«The very slight increases
in dystrophin production didn't seem to me reasonably likely to predict the possibility of clinical benefit,» says internist Aaron Kesselheim of Boston's Brigham and Women's Hospital, who was one of the FDA advisory committee members who voted against recommending approval of eteplirsen.
Duchenne muscular dystrophy, which strikes in 1 out of 5,000 newborn boys, results from a genetic deficiency
in dystrophin, a protein involved in repairing muscle fibers affected by daily movement and activities such as exercise.
It is essential the findings from the study
in the dystrophin - deficient mice are confirmed in human DMD patients before its potential applications in these patients can be considered.
Next, they used a virus to insert a gene into the cells that corrects the mutation
in the dystrophin gene.
The team previously found that NF - κB is active
in dystrophin - deficient muscle years before the onset of symptoms, suggesting that very early treatment of Duchenne muscular dystrophy patients with VBP15 may prevent or delay the onset of some clinical symptoms.
Although there was no dystrophin production at 12 weeks, participants showed a 23 percent increase
in dystrophin - positive muscle fibers by the 24 - week mark.
By week 48, participants had a 52 percent increase
in dystrophin - positive muscle fibers and were able to walk 67.3 meters farther than the placebo group on the six - minute walk test.
The study authors previously found out that NF - κB is active
in dystrophin - deficient muscle years before the onset of symptoms, suggesting that very early treatment of Duchenne Muscular Dystrophy patients with VBP15 may prevent or delay the onset of some clinical symptoms.
Scientists say the new strategy enhances the accuracy for surgical - like editing of the human genome, correcting mistakes in the DNA sequence that cause devastating diseases like DMD, a deadly condition caused by defects
in the dystrophin gene.
«CRISPR - Cpf1 gene - editing can be applied to a vast number of mutations
in the dystrophin gene.
Once the UCLA researchers had produced iPS cells that were free from Duchenne mutations, they differentiated the iPS cells into cardiac muscle and skeletal muscle cells and then transplanted the skeletal muscle cells into mice that had a genetic mutation
in the dystrophin gene.
The result was the largest deletion ever observed
in the dystrophin gene using CRISPR / Cas9, and the study was the first to create corrected human iPS cells that could directly restore functional muscle tissue affected by Duchenne.
Not exact matches
The inherited condition, most common
in boys, results from a lack of
dystrophin, a protein that's essential for healthy muscles.
Gersbach and his team first delivered the therapy directly to a leg muscle
in an adult mouse, resulting
in the restoration of functional
dystrophin and an increase
in muscle strength.
In the study, researchers worked with a mouse model that has a debilitating mutation on one of the exons of the
dystrophin gene.
Duchenne muscular dystrophy is caused by mutations
in a huge gene called
dystrophin.
Dystrophin appears yellow
in overlay image.
Duchenne mutations cause abnormally low production of the
dystrophin protein, which
in turn causes muscles to degenerate and become progressively weaker.
They had been working with a worm model of Duchenne muscular dystrophy, a severe form of the disease that strikes young boys and is caused by mutations
in the gene that encodes the
dystrophin protein.
«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.
Duchenne typically occurs through one mutation
in a gene called
dystrophin, which makes a protein with the same name.
In people without the disease, the
dystrophin protein helps strengthen and connect muscle fibers and cells.
Mice treated with antisense RNA (bottom) produced more
dystrophin — colored red
in this image — than did control mice (top).
That was enough for the muscle to carry some weight, and one injection produced
dystrophin for 3 months, the group reports
in the 6 July online Nature Medicine.
Like most genes, the RNA for the
dystrophin protein undergoes a process called splicing,
in which stretches of so - called «junk» are clipped out.
In normal mice, stem cells (pink) express dystrophin (green) and are able to easily generate new muscle fibers, but in the disease model, there is no dystrophin and the stem cells lose their sense of direction and have trouble generating new muscle fiber
In normal mice, stem cells (pink) express
dystrophin (green) and are able to easily generate new muscle fibers, but
in the disease model, there is no dystrophin and the stem cells lose their sense of direction and have trouble generating new muscle fiber
in the disease model, there is no
dystrophin and the stem cells lose their sense of direction and have trouble generating new muscle fibers.
For many years,
dystrophin was thought to be a simple structural protein only found
in muscle fibres.
