Re-Growth of Specific Nerve Cells to Restore Spinal Cord Function in Mice

Monday - September 25 2023, 03:59 UTC - 1 year ago

Scientists have made a breakthrough in restoring the function of damaged spinal cords in mice by re-growing specific nerve cells to their original destinations. A team of researchers from UCLA, the Swiss Federal Institute of Technology, and Harvard University tested two approaches of axon regeneration, unrestricted axonal regrowth and directed axonal regrowth, and found that directed axonal regeneration was much more effective for the recovery of walking ability in mice. The study emphasized the importance of restoring anatomical connectivity and suggests that directed axonal regeneration is a viable concept for treating severe spinal cord injuries.

Scientists have made a breakthrough in restoring the function of damaged spinal cords in mice. They have discovered that re-growing specific nerve cells to their original destinations can lead to recovery, while random re-growth does not work.

A spinal cord injury is a profoundly debilitating condition that exerts its impact upon countless individuals globally. It can cause paralysis, loss of sensation, and chronic pain. One of the main challenges in treating spinal cord injury is to regenerate the connections between nerve cells, or axons, that are severed by the injury.

Re-growing axons in nerve cells .

In a previous study published in Nature, a team of researchers from UCLA, the Swiss Federal Institute of Technology, and Harvard University had developed a treatment that could stimulate axons to re-grow across severe spinal cord lesions in rodents. However, this did not result in significant functional improvement.

In a new study published in Science, the same team aimed to find out whether directing the re-growth of axons from specific types of nerve cells to their natural targets could lead to better outcomes. They used advanced genetic techniques to identify the nerve cells that are responsible for walking improvement after a partial spinal cord injury.

They then tested two different approaches to regenerate these axons across a complete spinal cord injury in mice. One approach was to simply let the axons re-grow randomly, without any guidance. The other approach was to use chemical signals to attract and steer the axons to their natural destination in the lower part of the spinal cord.

The researchers found that the second approach was much more effective than the first one. The mice that received the guided regeneration showed significant improvements in walking ability, while the mice that received the random regeneration did not.

Significance .

The study unveiled the significance of both regenerating axons across injuries and directing them towards their natural destinations for achieving substantial neurological restoration after spinal cord injuries, as emphasized by Michael Sofroniew, MD, Ph.D., who serves as a professor of neurobiology at the David Geffen School of Medicine at UCLA and assumes the role of senior author in the recent research.

The researchers say that their findings have implications for developing therapies for spinal cord injury and other forms of central nervous system damage in larger animals and humans. However, they also acknowledge the challenges of promoting regeneration over longer distances and more complex environments.

The researchers draw the conclusion that the application of the principles detailed in their study will provide the key to achieving significant repair of spinal cord injuries and could potentially expedite recovery in cases of other central nervous system injuries and diseases.

The study was published in Science.

Study abstract: .

Axon regeneration can be induced across anatomically complete spinal cord injury (SCI), but robust functional restoration has been elusive. Whether restoring neurological functions requires directed regeneration of axons fro specific nerve cell types to their targets remains an open question. We characterized a small population of Dbx1-expressing commissural interneurons that restore partial hindlimb function. We then tested two strategies for channeling regenerating axons to their original destinations: unrestricted axonal regrowth versus directed axonal regrowth using chemorepellent guidance. We found that directed, but not unrestricted growth, enabled axons reaching beyond the lesion to restore anatomical connectivity and to considerably improved hindlimb locomotor functions. These results indicate that directed axonal regeneration is a viable concept for promoting substantial recovery after severe SCI.