Decellularized tracheal matrix scaffold for tracheal tissue engineering: in vivo host response.

BACKGROUND: The authors have previously demonstrated promising results with tissue engineered trachea in vitro using decellularized matrix scaffolds. The present study aims to investigate the applicability of the construct in vivo.
METHODS: Tracheae harvested from Brown Norway rats (donor) and Lewis rats (recipient) were decellularized with repeated detergent-enzymatic treatment cycles. Decellularized Brown Norway tracheal matrix scaffolds were seeded with Lewis rat stem cell-derived chondrocytes externally and tracheal epithelial cells internally to generate a bilaminated tracheal construct. Brown Norway tracheal matrix scaffolds (n = 6), Lewis rat scaffolds (n = 6), and the engineered constructs (n = 3) were implanted subcutaneously in Lewis rats and observed for 4 weeks. Fresh Brown Norway (n = 6) and Lewis rat (n = 6) tracheae were implanted as controls. Histologic analysis for macrophage, CD8, and CD4 cell infiltration was performed.
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 differences in macrophage infiltration were observed between syngeneic decellularized matrix scaffolds and tracheal isografts. 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.
CONCLUSIONS: Decellularized tracheal matrix scaffold did not induce significant allograft rejection or foreign body reaction in vivo. Although the construct supported reepithelialization, stem cell-derived chondrocytes failed to engraft in the heterotopic environment and represent a focus of future investigations.