MMP-8 and TIMP-1 expression in relation to pressure ulcer healing through negative pressure wound therapy in spinal cord injury patients

Introduction: We studied the relationship of chronic pressure ulcer (PU) wound tissue matrix metalloproteinase 8 (MMP-8) and its tissue inhibitor 1 (TIMP-1) with respect to surface area, depth, granulation tissue formation, removal of exudates and rate of healing through negative pressure wound therapy (NPWT) by our innovative negative pressure device (NPD) and standard wound care.

Material & Methods: 44 patients of stage 3 & 4 pressure ulcers were enrolled and equally divided into two groups. Group 1 received NPWT by our innovative NPD and Group 2 received standard wound care. The ulcers were cleansed to remove exudates and a 5 mm punch biopsy was taken for analysis of MMP-8 and TIMP-1 by enzyme linked immunosorbent assay (ELISA).

Results: The concentration of MMP-8 was increased 6-fold in biopsies of pressure ulcers in group 2 compared with Group 1 at week 2. At week 5, the concentration of MMP-8 reduced in Group-1 (p=0.001) as compared to Group 2. At week 8, as the level of MMP8 reduced, the level of TIMP-1 increased in NPWT group (Group 1) in comparison to standard wound care group (Group 2). Wound tissue MMP-8 was significantly negatively correlated to TIMP-1 (Pearson correlation coefficient, r = -0.311; p<0.0001) with respect to healing rate in NPWT group, whereas no such correlation was observed in the standard care group. In all the parameters, the decrease was higher in NPWT group compared with standard wound care group which was significant for exudates type (p=0.03) and granulation tissue formation (p=<0.05).

 

Conclusion: Negative pressure wound therapy leads to early wound healing with increased concentrations of TIMP-1 and decreased concentrations of MMP-8 compared with standard wound care. New treatment strategies for chronic pressure ulcers healing could be directed towards reducing concentrations of MMP-8 and increasing levels of TIMP-1.