What is Muscular Dystrophy?
Muscular dystrophy is a genetic disorder that primarily affects striated muscles in the body. It causes wasting of the muscles. There are several different types of muscular dystrophy. Each one of them is associated with a problem with a single gene.
Heart disease is present in several types of muscular dystrophies, and it often causes illness and death in those with the disorder. Another cause of death is lung issues.
But there’s hope for those who have loved ones with muscular dystrophy. In the last 5 years, doctors have had encouraging results with using adult stem cells to treat muscular dystrophies. These cells were able to maintain, generate, and replace cells that needed replacement. The exciting part was that these stem cells could also participate in regeneration of other organs, not just the ones they needed to replace.
The Types of Treatments They are Using Now
Doctors are now using gene therapy in combination with stem cell treatments to make a difference in the lives of muscular dystrophy patients. However, current gene delivery strategies are limited to the introduction of the corrected gene into only one tissue. This is a potential limiting factor n the effectiveness of the treatment.
In 2015, researchers demonstrated that induced pluripotent stem cells were able to engraft into both cardiac and skeletal muscles. The stem cells derived from these cells were then able to be corrected genetically. Once injected into mice, they were able to show the ability to restore function. This gives scientists another clue that maybe those with muscular dystrophy could have a normal life.
The Stem Cells That Affect Muscular Dystrophy
In muscular dystrophy, there are two types of stem cells that differentiate into skeletal muscle cells: mesenchymal stem cells and mesoangioblasts (MAB). They infiltrate the dystrophic muscle from the circulation, engraft into host fibers, and bring with them proteins that replace the functions of those that are missing or abnormal.
Satellite cells are precursor cells that regenerate muscle when there’s an injury or when there’s muscular dystrophy. Quite a few scientists worldwide are working with satellite cells to see what type of results they can get in their muscular dystrophy studies.
In another study using adipose stem cells injected into the calf muscle of mice that had muscular dystrophy, the muscle damage was reversed and the stem cells promoted the regeneration and survival of muscle cells. The fibrosis usually seen in muscles of those with dystrophy was inhibited.
Stem cells for muscular dystrophy treatment may come from urine of healthy donors as a source. Scientists from Rome and London showed that these urine stem cells were effective – and were not costly to obtain. Soon, there may be stem cell banks that contain urine stem cells, too.
The stem cells can’t come from muscular dystrophy patients’ own body because they will likely cause heart and skeletal muscle with the same defects, according to researchers at the New Jersey Medical School.
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What is Known About Factors That Affect Those with Muscular Dystrophy
Italian scientists discovered that the hormone ghrelin protects muscles from atrophy, promotes the stem cell differentiation and enhances muscle regeneration from lack of oxygen. Ghrelin also increases stem cell activity and fosters stem cell self-renewal and differentiation.
When they used the ghrelin in animal studies, they found reduced muscle degeneration, improved muscle function, increased stem cell self renewal – all showing significant therapeutic potential for preserving the muscles in dystrophies. But they’re still years out before they begin human trials.
In collagen VI-related muscle disorders, there’s a deficiency and/or dysfunction of extracellular matrix protein collagen VI. Researchers reported in the Stem Cell Research Therapy journal in 2014 that when adipose-derived stem cells were transplanted into the muscle of collagen VI-deficient mice, all three collagen VI chains were created in the body.
The scientists also saw that the stem cells can survive long-term and continually secrete the therapeutic collagen VI protein that is missing in the mutant mice. They’re excited because their findings suggest that stem cell therapy could provide therapeutic treatment for other muscle disorders and injuries.
Cell Markers Identified
In different disorders, there’s always a cell surface marker that helps the scientists isolate stem cells from the tissue where it’s important to find them. In muscular disorders, that cell surface marker is called CD82+ muscle cells.
Scientists at the Boston’s Children’s Hospital found that this cell marker is functionally involved in muscle homeostasis. It physically interacts with alpha-7-beta-1 integrin and with alpha-sarcoglycan, a member of the dystrophin-associated glycoprotein complex, both which are linked to muscular dystrophies.
The cell marker expression is decreased in Duchenne muscular dystrophy patients. Using this stem cell marker, researchers and doctors can determine whether or not a sample of stem cells is good enough for someone that has muscular dystrophy.
Human Studies on Muscular Dystrophy
The Chinese are far ahead of U.S. researchers when it comes to running human studies on the use of stem cells in those with muscular dystrophy. They ran a study in 2016 using human umbilical cord-derived mesenchymal stem cells in those with Becker muscular dystrophy. The patients were from a family of those affected with the disease and were aged 50, 46, 42, and 6 years old. Three of them received an IV drip of the stem cells over a 30-minute period of time.