A major challenge to the clinical translation of tissue-engineered ear scaffolds for ear reconstruction is the limited auricular chondrocyte (hAuC) yield available from patients. Starting with a relatively small number of chondrocytes in culture results in dedifferentiation and loss of phenotype with subsequent expansion. To significantly decrease the number of chondrocytes required for human elastic cartilage engineering, we co-cultured human mesenchymal stem cells (hMSCs) with HAuCs to promote healthy elastic cartilage formation. HAuCs along with human bone marrow-derived hMSCs were encapsulated into 1% Type I collagen at 25 million/mL total cell density with different ratios (HAuCs/hMSCs: 10/90, 25/75, 50/50) and then injected into customized 3D-printed polylactic acid (PLA) ridged external scaffolds, which simulate the shape of the auricular helical rim, and implanted subcutaneously in nude rats for 1, 3 and 6 months. The explanted constructs demonstrated near complete volume preservation and topography maintenance of the ridged “helical” feature after 6 months with all ratios. Cartilaginous appearing tissue formed within scaffolds by 3 months, verified by histologic analysis demonstrating mature elastic cartilage within the constructs with chondrocytes seen in lacunae within a Type II collagen and proteoglycan-enriched matrix, and surrounded by a neoperichondrial external layer. Compressive mechanical properties comparable to human elastic cartilage were achieved after 6 months. Co-implantation of hAuCs and hMSCs in collagen within an external scaffold efficiently produced shaped human elastic cartilage without volume loss even when hAuC comprised only 10% of the implanted cell population, marking a crucial step toward the clinical translation of auricular tissue engineering.

中文翻译：

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通过间充质干细胞伴侣对人耳软骨进行高效改造

组织工程耳支架用于耳重建的临床转化的一个主要挑战是患者的耳软骨细胞 (hAuC) 产量有限。从培养中相对少量的软骨细胞开始，会导致去分化和表型丢失，随后会扩展。为了显着减少人体弹性软骨工程所需的软骨细胞数量，我们将人间充质干细胞 (hMSC) 与 HAuC 共培养，以促进健康的弹性软骨形成。HAuCs 与人骨髓来源的 hMSCs 以 2500 万/mL 的不同比例（HAuCs/hMSCs：10/90、25/75、50/50）总细胞密度封装到 1% I 型胶原蛋白中，然后注入定制的3D 打印的聚乳酸 (PLA) 脊状外部支架，模拟耳廓螺旋缘形状，皮下植入裸鼠体内1、3、6个月。外植结构在 6 个月后以所有比率显示脊状“螺旋”特征几乎完全保留体积和形貌维持。3 个月时支架内形成软骨组织，经组织学分析证实，结构内有成熟的弹性软骨，软骨细胞在 II 型胶原和富含蛋白多糖的基质内的空隙中可见，并被新软骨膜外层包围。6 个月后达到了与人体弹性软骨相当的压缩机械性能。