Modelling alpha-1 antitrypsin deficiency using human induced pluripotent stem cell derived hepatocytes

Abstract

This thesis is split into four sections. First, it covers an attempt to improve the quality of hiPSC-derived hepatocyte generation, through an improved understanding of human liver developmental biology. This was investigated using single cell RNA sequencing of known stem cell compartments in fetal and adult human liver, as well as using hiPSC-derived hepatocytes:endothelial cell co-cultures. We identify that the bi-potent liver stem cells previously found in rodents (termed oval cells), also have a human analogue (we termed these cells HHyP). In addition, we identify several secreted proteins, including but not limited to IGFBP7, expressed highly in both the human fetal liver niche and in the hiPSC-derived hepatocyte:endothelial cell co-cultures. Adding these secreted factors into the differentiation media of hiPSC-derived hepatocytes could in the future yield more functional hiPSC-derived hepatocytes. Second, this thesis aimed to validate 7 targets identified from an annotated small molecule screen conducted on hiPSC-hepatocytes, generated from an alpha-1 antitrypsin deficiency (A1ATD) patient with clinically documented liver disease. We validated the results of the screen in three additional patients lines, all with clinically documented liver disease, with 7 compounds each tested at 8 doses. The goal was to identify promising small molecules capable of reducing intra-hepatic A1AT polymers and inflammation. The third section focuses on the small molecule CZC-25146, a putative inhibitor of LRRK2. The work in this thesis demonstrates that CZC-25146 reduces polymeric A1AT and inflammation in multiple patient-derived hiPSC-hepatocyte lines, and in the PiZ mouse model. LRRK2 is a well known target in the Parkinson’s field, thought to be safe to inhibit based on Parkinson’s studies. The work in this thesis was the first time LRRK2 has been investigated in the context of liver disease. One of the goals of this work was to investigate whether LRRK2 inhibition could be a useful therapeutic strategy in the context of A1ATD. The fourth and final section involves the generation of a new non-alcoholic fatty liver disease (NAFLD) model, using hiPSC-derived hepatocytes and hiPSC-derived adipocytes connected through a microfluidic system. The aim was to enable the investigation of how different patient genotypes influence disease progression in NAFLD, and to create a platform for NAFLD drug screening. The results presented in this thesis are preliminary, but it is hoped that this data can provide a useful starting point for future research on human liver developmental biology, hiPSC-derived hepatocyte and adipocyte maturation, NAFLD modelling, and investigations of LRRK2 in the context of liver disease.

Date of Award	1 Mar 2021
Original language	English
Awarding Institution	King's College London
Supervisor	Tamir Rashid (Supervisor)