Effect of chronic wound exudates and MMP-2/-9 inhibitor on angiogenesis in vitro

New evidence suggests that matrix metalloproteinases (MMPs) may facilitate angiogenesis as well as function to generate angiogenesis inhibitors. In this study, the angiogenic effect of wound exudates from patients with venous insufficiency ulcers was examined in an in vitro angiogenesis model with and without synthetic MMP-2/-9 inhibitor.

Wound exudates were obtained from 20 patients with venous insufficiency ulcers and 20 control patients with donor-site wounds after skin grafting for burns. In the angiogenesis model, suramin (20 microg/ml) was used in five wells without wound fluid as negative control, and vascular endothelial growth factor (1 microg/ml) was used in five other wells as positive control. Chronic wound fluids were analyzed without and with a synthetic MMP-2/-9 inhibitor with a concentration of 2 microM and 20 microM in the medium. The total length of tubules was calculated by map reader. Statistical analysis was performed using the Mann-Whitney test. The level of significance was considered to be p < 0.05.

Chronic ulcer exudates inhibited angiogenesis significantly (490 +/- 130 microm) compared with acute wound fluids (1740 +/- 320 microm; p < 0.05). In wells with chronic wound exudates and high concentrations of MMP-2/-9 inhibitor, angiogenesis was stimulated significantly (870 +/- 220 microm, p < 0.05).

In this model, reduced angiogenesis might be due to an antiangiogenic effect of MMP-2 and MMP-9. MMP-2/-9 inhibition results in a stimulation of angiogenesis and might be an approach for the treatment of patients with chronic wounds and reduced angiogenesis.