Scimitar Equity Blog

Researchers for the first time have induced robust regeneration of nerve tissue connections in injured adult spinal cord sites that control voluntary movement. Results appear in the 8/8/10 online edition of Nature Neuroscience.

These findings provide hope that it may be possible to design therapies for paralysis and other impairments of motor function arising from spinal cord injury.

• In rodent studies, the Children’s Hospital Boston, UC Irvine, and UC San Diego team made this breakthrough by turning back the developmental clock in a molecular pathway critical for the growth of nerves in the corticospinal tract;
• The corticospinal tract is a bundle of nerves connecting the brain and spinal cord;
• While some degree of nerve regeneration has been achieved in other regions of the mature central nervous system (CNS), adult corticospinal nerves have been particularly resistant to regeneration after injury;
• The corticospinal nerve regeneration was achieved by deleting PTEN, an enzyme that acts as a critical brake on cell growth;
• One of the key growth molecules whose activity can be reined in by PTEN is mTOR;
• In early stages of life, PTEN activity is low, allowing mTOR to promote developmental growth processes;
• In later stages, PTEN activity is increased and mTOR activity is decreased so that growth is more restricted;
• Much further study is needed to translate these findings into therapeutic strategies because PTEN is a tumor suppressor and is known to control numerous important cellular functions beyond nerve regeneration;
• A PTEN-targeted therapy would have to be delivered transiently and in a location-specific manner. Future studies may explore the efficacy of combining therapeutic approaches that target growth inhibitory molecules within nerve cells, like PTEN, with approaches that target the external growth inhibitory molecules found at CNS lesion sites.

Spinal cord injuries are due primarily to the interruption of connections between the brain and spinal cord. 

• An injury the size of a grape can lead to a complete loss of function below the level of the injury;
• An injury to the neck can cause complete paralysis of arms and legs, loss of ability to feel below the shoulders, loss of ability 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 inability to move the legs;
• Until now, such nerve regeneration has been impossible in the spinal cord.

Approximately 2% of Americans have some form of paralysis as a result of spinal cord injury according to Christopher & Dana Reeve Foundation data.

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