Towards the Translation of Bioprinted Ears: Strategies for Autogenous Human Cell Sourcing
Ope A. Asanbe, MD1, Benjamin P. Cohen, BS2, Rachel C. Hooper, MD1, Jennifer L. Puetzer, PhD2, Rachel Nordberg, BS2, Peipei Zhang, MBBS, PhD1, Wilmina N. Landford, BA1, Lawrence J. Bonassar, PhD2, Jason A. Spector, MD, FACS1.
1Weill Cornell Medical College, New York, NY, USA, 2Cornell University, Ithaca, NY, USA.
PURPOSE_The major obstacle to the clinical application of our previously described technique for fabricating patient-specific bioprinted ears remains cell sourcing. As 250 million auricular chondrocytes (AC) are required for full sized ear scaffolds, strategies must be devised to augment the few million chondrocytes available from patient donor sites (microtic remnant and contralateral conchal bowl). We hypothesized that co-culture of AC with mesenchymal stem cells (MSC) would result in formation of normal elastic cartilage while requiring fewer AC.
METHODS_ A 1:1 ratio of bovine auricular chondrocytes (BAC) and bovine mesenchymal stem cells (bMSC) was mixed with type 1 collagen (10 mg/ml) at a concentration of 25 million cells/mL collagen. The collagen mixture was extruded into 1 mm thick sheets, thermally gelled and fabricated into 8mm diameter scaffolds using a biopsy punch. 100% BAC and 100% bMSC scaffolds were fabricated as well. Scaffolds were implanted subcutaneously in dorsa of nu/nu mice, harvested after 3 months and processed for histology.
RESULTS_ Grossly, BAC:bMSC scaffolds maintained their size and exhibited cartilage-like elasticity 12 weeks after implantation. Comparatively, 100% BAC and 100% bMSC scaffolds partially resorbed. H&E staining demonstrated BAC:bMSC scaffolds sustained more lacunar chondrocytes with local deposition of cartilage than 100% BAC scaffolds. Furthermore, Verhoeff staining revealed BAC:bMSC scaffolds elaborated more dense elastin fibers than 100% BAC scaffolds.
CONCLUSIONS_BAC:bMSC hybrid constructs more readily form elastic cartilage than do BAC alone. Similar techniques using human cells are currently being explored, bringing us significantly closer to fabricating patient-specific, high fidelity human auricles.
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