Repopulation of human origin hepatocyte progenitor-like cell line, THLE-5b, in the SCID mouse liver under p21-mediated cell growth-arresting conditions.

The in vivo repopulation of hepatocytes depends on donor cell growth potential and recipient conditioning. We herein demonstrate the successful cell transplantation of a human hepatocyte cell line, THLE-5b, into the SCID mouse liver by means of a rather mild conditioning using a 55% hepatectomy and p21 transfection. Adult human liver-derived cells, THLE-5b, are SV40 T antigen-immortalized epithelial cells. A phenotypic examination of THLE-5b showed they expressed hepatic stem cell markers such as EpCAM, OCT3/4, and Thy-1, thus indicating the immature nature of the cells. A three-dimensional aggregate culture of THLE-5b showed a higher expression level of liver-specific genes such as albumin, α1-antitrypsin, and CYP3A4, thus suggesting that THLE-5b possess the capability to differentiate into hepatocytes. In a cell transplantation experiment, the cell cycle regulator p21 was transfected with adenoviral vector into the SCID mouse liver. On the next day, 8 × 10(5) cells of GFP-transfected THLE-5b were injected intrasplenically, together with the intraperitoneal administration of anti-asialo GM1 antibodies. The following day, a partial hepatectomy was performed. The GFP-THLE-5b cells were observed to have migrated and become integrated into the liver parenchyma 14 days after transplantation. The present protocol is thus considered to be a novel experimental model to elucidate the mechanism of hepatocyte repopulation and to develop efficient stem cell therapy in the liver.