Spinal cord regeneration deploys adult molecular programs that do not recapitulate embryonic development

Area of Science:

• Neuroscience
• Developmental Biology
• Regenerative Medicine

Background:

• Adult zebrafish exhibit remarkable spinal cord regeneration after injury, a process dependent on stem cells.
• These progenitors are thought to retain embryonic radial glial features and reactivate developmental programs.

Purpose of the Study:

• To investigate the extent to which spinal cord regeneration recapitulates developmental processes.
• To compare gene expression profiles across zebrafish development, homeostasis, and regeneration using single-cell RNA sequencing.

Main Methods:

• Integration of single-cell RNA-sequencing datasets from zebrafish development, adult homeostasis, and spinal cord injury regeneration.
• Annotation of larval progenitors based on dorso-ventral identities and chronological age.
• Inference of spatio-temporal features of adult sox2+ progenitors.

Main Results:

• Immune cell maturation and neuronal differentiation continue into juvenile stages.
• Only 25% of adult injury-responsive progenitors recapitulate larval progenitor identities.
• Dorso-ventral progenitor identities crucial for development are not maintained in adult homeostasis or regeneration.

Conclusions:

• Adult spinal cord regeneration repurposes developmental pathways into novel regenerative functions.
• Regeneration does not faithfully recapitulate embryonic or larval development.
• This study provides a comprehensive single-cell analysis comparing development and regeneration.