Naturally Occurring Extracellular Matrix as a Scaffold for Musculoskeletal Repair

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Abstract
The use of naturally occurring extracellular matrix materials as scaffolds for the repair and regeneration of tissues is receiving increased attention. The present study evaluates the use of the extracellular matrix derived from porcine small intestinal submucosa as a scaffold for anterior cruciate ligament replacement in a goat model. Sixty healthy adult female goats were divided into two equal groups of 30 each. The right anterior cruciate ligament of each goat was removed surgically and replaced with either a patellar tendon autograft or a small intestinal submucosa anterior cruciate ligament scaffold. Three animals from each group were sacrificed at 6 weeks, 3 months, 6 months, and 1 year after surgery and grafts were harvested for histopathologic examination. Six animals from each group were sacrificed immediately after surgery, 3 months, and 1 year after surgery and the grafts were harvested for biomechanical testing. There was no evidence for an adverse clinical response to the xenogeneic small intestinal submucosa scaffold. Anterior drawer values were not different between the two groups at any point. The failure force of the patellar tendon autograft increased from 253 N at Time 0 to 879 N at 12 months. The failure force for the small intestinal submucosa repair device was 721 N at Time 0, decreased to 293 N at 3 months, followed by an increase to 706 N at 12 months. Histopathologic analysis showed a mixed inflammatory cell presence within the small intestinal submucosa scaffold including macrophages and lymphocytes in the early months after surgery. The inflammatory cells disappeared in the later stages of remodeling and the histologic appearance of the small intestinal submucosa remodeled grafts and the patellar tendon autografts were indistinguishable at 12 months. Xenogeneic small intestinal submucosa holds promise as a resorbable bioscaffold for anterior cruciate ligament repair in the goat model.