Solving the Challenge of Cell Sourcing for the Translation of Patient-Specific Tissue Engineered Ears
Kerry A. Morrison, BA1, Benjamin P. Cohen, BS2, Ope A. Asanbe, MD1, Xue Dong, BA1, Alice Harper, BA1, Lawrence J. Bonassar, PhD2, Jason A. Spector, MD, FACS1.
1Laboratory of Bioregenerative Medicine & Surgery, Weill Cornell Medical College, New York, NY, USA, 2Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY, USA.
Previously, we fabricated patient-specific auricles using bovine auricular chondrocytes, which displayed effective permanence with structural, biochemical, and mechanical properties similar to native auricular cartilage after 6 months in vivo. To achieve clinical translation, we must surmount the large 250 million human auricular chondrocytes (hAuCs) requirement. Thus, we sought to generate human auricular cartilage through the combined implantation of hAuCs with human mesenchymal stem cells (hMSCs) as a novel cell sourcing strategy.
hAuCs from discarded otoplasty specimens and bone-marrow derived hMSCs were encapsulated into type I collagen hydrogels in ratios of 100:0, 50:50, and 0:100 hAuCs:hMSCs with a cell density of 25 million cells/mL hydrogel. 8 mm diameter constructs were implanted subcutaneously in the dorsa of nude mice for 1 and 3 months.
Constructs containing 100% hAuCs or 50:50 hAuCs:hMSCs maintained cylindrical geometry and white cartilage-like appearance while hMSCs contracted. hAuCs:hMSCs scaffolds developed an auricular cartilage microstructure, including organized perichondrium composed of collagen, rich proteoglycan, cellular lacunae, and a dense elastin fibers network. Biochemical analysis confirmed that mixed cell constructs featured significantly more proteoglycan content than the 100% hMSCs group; proteoglycan content increased significantly between 1 and 3 months.
Co-implantation of hAuCs with hMSCs in a 50:50 ration produces human auricular cartilage that is indistinguishable from native auricular cartilage. This approach reduces the autologous auricular chondrocyte requirement to clinically obtainable numbers (~1 mg of donor ear cartilage) making this a viable strategy for the generation of patient-specific, high fidelity tissue engineered ears.
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