The idea of a miracle cure, bodies healing themselves, holds a certain fascination. Stem cell research brings regenerative medicine a step closer, but there is also controversy. So what are stem cells, and why are they so important?
Stem cells are a type of cell that can develop into many other different types of cell. Stem cells can also renew themselves by dividing, even after they have been inactive for a long time.
When a stem cell divides, the new cells may either become a stem cell or a specific cell, such as a blood cell, a brain cell, or a muscle.
A stem cell is known as an “undifferentiated cell,” because it can still become any kind of cell. In contrast, a blood cell, for example, is a ‘differentiated’ cell, because it is already a specific kind of cell.
Stem cells in therapy
Stem cells could help the body to heal itself.
In some tissues, stem cells play an important role in regeneration, as they can easily divide, and they can keep replacing dead cells. Scientists believe this may offer potential treatments for conditions such as diabetes and heart disease.
For instance, if someone has damaged tissue in their heart, it might be possible to stimulate the growth of healthy tissue by transplanting laboratory-grown stem cells into the patient’s heart.
A small-scale study published in the Journal of Cardiovascular Translational Research trialed this method. The researchers reported a 40 percent reduction of the size of scarred heart tissue caused by heart attacks.
In the past, this kind of scarring has been seen as permanent and untreatable.
The patients, who all had advanced heart failure, had an average 30 percent improvement in heart function. They also reported a 70 percent improvement in quality of life 24 months after being injected with the stem cells.
However, this study involved only 11 participants. It is difficult to tell whether the improvement in heart function was caused by the transplantation of stem cells, or whether it was caused by something else.
All of the transplants took place while the patients were undergoing heart bypass surgery, for instance, so it is possible that the improvement in heart function could be due to the bypass rather than the stem cell treatment.
To investigate further, the researchers plan to do another study, this time including a control group of patients with heart failure who undergo bypass surgery, but who do not receive the stem cell treatment.
Another study published in Nature Communications suggested that stem cell therapies could form the basis of personalized diabetes treatment.
In mice and laboratory-grown cultures, the researchers successfully produced insulin-secreting cells from stem cells derived from the skin of people with type 1 diabetes.
“In theory, if we could replace the damaged cells in these individuals with new pancreatic beta cells – whose primary function is to store and release insulin to control blood glucose – patients with type 1 diabetes wouldn’t need insulin shots anymore.”
Jeffrey R. Millman, assistant professor of medicine and of biomedical engineering at Washington University School of Medicine and first author.
Millman hopes that these stem cell-derived beta cells could be ready for research in humans within 3 to 5 years. “What we’re envisioning is an outpatient procedure in which some sort of device filled with the cells would be placed just beneath the skin,” he said.
Stem cells could have vast potential in developing new therapies.
Are stem cells and regenerative medicine living up to their promises?
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Stem cells in drug development
One way that stem cells are used at the moment is in developing and testing new drugs.
Stem cells can help scientists to understand what causes diseases such as cancer.
The type of stem cells commonly used for this purpose are called induced pluripotent stem cells.
These are cells that have already become differentiated, but then they have been genetically “reprogrammed” using controlled viruses. In this way, they resemble undifferentiated embryonic stem cells.
New differentiated cells can be grown from these pluripotent stem cells to resemble, for instance, cancer cells. Creating these cells means that anti-cancer drugs can be tested using them.
A wide variety of cancer-cell types are already being made using this method. However, because these cells cannot yet be made to mimic cancer cells in a controlled way, the results cannot always be precisely replicated.
Do current therapies work?
In recent years, clinics have opened that provide stem cell treatments. A 2016 study published in Cell Stem Cell counts 570 of these clinics in the United States alone. They offer stem cell-based therapies for disorders ranging from sports injuries to cancer.