Hepatocyte Transplantation for Liver Based Metabolic Disease

分离的实质细胞的移植作为一种微创治疗和局部治疗具有很大的前景。 已报道成功治疗了几种罕见的代谢性肝病。该技术的主要局限性包括 无法移植足够数量的供体肝细胞，缺乏足够灵敏的技术， 监测移植细胞的状态。这一建议包括几个重大的创新认识 肝细胞移植生物学和优化其应用。在动物模型中，肝脏定向放射促进 通过移植的肝细胞使原生肝再生。不幸的是，标准的临床和实验室 在实体器官移植中识别排斥反应的迹象在细胞移植的受体中是无用的， 肝细胞移植后功能变化的敏感性不足以在移植前诊断排斥反应。 同种异体移植物的损伤是不可逆的。可以进行非侵入性监测的检测方法的可用性 移植物功能和排斥风险的评估将有助于更合理地管理患者， 肝细胞移植由于肝细胞移植治疗的靶向疾病很少， 大多数报告涉及不同患者人群的轶事经验，我们将移植患者， 苯丙酮尿症（PKU），一种发病率将使足够的患者招募成为可能的疾病。 苯丙氨酸羟化酶（PAH）缺乏症，传统上称为PKU， 基于人口的新生儿筛查然而，标准的饮食管理策略在老年人中失败了。 青少年和成年人由于难以坚持饮食，导致执行功能下降，以及其他 神经和神经精神问题。该提案有三个具体目标。目的1是确认安全性 肝定向辐射调节和文件5-10%的宿主肝细胞替代供体 肝细胞我们假设，使用多个供体和移植前肝脏放射预处理将 导致宿主肝脏的竞争性再增殖和PKU患者PAH缺乏的临床纠正， 用于治疗基于肝脏的代谢疾病的模型疾病。目的2是通过以下方法识别移植物排斥反应： 免疫监测和成功地治疗它之前的过程是不可逆转的。我们假设 通过经证实的供体特异性T细胞免疫反应性测定监测排斥风险可用于评估 细胞移植后免疫抑制的充分性。目标3是确定 使用供体肝细胞功能的实时测量，而不是使用替代物，将允许评估 肝细胞移植后的移植物功能。我们假设，同位素苯丙氨酸周转研究在北京大学， 患者可以比标准测量更有效地测量Phe代谢的变化。这些结果将 对于基因编辑的自体或干细胞衍生的肝细胞的可能移植是重要的。 离体向肝细胞递送基因编辑载体比体内递送显著更有效，并且 在患者来源的成纤维细胞中甚至更有效，所述成纤维细胞随后将转化为iPS来源的肝细胞。

Transplantation of isolated parenchymal cells has great promise as a minimally invasive therapy and partial success has been reported for several rare metabolic liver diseases. Major limitations to the technique include an inability to transplant an adequate mass of donor hepatocytes, and lack of a sensitive enough technology to monitor the status of transplanted cells. This proposal includes several major innovations in understanding hepatocyte transplant biology and optimizing its application. In animal models liver-directed radiation facilitates repopulation of the native liver by transplanted hepatocytes. Unfortunately, the standard clinical and laboratory signs that identify rejection in solid organ transplantation are not useful in recipients of cell transplants, and the sensitivity of functional changes following hepatocyte transplant is inadequate to diagnose rejection before damage to the allograft is irreversible. The availability of assays that would allow non-invasive monitoring of graft function and assessment of rejection risk would facilitate more rational management of patients following hepatocyte transplantation. As diseases targeted for treatment by hepatocyte transplantation are rare, and most reports involve anecdotal experience in a diverse patient population, we will transplant patients with phenylketonuria (PKU), a disease with an incidence that will make adequate patient enrollment possible. Phenylalanine hydroxylase (PAH) deficiency, traditionally known as PKU was the original motivation for population-based newborn screening. However, standard dietary management strategies have failed in older adolescents and adults due to difficulty in adhering to diet, leading to diminished executive function, and other neurologic and neuropsychiatric problems. The proposal has three specific aims. Aim 1 is to confirm the safety of liver-directed radiation conditioning and document 5-10% replacement of host hepatocytes by donor hepatocytes. We hypothesize that use of multiple donors and pre-transplant hepatic radiation conditioning will lead to competitive repopulation of the host liver and clinical correction of PAH deficiency in patients with PKU, a model disease for treatment of liver-based metabolic diseases. Aim 2 is to identify graft rejection by immunologic monitoring and to successfully treat it before the process is irreversible. We hypothesize that monitoring rejection risk by a proven assay of donor-specific T cell immune reactivity can be used to assess the adequacy of immune suppression following cell transplantation. Aim 3 is to determine the extent to which use of real-time measures of donor hepatocyte function, rather than use of surrogates, will allow assessment of graft function after hepatocyte transplantation. We hypothesize that isotopic Phe turnover studies in PKU patients can more effectively measure changes in Phe metabolism than standard measures. These results will be important for the possible transplantation of gene edited autologous or stem cell-derived hepatocytes. Delivery of gene editing vectors ex vivo to hepatocytes is significantly more efficient than in vivo delivery, and is even more efficient in patient-derived fibroblasts that would later be converted to iPS-derived hepatocytes.