Creation of a Vascularized Composite Graft with Acellular Dermal Matrix and Hydroxyapatite

Abstract

Biomaterials have shown promise as potential substitutes for human tissue. Studies have demonstrated that attachment of a vascularized pedicle to dermal matrix grafts yields tissues that are resilient enough to patch hernia defects in rats. The purpose of this study was to examine the possibility of creating a viable composite graft completely from biomaterials. Acellular dermal matrix was enveloped around a square wafer of hydroxyapatite bone substitute. This composite graft was inserted into an extraperitoneal pocket overlying the abdominal musculature. In 30 Sprague-Dawley rats, the superficial epigastric arteriovenous pedicle was dissected free and placed within the midportion of the matrix construct on one side of each animal. A second graft was inserted on the opposite side without the addition of a vascularized pedicle. Each animal served as its own control. Animals were divided into three equal groups and euthanized at time points of 30, 60, and 90 days. Histologic evaluation of specimens was performed using hematoxylin and eosin and trichrome stains. At 30 days, the dermal matrices demonstrated full-thickness cellular infiltration in all specimens. Collagen deposition was significantly greater in the experimental group at every time point. Cellularity was significantly greater in the experimental group at 30 days, but there were no significant differences between groups at 60 or 90 days. These results suggest that provision of an arteriovenous blood supply to nonbiologic tissue grafts significantly increases collagen deposition and early cellular deposition. Based on these findings, biomaterials may offer an exciting new method for tissue engineering.