DALLAS – April 12, 2017 – Using the new gene-editing enzyme CRISPR-Cpf1, researchers at UT Southwestern Medical Center have successfully corrected Duchenne muscular dystrophy in human cells and mice in the lab.
The UT Southwestern group had previously used CRISPR-Cas9, the original gene-editing system, to correct the Duchenne defect in a mouse model of the disease and in human cells. In the current work, they used a new variation of the gene-editing system to repair the defect in both a mouse model and in human cells.
“We took patient-derived cells that had the most common mutation responsible for Duchenne muscular dystrophy and we corrected them in vitro to restore production of the missing dystrophin protein in the cells. This work provides us with a promising new tool in the CRISPR toolbox,” said author Dr. Eric Olson, Chairman of Molecular Biology, Co-Director of the UT Southwestern Wellstone Muscular Dystrophy Cooperative Research Center, and Director of the Hamon Center for Regenerative Science and Medicine.
The research appears in the journal Science Advances.
CRISPR-Cpf1 differs from CRISPR-Cas9 in a number of key ways. Cpf1 is much smaller than the Cas9 enzyme, which makes it easier to package inside a virus and therefore easier to deliver to muscle cells.
“By either skipping a mutation region or precisely repairing a mutation in the gene, CRISPR-Cpf1-mediated genome editing not only corrects Duchenne muscular dystrophy mutations but also improves muscle contractility and strength,” said co-author Dr. Rhonda Bassel-Duby, Professor of Molecular Biology and Associate Director of the Hamon Center for Regenerative Science and Medicine.
Duchenne muscular dystrophy is caused by a mutation to one of the longest genes in the body. When there is a DNA error in the dystrophin gene, the body doesn’t make the protein dystrophin, which serves as a sort of shock absorber for the muscle fiber. Since there are numerous places in the dystrophin gene where a mutation can occur, flexibility for gene-editing treatment is crucial.
Duchenne occurs in about 1 in every 5,000 boys, according to the Centers for Disease Control and Prevention. Duchenne muscular dystrophy is a progressive disease affecting both muscle used for movement and heart muscle, with patients typically succumbing before age 30 due to heart failure.
“CRISPR-Cpf1 gene-editing can be applied to a vast number of mutations in the dystrophin gene. Our goal is to permanently correct the underlying genetic causes of this terrible disease, and this research brings us closer to realizing that end,” Dr. Olson said.
“CRISPR-Cpf1 differs from CRISPR-Cas9 in a number of key ways, including being easier to deliver to muscle cells, said Yu Zhang, a graduate student in Dr. Olson’s lab and the first author of this study.
Other UT Southwestern researchers who contributed to this work are Dr. Hui Li, research scientist; John R. McAnally, research scientist; Dr. Kedryn Baskin, postdoctoral researcher; and John M. Shelton, senior research scientist.
This work was supported by grants from the National Institutes of Health (NIH), a Paul D. Wellstone Muscular Dystrophy Cooperative Research Centers grant, and a Robert A. Welch Foundation grant.
Dr. Rhonda Bassel-Duby and Dr. Eric Olson are consultants for Exonics Therapeutics. Drs. Olson, Bassel-Duby, Zhang, and Long are listed on the patent entitled “Prevention of muscular dystrophy by CRISPR/Cpf1-mediated gene editing” (U.S. Patent 62/426,853, 28 November 2016).