Human hepatic progenitor cell as a transplantable source of biliary regeneration

Hepatic Progenitor Cells (HPCs) are bipotential cells (able to regenerate both cholangiocytes and hepatocytes). In mice they have been shown to arise from within the liver and promote regeneration after extensive damage in situations where other repair mechanisms are not able to compensate. It has not been shown whether HPCs can be isolated from human liver, expanded, and used to regenerate liver or biliary injury. This thesis has investigated the presence of a human HPC and investigated its ability to repair and regenerate the diseased biliary system. Candidate human HPCs were isolated from human livers discarded from the transplantation process using surface antigen profiles and expanded in vitro. Functional analysis was performed by assessing the cells ability to expand in culture and their single cell colony forming ability. EpCAM+CD24+CD133+ cells were identified as the most likely candidate for a human HPC. These cells were able to be differentiated towards hepatocyte like and biliary like phenotypes and RNA Sequencing analysis revealed upregulation of genes associated with liver regeneration. A novel immunodeficient genetic mouse model of biliary disease was developed, the CK19CreERMDM2flox/flox RAG2-/- Il2RG-/- mouse which develops biliary injury, cholangiocyte senescence and fibrosis. This mouse was used to test the in vivo regenerative capacity of these cells. EpCAM+CD24+CD133+ cells were transplanted into this mouse and were able to improve mouse survival and serum biochemistry. Histological examination revealed engraftment of human HPCs within the mouse intra-hepatic and extra-hepatic biliary tree with an associated restoration of normal histology