| Effect of the Vacuum-Assisted Closure on matrix metalloproteinases and its regulated factors in humanchronic wound Doctoral candidate ShiBingAdvisor Chen Shao-zongTherapy to chronic wound, which results in very heavier burden both in economy and psychology to patients, is a very sophisticated problem of plastic surgery.The appearance of VAC brought about a new hope toward the treatment of chronic wound. Many experimental and clinical studies suggested that VAC could promote acute and chronic wound healing owing to its increasing the blood flow in granulation wound, facilitating the remove of wound bacteria, necrosis tissue and drainage fluid. At present, VAC has been applying exclusively in foreign countries and it is being popularized gradually in our country. However, study on mechanisms of VAC promoting chronic wound healing has not been carried through systematically and relative reports are very seldom, especially variation of ECM components before and after VAC therapy had no report. Furthermore, as far as chronic wound itself, the potential formative mechanism has so far been disclosed clearly. MMP, a very important component of ECM was used as main content in our experiment. We observed the changes of value, localization and activity of MMPs, also we observed the changes of some regulated factors relative to MMPs, so asto partly explain the mechanisms of VAC promoting wound healing and of chronic wound formation.13 patients (5 cases pressure sore, 6 cases venous ulcer, 1 case skin defect after trauma, 1 case non-healing wound after operation of breast cancer) hospitalized in our department were treated with VAC (-120mmHg). We studied as follows in six parts:Parti: Using RT-PCR, we determined the expressions of MMP-1, 2,13and TIMP-1, 2 mRNA in granulation tissues from 9 patients with chronic wounds before and l,4,7days after treatment with VAC .We found that MMP-1, 13 mRNA took on an obvious tendency of decrease with the steepest variations in MMP-13. Although there were contradictory results in MMP-2mRNA, the decrease tendency was the same. There was no expression of TIMP-1, 2 mRNA before VAC. But TIMP-1, 2mRNA began to express after VAC as well as taking on obvious tendencies of increase with the time going.Part2: Using immunohistochemistry, we observed the variations ofMMP-1, 2, 8, 9, 13, TIMP-1, 2 protein in margin tissues from 9 patients with chronic wounds before and after 1, 4, 7 days after treatment with VAC. We found that in general, expression of MMP-1, 2, 8, 9, 13, became less and of TIMP-1, 2 became strong with time going after VAC. More MMP-1 expressions were found in keratinocyte layer with no obvious changes in dermis after VAC. There was less stain in keratinocyte layer and more stain in basal layer in MMP-2 and distinctly more stain in epidermis in MMP-9 after VAC. Not only can we observe the expressions of MMP-8 around inflammatory cells, but also can observe the expressionsin epidermis with no changes before and after VAC. But less expression can be found in dermis after VAC. Before VAC, MMP-13 stain can be found in keratinocyte layer, but becoming disappear after VAC. Mainly changes were that stain became less in dermis after VAC with becoming less and less approaching the wound margin. Before VAC, no TIMP-1, 2 expressions can be found, but expressions became stronger after VAC as well as stain being found around blood vessels.Part3: Collecting exudates of 4 acute wound (postoperative breast cancer)at day 1, 2, 3 postoperatively and 4 chronic wounds before and 2,4,6 days after treatment of VAC, we observed the type-Ill collagen degradation from exudates of every timepoint with zymography as well as the type of collagenase in exudates using doxycycline inhibition test. We found that drainage fluids from acute wound might degrade type-Ill collagen partly with no changes at day 1, 2, 3. There was high collagenase activity in chronic woud exudates. Exudates from patients before treatment with VAC co...
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