Human auricular tissue engineering in an immunocompetent animal model.

BACKGROUND: Tissue engineering has the potential to provide ear-shaped cartilaginous constructs in the near future. Previous attempts to engineer human ear-shaped constructs mimicked human shape and characteristics but were done in immunocompromised animal models.
OBJECTIVES: The authors design and evaluate a novel, 3-dimensional (3D) cell-copolymer construct resembling a human ear that was subsequently implanted in an immunocompetent rabbit model. MATERIALS: Mesenchymal progenitor cells that were obtained from perichondrium and chondrium of a rabbit auricular cartilaginous site were expanded in vitro to chondrocytes and seeded onto biodegradable alginate and silk polymer ear-shaped scaffolds. After implantation in the back of 6 immunocompetent rabbits for 8 weeks, cell/scaffold constructs were harvested and analyzed in terms of size, shape, and histology.
RESULTS: Data from this study suggest that auricular mesenchymal progenitor cells derived from rabbit perichondrium and chondrium are suitable for development of tissue-engineered human ear models with retention over time of 3D construct architecture. Gross morphology revealed that the silk alginate scaffold diminished slightly the size dimensions but maintained shape and flexibility. Histological analysis showed formation of cartilage tissue along with type II collagen and proteoglycan extracellular matrix components of the silk alginate construct.
CONCLUSIONS: This study demonstrates for the first time that it is possible to engineer an ear cartilage construct that resembles the human ear not only in shape but also in size and flexibility in a real test model. This study also confirms that the association of silk, alginate, and perichondrium and chondrium mesenchymal cells is a reliable method to produce an engineered auricular cartilage construct. Further long-term research needs to be done to confirm these observations.