The only currently available treatment for end stage liver disease is liver transplantation. Since the number of patients on the liver transplant list far exceeds the number of donor organs available, alternative treatment methods, such as hepatic cell transplantation, are under intensive investigation. However, studies to date with adult hepatocytes have met with only very limited success, except for those performed in animal model systems under highly pathologic circumstances. Several years ago, our laboratory discovered that fetal liver stem/progenitor cells (FLSPC) can replace 20-25% of hepatic mass in the normal adult rat liver by entering into cell competition with host hepatocytes. Recently, we observed that the level of tissue replacement by FLSPC increases dramatically (5-fold) as rats age. In addition, we have discovered that the level of activin A, a mediator of cell cycle arrest, as well as apoptosis, is increased in the aging rat liver. We hypothesize that increased activin A expression in the aging liver creates a host tissue microenvironment favoring replacement of hepatocytes by transplanted FLSPC. We hypothesize further that activin A mediates increased repopulation in the aging liver through increased cell competition between transplanted FLSPC and host hepatocytes. The goal of this project is to determine the specific mechanism(s) by which activin A mediates liver repopulation by transplanted FLSPC. Experiments will be performed 1) to identify specific apoptosis, anti-apoptosis, proliferation, cell cycle and senescence related genes whose expression is increased or decreased during liver repopulation by transplanted FLSPC in older vs younger cell transplant recipients, 2) to study the mechanism in vitro for activin A induced growth arrest and apoptosis in isolated hepatic cells and 3) to determine in an experimental model of liver disease (i.e. hepatic fibrosis) whether liver repopulation by FLSPC is augmented by endogenous secretion of activin A. Since both the number and age of patients with end-stage liver diseases will continue to increase over the next twenty years, the potential use of cell transplantation to treat these patients before the end-stage would be of substantial clinical benefit, especially in the elderly. Therefore, identifying the specific cell type(s) for effective cell transplantation to replace hepatic parenchyma and restore liver function in elderly patients with chronic liver diseases would represent a particularly valuable therapy. Results from the proposed studies will also provide critical understanding of the basic requirements and mechanisms that will serve as a guide for effective liver repopulation in patients of all ages.

Public Health Relevance

We have found that repopulation of adult rat liver with transplanted fetal liver cells increases with the age of the recipient and can be achieved in rats with advanced hepatic fibrosis. Since whole liver transplants are generally not performed in patients beyond age 65, if our findings are applicable to humans, this suggests that liver cell transplantation would represent a major new therapeutic approach for treatment of chronic liver diseases, especially in the elderly.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK090325-04
Application #
8723166
Study Section
Hepatobiliary Pathophysiology Study Section (HBPP)
Program Officer
Sherker, Averell H
Project Start
2011-09-21
Project End
2016-08-31
Budget Start
2014-09-01
Budget End
2015-08-31
Support Year
4
Fiscal Year
2014
Total Cost
Indirect Cost
Name
University of Pittsburgh
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
City
Pittsburgh
State
PA
Country
United States
Zip Code
15213
Pradhan-Sundd, Tirthadipa; Zhou, Lili; Vats, Ravi et al. (2018) Dual catenin loss in murine liver causes tight junctional deregulation and progressive intrahepatic cholestasis. Hepatology 67:2320-2337
Haridoss, Srividyameena; Yovchev, Mladen I; Schweizer, Hannah et al. (2017) Activin A is a prominent autocrine regulator of hepatocyte growth arrest. Hepatol Commun 1:852-870
Ono, Yoshihiro; Pérez-Gutiérrez, Angelica; Yovchev, Mladen I et al. (2017) Regeneration and Cell Recruitment in an Improved Heterotopic Auxiliary Partial Liver Transplantation Model in the Rat. Transplantation 101:92-100
Tao, Junyan; Zhang, Rong; Singh, Sucha et al. (2017) Targeting ?-catenin in hepatocellular cancers induced by coexpression of mutant ?-catenin and K-Ras in mice. Hepatology 65:1581-1599
Yovchev, Mladen I; Oertel, Michael (2017) Fetal Liver Stem/Progenitor Cell Transplantation: A Model to Study Tissue Mass Replacement and Cell-Based Therapies. Methods Mol Biol 1506:101-115
Yovchev, Mladen I; Locker, Joseph; Oertel, Michael (2016) Biliary fibrosis drives liver repopulation and phenotype transition of transplanted hepatocytes. J Hepatol 64:1348-57
Delgado, Evan; Okabe, Hirohisa; Preziosi, Morgan et al. (2015) Complete response of Ctnnb1-mutated tumours to ?-catenin suppression by locked nucleic acid antisense in a mouse hepatocarcinogenesis model. J Hepatol 62:380-7
Nishikawa, Taichiro; Bellance, Nadège; Damm, Aaron et al. (2014) A switch in the source of ATP production and a loss in capacity to perform glycolysis are hallmarks of hepatocyte failure in advance liver disease. J Hepatol 60:1203-11
Yovchev, Mladen I; Xue, Yuhua; Shafritz, David A et al. (2014) Repopulation of the fibrotic/cirrhotic rat liver by transplanted hepatic stem/progenitor cells and mature hepatocytes. Hepatology 59:284-95
Yovchev, Mladen I; Dabeva, Mariana D; Oertel, Michael (2013) Isolation, characterization, and transplantation of adult liver progenitor cells. Methods Mol Biol 976:37-51