Tissue engineering the human auricle by auricular chondrocyte-mesenchymal stem cell co-implantation

Children suffering from microtia have few options for auricular reconstruction. Tissue engineering approaches attempt to replicate the complex anatomy and structure of the ear with autologous cartilage but have been limited by access to clinically accessible cell sources. Here we present a full-scale, patient-based human ear generated by implantation of human auricular chondrocytes and human mesenchymal stem cells in a 1:1 ratio. Additional disc construct surrogates were generated with 1:0, 1:1, and 0:1 combinations of auricular chondrocytes and mesenchymal stem cells. After 3 months in vivo, monocellular auricular chondrocyte discs and 1:1 disc and ear constructs displayed bundled collagen fibers in a perichondrial layer, rich proteoglycan deposition, and elastin fiber network formation similar to native human auricular cartilage, with the protein composition and mechanical stiffness of native tissue. Full ear constructs with a 1:1 cell combination maintained gross ear structure and developed a cartilaginous appearance following implantation. These studies demonstrate the successful engineering of a patient-specific human auricle using exclusively human cell sources without extensive in vitro tissue culture prior to implantation, a critical step towards the clinical application of tissue engineering for auricular reconstruction.

小耳症（microtia）患儿在耳郭再造方面可选择的治疗方案极为有限。组织工程技术尝试利用自体软骨（autologous cartilage）复刻耳部复杂的解剖结构与形态，但受限于可临床获取的细胞来源匮乏。本研究报道了一例以1:1比例混合人耳郭软骨细胞（human auricular chondrocytes）与人间充质干细胞（human mesenchymal stem cells）后植入构建的全尺寸患者特异性人耳。此外，我们还分别以1:0、1:1、0:1的耳郭软骨细胞与间充质干细胞比例制备了圆盘状构造替代物。体内植入3个月后，仅含耳郭软骨细胞的单细胞圆盘构造，以及1:1比例的圆盘与耳构造均在软骨膜层呈现束状胶原纤维，伴随丰富的蛋白聚糖沉积与弹性纤维网络形成，其结构与天然人耳软骨高度相似，蛋白质组成与机械刚度亦匹配天然组织。采用1:1细胞比例制备的全尺寸耳构造可维持整体耳郭形态，植入后呈现软骨样外观。本研究证实，仅使用人类细胞来源即可在植入前无需大规模体外组织培养的情况下，成功构建患者特异性人耳郭，这一成果为组织工程技术应用于耳郭再造的临床转化迈出了关键一步。