An in vivo model of human proliferative scar.

Background: Many aspects related to the biology and the effective therapy of proliferative scars have remained undefined, in part due to a lack of an accurate and reproducible animal model with which to systematically study them. This report describes a new model for investigating the pathophysiology and manipulation of human proliferative scars.
Materials and Methods: Human proliferative scars (n = 86) were explanted into flaps based on isolated vascular pedicles in congenitally athymic rats. Serial analysis of the structural and functional integrity of the explanted scars was performed by microscopy and by measurement of human procollagen type III peptide (PIIIP) production, human factor VIII immunostaining, and in vitro cellular proliferation.
Results: By these methods, both fibroblastic and epithelial components of explanted scar specimens retained the histologic characteristics of original human scar specimens, for up to 12 months. Over the same duration, scar explants continued to have high levels of human PIIIP, comparable to those found in original surgical specimens. The microvasculature of scar explants demonstrated a double basement membrane, with no staining of human factor VIII in the inner capillary endothelial layer, suggesting that host vessels were growing into ghost vessels of the human donor scar. Human factor VIII staining decreased over time. Fibroblasts cultured from explanted scar demonstrated less aggressive growth characteristics than those from original surgical specimens.
Conclusions: This new model is the first to allow such long-term maintenance and serial evaluation of human proliferative scar on an accessible, isolated vasculature. It may prove useful in further defining the biology and therapy of this widespread pathologic process.