Engineering Human Stem Cell Models for Multiple Angelman Syndrome (Epi)Genotypes

Quick Overview

In this presentation, Albert Keung discusses the goal of establishing human stem cell models that can capture multiple genotypes and epigenotypes of Angelman syndrome. Keung’s lab at North Carolina State University is working on engineering stem cells to reflect specific molecular changes in the UBE3A region of different Angelman syndrome genotypes. The team aims to create isogenic stem cell lines that can be easily shared and customized by other researchers. They are using CRISPR technology to edit the DNA and create specific mutations or deletions. The engineered stem cells can then be differentiated into cerebral organoids, which are microtissues that mimic the complexity of the human brain. These organoids can be used for therapeutic screening and studying the effects of different genes and mutations in different cell types. The ultimate goal is to develop a better understanding of Angelman syndrome and identify potential therapeutic targets.


In this talk, I will be discussing several projects aimed at establishing human stem cell systems that can capture multiple Angelman syndrome genotypes and epigenotypes. The overall goal is to comprehensively address the different forms of Angelman syndrome. The research is being conducted at North Carolina State University in Raleigh, and I would like to introduce the team of young scientists who are driving the work in the lab. Their passion and dedication to making the world a better place is inspiring.

Mission 1: Sharing the Overall Goal and Strategy

The first mission is to share what we are doing and the overall goal and strategy of our research. We are focused on molecularly changing the DNA and genome to understand and address Angelman syndrome. To help visualize the molecular changes, I will be using a schematic of the two chromosomes, highlighting key regions such as UBE3A and surrounding genes.

Mission 2: Making Science Accessible

The second mission is to make the science accessible and understandable. I will explain the molecular changes we are making at the DNA level, particularly in relation to UBE3A. This understanding is crucial as much of our work involves molecularly altering the DNA and genome. By using a consistent schematic, I aim to help readers see what is changing and what is not.

Angelman Syndrome Genotypes and Epigenotypes

Angelman syndrome is diverse, with various genotypes and epigenotypes. These include class I and II deletions, over 30 known UBE3A mutations, parental disomy, imprinting center defects, and other deleted genes. Our goal is to recreate these genotypes and epigenotypes in human stem cell systems to study their impacts on neuronal function and develop therapeutic approaches.

Engineering Stem Cell Lines

To achieve our goals, we are using molecular engineering and CRISPR tools to edit the DNA of stem cells. We start with a neurotypical stem cell line and use CRISPR to target specific regions in the genome. We can create large deletions, edit the epigenetic state, and recreate uniparental disomy or imprinting center defects. Although CRISPR is relatively inefficient, we have developed a landing pad system that allows us to efficiently introduce specific genes or mutations into the stem cells.

Advantages of Isogenic Stem Cell Lines

Our approach differs from induced pluripotent stem cells (iPSCs) as we aim to create isogenic stem cell lines. These lines have the same genetic background except for the Angelman mutations or deletions. This reduces variability in experiments and therapeutic screening, facilitates comparisons between researchers and institutes, and allows us to leverage fast funding for further research.

Differentiating Stem Cells into Cerebral Organoids

We are interested in differentiating the stem cells into human cerebral organoids, which are microtissues containing 30 to 50 different neuronal cells from the human brain. These organoids better mimic the complexity and structure of the brain. We have successfully generated organoids from stem cells with Angelman genotypes, which exhibit the specific silencing of UBE3A in neurons. These organoids can be used for therapeutic screening and studying functional changes in neurons.

Analyzing Cellular Diversity in Organoids

One advantage of organoids is their cellular diversity, containing multiple types of neurons from different brain regions. Advances in analytical technologies allow us to analyze gene expression signatures from individual cells within the organoids. This enables us to study how therapeutics impact gene expression in different cell types and brain regions.


The overall goal of our projects is to create stem cells that capture various Angelman syndrome genotypes and epigenotypes. We aim to generate organoids from these stem cells to understand the effects of specific genes and develop screening protocols. Our team of passionate scientists and students is dedicated to advancing this research. We are grateful for the collaboration within the research community and the funding provided by FAST. If you have any questions, please feel free to reach out to me.

Talk details

  • Title: Engineering Human Stem Cell Models for Multiple Angelman Syndrome (Epi)Genotypes
  • Author(s): Albert Keung
  • Author(s)’ affiliation: North Carolina State University
  • Publication date: 2022-01-04
  • Collection: 2021 FAST Science Summit