MOLECULAR ANALYSIS OF DIFFERENT PHASES IN HUMAN WOUND-HEALING

Cultured granulation fibroblasts grown from punch biopsies of the same lower arm area, obtained 3, 6, 9 and 14 days after wounding, were use d as a human wound healing model in comparison to quiescent fibroblast s. We investigated the expression of key extracellular matrix componen ts at the protein level by flow cytometry and mRNA steady state levels by Northern blotting of the different fibroblasts and compared these data to the ability to migrate towards a chemotactic signal. Procollag en al (I), fibronectin and matrix metalloprotease-1 synthesis was stro ngly upregulated at the mRNA steady state level on days 3 and 14. Tiss ue inhibitor of metalloprotease-l mRNA is only 20% down-regulated betw een day 3 and 14. Chemotaxis towards conditioned medium reflects a net effect of several factors and is distinctly different from chemotaxis towards platelet-derived growth factor, which peaks at day 3. Compare d to the protein level, the enhanced expression of the corresponding P DGF receptor beta chain mRNA is delayed by 3 to 6 days. PDGF receptor a shows no regulatory changes during the observation period. This data further supports the idea that functionally divergent subpopulations of fibroblasts exist during wound healing.