The role of pores in acellular dermal matrix substitute.

To promote the engraftment rate of autologous skin combined with acellular dermal matrix (ADM), ADM was punched to produce regular pores from 500 to 800 µm in diameter, separated by a distance of 3 to 5 mm. The porous ADM was then implanted beneath the flap and transplanted onto an open full-thickness defect wound combined with autografts about 0.2 mm thick in a rat model. The change in diameter of pores in ADM and the neovascularization of ADM matrix were evaluated, and the take rate of porous ADM combined with overlying autologous skin was compared with that of non-porous ADM. The results showed that when porous ADM was grafted onto the full-thickness skin excised wound, plasma penetrated from the wound bed to the surface of ADM through these pores, i.e. the pores punched on ADM were responsible for the imbibition function. Subdermal implantation of ADM indicated that one week post-operation the pores in ADM were still detectable, and some of them contained red blood cells. Two to three weeks after grafting the pores became smaller, partly because of newly synthesized collagen matrix deposition. In Sprague-Dawley rats the engraftment rate of autologous sheet skin graft placed over ADM with pores was 89.5%, which was significantly higher than ADM without pores (63.2%). It is concluded that porous ADM could serve as a good dermal substitute.