In the current study, Dr. Rudnicki and his team discovered that muscle stem cells also express the dystrophin protein, and without this protein, they produce ten-fold fewer muscle precursor cells, which in - turn generate fewer functional muscle fibre
In the current study, Dr. Rudnicki and his team discovered that muscle stem cells also express the
dystrophin protein, and without this protein, they produce ten-fold fewer muscle precursor cells, which
in - turn generate fewer functional muscle fibre
in - turn generate fewer functional muscle fibres.
Researchers at the University of Michigan Health System have identified a new way of triggering the role of the muscle protein
dystrophin, which is found
in the muscles used for movement and
in cardiac muscle cells.
«Our work suggests that AMPK signaling may be one of the links between the loss of
dystrophin and the impaired nNOS function that is seen
in muscular dystrophy,» says Michele, senior study author and professor of molecular & integrative physiology and internal medicine at the University of Michigan.
Experiments have shown treatment with sildenafil significantly improved heart function
in mice missing the
dystrophin protein.
This balance can be disrupted
in diseases such as Duchenne muscular dystrophy, which is caused by the lack of a muscle - specific protein,
dystrophin.
Their study published online ahead of print
in PNAS Early Edition suggests a new therapeutic strategy for patients with Duchene muscular dystrophy, a progressive neuromuscular condition, caused by a lack of
dystrophin, that usually leaves patients unable to walk on their own by age 10 - 15.
Manipulating proteins
in the body to compensate for the lack of
dystrophin is one of many strategies being investigated to halt or reverse the muscle damage caused by DMD.
«AMPK normally helps to turn on nNOS function
in muscle cells, for instance when we exercise, and when
dystrophin is lost, AMPK does not turn on appropriately.»
DMD is a rare disease affecting primarily boys and is caused by defects
in the gene that makes the
dystrophin protein.
Dr. Eric Olson (right) shows the
dystrophin protein (red) produced
in gene - edited heart muscle cells taken from a DMD patient's blood.
12 guide RNAs developed to find mutation «hotspots» along the
dystrophin gene helped rescue cardiac function to near - normal levels
in human heart muscle tissue.
For example, researchers would like to know how the drug affects
dystrophin production
in muscles throughout the limbs and whether some muscles may get a bigger boost than others.
The exact mutation varies from patient to patient but
in 65 percent of cases, the
dystrophin gene is missing large sections of DNA called exons, which carry the instructions for protein production.
«We know that if you have an area that is not expressing
dystrophin, the membrane will be fragile and vulnerable to activity - related degeneration,» says Dr. Mendell, who also is director of the Neuromuscular Disorders program at Nationwide Children's and a professor of pediatrics
in The Ohio State University College of Medicine.
Using the natural human development process as a guide, the researchers developed ways to mature muscle cells
in the laboratory to create muscle fibers that restore
dystrophin, the protein that is missing
in the muscles of boys with Duchenne.
But cardiomyopathy can also be brought on by genetic disorders like muscular dystrophy, which causes abnormalities
in a protein called
dystrophin.
The study is the first to show that damaged
dystrophin underlies both genetic and acquired cardiomyopathy, says Jeffrey A. Towbin, a cardiologist with the Baylor College of Medicine and Texas Children's Hospital
in Houston.
Once they were able to isolate skeletal muscle cells using the newly identified surface markers, the research team matured those cells
in the lab to create
dystrophin - producing muscle fibers.
This similarity suggests that researchers should target the underlying process
in the different varieties of the disease, he says, for example by developing a drug to prevent
dystrophin from breaking down.
When they killed the animals a week later, they found that the virus had broken apart
dystrophin in their hearts and that the membranes of heart cells infected with Coxsackie B virus were more permeable to blue dye than uninfected cells.
«This is the first study to demonstrate that functional muscle cells can be created
in a laboratory and restore
dystrophin in animal models of Duchenne using the human development process as a guide.»
Researchers at the Center, co-directed by Drs. Olson and Mammen, have successfully edited mutations
in the X-linked DMD gene that encodes the protein
dystrophin in human cells.
A particular type of stem cell found
in muscle can give rise to new muscle tissue, so a team led by geneticist Luis Garcia of Généthon, a nonprofit biotechnology firm
in Évry, France, investigated whether these cells could be used to reverse the
dystrophin problems.