Differential expression of matrix metalloproteinases and their tissue-derived inhibitors in cutaneous wound repair

Wound extracellular matrix is a key regulator of cell adhesion, migration, proliferation, and differentiation during cutaneous repair. The amount and organization of normal wound extracellular matrix are determined by a dynam ic balance among overall matrix synthesis, deposition, and degradation. Mat rix metalloproteinases (MMPs) are one family of structurally related enzyme s that have the collective ability to degrade nearly all extracellular matr ix components. The MMPs are broadly categorized into collagenases, gelatina ses, stromelysins, and membrane-type MMPs by their substrate specificity. T he aim of this study was to characterize the temporal changes in mRNA profi les for I-at collagenase [matrix metalloproteinase-1 (MMP-1)], gelatinase A (MMP-2), matrilysin (MMP-7), gelatinase B (MMP-9), and membrane type 1-MMP (MT1-MMP), as well as tissue inhibitor of metalloproteinases-l (TIMP-1),TM P-2, and TIMP-3 during the inflammatory, granulation, and early remodeling phases of excisional skin repair. Eight full-thickness skin wounds were mad e on the backs of each rat (7-mm(2) wounds; 16 rats; n = 128 wounds). Two a nimals at a time were re anesthetized, and all eight wounds on each animal were excised at 12 and 24 hours and at 2, 3, 5, 7, 10, and 14 days after in jury. Six wounds fr om each animal were excised for RNA isolation, whereas two wounds were excised for histology. Controls consisted of nonwounded ski n from identical locations in four animals. Total RNA from each time point was isolated and relative mRNA quantitation per formed by using reduced-cyc le reverse transcription-polymerase chain reaction. Correct polymerase chai n reaction product amplification was confirmed by probing the blotted polym erase chain reaction product with a P-32-labeled oligonucleotide specific f or a given MMP or TIMP. we demonstrated that the majority of MMP and TIMP m RNA induction and peak expression coincided temporally with the well-charac terized inflammatory and granulation stages of repair. In conclusion, there is a distinct pattern of MMP and TIMP expression during normal excisional wound repair.