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New Procedure Repairs Severed Nerves in Minutes, Restoring Limb Use in Days or Weeks


ScienceDaily (Feb. 3, 2012) — American scientists believe a new procedure to repair severed nerves could result in patients recovering in days or weeks, rather than months or years. The team used a cellular mechanism similar to that used by many invertebrates to repair damage to nerve axons.

Their results were recently published in the Journal of Neuroscience Research.

"We have developed a procedure which can repair severed nerves within minutes so that the behavior they control can be partially restored within days and often largely restored within two to four weeks," said Professor George Bittner from the University of Texas. "If further developed in clinical trials this approach would be a great advance on current procedures that usually imperfectly restore lost function within months at best."

The team studied the mechanisms all animal cells use to repair damage to their membranes and focused on invertebrates, which have a superior ability to regenerate nerve axons compared to mammals. An axon is a long extension arising from a nerve cell body that communicates with other nerve cells or with muscles.

This research success arises from Bittner's discovery that nerve axons of invertebrates which have been severed from their cell body do not degenerate within days, as happens with mammals, but can survive for months, or even years.

The severed proximal nerve axon in invertebrates can also reconnect with its surviving distal nerve axon to produce much quicker and much better restoration of behaviour than occurs in mammals.

"Severed invertebrate nerve axons can reconnect proximal and distal ends of severed nerve axons within seven days, allowing a rate of behavioural recovery that is far superior to mammals," said Bittner. "In mammals the severed distal axonal stump degenerates within three days and it can take nerve growths from proximal axonal stumps months or years to regenerate and restore use of muscles or sensory areas, often with less accuracy and with much less function being restored."

The team described their success in applying this process to rats in two new research papers. The team were able to repair severed sciatic nerves in the upper thigh, with results showing the rats were able to use their limb within a week and had much function restored within 2 to 4 weeks, in some cases to almost full function.

"We used rats as an experimental model to demonstrate how severed nerve axons can be repaired. Without our procedure, the return of nearly full function rarely comes close to happening," said Bittner. "The sciatic nerve controls all muscle movement of the leg of all mammals and this new approach to repairing nerve axons could almost-certainly be just as successful in humans."

To explore the long term implications and medical uses of this procedure, MD's and other scientist- collaborators at Harvard Medical School and Vanderbilt Medical School and Hospitals are conducting studies to obtain approval to begin clinical trials.

"We believe this procedure could produce a transformational change in the way nerve injuries are repaired," concluded Bittner.

UT researchers may be closer to curing paralysis

AUSTIN, Texas – Researchers at the University of Texas could be on the right track to cure paralysis. This truly remarkable research is allowing lab rats to almost fully recover from peripheral nerve surgery in a matter of days and weeks, instead of months or years. The key is something that many of us have in our homes or garages already.

As a standout defensive lineman for the Texas Longhorns and the Detroit Lions, Doug English got more than his share of cheers. Today, as the head of the Lone Star Paralysis Foundation, he’s cheering loudest for a team of lab rats at UT.

"When you sever a nerve, that is it," said English, who has undergone neck surgery. "The distal end goes away. The best you are going to get is a slow nerve growth coming back, if you get that.　 To be able to re-energize the distal end of a nerve has never been done."
But it’s being done on the UT campus under the watchful eye of Dr. George Bittner, a professor of Neurobiology at UT. For almost four decades, Bittner has studied rats that have had their peripheral nerves cut.

"All that motor control and sensory sensation is lost," said Bittner.
Bittner says whether it is rats or humans, when peripheral nerves are cut the best procedures today may only restore 10-20 percent of nerve function over a period of months or years.

"Our procedure, within a couple of weeks, restores in rats 60-80 percent of the lost function," said Bittner.

Bittner says the procedure saturates the two separate, severed cell membranes with various solutions. He says the most important of those solutions is something called "PEG."
"Polyethylene glycol is essentially long, chain antifreeze," said Bittner.
Antifreeze helps induce the two cut ends to flow into each other like two soap bubbles becoming one.

"It is exciting because it has not been done," said English.
English has witnessed the peripheral nerve recovery of rats at UT. He’s hoping soon this same process can be used to treat spinal cord injuries.

"Baby steps is the nature of the business," said English. "Right now we are in mammals. We are going to move it right from the sciatic nerve and peripheral nerve into the spinal cord and keep pushing until we go all the way."

Dr. Bittner says currently the peripheral nerve recovery surgery has been performed on rats, rabbits and guinea pigs. He says it is quite possible that clinical trials on humans could begin in a couple of years.