Institute of Advanced Biomedical Engineering and Science, Tokyo Women's Medical University, Tokyo, Japan; Department of Applied Chemistry and Biotechnology, Graduate School of Engineering, Chiba University, Chiba, Japan.
Department of Pathology, McGowan Institute for Regenerative Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA; Department of Surgery, Takamatsu Red Cross Hospital, Kagawa, Japan.
J Hepatol. 2018 Apr;68(4):744-753. doi: 10.1016/j.jhep.2017.12.016. Epub 2017 Dec 26.
BACKGROUND & AIMS: Since the first account of the myth of Prometheus, the amazing regenerative capacity of the liver has fascinated researchers because of its enormous medical potential. Liver regeneration is promoted by multiple types of liver cells, including hepatocytes and liver non-parenchymal cells (NPCs), through complex intercellular signaling. However, the mechanism of liver organogenesis, especially the role of adult hepatocytes at ectopic sites, remains unknown. In this study, we demonstrate that hepatocytes alone spurred liver organogenesis to form an organ-sized complex 3D liver that exhibited native liver architecture and functions in the kidneys of mice.
Isolated hepatocytes were transplanted under the kidney capsule of monocrotaline (MCT) and partial hepatectomy (PHx)-treated mice. To determine the origin of NPCs in neo-livers, hepatocytes were transplanted into MCT/PHx-treated green fluorescent protein transgenic mice or wild-type mice transplanted with bone marrow cells isolated from green fluorescent protein-mice.
Hepatocytes engrafted at the subrenal space of mice underwent continuous growth in response to a chronic hepatic injury in the native liver. More than 1.5 years later, whole organ-sized liver tissues with greater mass than those of the injured native liver had formed. Most remarkably, we revealed that at least three types of NPCs with similar phenotypic features to the liver NPCs were recruited from the host tissues including bone marrow. The neo-livers in the kidney exhibited liver-specific functions and architectures, including sinusoidal vascular systems, zonal heterogeneity, and emergence of bile duct cells. Furthermore, the neo-livers successfully rescued the mice with lethal liver injury.
Our data clearly show that adult hepatocytes play a leading role as organizer cells in liver organogenesis at ectopic sites via NPC recruitment.
The role of adult hepatocytes at ectopic locations has not been clarified. In this study, we demonstrated that engrafted hepatocytes in the kidney proliferated, recruited non-parenchymal cells from host tissues including bone marrow, and finally created an organ-sized, complex liver system that exhibited liver-specific architectures and functions. Our results revealed previously undescribed functions of hepatocytes to direct liver organogenesis through non-parenchymal cell recruitment and organize multiple cell types into a complex 3D liver at ectopic sites. Transcript profiling: Microarray data are deposited in GEO (GEO accession: GSE99141).
自从普罗米修斯神话的首次记载以来，肝脏令人惊叹的再生能力因其巨大的医学潜力而引起了研究人员的关注。肝脏再生是由多种类型的肝细 胞（包括肝细胞和肝非实质细胞（NPC））通过复杂的细胞间信号促进的。然而，肝 脏发生的机制，特别是成年肝细胞在异位部位的作用，仍然未知。在这项研究中， 我们证明了仅肝细胞就能刺激肝发生，形成一个器官大小的复杂 3D 肝脏，该肝脏在 小鼠的肾脏中表现出固有肝脏的结构和功能。
将分离的肝细胞移植到马兜铃酸（MCT）和部分肝切除（PHx）处理的小 鼠的肾包膜下。为了确定新肝脏中 NPC 的起源，将肝细胞移植到绿色荧光蛋白转基 因小鼠的 MCT/PHx 处理或从绿色荧光蛋白小鼠移植的骨髓细胞分离的野生型小鼠 中。
肝细胞在小鼠的肾下间隙植入后，在固有肝脏的慢性肝损伤中持续生长。 1 年半多以后，形成了比受损固有肝脏更大质量的整个器官大小的肝脏组织。最显 著的是，我们揭示了至少三种具有与肝脏 NPC 相似表型特征的 NPC 类型是从宿主组 织（包括骨髓）募集而来的。肾脏中的新肝脏表现出肝脏特异性功能和结构，包括 窦状血管系统、区域异质性和胆管细胞的出现。此外，新肝脏成功挽救了致死性肝 损伤的小鼠。
我们的数据清楚地表明，成年肝细胞通过 NPC 的募集在异位部位的肝脏 发生中发挥主导作用作为组织者细胞。
成年肝细胞在异位部位的作用尚未阐明。在这项研究中，我们证明了移植 到肾脏的肝细胞增殖，从宿主组织（包括骨髓）募集非实质细胞，最终创建了一个 器官大小的、复杂的肝脏系统，该系统表现出肝脏特异性的结构和功能。我们的结果 揭示了肝细胞以前未被描述的功能，即通过非实质细胞募集来指导肝脏发生，并将多 种细胞类型组织成一个复杂的 3D 肝脏在异位部位。
微阵列数据已存入 GEO（GEO 注册号：GSE99141）。
