New approach for treating genetic muscle wasting disease shows promise in mice
HealthCanal.com | March 6, 2012
OTTAWA — Scientists from the Ottawa Hospital Research Institute (OHRI) and the University of Ottawa (uOttawa) have discovered that a drug called fasudil can extend the average lifespan of mice with Spinal muscular atrophy (SMA) from 30.5 days to more than 300 days.
The study is published today in BioMed Central’s open access journal BMC Medicine, by Dr. Rashmi Kothary, his graduate student Melissa Bowerman and others.
SMA is the leading inherited cause of death in infants and toddlers, affecting approximately 25,000 people in Canada and the United States. Scientists have known for many years that this disease is caused by inherited mutations in a gene called survival motor neuron 1 (SMN1). Most early attempts at developing treatments for SMA focused on replacing this gene, however, Dr. Kothary’s group has focused on understanding and targeting the physiological defects present in certain nerve cells with SMA. These cells have a weakened internal scaffold, which hinders their ability to connect with muscle cells and contributes to the severe muscle weakness associated with SMA.
Two years ago, Dr. Kothary and his team showed that a laboratory compound called Y-27632, which targets an enzyme that is involved in maintaining the cellular scaffold, could greatly increase lifespan in a certain mouse model of SMA. In this new study, they tested a compound called fasudil, which is similar to Y-27632, but has the advantage that it has already been approved for human clinical trials for other conditions, meaning that it could possibly be re-targeted to use in clinical trials for SMA more quickly than a completely new drug.
The Kothary group found that fasudil-treated SMA mice survived for an average of more than 300 days, compared to just 30.5 days for untreated SMA mice. However, the average lifespan of fasudil-treated SMA mice was still only about half as long as that of normal mice. Fasudil-treated SMA mice also had larger muscle fibres than the untreated SMA mice, and they behaved more normally with respect to grooming and other regular activities. However, they did not perform any better in strength and balance tests and they still had low numbers of motor neurons, which is typical for SMA.
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