SMA mice, treated at one day old, showed increased levels of SMN in the brain, spinal cord and muscles within ten days. Although levels remained lower than in normal mice, the increase appeared to be sufficient to reverse the effects of the disease and the team believe that the same would be true in children with the disease. Dramatic improvements were seen only in mice treated within the first two days of life and the potential treatment window for children is not yet clear. The researchers hope to be able to progress to human clinical trials and, as a first step, have shown that the virus is also able to cross the blood-brain barrier and penetrate motor neurones in a one day old macaque. One difficulty in translating the research into a treatment option for children with SMA is that symptoms are typically absent in very young infants and the only available screening method for newborns is considered to be prohibitively expensive.
The study is published in Nature Biotechnology.