Researchers at Duke University have shown that a single systemic treatment using CRISPR genome editing can safely correct Duchenne muscular dystrophy (DMD) in mice for over a year. In 2016 the first successful use for CRISPR to treat an animal model of a genetic disease was published by, Charles Gersbach, the Professor of Biomedical Engineering at Duke. The strategy used by Gersbach can potentially be used for human therapy.
Since 2009, Gersbach has been working on finding a genetic treatment for DMD and his lab was one of the firsts to focus on CRISPR, which is a defense system that slices apart the DNA of invading viruses.The goal was to cut out the dystrophy exons around the mutation and then let the body naturally repair the DNA and stitch it back together to create a shortened dystrophy gene. After eight weeks it was observed in the mice used for the experiment that functional dystrophin was restored and muscle strength increased but the long term effects of the treatment had not been explored.
The new goal of Gersbachs study was to figure out these long term effects. To determine this, doctor Christopher Nelson gave both adult and newborn mice with the dystrophy gene a dose of CRISPR. The mice were monitored over the year to see what kind of genetic alterations were made as well as any immune responses. There were no results of toxicity in any of the mice. Although this is a positive result Gersbach and Nelson know that a mouse immune system can function differently than a human immune system which brings further questions of reliability of CRISPR in humans to the table.
In my AP biology class we recently learned about gene expression. CRISPR systems have been engineered to control gene expression in bacteria. CRISPR is used to target precise parts of DNA which could help to correct abnormalities that cause diseases.
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