The embryonic node behaves as an instructive stem cell niche for axial elongation

Area of Science:

• Developmental Biology
• Stem Cell Biology
• Embryogenesis

Background:

• Vertebrate axial tissues develop from Hensen's node, a posterior growth zone.
• Hensen's node is hypothesized to harbor resident stem cells crucial for development.
• The niche-specific factors promoting stem cell self-renewal within Hensen's node remain unidentified.

Purpose of the Study:

• To investigate whether Hensen's node acts as an instructive niche for resident stem cells.
• To identify the cellular and molecular characteristics of resident stem cells within Hensen's node.

Main Methods:

• Heterotopic transplantation of cell groups and single cells from Hensen's node.
• Long-term cell tracking and analysis of resident cell populations.
• Single-cell RNA sequencing (scRNA-seq) of resident cells.

Main Results:

• Cells not initially destined for Hensen's node can become resident and self-renew within it.
• Long-term resident cells are localized to the posterior region of Hensen's node.
• Resident cells predominantly express genes related to the G2/M phase of the cell cycle.

Conclusions:

• Hensen's node functions as a niche that maintains the self-renewal of axial progenitor cells.
• The posterior region of Hensen's node supports resident stem cell maintenance.
• Cell-cycle gene expression highlights a mechanism for progenitor self-renewal within the node niche.