News

Developmental Biology Retreat

The Theunissen Lab attended the 4th Annual Joint Retreat of the Developmental, Regenerative, and Stem Cell Biology (DRSCB) Program, the Department of Developmental Biology, and the Center of Regenerative Medicine at Pere Marquette Lodge (September 6-7, 2022). Our postdocs Shafqat Khan and Rowan Karvas gave poster presentations. Exciting to share our latest work with our colleagues!

New arrivals

We recently welcomed two new members to our team: Brittany Meyer and Joey Zemke.

Brittany received her Bachelor of Science in Biology from Eastern Illinois University. She also received her Master of Science in Biology from Eastern Illinois University in 2019. She joined the Theunissen lab in August of 2022 as a Research Technician II. She previously worked as an Adjunct Biology instructor at Lake Land Community College in Mattoon, IL. Brittany is interested in researching stem cells and their applications in disease therapy and regenerative medicine. Brittany is an active member of the American Chemical Society and is a Women in STEM Mentor. Outside the lab, she spends time with her husband, daughter, and two huskies. In her free time, she loves to read!

Joey graduated from the University of Washington in 2019 with a degree in Biology. While at UW, they studied resource allocation in Brassica rapa and lateral root development in Arabidopsis thaliana in the laboratory of Professor Jennifer Nemhauser as both an undergraduate researcher and laboratory technician. The idea of plant cell plasticity and regenerative capacity lead them to pursue a PhD in the Developmental, Regenerative, and Stem Cell Biology program at Washington University School of Medicine in St. Louis. Joey joined the Theunissen lab in April of 2022. They are interested in stem cell pluripotency and using stem cells to create models of disease and early human development.

Recent departures

The Theunissen lab recently said goodbye to three lab members: Kyoung Mi Park, Chen Dong, and Brian Chew.

Kyoung served as Research Technician and subsequently as Senior Research Technician in the Theunissen lab from 2018 to 2022. She played a major role in starting the lab and contributed to our studies on naive pluripotency and trophoblast differentiation. She also collaborated closely with Dr. Jianlong Wang’s lab at Columbia University on the OCT4 protein interaction network in naive and primed hPSCs, identifying pluripotent-state-specific interactions with distinct subunits of the BAF chromatin remodeling complex. In 2022 Kyoung joined the Developmental, Regenerative, and Stem Cell Biology (DRSCB) PhD Program at WashU.

Chen was a graduate student in the Developmental, Regenerative, and Stem Cell Biology (DRSCB) Program from 2018 to 2022. His PhD thesis was focused on methods for deriving human trophoblast stem cells (hTSCs) and specialized trophoblast cell types from naive hPSCs. He also performed a genome-wide CRISPR screen in collaboration with Bo Zhang’s lab at WashU, identifying essential and growth-restricting genes in hTSCs. Chen holds the distinction of being the first student to graduate from our lab. In 2022 he joined the Boston Consulting Group as a Consultant.

Brian was a Research Technician in the Theunissen lab from 2020 to 2022. He contributed to our studies on naive pluripotency, working closely with Shafqat Khan, and 2D and 3D models of trophoblast development, working under supervision of Chen Dong and Rowan Karvas. In 2022 Brian joined the Interdisciplinary Biomedical Graduate Program at the University of Pittsburgh.

We thank them for the contributions and wish them all the best with their future endeavors!

A genome-wide CRISPR-Cas9 screen in human trophoblast stem cells

Our study describing a genome-wide CRISPR-Cas9 knockout screen for essential and growth-restricting genes in human trophoblast stem cells (hTSCs) was published in Nature Communications today. By cross-referencing our results to those from similar genetic screens performed in other cell types, as well as gene expression data from early human embryos, we define hTSC-specific and -enriched regulators. These include both well-established and previously uncharacterized trophoblast regulators. Integrated analysis of chromatin accessibility, gene expression, and genome-wide location data reveals that the hTSC-specific essential transcription factor TEAD1 regulates the expression of many trophoblast regulators in hTSCs. In the absence of TEAD1, hTSCs fail to complete faithful differentiation into extravillous trophoblast (EVT) cells and instead show a bias towards syncytiotrophoblast (STB) differentiation. Overall, our study provides a valuable resource for dissecting the molecular regulation of human placental development and pregnancy-related diseases. Congratulations to Chen Dong, who spearheaded this project in collaboration with Shuhua Fu in Bo Zhang’s lab at WashU, and all other contributors!

