Is CRISPR Gene Editing the Answer to Muscular Dystrophy?

CRISPR gene editing is opening doors to curing a variety of diseases, including sickle cell and hemophilia. Researchers in Germany are also trying to add certain forms of incurable muscular dystrophy (MD) to the list. So far, testing is only done on mice, but the results are promising. 

What Is CRISPR Gene Editing?

As the name suggests, CRISPR allows scientists to edit DNA, which is already creating opportunities to cure certain hereditary diseases and correct gene mutations. The process is based on a concept that already exists in nature. 

Bacteria have a way of marking invading viruses so they can detect them if they return. The bacteria capture a small piece of the virus’s DNA and use it like a code. They edit the strand of DNA into their own and then use it to recognize viruses in the future. 

The bacteria use an enzyme called Cas-9 as a pair of scissors to slice through the DNA of the virus and make it inert. Researchers can adapt this same process to other animals, including humans. 

CRISPR and Muscular Dystrophy

A recent study published in the Molecular Therapy Nucleic Acids journal is detailing German research using CRISPR to repair the gene mutation that causes certain forms of muscular dystrophy, specifically Duchenne MD.

Muscular dystrophy is a rare neuromuscular disease that causes progressive weakness over time. There are currently 30 different forms of MD, and Duchenne makes up about 50 percent of all cases. 

The study conducted at the Experimental and Clinical Research Center in Germany is paving the way for more clinical trials. The study author states the goal was to use CRISPR gene editing to correct faulty genes that cause MD. They would remove muscle stem cells, make alterations to the genetic code and then inject the cells back into muscle tissue. 

Their studies on mice were successful, but they could not use the process on humans. They attempted to use plasmids, double-stranded DNA molecules that come from bacteria, to introduce the gene editor into stem cells but found complications. They needed a different transport mechanism. 

Finding a Work Around

In this study’s current version, researchers use messenger RNA (mRNA) instead of plasmids. mRNA is a single-stranded RNA molecule created during transcription, which is the process of copying segments of DNA. 

The problem was finding a way to get the mRNA into stem cells to inject them into muscle tissue. To make that happen, the study authors use electroporation. This makes the cell membranes temporarily permeable. 

They first tried the procedure using mRNA containing a fluorescent dye to ensure that the strand could cross the stem cell membrane. Once they proved it effective, they used a form of CRISPR gene editing that can alter just one spot in the DNA instead of cutting both strands. 

Once they perfect their procedure, they will be ready to enter a clinical trial with humans who have muscular dystrophy. If successful, they should be able to correct the underlying genetic cause of the disease, allowing patients to make healthy muscle cells and avoid the deterioration that is a benchmark of MD.