Experimental abdominal wall defect repaired with acellular matrix

In the surgical repair of congenital abdominal-wall defects (AWD), the ready availability of a non-immunogenic and non-prosthetic biomaterial that could guide the regeneration of normal tissue is a fascinating possibility. Biomaterials are already in use, but in our experience, an acellular matrix (ACM) can stimulate exact regeneration of the absent tissue. We explored the possibility of using an ACM to repair a muscular AWD in an animal model. Male New Zealand white rabbits (3-4 kg, n = 18) were anesthetized and the abdominal wall was shaved and scrubbed; a vertical incision was made in the left lower quadrant and a large patch of external-oblique muscle was resected (3 x 3 cm). The animals underwent reconstruction with homologous diaphragm acellular matrix (HDAM) grafts that were previously prepared using a detergent enzymatic method. The patches were evaluated histologically at 9 (n = 6), 40 (n = 6), and 90 (n = 6) days post-surgery in each group; moreover, 90 days post-surgery an electromyogram (EMG) (n = 6) of the implanted matrix was recorded. Histologic analysis demonstrated that the HDAM supported fibroblast migration, deposition of newly-formed collagen, and neovascularization. No signs of necrosis, or evidence of skeletal-muscle-cell ingrowth were detected. The EMG revealed minimum muscular electrophysiologic activity, probably due to muscle underlying the patch. The HDAM we employed was thus not able to produce reconstruction of the skeletal muscle, and was progressively remodeled into fibrous tissue. Since the ultimate reason for failure of muscle regeneration is a lack of myogenesis, future studies will use ACMs preconditioned by various regulators of myoblast proliferation and differentiation.