Tissue Engineering of an Auricular Cartilage Model Utilizing Cultured Chondrocyte-Poly(L-lactide- -caprolactone) Scaffolds

To determine the potential development in vivo of tissue-engineered auricular cartilage, chondrocytes from articular cartilage of bovine forelimb joints were seeded on poly(L-lactic acid- -caprolactone) copolymer scaffolds molded into the shape of a human ear. Copolymer scaffolds alone in the same shape were studied for comparison. Chondrocyte-seeded copolymer constructs and scaffolds alone were each implanted in dorsal skin flaps of athymic mice for up to 40 weeks. Retrieved specimens were examined by histological and molecular techniques. After 10 weeks of implantation, cell-seeded constructs developed cartilage as assessed by toluidine blue and safranin-O red staining; a vascular, perichondrium-like capsule enveloped these constructs; and tissue formation resembled the auricular shape molded originally. Cartilage matrix formation increased, the capsule persisted, and initial auricular configuration was maintained through implantation for 40 weeks. The presence of cartilage production was correlated with RT-PCR analysis, which showed expression of bovine-specific type II collagen and aggrecan mRNA in cell-seeded specimens at 20 and 40 weeks. Copolymer scaffolds monitored only for 40 weeks failed to develop cartilage or a defined capsule and expressed no mRNA. Extensive vascularization led to scaffold erosion, decrease in original size, and loss of contour and shape. These results demonstrate that poly(L-lactic acid- -caprolactone) copolymer seeded with articular chondrocytes supports development and maintenance of cartilage in a human ear shape over periods to 40 weeks in this implantation model.