Biochemical properties of tissue-engineered cartilage.

OBJECTIVE: Microtia is treated with rib cartilage sculpting and staged procedures; though aesthetically pleasing, these constructs lack native ear flexibility. Tissue-engineered (TE) elastic cartilage may bridge this gap; however, TE cartilage implants lead to hypertrophic changes with calcification and loss of flexibility. Retaining flexibility in TE cartilage must focus on increased elastin, maintained collagen II, decreased collagen X, with prevention of calcification. This study compares biochemical properties of human cartilage to TE cartilage from umbilical cord mesenchymal stem cells (UCMSCs). Our goal is to establish a baseline for clinically useful TE cartilage.

METHODS: Discarded cartilage from conchal bowl, microtic ears, preauricular tags, rib, and TE cartilage were evaluated for collagen I, II, X, calcium, glycosaminoglycans, elastin, and fibrillin I and III. Human UCMSCs were chondroinduced on 2D surfaces and 3D D,L-lactide-co-glycolic acid (PLGA) fibers.

RESULTS: Cartilage samples demonstrated similar staining for collagens I, II, and X, elastin, and fibrillin I and III, but differed from rib. TE pellets and PLGA-supported cartilage were similar to auricular samples in elastin and fibrillin I staining. TE samples were exclusively stained for fibrillin III. Only microtic samples demonstrated calcium staining.

CONCLUSIONS: TE cartilage expressed similar levels of elastin, fibrillin I, and collagens I and X when compared to native cartilage. Microtic cartilage demonstrated elevated calcium, suggesting this abnormal tissue may not be a viable cell source for TE cartilage. TE cartilage appears to recapitulate the embryonic development of fibrillin III, which is not expressed in adult tissue, possibly providing a strategy to control TE elastic cartilage phenotype.