Proliferation and Differentiation of Fetal Liver Epithelial Progenitor Cells after Transplantation into Adult Rat Liver

Abstract

To identify cells that have the ability to proliferate and differentiate into all epithelial components of the liver lobule, we isolated fetal liver epithelial cells (FLEC) from ED 14 Fischer (F) 344 rats and transplanted these cells in conjunction with two-thirds partial hepatectomy into the liver of normal and retrorsine (Rs) treated syngeneic dipeptidyl peptidase IV mutant (DPPIV(-)) F344 rats. Using dual label immunohistochemistry/in situ hybridization, three subpopulations of FLEC were identified: cells expressing both alpha-fetoprotein (AFP) and albumin, but not CK-19; cells expressing CK-19, but not AFP or albumin, and cells expressing AFP, albumin, and cytokeratins-19 (CK-19). Proliferation, differentiation, and expansion of transplanted FLEC differed significantly in the two models. In normal liver, 1 to 2 weeks after transplantation, mainly cells with a single phenotype, hepatocytic (expressing AFP and albumin) or bile ductular (expressing only CK-19), had proliferated. In Rs-treated rats, in which the proliferative capacity of endogenous hepatocytes is impaired, transplanted cells showed mainly a dual phenotype (expressing both AFP/albumin and CK-19). One month after transplantation, DPPIV(+) FLEC engrafted into the parenchyma exhibited an hepatocytic phenotype and generated new hepatic cord structures. FLEC, localized in the vicinity of bile ducts, exhibited a biliary epithelial phenotype and formed new bile duct structures or were incorporated into pre-existing bile ducts. In the absence of a proliferative stimulus, ED 14 FLEC did not proliferate or differentiate. Our results demonstrate that 14-day fetal liver contains lineage committed (unipotential) and uncommitted (bipotential) progenitor cells exerting different repopulating capacities, which are affected by the proliferative status of the recipient liver and the host site within the liver where the transplanted cells become engrafted. These findings have important implications in future studies directed toward liver repopulation and ex vivo gene therapy.

Bmi1promotes hepatic stem cell expansion and tumorigenicity in bothInk4a/Arf-dependent and -independent manners in Mice

“…16,17 These findings suggest that Alb þ CK7 þ cells, which have the capacity to give rise to both Alb þ CK7 À and Alb À Ck7 þ progenies, function as hepatic stem/progenitor cells. Therefore, the quantification of Alb þ CK7 þ impotent cells is one of the approaches to evaluate the content of hepatic stem/progenitor cells, although not all Alb þ CK7 þ cells necessarily have the capacity for bipotential differentiation.…”

Quantitative Gene Expression Analysis Reveals Transition of Fetal Liver Progenitor Cells to Mature Hepatocytes after Transplantation in uPA/RAG-2 Mice

“…A small fraction of cells even exhibit bipotential activity and generate both epithelial cell types. 15,17 Fetal liver progenitor cells proliferate extensively in vitro 16 and differentiate into adult parenchymal phenotypes after transplantation into a host animal. 17,25 In the present study we used EGFP-transgenic mice as donors for fetal liver progenitor cells.…”

“…15,17 Fetal liver progenitor cells proliferate extensively in vitro 16 and differentiate into adult parenchymal phenotypes after transplantation into a host animal. 17,25 In the present study we used EGFP-transgenic mice as donors for fetal liver progenitor cells. In contrast to other transplantation systems such as the DPPIV rat model, 26 which relies on staining of a developmentally regulated membrane enzyme, all nucleated cells in EGFP mice starting from oocytes constitutively express the fluorogenic transgene.…”

“…15 Fetal liver cells from rats and mice have been shown to differentiate into cells with biliary and hepatic phenotype after transplantation into recipient animals. 16,17 Lack of normal nontransformed liver progenitor cell lines has resulted in limited understanding of the linear relationships of different stages of liver cell differentiation. Consequently, differentiation and transdifferentiation of stem cells into fully functional hepatocytes have been observed only after transplantation experiments in vivo.…”

Stem cells in liver regeneration, fibrosis and cancer: the good, the bad and the ugly

“…Shafritz and colleagues [48] have shown that fetal liver epithelial progenitors (FLEPs) from ED14 rats are more clonogenic than normal adult hepatocytes, for when wild-type FLEPs were injected into recently hepatectomized syngeneic DPPIV-deficient F344 rats they proliferated for at least 6 months and constituted 7% of the recipient liver at this time, compared to colonization of only 0.06% of the liver by wild-type adult hepatocytes. However, much greater colonization of the mutant liver was observed when the recipient rats were given prior administration of retrorsine (a compound whose metabolites form DNA adducts in hepatocytes, preventing them from undergoing DNA replication); at 6 months after transplantation, 60-80% of the recipient liver was occupied by DPPIV + hepatocytes [49]. Important from a human standpoint, such cells can be cryopreserved for up to 20 months with no loss of repopulating activity [50].…”