiological) med ium, this difference in proliferation rate between diabetic ulcer fibroblas ts and nonlesional diabetic fibroblasts remained (P < 0.0001 for high-gluco se and P < 0.0009 for low-glucose on day 7). Fibroblast proliferation in al l three groups was slightly lower in high-glucose than in low-glucose mediu m, although not significantly at any time-point. Light microscopy showed di abetic ulcer fibroblasts to be large and widely spread. Transmission electr on microscopy of cultured diabetic ulcer fibroblasts and nonlesional diabet ic skin fibroblasts revealed a large dilated endoplasmic reticulum, a lack of microtubular structures and multiple lamellar and vesicular bodies. Thes e results show a diminished proliferative capacity and abnormal morphology of fibroblasts derived from diabetic ulcers of non-insulin-dependent diabet es patients.