Retinoic acid induces human gastruloids with posterior embryo-like structures

Area of Science:

• Developmental Biology
• Stem Cell Biology
• Human Embryogenesis

Background:

• Gastruloids are in vitro models of early human development.
• Existing human gastruloids lack morphological resemblance to post-implantation human embryos.

Purpose of the Study:

• To develop an improved human gastruloid model that more closely mimics early human embryonic development.
• To investigate the molecular mechanisms regulating human gastruloid formation and patterning.

Main Methods:

• Treatment of human gastruloids with an early pulse of retinoic acid (RA) and subsequent Matrigel application.
• Single-cell RNA sequencing for in silico staging and developmental trajectory analysis.
• Chemical and genetic perturbations to investigate signaling pathways and transcription factor functions.

Main Results:

• RA-treated human gastruloids exhibit posterior embryo-like structures, including neural tubes and somites.
• Diverse cell types such as neural crest, progenitors, and myocytes are generated.
• In silico staging reveals advanced developmental progression compared to other models, aligning with specific embryonic stages in mice and monkeys.
• WNT, BMP signaling, TBX6, and PAX3 are identified as key regulators of somite and neural tube development.

Conclusions:

• RA-induced human gastruloids provide a robust and scalable model for studying early human embryogenesis.
• This model facilitates the investigation of developmental processes and potential congenital disorders.
• RA-gastruloids represent a significant step forward in recapitulating human embryonic development in vitro.