Duncan Lab Members and Alumni

James Heslop, Ph.D.
Postdoctoral Fellow
Project: Molecular Basis of Human Hepatocyte Formation

Human liver development is incompletely understood. In part, this is due to the lack of available material to study the complex processes of differentiation, with most of our current understanding derived from mouse models. The recent establishment of protocols which allow for the scalable, reproducible and manipulatable differentiation of human induced pluripotent stem cells to hepatocyte-like cells has allowed for researchers to investigate human liver development in a dish. My projects focus on some of the earliest stages of differentiation, investigating the role of the GATA family of transcription factors during endoderm formation and the role of FGF signaling in hepatic specification. Both of these pathways have been shown to be essential for liver development, but the exact mechanisms which underlie their importance requires further investigation.

Ray Jui-Tung Liu, Ph.D.
Postdoctoral Fellow
Project: Identification of Small Molecules to Enhance the Formation of Hepatocytes From iPSCs

My project is using novel high throughput reporter assays to identify pathways that regulate hepatocyte maturation. We have generated human iPSC-lines that express secreted reporter proteins from genes that are characteristic of mature hepatocytes. We are using these cell lines to identify small molecules that impact the efficiency of differentiation. These studies will provide novel insight into the mechanisms that control hepatocyte maturation as well generate new procedures to efficiently produce human hepatocytes from stem cells.

James Corbett, Ph.D.
Postdoctoral Fellow
Project: Modeling Mitochondrial DNA Depletion Syndrome Using iPSC-derived Hepatocytes

Mitochondrial DNA Depletion Syndromes (MTDPS) are a group of rare congenital diseases that result in disruption of mitochondrial DNA and often cause severe disability or death in early childhood. I am investigating the utility of iPSC derived hepatocytes with engineered CRISPR-Cas9 mutations in genes vital for the maintenance of mitochondrial DNA, to model MTDPS in vitro. We are combining miniaturized cell differentiation platforms with high throughput drug screening to identify small molecules that can potentially reverse the disease phenotype as well as investigate the mechanisms underlying disease severity in MTDPS mutant cells. We hope to develop models to inform clinical strategies for treating MTDPS of varying severity as well as identify novel or repurposed therapeutics that can aid in the treatment of the disease.

Behshad Pournasr
Postdoctoral Fellow
Project: Modeling inborn errors in hepatic metabolism using iPSCs derived hepatocytes.

Inborn errors in hepatic metabolism are caused by deficiencies commonly in a single enzyme as a consequence of gene mutations. Unfortunately, cellular and animal models that accurately recapitulate these rare diseases have been lacking. Induced pluripotent stem cells can differentiate into a wide variety of cell types, including hepatocytes, thereby offering an innovative approach to unravel the mechanisms underlying inborn errors in hepatic metabolism. Moreover, such cell models could potentially provide a platform for the discovery of therapeutics. My project focuses on organic acidemias (OA) and I am using CRISPR/Cas9 technology to target genes encoding key enzymes. The goal is to generate a cellular model to advance our0 understanding of disease mechanism and to provide a platform to identity novel treatments.

Caren Doueiry
Graduate Student
Molecular and Cell Biology Program, MD/PhD Program
Project: Modeling Nonalcoholic Fatty Liver Disease Using iPSC-Derived Hepatocytes

The incidence of Nonalcoholic Fatty Liver Disease (NAFLD) has been dramatically increasing. NAFLD can progress to steatosis, fibrosis, and liver cancer. It is also projected to be the leading cause of hepatocellular carcinoma in the next decade. Several etiologies, including genetic variants, contribute to NAFLD progression. Besides weight loss, there are no treatments currently available. My project uses CRISPR/Cas 9 genome engineering to investigate the effect of genetic variants associated with NAFLD and its progression. Using that information, Iaimtouse high-throughput drug screening for discovery of potential NAFLD therapeutics.

Matthew Savoca
Graduate Student
Masters in Biomedical Sciences Program
Project: Identification of Small Molecule Therapeutics for Mitochondrial DNA Depletion Syndrome

Although rare, Mitochondrial DNA Depletion Syndromes (MTDPS) often have very unfortunate prognoses. These mitochondrial disorders are marked by a significant reduction in mitochondrial DNA affecting several organs including the liver. The outcome is commonly early childhood lethality. My project uses hepatocytes derived from induced pluripotent stem cells as translational model to conduct small molecule drug screens to identify potential therapeutics for MTDPS.

Paige Lamprecht, M.Sc.
Technician and Lab Manager
Project: Screen of Novel Small Molecules for Potential Treatment for Mitochondrial DNA Depletion Syndrome 3

Mitochondrial DNA Depletion Syndrome 3 (MTDPS3) is a heritable disease that causes a reduction in the mitochondrial genome. As consequence proteins encoded by the mtDNA including electron transport chain complexes are depleted resulting in decreased ATP production by oxidative phosphorylation. Complications associated with MTDPS3 include hepatic failure with onset occurring during infancy. Because there is currently no treatment for MTDPS3, patients commonly die from hepatic failure in early childhood. In my project, I am working with IPSC-derived hepatocyte-like cells that recapitulate the MTDPS3 disease state. Using these cells, we are performing a high throughput screen of novel small molecules in an attempt to identify those with the potential to be used therapeutically.

Christiana S. Kappler, Ph.D.
Staff Scientist II
Cell Models Core

The Cell Models Core is a component of the COBRE in Digestive and Liver Disease (CDLD) and the Digestive Disease Research Core Center (DDRCC). The core uses CRISPR-Cas9 genome engineering techniques in combination with stem cell technologies to generate cell models of human digestive and liver diseases. The use of induced pluripotent stem cells (iPSCs) for modeling diseases has fostered significant progress in exploring the mechanisms that mediate digestive and liver diseases.Using CRISPR-Cas9 technology to knockout specific genes or modify specific genetic sequences allows us to provide researchers with the tools to investigate the mechanisms underlying various diseases by mimicking the mutations observed in patients. The capacity to induce differentiation of these iPSCs into tissue-specific cells can then be utilized for both determining the consequences of these mutations and for drug screening studies to identify potential therapeutic agents.

Alumni

Ran Jing, PhD
Postdoctoral Fellow
Harvard University, laboratory of George Daley