CRISPR is a gene editing technique that is inspired by the body’s natural ability to defend itself from viruses. It is primarily used to treat inherited diseases by replacing mutations in the genome to alter DNA sequences.
It has, up until now, shown to be ineffective when it comes to long-term, chronic conditions, but a team of researchers at the University of Missouri School of Medicine may have found a way of using CRISPR to treat these illnesses, starting with Duchenne muscular dystrophy (DMD).
DMD is a genetic mutation in children which prevents the body from producing dystrophin, a protein which keeps muscle cells strong. Children with DMD may lose the ability to walk and even breathe as the muscles required to do this become weaker and stop working.
Lead Researcher on the team and Professor in medical research in the molecular microbiology and immunology department at the University of Missouri School of Medicine, Dongsheng Duan describes that CRISPR “essentially cuts out the mutation and stitches the gene back together.”
In order to do this, the ‘molecular scissors’ in CRISPR, known as Cas9, must know where to cut. The location to cut is flagged by a molecule called gRNA. We were surprised to find that by increasing the quantity of flags, we could extend the effectiveness of the therapy from three months to 18 months in our mouse model.”
The research Duan’s team carried out consisted of treating six-week-old mice with DMD intravenously using CRISPR, injecting the mice with more gRNA than would normally be administered by researchers.
After 18 months, it was found that doing this significantly increased the amount of dystrophin in both skeletal and heart muscles and reduced muscle scarring. Muscle and cardiac functions were also found to have improved.
The results of the research are promising, with Duan stating that gRNA loss is “unique barrier” for long-term systemic CRISPR therapy but a barrier that can “be overcome by increasing and optimizing gRNA doses.”
Research into this treatment will continue to be tested and refined, with hopes that it could eventually be used to treat DMD in humans, as well as other chronic illnesses.