OBJECTIVETo study the variations of collagenase activity in exudates of human chronic wound before and after treatment of VAC so as to partly disclose the mechanisms of VAC in promoting chronic wound healing.

METHODSThe exudates of acute wounds (postoperative breast cancer) were postoperatively collected at day 1, 2, 3, and in 6 chronic wounds (4 cases of venous ulcer, 2 cases of pressure sore) the exudates were also collected before and 2, 4, 6 days after the treatment with VAC. The type-III collagen degradation from the exudates was checked with zymography timepoint. The types of the collagenase in exudates were evaluated by using doxycycline inhibition.

RESULTSDrainage fluids from acute wound might degrade type-III collagen partly with no changes at day 1, 2, 3. There were high collagenase activities in chronic wound exudates. Exudates from patients before treatment with VAC can degrade type-III collagen completely. But collagenase activities became less and less after VAC. Doxycycline inhibition tests indicated that it can't inhibit the activity of collagenase at 100 micromol/L concentration, until it reached 600 micromol/L.

CONCLUSIONSCollagenase activity is elevated in chronic wounds. VAC may be lower the collagenase activity, prevent collagen from degrading abundantly and promote wound healing. Collagenase is mainly MMP-1 type (fibroblast-type) in chronic wound exudates.