Emerging Research on Stem Cells
Stem cell research is an exciting area of research for Parkinson’s disease (PD). Stem cells are cells that can become any different type of cell in the body. One of the best examples of stem cells is the embryonic stem cell that is found in the early stages of an embryo. Embryonic stem cells become all of the major cell types in the body and are called pluripotent. (“Pluri” meaning several, and “potent” meaning having great power.)1
Stem cells can also be found in the tissues and organs in the body, such as bone marrow, heart, muscles, and brain. The stem cells found in these organs are considered adult stem cells, and they are important in the maintenance and repair of the tissues. However, they can only become the type of cell where they originate (bone marrow stem cells become the different blood cells), and they are called multipotent.1
Induced pluripotent stem cells
Scientists have discovered the ability to reprogram mature cells, such as those from adult skin cells, to an embryonic-like state, creating them into stem cells. These are called induced pluripotent stem (IPS) cells. IPS cells provide two important potentials for research in PD: they could be used in cell replacement treatment and they can provide a cellular model.1,2
In creating an IPS cell, a scientist can take a mature skin cell from a person and change it into a stem cell. Because IPS cells are pluripotent, that cell can then be encouraged to become any other type of cell in the body, like a dopaminergic neuron (nerve cell). In people with PD, the dopaminergic neurons become damaged, which causes the motor symptoms of PD to appear. IPS cells could potentially be used to replace the damaged neurons in people with PD, possibly reducing or stopping the symptoms of PD.1,2
IPS cells are also important in that they may provide disease models for scientists to study. Theoretically, scientists can create an IPS cell from a person with PD and evaluate how the cell responds to external factors. This research could help scientists understand how PD develops and the factors that are a part of the disease process. IPS cells from a person with PD may also provide cellular models that can be helpful in the testing of potential new therapies for PD. This cellular model is also called an “in vitro” model, and it provides an opportunity for scientists to view and study PD outside of the body.1,2
What’s next for stem cell research
While stem cell research is promising, there are still challenges to be overcome before stem cell therapy becomes a treatment for PD. Scientists are still learning how to generate a quantity of stem cells, as well as generating the necessary quality of the stem cells. In addition, research is ongoing for how to introduce them into the brain of a patient to function properly.
Stem cell-based therapies for PD are rapidly moving towards clinical trials, where they will be tested in humans. A collaboration between researchers from the United Kingdom, Sweden, Australia, and the United States outlined five key questions that should be addressed prior to clinical trials of stem cell research in humans:
- What is being transplanted, and what is the proposed mechanism of action?
- What are the pre-clinical safety and efficacy data supporting the use of the proposed stem cell product?
- Can arguments concerning ethics, risk mitigation, or trial logistics outweigh concerns regarding the expected efficacy of the cell and constitute a primary justification for choosing one cell type over another in a clinical trial?
- What is being claimed regarding the potential therapeutic value of the stem cell-based therapy – better control of symptoms or a cure?
- What is the regulatory oversight of the trial, and is it guided by input from experts in the field?
By considering these questions, experts believe that the research can move forward in ways that benefit both people with PD and the scientific community and avoid mistakes that have been made previously.3