Restoring Muscle Strength in DMD Mice

Duchenne muscular dystrophy (DMD) is a genetic disease characterized by the absence of a protein that protects muscles against mechanical stress occurring during physical activities. In patients with DMD, the lack of this protein, called dystrophin, leads to progressive muscle degeneration.

DMD is caused by a mistake, or mutation, in the genetic code. This mutation prevents the body from producing the dystrophin protein. But what if researchers could change how the body “reads” this part of the code, called the mRNA?

A recent research article published by Yin, et al. in Molecular Therapy showed success in using small biochemical molecules called morpholinos to restore dystrophin in mice. The morpholinos block specific regions of the dystrophin mRNA – causing the mutation to be skipped and thereby allowing the proper production of the dystrophin protein.

Mice in the study received biweekly injections over a 12-week period. One week after the final injection, tissue samples from multiple skeletal muscles – such as the diaphragm, biceps or quadriceps – showed that all the muscle fibers contained dystrophin. Moreover, the muscle strength of the treated mice was comparable to normal, non-dystrophic mice.

Researchers also noted a significant decline of the creatine kinase protein, which is released when muscles are damaged, indicating that the muscle fibers of the treated mice were less damaged. Additionally, the mice did not show any adverse effects after the morpholino treatment.