Sir William Richard Gowers, neurologist, researcher and artist, drew this illustration in 1886 as part of his documentation of Parkinson’s Disease.
Human Stem Cell Trial for Parkinson’s Disease Treatment
A new clinical trial involving induced pluripotent stem cells (iPSC) may give patients with Parkinson’s Disease (PD) hope for future treatments. Researchers in Japan, under the lead of stem-cell scientist Jun Takahashi, have designed a human stem cell trial for Parkinson’s Disease treatment, where iPSCs will be used to create precursor cells related to dopamine production. During the trial they hope to see the resulting cells generate new dopamine-creating neurons.
Produced by neurons, dopamine is vital to voluntary muscle control, but humans lack the natural ability to regenerate damaged or diseased neurons. Permanent, progressive loss of neurons that manufacture dopamine is a chief characteristic of PD. Researchers believe that genetics, environmental factors and a history of head injuries can all produce PD. Currently there is no cure for the condition, and pharmaceutical interventions do not address its root causes.
What is Parkinson’s Disease?
About 200,000 people in the United States receive a PD diagnosis each year. Worldwide, the disease affects about 6 million people. The majority of affected patients are 60 years old or older. About 1% of the world’s 60+ population has the disease. An early-onset form of the disease can affect pre-adolescent, adolescent and young adult individuals. Diagnosis before the age of 50 is considered early-onset PD.
In addition to degenerating voluntary muscle control, PD can also produce negative cognitive and emotional impairments. Parkinson’s patients commonly exhibit signs of dementia, depression, anxiety and emotional and behavioral problems. The non-motor symptoms worsen as the disease progresses.
Conventional pharmaceutical treatments regularly include levodopa, an amino acid that is a precursor to dopamine. When initial pharmacological treatments begin to lose their effectiveness, doctors often switch to dopamine agonists, which is a different class of PD medication. In addition, some surgical interventions to enable deep-brain stimulation may provide relief to some patients. The progressive nature of the disease tends to frustrate long-term suppression of physical symptoms.
Stem cell treatments may address PD’s root cause
Takashi’s team at Kyoto University Hospital will transplant about 5 million reprogrammed precursor cells in to 7 affected patients. Following the transplant, doctors will observe the patients for two years.
An earlier primate study using macaque monkeys with an acquired form of PD employed the same technique. That study showed that transplanted cells developed into dopamine-producing neurons. The resulting neurons improved the monkeys’ voluntary movements. In that study, researchers noted that the monkeys showed sustained improvement over two years following the transplantation. They also noted that the monkeys suffered no apparent negative side effects.
Potential side effects of using pluripotent stem cells include the development of tumors and uncontrollable immune responses. These side effects are known considerations when using pluripotent stem cells. In the human trial, researchers will monitor participants for signs of these side effects.
Researchers hope that stem cell based therapies may help replenish the human subjects’ complement of dopamine producing neurons. If successful, the approach may one day halt the progression of the disease, or potentially reverse its disastrous effects.
The trial represents the third use of induced pluripotent stem cells to address human diseases in Japan. In 2014, a research team used the stem cell technique to treat retinal disease. A second trial used reprogrammed stem cells to treat heart disease.
PD stem cell research is active globally
Worldwide, other PD research teams are using stem cells to develop new treatments. Chinese researchers are working with other types of stem cells to develop neural precursors. Teams in the US, UK and Sweden also plan future stem cell trials with other types of stem cells.
Some US researchers believe that IPS cells derived from the patient can produce the same or similar results. This approach would minimize the risk of a rejection. In addition, they hope to avoid mutations that could lead to tumor growth. Using the patients’ own cells, however, can be both expensive and time-consuming.
US researchers hope to begin clinical trials using various types of stem cells in 2019, including iPSC. One goal of the research is to determine the volume of stem cells needed to achieve therapeutic results.
This study is another example of the potential of stem cell based treatments. Although these treatments are in the experimental stage, they will help inform future approaches to PD treatment. Banking stem cells for the future puts individuals and families in a position to take advantage of future advances in stem cell therapy. If you would like more information about stem cells and the work of the National Dental Pulp Laboratory, please visit our website at or call us at (774) 843-2984.
