Derivation of Haploid Trophoblast Stem Cells via Conversion In Vitro

Area of Science:

• Developmental Biology
• Stem Cell Biology
• Genetics

Background:

• Haploid cells, with their single genome, are valuable for genetic screening in mammals.
• The absence of haploid extraembryonic lineage cells has hindered placental genetic screening.
• Previous methods lacked suitable tools for haploid placental cell research.

Purpose of the Study:

• To generate a novel haploid trophoblast stem cell (haiTSC) line.
• To establish a system for high-throughput genetic screening in placental development.
• To identify genes involved in spongiotrophoblast specification.

Main Methods:

• Overexpression of Cdx2 in haploid embryonic stem cells.
• p53 deletion to minimize diploidization during cell conversion.
• Long-term maintenance of haploidy using FGF4 and heparin, with periodic cell sorting.
• PiggyBac-mediated high-throughput mutagenesis for genetic screening.

Main Results:

• Successfully generated haploid-induced trophoblast stem cells (haiTSCs) from haploid embryonic stem cells.
• Demonstrated that haiTSCs possess multipotency for placental lineages and maintain haploidy long-term.
• Identified Htra1 as a critical gene blocking spongiotrophoblast specification through genetic screening.

Conclusions:

• The generation of haiTSCs overcomes limitations in haploid extraembryonic cell research.
• haiTSCs provide a powerful platform for genetic screening in placental development.
• Htra1 plays a key role in regulating spongiotrophoblast differentiation.