Heterogeneous 3D-printed scaffolds for control of biliary tree formation in vitro

1.项目总结 在受损或患病的肝脏内胆汁树的再生是一个长期存在的问题， 在医学界仍未解决。导致胆管变性的慢性疾病，包括 在美国，大多数肝移植手术都与胆管炎和肝硬变有关。需要 为移植提供替代方案对肝脏医学的进步至关重要。这个 指导胆管生成和成熟的肝脏微环境一直难以 以有序或功能性的方式重建，这是我们对开发新型支架感兴趣的原因，这种支架 可作为研究这些机制的平台，并可能导致功能性肝替代 未来。 我们提出了一种3D打印、分级多孔的聚(乳酸-乙醇酸)(PLGA)的设计。 细胞外基质衍生水凝胶支架用于胆管细胞的研究 成长、差异化和组织性。在本研究中，PLGA组件旨在提供机械 可调性，而注入的水凝胶是作为定向胆管细胞培养的管道。 通常与体内其他功能和组织相关的信号因子已受到关注 因为它们有能力控制胆管细胞的发育。我们有兴趣调查 γ-氨基丁酸、卵泡刺激素和转化生长因子-β-1三种因子在三维定向支架中的再生作用 [2-4]。 虽然其他方法已经使用熔融的聚(卡普罗内酯)(PCL)作为3D的支撑结构 印刷的水凝胶，这些支架机械上很僵硬，不利于植入柔软的体内或周围 组织，如肝脏[5]。此外，其他研究小组还研究了肝外胆汁的形成。 胆管在体外，但我们的目标是更好地了解肝内胆管再生，这是充分肝脏所必需的 函数[6-9]。尽管有研究探讨肝内胆管再生的生物学机制，但 胆汁树组织工程对再生肝组织的需求未得到满足是这一现象的主要动机 项目[4，10]。将非实质肝细胞工程成分离的血管和上皮性小管结构 如果不利用有问题的组织和细胞的固有形态形成质量，就不太可能实现 除了新的生物材料和细胞图案化方法。我们提议的工作旨在展示一个 随着我们共同迈向更复杂的3D器官工程系统，社区的模型系统 为了最终植入的目的，它更接近于模仿天然组织。

1. PROJECT SUMMARY The regeneration of the biliary tree within damaged or diseased livers is a long-standing issue that remains unsolved in the medical community. Chronic conditions which lead to biliary degeneration, including forms of cholangitis and cirrhosis, are associated with most liver transplants in the United States [1]. The need to provide alternatives to transplantation is paramount to the advancement of hepatic medicine. The microenvironment of the liver that directs the generation and maturation of bile ducts has been difficult to recreate in an orderly or functional manner, and is cause for our interest in developing novel scaffolds which can serve as a platform to study these mechanisms and possibly lead to functional liver replacements in the future. We propose the design of a 3D-printed, hierarchically porous poly(lactic-co-glycolic acid) (PLGA) scaffold which has been infused with extracellular matrix-derived hydrogel for the study of cholangiocyte growth, differentiation, and organization. In this study, the PLGA component is intended to provide mechanical tunability, whereas the infused hydrogel is meant to serve as the conduit for directed cholangiocyte culture. Signaling factors commonly associated with other functions and tissues within the body have gained attention for their ability to manipulate the development of cholangiocytes. We are interested in investigating the regenerative effects of three such factors, GABA, FSH, and TGF-β1, in our 3-dimensionally oriented scaffold [2–4]. While other approaches have used melted poly (capro lactone) (PCL) as a support structure for 3D printed hydrogels, these scaffolds are mechanically stiff and unfavorable for implantation in or around soft tissue, such as the liver [5]. Additionally, other groups have investigated the formation of extrahepatic bile ducts in vitro, but we aim to better understand intrahepatic biliary regeneration, which is necessary for full liver function [6–9]. Despite studies investigating the biological mechanisms of intrahepatic duct regeneration, the unmet need of biliary tree tissue engineering for regenerating liver tissue is the primary motivation of this project [4,10]. Engineering nonparenchymal liver cells into separate vascular and epithelial tubular structures is unlikely to be achieved without employing the innate morphogenic quality of the tissues and cells in question in addition to novel biomaterial and cell patterning approaches. Our proposed work is intended to demonstrate a model system for the community as we collectively move toward more complex 3D organ engineering systems that more closely mimic native tissue for the purposes of eventual implantation.