The cause of spinal muscular atrophy, a condition that leads to muscle weakness, has been uncovered by stem cell research. The findings come from researchers at the Advanced Gene and Cell Therapy Lab at Royal Holloway.
The researchers used stem cell techniques to get a better understanding as to why some cells are at a higher risk of degenerating in spinal muscular atrophy than others.
The researchers used Induced Pluripotent Stem Cells (iPSCs), which were reprogrammed and coerced into forming motor neurons that are found in the spine to help control movement and breathing.
During the differentiation stage when the stem cells change into their final shape, two key proteins in motor neurons change in a significant way, which could help explain why these cells are more vulnerable to spinal muscular atrophy degeneration than others.
Dr. Rafael Yáñez said, “We have observed a progressive reduction of SMN and PLS3 proteins during differentiation of induced pluripotent stem cells to motor neurons, similar to some reports in animals and some controversial data from human development. These changes may underpin the susceptibility of motor neurons to spinal muscular atrophy. We now will investigate the reason for the changes, and more importantly, progress our research for novel therapies taking these protein changes into account. The research also shows how we are trying to reduce reliance on animal experiments whenever possible, as these stem cells now allow the production of human cells that cannot be obtained directly from patients and we can study the cells in lab dishes.”
There are four different types of spinal muscular atrophy:
Type 1: The most severe. Symptoms seen in babies who never develop the ability to sit unsupported.
Type 2: Less severe than type 1. Symptoms occur in babies seven to 18 months old. Sitting and standing is possible, but they are unable to walk unsupported.
Type 3: The mildest form of spinal muscle atrophy affecting children. Symptoms are seen in babies 18 months and older. Children are able to achieve majority of motor function milestones.
Type 4: Only seen in adults.
In type 1, children often don’t live past the age of two as respiratory complications arise. In type 2, life expectancy may be shortened by the condition, but improvements in care can help the patients survive into adulthood. In types 3 and 4, life expectancy is unaffected.
The primary symptom of spinal muscular atrophy (SMA) is muscle weakness in voluntary muscles. Muscles located near the center of the body are mainly affected, including the shoulders, hips, thighs, and upper back.
Complications arise when the respiratory system muscles become affected, making swallowing and breathing difficult. If back muscles become weak, it can lead to curvatures of the back.
There is no treatment for the genetic cause of SMA, but experimental therapies are underway to potentially bring a better, more effective treatment for those in need in the future. Support and management of symptoms is necessary in order to boost life quality in patients.
Treatment may involve a number of things, including exercise, physical therapy, equipment to improve breathing, feeding tubes or nutrition device, and bracing or surgery for back curvatures.
Furthermore, it takes more than one doctor in order to properly treat SMA, including:
These doctors will often work together in order to provide the best form of treatment for the patient to achieve the highest levels of success.
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