A Nationwide Children's Hospital study describes a new gene therapy approach capable of delivering full-length versions of large genes and improving skeletal muscle function. The strategy may hold new hope for treating dysferlinopathies and other muscular dystrophies.
A group of untreatable muscle disorders known as dysferlinopathies are caused by mutations in the dysferlin gene. Patients with these disorders, including limb girdle muscular dystrophy type 2B, are typically diagnosed in their early twenties. Approximately one-third will become wheelchair dependent by their mid-30s.
Gene therapy using adeno-associated virus (AAV) to deliver genes to cells has been pursued as an option for some patients with muscular dystrophy. However, AAV's packaging limitations have served as obstacles in using gene therapy to deliver large genes like dysferlin. Scientists in the past have attempted to work around AAV's packaging limitations by inserting a small version of large genes into the viral vector to induce gene expression. Some have also used more than one viral vector at a time to deliver a large gene. However, micro and mini versions of large genes don't always have the power of full-length gene expression and an increased viral load can lead to negative side effects.
"We have had success in the clinic using AAV gene therapy with limb girdle muscular dystrophy type 2D, which is caused by mutations in the alpha-sarcoglycan gene," said Louise Rodino-Klapac, PhD, principal investigator in the Center for Gene Therapy at The Research Institute of Nationwide Children's Hospital. "However, the dysferlin gene is very large, about six times larger than the alpha-sarcoglycan gene and can't fit into a traditional AAV vector."
A 2008 study identified AAV5, an AAV serotype that could package large transcripts. "This made us wonder whether it could be used for gene replacement requiring inserts as large as the dysferlin gene," said Dr. Rodino-Klapac.
In their 2012 study appearing in PLoS ONE, Dr. Rodino-Klapac's team used AAV5 to package a full-length, intact dysferlin gene and directly deliver it to the diaphragm of dysferlin-deficient mice. They also injected the leg muscles of dysferlin-deficient mice using both intramuscular and vascular approaches to further evaluate whether the gene delivery could improve skeletal muscle function.
They found that both the intravascular and intramuscular delivery approaches led to full-length, intact dysferlin gene expression in the leg and diaphragm muscle cells of the mice. More importantly, they saw that the newly-restored dysferlin repaired membrane deficits previously seen in the dysferlin-deficient mice.
"Our findings demonstrate highly favorable results with full restoration of dysferlin without compromise in function," said Dr. Rodino-Klapac. "With regard to neuromuscular diseases, these studies provide new perspective for conditions caused by mutations of large genes. Duchenne muscular dystrophy is the most common severe childhood muscular dystrophy and would seem to benefit from expression of the larger transcripts than mini- and micro-dystrophins that only partially restore physiologic function in mouse models of the disease."
Dr. Rodino-Klapac and her team are currently defining a path for a dysferlin clinical gene therapy trial. "We have shown that AAV5-dysferlin delivery is a very promising therapeutic approach that could restore functional deficits in dysferlinopathy patients," she says.
Grose WE, Clark KR, Griffin D, Malik V, Shontz KM, Montgomery CL, Lewis S, Brown RH Jr, Janssen PM, Mendell JR, Rodino-Klapac LR. Homologous Recombination Mediates Functional Recovery of Dysferlin Deficiency following AAV5 Gene Transfer. PLoS One. 2012;7(6):e39233. Epub 2012 Jun 15.For more information on the Center for Gene Therapy, visit http://www.nationwidechildrens.org/center-for-gene-therapy
For more information on Dr. Louise Rodino-Klapac, visit http://www.nationwidechildrens.org/louise-rodino-klapac
Erin Pope | EurekAlert!
Colorectal cancer: Increased life expectancy thanks to individualised therapies
20.02.2020 | Christian-Albrechts-Universität zu Kiel
Sweet beaks: What Galapagos finches and marine bacteria have in common
20.02.2020 | Max-Planck-Institut für Marine Mikrobiologie
The operational speed of semiconductors in various electronic and optoelectronic devices is limited to several gigahertz (a billion oscillations per second). This constrains the upper limit of the operational speed of computing. Now researchers from the Max Planck Institute for the Structure and Dynamics of Matter in Hamburg, Germany, and the Indian Institute of Technology in Bombay have explained how these processes can be sped up through the use of light waves and defected solid materials.
Light waves perform several hundred trillion oscillations per second. Hence, it is natural to envision employing light oscillations to drive the electronic...
Most natural and artificial surfaces are rough: metals and even glasses that appear smooth to the naked eye can look like jagged mountain ranges under the microscope. There is currently no uniform theory about the origin of this roughness despite it being observed on all scales, from the atomic to the tectonic. Scientists suspect that the rough surface is formed by irreversible plastic deformation that occurs in many processes of mechanical machining of components such as milling.
Prof. Dr. Lars Pastewka from the Simulation group at the Department of Microsystems Engineering at the University of Freiburg and his team have simulated such...
Investigation of the temperature dependence of the skyrmion Hall effect reveals further insights into possible new data storage devices
The joint research project of Johannes Gutenberg University Mainz (JGU) and the Massachusetts Institute of Technology (MIT) that had previously demonstrated...
Researchers at Chalmers University of Technology, Sweden, recently completed a 5-year research project looking at how to make fibre optic communications systems more energy efficient. Among their proposals are smart, error-correcting data chip circuits, which they refined to be 10 times less energy consumptive. The project has yielded several scientific articles, in publications including Nature Communications.
Streaming films and music, scrolling through social media, and using cloud-based storage services are everyday activities now.
After helping develop a new approach for organic synthesis -- carbon-hydrogen functionalization -- scientists at Emory University are now showing how this approach may apply to drug discovery. Nature Catalysis published their most recent work -- a streamlined process for making a three-dimensional scaffold of keen interest to the pharmaceutical industry.
"Our tools open up whole new chemical space for potential drug targets," says Huw Davies, Emory professor of organic chemistry and senior author of the paper.
12.02.2020 | Event News
16.01.2020 | Event News
15.01.2020 | Event News
21.02.2020 | Medical Engineering
21.02.2020 | Health and Medicine
21.02.2020 | Physics and Astronomy