In vivo tissue engineering of patient specific chimeric liver tissue for wholeorgan liver transplantation

欧洲每年有超过70，000名患者死于各种形式的肝功能衰竭。对于一些肝脏疾病，正在开发基于细胞的疗法，组织工程或基因疗法，但大多数患者将需要可移植的器官才能最终治愈。猪异种器官移植在肾脏、心脏或胰腺（胰岛）等方面有着广阔的应用前景，利用多转基因猪的器官控制免疫排斥反应已取得了显著进展。然而，猪肝在很大程度上与人类的生理机能不相容。因此，用患者自身的细胞重新繁殖异种肝脏可能有希望使该器官适应特定的患者。在这里，我们建议使用胚泡注射诱导多能干细胞（iPSC），以产生受体衍生的小鼠和大鼠的肝嵌合体。在一个新的器官移植动物模型中，我们将分析嵌合肝脏与同种异体和异种支架的功能和细胞适应性。我们将采用免疫抑制策略并分析受体来源的细胞替代、长期免疫抑制和可能的耐受诱导的程度。与实验室动物实验平行，我们将猴和人iPS细胞注射到GAL +/FAH+猪胚泡中以产生大型嵌合动物，作为将嵌合肝概念转化为临床应用的重要步骤。

Annually, more than 70.000 patients in Europe die fi'om various forms of liver failure. For some liver diseases cell based therapies, tissue engineering or gene therapies are being developed, but the majority of patients will require a transplantable organ for ultimate cure. Xenotransplantation of porcine organs is promising for kidney, heart or pancreas (islets), and significant progress hasbeen made in controlling the immunological rejection by using organs fi'om multi-transgenic pigs. The porcine liver, however, is largely incompatible with the human physiology.Repopulation of a xenogeneic liver by the patient's own cells could thus be promising to adapt the organ to a particular patient. Here, we propose to use blastocyst injection of induced pluripotent stem cells (iPSCs) to generate recipient derived liver chimeras in mice and rats. In a novel organ transplantation animal model we will analyze the fijnctionality and cellular adaptation of chimerized livers with allogeneic and xenogeneic scaffolds. We will employ immunosuppressive strategies and analyze the degree of recipient derived cellular substitution, long term fijnction and possible tolerance induction. In parallel to experiments with laboratory animals, we will inject monkey and human iPS cells into GAL"^"/FAH"'"porcine blastocysts to produce a large chimeric animal as an important step for translation of the chimeric liver concept towards clinical application.