Regional Signaling Controls Stem Cell-Mediated Regeneration in an Invertebrate Chordate

Area of Science:

• Developmental Biology
• Regenerative Medicine
• Stem Cell Biology

Background:

• Quiescent stem cells in many tissues activate after injury, but the regulation by local signals remains unclear.
• The solitary ascidian Ciona robusta presents a model where upper body fragments regenerate, but lower fragments do not.

Purpose of the Study:

• To investigate the differences in transcriptional dynamics and signaling environments between regenerative and non-regenerative contexts in Ciona robusta.
• To understand how local signals regulate stem cell activation and tissue repair following injury.

Main Methods:

• Utilized flow cytometry, single-cell RNA sequencing (scRNA-seq), transplantation experiments, and fate mapping.
• Compared gene expression and cellular behavior in regenerative versus non-regenerative ascidian fragments.

Main Results:

• Identified a candidate stem cell population with significant proliferative and differentiation potential upon transplantation.
• Demonstrated that regenerative capacity is determined by region-specific signaling cues, not solely stem cell abundance.
• Observed distinct local expression of metabolic, immune, and differentiation-related factors in different body regions.

Conclusions:

• The divergence of injury response into regeneration or failure is governed by spatially distinct signaling environments.
• These findings highlight principles of tissue repair that could potentially be applied to enhance regeneration in other systems.