Cartilage Tissue Engineering: Implications for Microtia Reconstruction

Objective: Nanofiber-supported, in vitro-generated cartilage may represent an optimal starting material for the development of a cartilage implant for use in microtia reconstruction. We aim to characterize the molecular composition of endogenous auricular cartilage and determine if human umbilical cord mesenchymal stem cells (hUCMSCs) can be differentiated into cartilage in vitro. Method: Human ear cartilage from normal adults, patients with microtia, and pediatric patients with preauricular appendages were analyzed for collagen I, II, and X, and elastin expression. In parallel, hUCMSCs were cultured on nanofiber scaffolds for 21 days under chondrogenic conditions. Cells were harvested for histologic, biochemical, and quantitative PCR analysis. Results: Histologic analysis of human ear cartilage revealed similar levels and distribution of collagens I, X, and elastin. Collagen II was not highly expressed in the microtia samples (P ≤ .0001). hUCMSC cultures stained positively for glycosaminosglycans and sulfated proteoglycans. Compared with control cells, hUCMSCs grown on PLGA nanofiber scaffolds had more extensive glycosaminosglycan production (P ≤ .03), a higher differentiation index (P ≤ .02), and higher levels of collagen X mRNA expression (P ≤ .005). Conclusion: These data provide information regarding the composition of endogenous ear cartilage and suggest that hUCMSCs grown on PLGA nanofiber scaffolds may represent an optimal starting material for the development of a cartilage implant for use in microtia reconstruction.