In breakthrough, nerve connections are regenerated after spinal cord injury

Researchers for the first time have induced robust regeneration of nerve connections that control voluntary movement after spinal cord injury, showing the potential for new therapeutic approaches to paralysis and other motor function impairments.

In a study on rodents, the UC Irvine, UC San Diego and Harvard University team achieved this breakthrough by turning back the developmental clock in a molecular pathway critical for the growth of corticospinal tract nerve connections.

They did this by deleting an enzyme called PTEN (a phosphatase and tensin homolog), which controls a molecular pathway called mTOR that is a key regulator of cell growth. PTEN activity is low early during development, allowing . PTEN then turns on when growth is completed, inhibiting mTOR and precluding any ability to regenerate.

Trying to find a way to restore early-developmental-stage cell growth in injured tissue, Zhigang He, a senior neurology researcher at Children's Hospital Boston and Harvard Medical School, first showed in a 2008 study that blocking PTEN in mice enabled the regeneration of connections from the eye to the brain after optic nerve damage.

He then partnered with Oswald Steward of UCI and Binhai Zheng of UCSD to see if the same approach could promote nerve regeneration in injured sites. Results of their study appear online in .

"Until now, such robust nerve regeneration has been impossible in the spinal cord," said Steward, anatomy & neurobiology professor and director of the Reeve-Irvine Research Center at UCI. "Paralysis and loss of function from spinal cord injury has been considered untreatable, but our discovery points the way toward a potential therapy to induce regeneration of following spinal cord injury in people."

According to Christopher & Dana Reeve Foundation data, about 2 percent of Americans have some form of paralysis resulting from spinal cord injury, which is due primarily to the interruption of connections between the brain and spinal cord.

An injury the size of a grape can lead to complete loss of function below the level of injury. For example, an injury to the neck can cause paralysis of arms and legs, loss of ability to feel below the shoulders, inability to control the bladder and bowel, loss of sexual function, and secondary health risks including susceptibility to urinary tract infections, pressure sores and blood clots due to an inability to move the legs.

"These devastating consequences occur even though the spinal cord below the level of injury is intact," Steward noted. "All these lost functions could be restored if we could find a way to regenerate the connections that were damaged."

He and his colleagues are now studying whether the PTEN-deletion treatment leads to actual restoration of motor function in mice with spinal cord injury. Further research will explore the optimal timeframe and drug-delivery system for the therapy.

Provided by University of California - Irvine
Citation: In breakthrough, nerve connections are regenerated after spinal cord injury (2010, August 8) retrieved 18 August 2019 from
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Aug 08, 2010
I completely agree with you. The medical approval procedure in America is far behind the pace of innovation. It is unfortunate this is the case in the country that does the majority of the world's medical research.

I think that Asian countries will be the best bet for access to "unproven" medical procedures, as it's unlikely the FDA will make it any easier in the near future. India and China may not be known for their healthcare, but I think that will change in the coming decade.

Aug 08, 2010
But those Asian countries may also become known for the next Thalidomide. Looser regulations can cut both ways unfortunately.

I'm all for experimental and cutting edge medicine, but only if the patient fully understands that experimental medicine is potentially lethal. If you're going to die of cancer, or stuck in a wheelchair for the rest of your life, sure. If you're experiencing morning sickness (as was the case of Thalidomide) you should take something else and/or slug it out until the FDA is through with it.

Aug 09, 2010
Approval time should be related to the severity of the illness and chances for making things worse. Cancer and paralysis treatments should be on really fast tracks; pimples and gray hair should be treated differently. Why is so hard to figure out???
Three and five year waits (or more) for terminally ill patients is ridiculous.
As long as it is impossible to sue someone if you have signed off on the dangers, then there should be little to no liability issues for the researchers.

Aug 09, 2010
The problem is that it *isn't* impossible to sue the research company even if you've signed off on the dangers. It isn't uncommon for the families of test subjects to sue the companies preforming the tests, despite the fact that the patients knew darned well that it was a highly experimental treatment with potentially lethal consequences (...which covers every experimental treatment, pretty much).

Until the "sue their pants off because I spilt hot coffee on myself" culture in the USA goes away, companies and government labs will continue to take the cautious path with drug development.

Aug 12, 2010
The FDA kept beta blockers off the US market for 10 years despite wide sucess in Europe. Beta blockers save about 10,000 lives a year.

The headline when they did approve the drug was "FDA approves new wonder drug to save an estimated 10,000 lives a year".

It wasn't "The FDA killed 100,000 before finally approving a drug that's worked for 10 years in the market".

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