# Human Trophoblast Stem Cells:  the In Vivo Niche and Relationship to Pluripotent Stem Cells

> **NIH NIH R01** · UNIVERSITY OF CALIFORNIA, SAN DIEGO · 2020 · $458,834

## Abstract

Project Summary/Abstract
The human placenta plays a major role in maintaining the proper environment for fetal growth, but remains as
the most poorly understood organ. This project aims to substantially improve our knowledge of this important
human organ by studying its early development in a systematic, detailed manner, then to combine this
knowledge with the latest technologies in regenerative medicine in order to develop in vitro models for the
study of both normal and abnormal placental development. Specifically, we aim to understand the
mechanisms underlying the establishment and maintenance of a multipotent human trophoblast stem (TS) cell,
one which can give rise to all other subtypes of trophoblast, the epithelial cells of the placenta. Over the past
few years, we have identified a key pathway, directed by the p53-related protein, p63, which is required for
maintenance of undifferentiated cytotrophoblast (CTB) stem cells in the early placenta. More recently, we have
noted that a subset of these CTB co-express CDX2, a transcription factor required for maintenance of TS cells
in mice, and hypothesize that these CDX2+/p63+ CTB are multipotent human TS cells. We will
characterize this subpopulation further, using a combination of FACS sorting, followed by differentiation assays
and both bulk and single cell transcriptome profiling. In this discovery-based approach, we will focus our
analysis on identification of transcription factors and cell surface markers, which characterize this cell
population in the early human placenta. At the same time, we will take a more gene-focused approach, probing
the specific role(s) of p63 and CDX2 in first trimester CTB proliferation and differentiation, including their
downstream targets. Finally, we will apply this knowledge to human pluripotent stem cells (hPSCs)--both
embryonic (hESCs) and induced pluripotent stem cells (hiPSCs)—in order to develop in vitro models for the
study of human trophoblast lineage specification and differentiation. We have established a novel
differentiation protocol for step-wise differentiation of hPSCs, first into CTB, and subsequently into hCG-
secreting syncytiotrophoblast (STB) and HLA-G+ extravillous trophoblast (EVT). Using this protocol, we have
found that Trisomy 21 iPSC spend a prolonged period in the CTB stem cell state, and show blunted
differentiation into functional STB, identical to the phenotype of primary CTB isolated from placentas with
Trisomy 21. These exciting preliminary data suggest that hPSCs may be useful for modeling trophoblast
differentiation defects, which are the basis for placental dysfunction. We will compare hPSC-derived
trophoblast to primary trophoblast from both pre- and post-implantation tissues in order to determine which
they most resemble. The successful completion of this project has the potential to transform the field of human
placental biology, by both identifying human TS cells within the placenta, and establishing hPSC-based models
o...

## Key facts

- **NIH application ID:** 9857487
- **Project number:** 5R01HD089537-04
- **Recipient organization:** UNIVERSITY OF CALIFORNIA, SAN DIEGO
- **Principal Investigator:** Mana M Parast
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $458,834
- **Award type:** 5
- **Project period:** 2017-03-15 → 2022-02-28

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9857487

## Citation

> US National Institutes of Health, RePORTER application 9857487, Human Trophoblast Stem Cells:  the In Vivo Niche and Relationship to Pluripotent Stem Cells (5R01HD089537-04). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/9857487. Licensed CC0.

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