Paper on stem-cell-derived trophoblast organoids

Our paper on stem-cell-derived trophoblast organoids (SC-TOs) was published in Cell Stem Cell today. In this work we describe a methodology for deriving self-renewing 3D trophoblast organoids from naive human pluripotent stem cells (hPSCs). Using single cell transcriptome analysis, we demonstrate that these organoids contain diverse trophoblast progenitor and specialized cell types that closely correspond to trophoblast identities in the post-implantation embryo. These organoid cultures also model placental X inactivation dynamics and selective vulnerability to emerging pathogens (SARS-CoV-2 and Zika virus). Big congrats to all members of the team, especially Rowan Karvas, and our collaborators Indira Mysorekar, Sabine Dietmann, Jacco Boon, and Liang Ma!

Chen Dong defends PhD thesis

Chen Dong successfully defended his PhD thesis, entitled “Investigating the specification and regulation of the human trophoblast lineage using cell culture models” on Friday, April 29th, 2022. Chen pioneered our efforts to derive human trophoblast stem cells (hTSCs) from naive pluripotent stem cells and performed a genome-wide CRISPR screen that identified essential and growth-restricting genes in hTSCs. He’s also the first PhD student to graduate from the Theunissen Lab. Congratulations Dr. Dong!

Rowan Karvas wins Poster Award at SSR Annual Meeting

Dr. Rowan Karvas won first place in the poster competition for postdoctoral trainees at the Annual Meeting of the Society for the Study of Reproduction in St. Louis, MO, for her poster entitled “3D organoids generated from human trophoblast stem cells model early placental development and susceptibility to emerging viral infections“. Well done Rowan!

OCT4 cooperates with distinct ATP-dependent chromatin remodelers in naïve and primed pluripotent states in human

Our paper mapping the interactomes of the master transcription factor OCT4 in naive and primed human embryonic stem cells (hESCs) was published today in Nature Communications. We report that OCT4 cooperates with cell state-specific chromatin modifiers in naive and primed hESCs to promote an open chromatin architecture at blastocyst-associated and pan-ectodermal genes, respectively. This work was a collaboration between our team at WashU, Xin Huang and Jianlong Wang at Columbia University, Cigall Kadoch at the Dana-Farber Cancer Institute, and Rudolf Jaenisch at the Whitehead Institute. The WashU team was spearheaded by Kyoung-mi Park in the Theunissen lab in collaboration with the labs of Bo Zhang, Sabine Dietmann, and Ting Wang.

Virtual Presentations at the ISSCR 2021 Annual Meeting

Chen Dong will present his work on a CRISPR-Cas9 knockout screen to identify essential and growth-restricting genes in human trophoblast stem cells in the concurrent session on Comparative Early Development. In addition, Rowan Karvas will present her work on 3D organoids generated from human trophoblast stem cells in the concurrent session on Complex 3D Systems for Therapy and Drug Discovery. Congrats Chen and Rowan!

Probing the signaling requirements for naive human pluripotency

Our paper investigating the signaling requirements for naive human pluripotency by high-throughput chemical screening was published today in Cell Reports. We report that naive hESCs can be maintained by blocking distinct nodes in the FGF signaling pathway and that dual MEK/ERK inhibition promotes efficient primed-to-naive resetting in combination with Activin A. This study was a collaboration between Washington University School of Medicine, the Novartis Institutes for Biomedical Research, and the Whitehead Institute for Biomedical Research

Laura Fischer receives NSF GRFP honorable mention

Laura Fischer, a second-year Ph.D. student in the Theunissen lab, has received an honorable mention from the National Science Foundation’s (NSF) 2020 Graduate Research Fellowship Program (GRFP).

The program recognizes and supports outstanding graduate students in NSF-supported science, technology, engineering, and mathematics disciplines who are pursuing research-based master’s and doctoral degrees at accredited United States institutions.

Kudos to Laura. We’re looking forward to your exciting studies!

Trophoblast stem cells derived from naive human stem cells

Our paper examining the trophoblast potential of distinct human stem cell states was published today in eLife. We report that naive, but not primed, human pluripotent stem cells (hPSC) can directly differentiate into trophoblast stem cells (TSC). The derivation of TSCs from naïve hPSCs presents a new model system to elucidate early mechanisms  governing placental development and associated pathologies. This study was a collaboration with the Solnica-Krezel, Wang and Kommagani labs at Washington University.

Image of naive hPSC-derived human TSCs stained with a KRT7 antibody by Chen Dong (Theunissen Lab).