Design and fabrication of a biomimetic artificial ear with enhanced mechanical properties
Microtia is a congenital malformation of the external part of the human ear. Recently, bioprinted auricles have been implanted in the first human patient. The remaining challenge in bioprinting of human ear is a post-implantation maintenance of bioprinted auricular construct size and shape. We hypothesize that the use of polylactide stiffeners will enable bioprinting of hybrid auricular constructs with stable post-implantation size and shape. Using the hybrid bioprinting method, auricular implants consisting of a custom-shaped polyurethane frame with polylactide stiffeners and filled with collagen hydrogel containing chondrocytes were printed. Mechanical testing of the implants was performed and it was shown that adding stiffeners to the frame increased the resistance of the structure to deformation. The implants were sutured under the temporal fascia in two mini-pigs for three months, after which a histologic and immunohistochemical study was performed. The formation of regenerated connective tissue with its own vascular network was observed, filling the entire volume of the implant. There was no evidence of inflammation or rejection. The implants maintained their size and shape after implantation. Thus, the in vivo evaluation of the auricular implant bioprinted by the described hybrid method gave satisfactory results in preclinical testing and the next logical step is a clinical translation.
