Researchers Hope to Move Closer to DMD Treatment with Genetic Editing

Researchers in the United Kingdom are using genetic editing and stem cell technology to learn more about Duchenne muscular dystrophy (DMD) and potentially develop new treatments.

DMD is a form of muscular dystrophy typically occurring in males, but in rare cases, it can affect females. The rare disease is inherited, with the gene for DMD located on the X chromosome. A female must have the changed copy of the DMD gene on each of her X chromosomes to have the disorder, while a female with just one X chromosome with the gene is typically an asymptomatic carrier of DMD. In children, some early signs of the rare disease include the delayed ability to sit, stand, or walk, and difficulties learning to speak. Individuals with DMD develop progressive weakness and loss of skeletal and heart muscles and usually show signs of muscle weakness in the hips, pelvic area, upper legs, and shoulders by age 3 to 4 years. Other physical signs include enlarged calves, unusual walk, and difficulty running, climbing stairs, and standing up. As symptoms worsen, children with DMD often use a wheelchair full-time by age 13, and life-threatening heart and respiratory muscle problems can begin soon after.

The Centers for Disease Control and Prevention (CDC) notes that the prevalence of Duchenne and Becker muscular dystrophy (DBMD) in the United States is 1 in every 7,250 males ages 5 to 24 years. At the end of 2007, only 58% of males with DBMD who were ages 20 to 24 years were still living. There is currently no cure for DMD, though patients can manage symptoms with gentle physical exercise to maintain muscle strength and function and steroids to also improve lung function.

Scientists from the Queen Mary University of London recently announced that they are now utilizing new technology to create a model of human cells with DMD capable of mimicking what happens in the muscles of a patient with the disorder.

Using stem cells to grow skeletal and cardiac muscle cells, the researchers will develop a model of human cells with DMD. They will also be using CRISPR, the gene editing tool, to precisely edit the section of the genetic code from stem cells of patients with DMD to repair the code and replace original cells with healthy muscle cells. This will allow researchers to compare differences between healthy muscle cells and those of a DMD patient.

“We use CRISPR to correct the defective gene of a patient’s cell and therefore, create a healthy cell that has the same genetic background as the original patient’s cell. This enables us to accurately compare functional differences and test potential drug candidates,” explained researcher Yung-Yao Lin, PhD, in an interview with Rare Diseases Report^®. The repaired cells will provide a cell-based platform for the testing of drug candidates for DMD.

“We are still at the early stage of the drug discovery process. With our novel cell-based platform, we envisage facilitating this process,” he added. The work, according to the researchers, is broadly applicable to similar treatment development for other forms of muscular dystrophy.