Gene therapy: Duchenne muscular dystrophy soon healed?
Researchers of the Faculty of Medicine of the Université Laval have just demonstrated that it is possible to repair the defective gene at the origin of Duchenne muscular dystrophy, a hereditary disease that strikes a boy out of 3,500.
Duchenne muscular dystrophy causes progressive degeneration of the muscles which, beginning in early childhood, usually leads to death of the patient before the age of 25 years. It is caused by mutations that affect a protein called dystrophin. These alter the normal nucleotide sequence of the gene of this protein and stop the synthesis.
Professor Tremblay's team has partnered with Cellectis, a specialized firm, to design meganucleases, enzymes capable of recognizing and extracting mutated regions of the genome of people with Duchenne dystrophy. In in vitro assays, researchers introduced genes encoding different meganucleases into human muscle cells. They repeated the in vivo experiment with mice carrying the mutation that causes the disease. Both sets of tests have shown that these meganucleases can lead to a restoration of the normal nucleotide sequence of the dystrophin gene and its expression in muscle cells.
There are still several steps to take before considering the use of this approach in humans, warns Professor Tremblay. It will first be necessary to demonstrate in laboratory animals that it is possible to directly introduce a meganuclease into muscle cells and that the synthesis of dystrophin may result. "It will probably take two to three years to get there," says the researcher. "Subsequent phases, including testing on human subjects, could take even longer," he concludes.