Decellularized Ovine Arterial Tissue: A Three-dimensional Tubular Scaffold For Tissue Engineering Small Diameter Vascular Conduits
Objective: We have demonstrated that decellularized xenograft arterial tissue can function as scaffold for tissue engineering small diameter vascular grafts. Our goal is to optimize decellularization process to decrease immunogenecity, but preserve biomechanical properties of these xenograft vessels.
Design: Experimental Animal Model
Setting: Tissue Engineer a suitable alternative to autologous blood vessels.
Patients: Dover Sheep (40-50Kgs), C57/Bl6 mice (25-40gm)
Interventions: Carotid arteries were harvested from sheep and decellularized using hypotonic cell lysis, detergent, enzymatic and mechanical treatments. Decellularized tissue was sterilized using radiation (3000Rads). Sterility was confirmed by measuring bacterial count when grown in sheep agar. Unprocessed and processed vessels were evaluated morphologically, biomechanically, and immunologically. Young’s modulus was determined axially using Instron tensile test machine with low load capabilities. Processed and unprocessed specimens were implanted subcutaneously for either two or four weeks in mice. Harvested specimens were stained with H&E, Masson trichrome, and macrophage specific antibody to compare immune response. Protein extracts were prepared and injected subcutaneously to detect delayed-type hypersensitivity (DTH) response.
Main Outcome Measures: Cellularity, bacterial count, Young’s modulus, Macrophage recruitment and DTH response
Results: Morphological evaluation of processed and unprocessed tissue demonstrated greater than 99% cell removal with preservation of extracellular architecture. Biomechanical testing confirmed maintenance of properties, including compliance, demonstrated by equivalent Young’s modulus (1.13 vs. 1.05MPa). Immunological evaluation showed substantially diminished immunogenic response of processed compared to unprocessed tissues demonstrated by decreased macrophage recruitment, decreased inflammation and absence of DTH response.
Conclusion: Our decellularization process of xenograft tissues can be used to create sterile, three-dimensional scaffolds with biomechanical properties similar to native vessels with limited immunogenicity. These can be used as scaffolds for small diameter tissue engineered vascular grafts.
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