Increased levels of matrix metalloproteinase-8 & 9 against TIMP-1 predicts poor healing of pressure injury in people with spinal cord injury

Introduction: Chronic wounds such as pressure injury (PIs) are a major clinical problem with considerable morbidity and associated costs in peoples with spinal cord injury (SCI). The excess Matrix metalloproteinases (MMPs) activity can change an acute wound into chronic nonhealing state. This study was evaluated the wound healing outcome measures (Surface area, depth and exudate volume) with MMP-8, 9 and tissue inhibitor 1 (TIMP-1) levels in PIs treated with novel negative pressure device (NPD) as compared to PIs managed with wet to moist gauze dressings.

Material and Methods: This study expands our work reported previously which evaluated wound-healing outcomes in patients treated with a novel NPD including the focus on MMP-8 levels during treatment. In current study we measured the levels of MMP-9 and TIMP-1 in addition to MMP-8 with new patient cohorts. Thirty SCI cases with PIs of grade 4 were participated in the study. Levels of MMP-8, MMP-9 & TIMP-1 were analysed in the tissue homogenates of PIs at week 0, 3, 6 and week 9 by ELISA.

Results: The level of MMP-8 & 9 was found decreased in PIs managed with NPD at 6^th week (P<0.05) which further reduced at 9^th week (p=0.001). In contrast, the change in MMP-8 & 9 concentration did not reach statistical significance in PIs treated with wet to moist standard wound care. Significantly reduced surface area of NPD treated PIs was observed at week 6 (p=0.04) and at week 9 (p=0.001) as compared to standard wound care group. Similarly, significant reduction of depth was observed in NPD treated PIs at week 9 (p<0.05) and exudate became significantly (p=0.001) lower from week 6 to 9.

Conclusion: Detecting MMP-8, 9/TIMP-1 ratio on admission might be a predictor of healing. Negative pressure wound therapy is capable to balance the protease activity of the wounds.