Adult brain cells reveal a surprising ability to repair damaged tissue.
Researchers using live imaging in adult mice found that surviving astrocytes divided and moved their nuclei into a patch of cortex where astrocytes had been selectively destroyed, refilling it within weeks.
A study describes how astrocytes, a type of support cell in the brain, regrow after a small area of them is lost. The researchers report that surviving astrocytes at the edge of the damage repopulated the empty zone within a few weeks in adult mice.
The team created focal lesions in the somatosensory cortex by injecting an antibody against aquaporin-4, a water channel found almost only on astrocytes, together with complement. The model relates to neuromyelitis optica spectrum disorder, an autoimmune disease in which astrocytes are attacked. The injection left cylindrical areas without astrocytes. According to the authors, blood vessel structure and capillary blood flow did not change, and neurons were still present in the area. They followed the same regions with two-photon microscopy for up to 60 days.
Astrocytes next to the lesion changed shape in the first days. Their processes lengthened, peaking at 5 days after injection, and pointed toward the lesion center. A marker of astrocyte reactivity, GFAP, rose briefly and then returned to control levels. Calcium activity in these cells increased at 5 days and had normalized by 14 days. Unlike in traumatic brain injury or stroke models, no glial border formed around the lesion.
By tracing individual cells, the researchers found that about 60% of astrocytes bordering the lesion divided within 60 days, compared with about 1% near control injections. Some cells divided several times, producing up to four daughter cells, and the division was not limited to cells near blood vessels. Roughly 75% of daughter nuclei moved within the first 7 days, and more than 60% of those traveled over 30 micrometers from the mother cell. Electron microscopy showed that a mother and daughter nucleus shared the same cytoplasm. Spatial transcriptomics showed an injury-related gene response that faded as the astrocyte network was restored.
The authors report that this repopulation was more limited in stroke lesions of comparable size. Experiments with a different method of removing astrocytes suggested that the extent of astrocyte loss may influence the response. They also note that similar astrocyte features appeared in lesions from patients with the disorder. The central experiments were carried out in mice, and the authors describe their conclusions as a proposal.
Note: The headline does not say the work was done in adult mice. The page reports a mouse model, with comparable features seen in lesions from patients, not a demonstrated repair ability in humans.
At a Glance
- About 60% of astrocytes bordering the lesion divided within 60 days, versus about 1% in control-injected areas.
- Astrocyte process length peaked 5 days after injection, and calcium activity had normalized by 14 days.
- Around 75% of daughter-cell nuclei relocated within 7 days; over 60% of those moved farther than 30 micrometers.
- Mice were imaged for up to 60 days after antibody injection into the somatosensory cortex.
- No glial border formed around the lesions, unlike in traumatic brain injury and stroke models.
Sources
This brief was written by Brightside Report from the reporting linked above. Spot an error? Request a correction.