Researchers at Cedars‑Sinai have uncovered a previously unknown repair program in the central nervous system that may pave the way for novel therapies aimed at spinal cord trauma, stroke, and autoimmune conditions such as multiple sclerosis. The study, appearing in Nature, spotlights an unexpected function of astrocytes—support cells that make up a large portion of the brain and spinal cord.
The team coined the term “lesion‑remote astrocytes” (LRAs) for a group of astrocytes that sense damage from a distance and activate a cascade of healing actions. Among several sub‑types, one particular LRA releases the protein CCN1, which talks directly to microglia, the brain’s resident immune cleaners.
How the Spine Reacts to Damage
The spinal cord runs as a thick cable of nerve tissue from the brain down the back. Its inner gray matter houses neuronal cell bodies and astrocytes, while the surrounding white matter contains long axons that ferry signals throughout the body. Astrocytes maintain the chemical balance that allows these signals to travel smoothly.
When the cord is cut or bruised, axons tear, leading to loss of movement, sensation, and sometimes severe paralysis. The broken fibers generate fatty debris that can linger and trigger inflammation far beyond the original wound because axons stretch long distances.
Lesion‑Remote Astrocytes Direct Immune Cleanup
In mouse models of spinal injury, LRAs were observed rallying microglia to the injury zone. The CCN1 protein they secreted reprogrammed microglia’s metabolism, enabling the cells to actually break down the fatty waste rather than merely engulf it. When the researchers blocked CCN1 production in astrocytes, microglia still ate debris but failed to digest it, resulting in clusters of overloaded immune cells and heightened inflammation that impeded recovery.
Human spinal cord samples showed the same CCN1‑driven interaction, suggesting the mechanism operates in patients as well.
Broader Implications for Neurological Diseases
Examination of tissue from individuals with multiple sclerosis revealed an identical CCN1 signaling pattern, indicating that lesion‑remote astrocytes may also temper chronic inflammation in demyelinating disorders. Experts believe the findings could extend to traumatic brain injury and other neurodegenerative conditions.
“Astrocytes have been dramatically underappreciated in central nervous system repair,” said David Underhill, PhD, chair of Biomedical Sciences. “Targeting lesion‑remote astrocytes offers a realistic route to curb lingering inflammation, boost functional regeneration, and improve outcomes after both spinal and brain injuries.”
The next phase of research will focus on pharmacologically activating the CCN1 pathway and exploring how it influences aging‑related neuroinflammation.
Funding Acknowledgement: This work was supported by multiple grants from the U.S. National Institutes of Health, the Paralyzed Veterans Research Foundation, Wings for Life, the Department of Defense, and several academic fellowships.