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PURPOSE: We have previously demonstrated promising results with tissue engineered trachea in vitro using decellularized tracheal allograft. The present study aims to investigate the applicability of the construct in vivo, in particular the scaffold-tissue compatibility, cellular engraftment, and viability.
METHODS: Trachea harvested from Brown Norway rats (BN) (donor rat) and Lewis rats (recipient rat) were decellularized with repeated detergent-enzymatic treatment (DET) cycles. (graphic 1) BN decellularized tracheal matrix scaffolds were seeded with Lewis rat stem cell-derived chondrocytes on the outer surface and tracheal epithelial cells on the luminal surface to generate a bilaminated tracheal construct in a culture incubator. BN tracheal matrix scaffolds (n=6), Lewis rat scaffolds (n=6), and the engineered constructs (n=3) were implanted subcutaneously in Lewis rats. In addition, fresh tracheae from BN (n=6) and Lewis rats (n=6) were transplanted as controls. Specimens were harvested four weeks later and subjected to histologic analysis.
RESULTS: Allogeneic decellularized matrix scaffold showed significantly decreased macrophage, CD8+ and CD4+ cell infiltration compared with tracheal allografts, and demonstrated similar level of cell infiltration to syngeneic decellularized matrix scaffold. No significant difference in macrophage infiltration was observed between syngeneic decellularized matrix scaffolds and tracheal isografts.(graphic 2 and 3) The engineered constructs achieved complete epithelial cell coverage and preserved lumen patency; however, chondrocytes failed to repopulate the cartilaginous matrix with statically seeding stem cell on scaffold.(graphic 4)
CONCLUSION: Decellularized tracheal matrix scaffold did not induce significant allograft rejection or foreign body reaction. While the construct supported re-epithelialization, stem cell-derived chondrocytes failed to engraft in the heterotopic environment and represents a focus of future investigations.