Where do stem cells come in?
Parkinson’s disease is a progressive neurological disorder in which your brain starts to lose the neurons that produce dopamine. As dopamine levels decline, so does your ability to regulate movement. This can lead to slowed movements, tremors, and balance issues.
Stem cells are a self-renewing source of tissue. They can be reprogrammed to become different types of cells in the body. The hope is that stem cells can be used to develop dopamine-producing neurons, which would replace those that you’ve lost.
Keep reading to learn about different types of stem cells and how they may someday help people with Parkinson’s disease.
What exactly are stem cells?
Your body is made up of more than 300 trillion cells. Most have specialized functions. But stem cells aren’t fully mature and don’t have a particular function. As stem cells divide, the new cells have the potential to remain a stem cell or develop into another, more specialized cell.
Embryonic and adult stem cells
Embryonic stem cells can be found in human embryos from 7 to 10 days after fertilization. They’re pluripotent, meaning they can generate into any type of cell.
Adult (somatic) stem cells can be taken from other tissues, such as bone marrow, muscle, heart, gut, and brain. Adult stem cells are mostly multipotent, which means there’s a limit to the types of cells they can become.
Induced pluripotent stem cells
Scientists have learned how to manipulate mature cells, such as skin cells, to behave like embryonic stem cells. These “man-made” stem cells are called induced pluripotent stem cells (iPS).
Induced pluripotent stem cells have been around since 2007. They’re an important and encouraging development in stem cell research relating to Parkinson’s disease.
Around the world, researchers continue to study these different types of stem cells and how they can be used to treat illness.
How stem cells could be used to treat Parkinson’s disease
Like human embryonic stem cells, iPS cells have the potential to become any type of cell in the body. By coaxing them into becoming dopamine-producing cells that work in humans, researchers might be able to develop a disease-modifying treatment. Such a therapy would not only improve symptoms, but actually slow or halt disease progression.
The science isn’t quite there yet, but there has been enormous progress. In a 2014 study, researchers made dopamine cells from embryonic stem cells. Then they transplanted them into the brains of rats to replace cells lost to Parkinson’s. The new cells were able to survive and restore dopamine production.
Other recent studies have also shown that these cells can be manufactured and transplanted in rats and primates. The cells were able survive and improve symptoms of Parkinson’s disease.
In 2017, Japanese neurosurgeons reported more encouraging new developments. Monkeys with symptoms of Parkinson's disease showed significant improvement over two years after being transplanted with neurons made from iPS cells. This research indicated that the neurons made from iPS cells were just as good as those made from embryonic stem cells.
Risks and challenges of stem cell therapy for Parkinson’s disease
There are always risks when conducting clinical trials in humans. The short- and long-term health and safety of participants must be carefully considered.
Scientists are working to overcome some challenges of iPS cells, such as:
- making certain the preparations are pure and don’t contain undifferentiated cells that could lead to the formation of tumors
- figuring out exactly how to deliver stem cells into people with Parkinson’s so they integrate appropriately in the brain
- ensuring that the stem cells can survive and function as they should in humans, improving symptoms of Parkinson’s disease
Clinical research is a way for doctors to learn about the safety and effectiveness of experimental therapies. And it’s how we’ll increase our understanding of the role stem cells may play in the treatment of Parkinson’s disease.
An observational study is currently under way to determine if adipose stem cells can be used to treat Parkinson’s disease. Adipose stem cells are taken from a person’s own fat. The study will evaluate quality of life changes for up to a year after treatment.
Other current trials involving stem cells and Parkinson’s disease include:
- Allogenic Bone Marrow-Derived Mesenchymal Stem Cell Therapy for Idiopathic Parkinson’s Disease: This trial will assess the safety, feasibility, and efficacy of intravenous allogeneic bone marrow-derived mesenchymal stem cell therapy.
- Molecular Analysis of Human Neural Stem Cells: This trial will develop and optimize methods to isolate, propagate, and differentiate adult human neural stem cells from patients.
- Neurologic Stem Cell Treatment Study: This trial will determine if autologous bone marrow-derived stem cells will improve neurologic function.
- Open-label, Non-Randomized, Multi-Center Study: This trial will assess the safety and effects of autologous adipose-derived stromal cells delivered intravenously and intranasally.
Currently, there are no approved stem cell therapies for Parkinson’s disease, other than what can be used in research and in clinical trials. You should be skeptical of any claims to the contrary. Human stem cell injections can cause serious adverse effects.
If you’re interested in participating in a clinical trial, talk to your doctor. You should ask about the:
- criteria for participation
- purpose of study and how it’s being funded
- details on how it will be conducted
- potential short- and long-term risks
It will take some time before stem cells can be used as treatment for Parkinson’s disease. But it’s certainly a promising area of research. Even if it doesn’t result in disease-modifying medication derived from stem cells, such research is expanding our knowledge of Parkinson’s disease.
Every step forward offers more potential to improve quality of life for people living with Parkinson’s disease.