Dopamine neurons derived from a Parkinson’s disease patient’s iPSCs. Image source: Loring lab.
Using stem cells to treat Parkinson’s Disease
Japanese researchers announced that they have begun a clinical trial using stem cells to treat Parkinson’s disease (PD). The scientists re-engineered skin cells from an anonymous donor, causing them to revert to cells with a pluripotent state, called induced pluripotent stem cells (iPS). In this state, stem cells can morph into a variety of cell types, including neural cells. Although this trial used donor cells, iPS cells can also be derived from the patient’s own cells, including dental pulp stem cells.1
Trial Specifics
In this trial, Kyoto University neurosurgeon Takayuki Kikuchi transplanted about 2.5 million modified iPS cells into the brain of a 50 year old man with Parkinson’s disease. The team used earlier work from stem cell researcher Jun Takahshi. According to Takahashi, the team did not put the iPS cells directly into the site where most dopamine cells naturally form. However, they hope to see the transplanted cells develop into dopamine-producing cells.
The Kyoto University researchers used the same technique they tried in an earlier study of macaque monkeys with PD. In that study, the monkeys developed dopamine-producing cells following treatment, the desired result. In addition, the test monkeys did not experience complications from the procedure.
The researchers will study the patient for six months, for signs of both improvement and complications. If they see no complications in that time, they will repeat the implantation procedure. The researchers plan to treat six more patients with the same protocol. They will observe the study subjects closely and hope to be able to report their results by the end of 2020.
Typically, PD affects 1% of people over the age of 60. However, some patients form an early onset version of the disease. In these patients, symptoms of the disease can appear prior to age 40. The researchers have not yet said whether their trial subjects also include more typical (late-onset) PD patients.
The Mechanics of Parkinson’s disease
Doctors do not know what causes PD. Researchers think that genetics, environment and brain injury can all cause the disease. Others believe that substance abuse may change or damage dopamine-producing cells. PD patients steadily lose dopamine-producing cells, which affects muscle control. They also show emotional and psychological impairments. These include depression, dementia, trouble with logical thinking, anxiety and change in behavior.
Regardless of how the disease begins, the progressive loss of dopamine-producing cells in the brain occurs. Dopamine is a neurotransmitter which controls voluntary muscle movement, provides emotional control and drives the brain’s reward center. Most (75%) dopaminergic cells reside in clusters in the ventral midbrain. Although the clusters control different brain functions, PD affects them equally. As the disease advances, radiologic studies show organic changes in the brain.
Parkinson’s disease treatment
Drug treatments, which include levodopa, a dopamine precursor, have a limited effect that decreases over time. As the disease progresses, symptoms worsen and treatment effectiveness drops. Once levodopa treatments stop working, physicians may try dopamine agonists, which mimic the effects of dopamine. Dopamine agonists may provide some relief from PD symptoms, but they also have side effects, including hallucinations, nausea, narcolepsy and dizziness.
The researchers say that they do not believe this treatment, even if successful, will become a replacement therapy for PD sufferers, and that it is unlikely to return patients to a completely symptom-free state. Instead, they envision the treatment of using stem cells to treat Parkinson’s disease as one option in an array of treatments to slow the progression of the disease and improve the patient’s quality of life.
This clinical trial tests the potential of stem cell based treatments on humans. Although this treatment is experimental, it may eventually expand options for successful PD treatment. It also helps show the potential advantages of banking stem cells for future use. If you would like more information about stem cells and banking dental stem cells with National Dental Pulp Laboratory, please visit our website or call us at 774-843-2984.
References
- Rishikaysh V. Pisal, Jakub Suchanek, Richard Siller, Tomas Soukup, Hana Hrebikova, Ales Bezrouk, David Kunke, Stanislav Micuda, Stanislav Filip, Gareth Sullivan & Jaroslav Mokry. Directed reprogramming of comprehensively characterized dental pulp stem cells extracted from natal tooth. Scientific Reports volume 8, Article number: 6168 (2018)
