(OP 28) Biocompatibility of a Decellularised Ureteric Scaffold for Tissue Engineering Small Diameter Vessels

Introduction: Allogenic vein or artery is not always available for revascularization. This study investigated the biocompatibility of an acellular porcine ureteric scaffold (AU) for tissue engineering vessels. Methods: Ureters were decellularized by sequential incubation in PBS, hypotonic Tris buffer [10 mM plus 0.1% (w/v) EDTA, aprotinin (10 KIU/ml) pH 8.0], 0.1%(w/v) SDS, in Tris buffer 0.1% (w/v) with proteinase inhibitors, nuclease (1 U/ml RNase & 0.5 U/ml DNase) solution and PBS. Expression of the major xenoepitope alpha -gal was studied by immunohistochemistry and antibody absorption. The cytotoxicity of the scaffold was determined using standard contact and extract cytotoxicity tests with porcine endothelial (EC) and smooth muscle cells (SMC). In order to determine the host response to the scaffold, 0.5 cm2 sections of AU, fresh tissue, and AU treated with alpha -galactosidase were implanted subcutaneously into GTKO mice. Tissues were explanted and examined after one month. Results: The AU was devoid of alpha -gal. In contact cytotoxicity assays SMC and EC grew up to and in contact with AU with no change in morphology. Following incubation with extracts of AU the ATP content of SMC and EC was not significantly different from DMEM controls whereas fresh tissue extracts were toxic. Explanted fresh tissues showed a typical host response with thick capsules (242 mu m), CD3+ve T-cells and macrophages. The explants were vacuolated. AU explants had thin capsules (74 mu m) and only sporadic CD3+ve T-cells The tissue remained intact and was infiltrated with macrophages, endothelial cells and fibroblastic cells. Conclusion: This study demonstrates proof of concept for AU scaffold in vascular tissue-engineering.