Researchers led by Kyoto University's Shinya Yamanaka compared the use of CRISPR- and TALEN-based approaches to edit dystrophin gene mutations in iPS cells derived from a Duchenne muscular dystrophy patient.
As they report in Cell Stem Cell, Yamanaka and his colleagues also tried three different strategies for modifying the loss-of-function dystrophin gene mutation: exon skipping, frameshifting by adding indel mutation, and knock-in of the missing exon. Exon knock-in, which restored full-length dystrophin protein, worked best, the researchers report.
Corrected iPS cells, they further report, could be differentiated into skeletal muscles. Using patient-derived iPS cells to treat Duchenne muscular dystrophy may limit rejection, though the researchers note that additional challenges, such as how to best transplant iPS cell-derived myogenic cells, need to be overcome before it can be tried clinically.
The researchers also report that using a k-mer database enabled them to find a unique target region and reduce off-target effects.
While such an approach can't fix all the muscle fibers in a patient, the Guardian's Ian Sample notes that if enough muscle fibers can be targeted with a fix, it could still improve quality of life.
"It's a lovely approach. If these cells integrate into muscle in animals I'd expect it to work in humans because skeletal muscle is skeletal muscle," Chris Mason from University College London tells Sample. "You don't need to correct everything. If you can improve muscle strength by a small amount, you can help people in normal daily [activities]."