Movement restored in paralyzed mice after breakthrough in genetic engineering

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DALLAS – About 5.4 million Americans are currently living with paralysis, of which 27.3% are due to spinal injuries. According to a recent study, movement can be restored in mice paralyzed by genetically engineered spinal injuries. Scientists say this breakthrough could ultimately help paraplegic and quadriplegic patients walk again.

About 2,500 people a year suffer from life-changing paralysis, usually as a result of car or sports accidents, violence and falls. After the initial damage, the sticky scar tissue prevents repair by acting like glue, resulting in paralysis under the site.

Scientists at the University of Texas Southwestern have discovered a protein in the body that makes regeneration possible. The chemical, known as SOX2, stops scar formation and nourishes nerve cells. It is produced by cells in the central nervous system called NG2 glia.
According to study leader Chun-Li Zhang, PhD, this opens the door to safe and effective therapy that stimulates SOX2 in humans. This would help heal injuries to the spine by making new neurons and reducing scar tissue.

New spinal neurons converted from the glia. Movement was restored in mice paralyzed by spinal injuries. (University of Texas Southwestern)

“The area of ​​spinal cord injury has been the subject of extensive research trying to heal the damage with stem cells that produce new neurons. However, what we are offering here is that we may not need to transplant cells from the outside. By encouraging the NG2 glia to produce more SOX2, the body can make its own new neurons, rebuilding itself from the inside out, ”says Zhang, professor of molecular biology at the university.

The results offer hope for the hundreds of thousands of people around the world who suffer from a spinal cord injury each year. Cells in some tissues and organs proliferate after damage as part of the healing process. This does not apply to the spinal cord – a key obstacle to recovery, explained Professor Zhang.

A promising breakthrough for patients with spinal cord injury

The spinal cord is the key junction for the constant flow of electrical signals between the brain and the rest of the body. Once injured, injuries tend to be permanent because nerve cells cannot regenerate. Communication is then interrupted, causing paralysis, loss of sensation and sometimes fatal consequences such as an inability to control breathing or heart rate.

The brain has a limited ability to repair itself with the help of progenitor cells which can turn into a specific type, such as stem cells. Professor Zhang and his colleagues looked for cells that might play a similar role in the spinal cord and identified the NG2 glia in laboratory rodents.

In a series of experiments, they engineered their DNA to make cells overproduce SOX2. After their spinal cord ruptured, mice produced tens of thousands of new, mature nerve cells. Analysis showed that they integrated into the injured area, making connections with existing neurons that are needed to relay signals between the brain and the body.

“What is even more promising is that this genetic engineering has led to functional improvements. Animals designed to overproduce SOX2 in their NG2 glia performed better on motor skills weeks after spinal cord injury compared to those that produced normal amounts of SOX2, ”explains Zhang. “The reasons for this improvement in performance seemed to be multiple. These animals had new neurons that seemed to take over from those damaged in injury. They also had much less scar tissue at the injury site, which could hamper recovery. “

A full recovery from a spinal cord injury would have significant social and economic benefits for millions of people.

The results are published in the journal Cellular stem cell.

SWNS writer Mark Waghorn contributed to this report.

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