Generation of a tissue-engineered tracheal equivalent

In this Minireview we summarize efforts to generate an autologous tissue-engineered trachea (TET) shaped as a cylinder containing a helix of cartilage to form the structural component of a functional tracheal replacement. Our first step was to demonstrate that a composite engineered tracheal equivalent composed of cartilaginous cylinder could be lined with nasal epithelial cells in a nude-mouse model. We then demonstrated the feasibility of creating the cartilage and fibrous portion of the trachea using autologous tissue harvested from a single procedure in both nude-rat and sheep models. Gross morphology and tissue morphology of these TET series were similar to that of native trachea. Histological data indicated the presence of mature cartilage formation of a pseudostratified columnar epithelium and the presence of mature cartilage surrounded by connective tissue, as would be expected of native trachea. Regarding the biomechanical properties, the cartilage was excellent in nude model; however, sheep autologous TET provided less support and therefore collapsed easily. In addition to utilizing the angiogenic qualities of cytokines, we hope to exploit the growth potentials of stromal cells derived from bone marrow for the production of a clinically practical, bioengineered trachea.