Developmental differences in the expression of FGF receptors between human and mouse embryos

Area of Science:

• Developmental Biology
• Stem Cell Biology
• Reproductive Biology

Background:

• Fibroblast growth factor (FGF) signaling is vital for mouse trophoblast stem (TS) cell expansion and maintenance.
• FGFs are used in vitro to derive TS cells from mouse embryos.
• The role of FGF signaling in human trophoblast development remains unclear.

Purpose of the Study:

• To investigate the potential of deriving human trophoblast stem (TS) cells from blastocysts.
• To explore the expression of FGF receptors (FGFRs) in human blastocysts and early placentae.
• To understand the role of FGF signaling in early human trophoblast development.

Main Methods:

• Attempted derivation of human TS cells from blastocysts under various culture conditions, including FGFs and stem cell factor (SCF).
• Analyzed FGFR expression in human blastocysts and first-trimester placentae.
• Examined FGFR2 and activated ERK1/2 expression in human placental tissues.

Main Results:

• SCF improved human blastocyst outgrowths, but stable human TS cell lines were not established.
• FGFR transcription was rarely observed in human blastocysts, and FGFR2 protein was undetectable.
• Robust FGFR2 expression and activated ERK1/2 were found in the cytotrophoblast layer of early human placentae.

Conclusions:

• FGF-dependent trophoblast expansion in humans likely initiates later in development than in mice.
• FGF signaling is unlikely to maintain a TS cell compartment during the human peri-implantation period.
• Early human placental cytotrophoblasts represent a potential source for FGF-dependent human TS cells.