CLINICAL IMPROVEMENT FOLLOWING DERMABRASION OF PHOTOAGED SKIN CORRELATES WITH SYNTHESIS OF COLLAGEN-I

Background and Design: The ability of superficial dermabrasion to impr ove clinical features of photoaged skin is well known, but the specifi c biological mechanisms involved are poorly understood. The so-called repair zone, as visualized by routine histologic examination, has been attributed to new collagen formation within the papillary dermis and may be responsible for clinical improvement following dermabrasion. We investigated molecular and histologic events occurring in dermabraded skin and correlated them with clinical improvement. Ten photoaged pat ients (mean age, 59 years) underwent facial dermabrasion to the level of the papillary dermis. Clinical severity of photoaging was graded in a blinded manner at baseline and 12 weeks after dermabrasion. Biopsy specimens obtained at baseline and 3 and 12 weeks after dermabrasion w ere analyzed histologically and by in situ hybridization for fibroblas t procollagen I mRNA, immunohistologically and by Western blotting wit h a monoclonal antibody specific for the aminoterminal cleavage site o f procollagen I. Results: Masson's trichrome staining demonstrated an increase in collagen from baseline (as an upper dermal band in the der mabrasion ''repair zone'') at 3 and 12 weeks' postdermabrasion. Immuno histologic examination demonstrated papillary dermal fibroblast staini ng for procollagen I at baseline that increased by threefold at 3 week s' postdermabrasion and by 1.5-fold at 12 weeks' postdermabrasion. Wes tern blotting demonstrated an average-fold increase in pN collagen I o f 4.2 +/- 1.5 at 3 weeks and of 2.7 +/- 0.7 at 12 weeks. By in situ hy bridization, baseline levels of procollagen I mRNA in papillary dermal fibroblasts increased sixfold at weeks 3 and 12 postdermabrasion. Inc rease in procollagen I mRNA correlated with clinical improvement, ie, reduction in wrinkling. Conclusion: Superficial dermabrasion clinicall y improves photoaged skin, and this improvement correlates strongly wi th increased collagen I gene expression.