Autologous transplantation of tissue-engineered auricular cartilage in a rabbit model

Introduction The gold standard of auricular reconstruction entails the assembly of the auricular construct from autologous rib cartilage, which is highly skill-dependent, requires multiple interventions and may lead to donor-site morbidity. Tissue engineering (TE) provides an alternative approach to producing a pinna that can be tailored individually to the patient and only requires a small biopsy, thus reducing the risks of the surgery. Autologous animal models present the means for the preclinical evaluation of TE constructs.

Materials and Methods Autologous rabbit auricular chondrocytes were embedded in a bioink made of hyaluronic acid and alginate (HATG-Alg) and bioprinted into disc-shaped constructs (ø1 cm) at the Laboratory of TE and Biofabrication (ETH, Zurich). The constructs were allowed to mature in vitro for 9 weeks before being transplanted to the dorsum of the donor animal. Cell-free discs and autologous ear cartilage were transplanted as controls. The discs were harvested after 13 weeks, the biocompatibility was evaluated by histological analysis, and cartilage-relevant proteins were detected by immunohistochemistry.

Results Macroscopically, the shape of the transplants was retained; however, the histological analysis revealed fibrous encapsulation and varying degrees of peripheral degradation with inflammatory cell infiltration in all HATG-Alg implants. The analysis of biocompatibility showed moderate to strong irritation in response to the TE samples. Characteristic collagen II and safranin O staining were present in autologous but not in the HATG-Alg transplants.

Conclusion  Strong to moderate immune response to the transplanted TE constructs accompanied by the disappearance of typical cartilage histology was observed irrespective of the cell content.

Swiss National Science Foundation (CRSII5_173868 to NR)

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Artikel online veröffentlicht:
12. Mai 2023