Gene Therapy Improves Mouse Genetic Nerve Disorder

About 1 in 6000 babies is born with a genetic disorder of the nervous system called Spinal muscular atrophy (SMA). The equivalent of SMA in mice has now been treated using gene therapy with substantial improvement.

COLUMBUS, Ohio – Reversing a protein deficiency through gene therapy can correct motor function, restore nerve signals and improve survival in mice that serve as a model for the lethal childhood disorder spinal muscular atrophy, new research shows.

This muscle-wasting disease results when a child’s motor neurons – nerve cells that send signals from the spinal cord to muscles – produce insufficient amounts of what is called survival motor neuron protein, or SMN. This reduced protein in motor neurons specifically – rather than in other cells throughout the body that contain the protein – is caused by the absence of a single gene.

Better ways to deliver gene therapy will eventually enable many types of human body repair. The gene therapy delivered inside a virus reached almost half of mouse neurons which is an impressive delivery rate. The result was better functioning nervous systems and better muscle control.

The researchers used an altered virus to deliver a portion of DNA that makes the SMN protein into the veins of newborn mice ranging in age from 1 to 10 days old. The SMN-laced viral vector injected into the youngest mice reached almost half of their motor neurons, resulting in improved muscle coordination, properly working electrical signals to the muscles and longer survival than in untreated mice, scientists said.

The superiority of gene therapy should not be surprising because the gene therapy fixes the root cause. Fix the gene that causes the disease and the disease gets better.

“We’re replacing what we know is lost. And we have shown that when you put the protein in postnatally, it will rescue the genetic defect,” said Arthur Burghes, professor of molecular and cellular biochemistry at Ohio State University and a senior co-author of the study. “This technique corrects the mice considerably more than any drug cocktails being studied as a potential treatment in humans.”

We need better carriers of gene therapy into cells. Viruses elicit an immune response and they do not reach all the cells that need the gene therapy payload they carry. Plus, once genes reach inside cells they are at risk of integrating into the genome in locations that can cause cancer. But solve all those problems and then we can do some serious updating of our genetic software.