Testing Elevated Protease Activity: Prospective Analysis of 160 Wounds.

OBJECTIVE: Given that local elevated protease activity (EPA) has been implicated in impaired wound healing, a prospective single-center study was conducted to assess protease activity in various wound types. METHODS: Protease activity was determined using an easy-to-use test system (Woundchek Protease Status Test Kit; Systagenix, Gatwick, United Kingdom) in 160 wounds in 143 patients. The assay detects the combined activity of inflammatory proteases, mainly matrix metalloproteinases 8 and 9 and human neutrophil elastase. RESULTS: Local EPA was detected in 29 of 153 validly tested wounds (18.95%). No difference was detected between acute and chronic wounds, regardless of associated or causative conditions, with the sole exception of surgical wounds. Surgical wounds showed EPA significantly less frequently than nonsurgical wounds. Among nonsurgical wounds, EPA was detected more frequently in acute compared with chronic wounds. Wounds with signs of unimpeded healing (granulation or epithelialization) showed EPA less often than wounds covered with necrotic tissue or a fibrin layer. However, 14% of wounds with epithelialization or granulation exhibited EPA potentially impeding wound healing. Wounds treated with moisture-retentive wound dressings showed EPA significantly less frequently compared with wounds bandaged with dressings with less moisture-retentive properties. Remarkably, none of the wounds treated with collagen/oxidized regenerated cellulose/silver, which is a protease-modulating dressing, showed EPA. CONCLUSIONS: To the study authors' knowledge, this is the largest study assessing EPA in various wound types. The convenient applicability of the test system provides a basis for future studies assessing the pathophysiologic relevance of EPA. In some unsuspicious wounds, early detection of EPA might precede impaired healing and prompt protease-modulating treatment before failure to heal becomes apparent.

Cilostazol prevents foot ulcers in diabetic patients with peripheral vascular disease.

Diabetic patients are at high risk of foot ulcerations that may lead to limb amputations with important socio-economic impact. Peripheral vascular disease may be frequently associated in diabetes mellitus type II with its main symptom, intermittent claudication. Many studies reported the known efficacy of cilostazol in treating vascular claudication. Metalloproteinase-9 (MMP-9) seems to be a biochemical marker implicated in chronic wounds and in particular in diabetic foot ulcers. Cilostazol appears to have a lowering effect on MMP-9 levels and this may suggest a beneficial effect in order to prevent or retard the onset of foot ulcer in diabetic patients. In our study, two groups of diabetic patients with peripheral vascular disease were divided into two groups according to the presence of claudication in order to receive cilostazol. Group A (31 patients without claudication) were not eligible to receive cilostazol whereas Group B (47 patients with claudication) received cilostazol administration for 24 weeks (100 mg orally twice daily). Median follow up was of 16 months. During the follow up, 4·25% of patients of Group B and 35·48% of patients of Group A (P < 0·01) showed onset of foot ulceration. Although further randomised and controlled studies are required cilostazol seems to show beneficial effects for primary prevention of diabetic foot ulcers.

Increased matrix metalloproteinase-9 predicts poor wound healing in diabetic foot ulcers.

OBJECTIVE: We studied the relationships of diabetic ulcer wound fluid matrix metalloproteinases (MMPs), tissue inhibitors of metalloproteinases (TIMPs), and transforming growth factor-beta1 (TGF-beta1) with wound healing rate. RESEARCH DESIGN AND METHODS: The ulcers were cleansed to remove exudates, and wound fluids were collected for analysis of MMP-2 and -9, TIMP-1, and TGF-beta1. RESULTS: At presentation, MMP-9 and the MMP-9-to-TIMP-1 ratio correlated inversely with the wound healing rate at 28 days (P < 0.001). MMP-9 and the MMP-9-to-TIMP-1 ratio were lower in the 23 patients who achieved complete healing at 12 weeks versus the 39 who did not. The pro-MMP-9 concentration was predictive of healing within 12 weeks. Addition of cutoffs for TIMP-1 (>480 pg/ml) and TGF-beta (>115 pg/ml) further improved its predictive power (area under the curve 0.94). CONCLUSIONS: These findings suggest that a milieu with high MMP-9 may be indicative of inflammation and poor wound healing. Measurements of MMP-9, TIMP-1, and TGF-beta in wound fluid may help to identify ulcers at risk of poor healing.

Functionally modified gelatin microspheres impregnated collagen scaffold as novel wound dressing to attenuate the proteases and bacterial growth.

An attempt was made to develop a new therapeutic delivery system which would play a dual role of attenuating MMP activity in the wounds and also prevent infection by controlled delivery of antimicrobials. A catechol type MMP inhibitor 2,3-dihydroxybenzoic acid (DHBA) was conjugated to gelatin microspheres using EDC/NHS as coupling agents. The potential of the modified gelatin microspheres (DHB-MS) to attenuate the proteases such as MMP 2 and MMP 9 in the diabetic wound tissues was investigated by gelatin zymography. Further the modified microspheres were loaded with doxycycline and impregnated in a reconstituted collagen scaffold as novel wound dressing. The in vitro release behavior of doxycycline from both DHB-MS and DHB-MS impregnated collagen scaffold was investigated. DHB-MS when incubated with the tissue lysate for 6h displayed the complete inhibition of the MMPs in the tissue lysate. The in vitro drug release studies from the collagen scaffold exhibited the burst release of 44%, exerted immediate chemo prophylaxis and sustained delivery for 72 h. The MTT assay and fluorescent labeling with calcein AM indicated that the DHB-MS is biocompatible to human foreskin fibroblasts. Thus the system developed provides wider scope to control the pathogens involved in infection and also the excess matrix degradation.