Implantation of a porcine acellular dermal graft in a primate model of rotator cuff repair

Background: Non-cross-linked xenogeneic extracellular matrix graft materials have typically elicited a hypersensitivity reaction when implanted into humans or other primates. The purpose of this study was to examine the histologic and immune response to a non-cross-linked porcine-derived dermal extracellular matrix graft processed to remove the alpha-gal epitope. Materials and methods: Eight African green monkeys were implanted with porcine acellular dermal matrix (Conexa Reconstructive Tissue Matrix; Tornier Inc, Edina, MN, USA) to repair and augment a partial excision defect of the supraspinatus tendon of the rotator cuff. Four animals each were sacrificed at 3 months and 6 months, and histologic samples were compared with tissues harvested from unoperated shoulders. Results: Gross examination of grafted Conexa showed the appearance of integration proximally with tendon and distally with bone in each operated rotator cuff complex. Histologically, Conexa appeared to have remodeled to tendon-like architecture, with homogeneous distribution of fibroblast cells and parallel alignment of collagen fibers, with the direction of force evident by 3 months after implantation. Abundant vasculature observed at 3 months, which diminished to native tendon levels by 6 months, also indicated this to be a period of significant remodeling with an absence of significant inflammation, as evidenced by immunochemical methods and serum analysis. Conclusion: Conexa porcine acellular dermal matrix allows for incorporation of host tendon tissue without a hypersensitivity reaction in a primate model and should be a safe material for augmentation of human rotator cuff repair. (c) 2012 Journal of Shoulder and Elbow Surgery Board of Trustees.