Parkinson's disease is a slowly progressive disease, and current medical treatment is aimed at palliative treatment.
Under such circumstances, clinical trials of regenerative medicine using iPS cells are progressing, and the light of new treatments has come into view.
Some of you may be wondering about the details of regenerative medicine, which is an effective treatment method for Parkinson's disease, and the causes.
By reading this article, you can deepen your understanding of the symptoms of Parkinson's disease and iPS cells, which are the cornerstone of regenerative medicine.
If you are concerned about the details of Parkinson's disease or are worried about symptom control with drugs, please refer to it.
table of contents
1. Is Parkinson's disease curable?
Parkinson's disease is designated as an intractable disease, and there is a government-established system for research aimed at elucidating the cause and establishing treatment.
Categorical evaluation of symptoms is important because the symptoms are complex and have a large impact on daily life.
1-1. Decreased motor function due to Parkinson's disease
Parkinson's disease presents with the following four major symptoms:
- Resting tremor (regular shaking at rest)
- Rigidity (jerky muscle resistance when the joint is flexed)
- Immobility, hypokinesia (body movements are sluggish and facial expressions are lacking)
- Postural reflex disorder (short gait, forward leaning, susceptibility to falls) tremor
Symptoms that appear from the early stage often include tremor, muscle rigidity, and immobility, and the course is slowly progressive. Although there are individual differences, it is generally possible to live independently for about 10 years after the onset of symptoms.
After that, however, they tend to require more assistance.
1-2. Classification of “severity” by the intractable disease medical expense subsidy system
Parkinson's disease is the most common neurological disease. Depending on the severity of your symptoms, you can use the Intractable Disease Medical Expenses Subsidy System.
The intractable disease medical expense subsidy system is a system that supports the burden of medical expenses until an effective treatment for the disease is established.
The purpose is to promote research by understanding the patient's medical condition and treatment details.
Those with Parkinson's disease who are classified as stage 3 or higher are eligible for the Intractable Disease Medical Expenses Subsidy System.
Severity Classification for Parkinson's Disease
| stage 1 | Disability is limited to one side of the body and has little impact on daily life |
| stage 2 | Disabled on both the left and right sides of the body, no assistance required for daily living |
| stage 3 | Appearance of clear gait disturbance, progress of disability in activities of daily living |
| stage 4 | Decreased activities of daily living such as standing up and walking, requiring a lot of assistance |
| stage 5 | Wheelchair mobility with assistance or bedridden, full assistance required |
1-3. Classification of "Degree of Life Impairment" by Medical Expense Subsidy System for Intractable Diseases
Patients with the following life dysfunction degree 2 or higher are eligible for the "intractable disease medical expense subsidy system" for various intractable diseases such as Parkinson's disease.
degree of disability
| 1 degree | Requires almost no assistance in daily life and hospital visits |
| 2 degrees | Requires partial assistance for daily activities and hospital visits |
| 3 degrees | Requires full assistance in daily life, unable to stand up |
This support system is valid for one year, and the copayment amount is determined according to the income of the household. If you wish to continue to receive medical expenses, you will need to apply for renewal.
2. Regenerative medicine using iPS cells attracting attention for the treatment of Parkinson's disease
In 2018, the iPS Cell Research Institute of Kyoto University started the world's first clinical trial using iPS cells (induced pluripotent stem cells) to improve the symptoms of Parkinson's disease.
We will introduce the latest regenerative medicine, which is attracting a lot of attention, so that you can live on your own while coping with your symptoms.
2-1. iPS cells (induced pluripotent stem cells) that are effective in treating Parkinson's disease
iPS cells are cells that have the ability to proliferate cells of new tissues and organs by introducing a small number of factors into cells such as human skin and blood and culturing them.
By creating dopaminergic neurons from iPS cells and transplanting them into the brain, the amount of dopamine in the brain is increased and the symptoms are improved.
“Allotransplantation,” in which cells from other people are transplanted, can prepare a large number of cells at once, saving a lot of money and labor.
On the other hand, the risks are as follows.
- Possibility of immune reaction occurring due to perception of the transplanted material as a foreign body in allogeneic transplantation
- During transplantation, the original cells are damaged. Or there is a concern that iPS cells may turn into tumors due to undifferentiated cells remaining
Through meticulous research, we have steadily achieved results and succeeded in improving safety.
2-2.Results Confirmed with iPS Cells as Regenerative Medicine
The research group used human iPS cells and confirmed the following safety and efficacy.
- Dopaminergic neurons made from iPS cells function normally in the brains of Parkinson's model animals, resulting in improved behavior
- Induced dopaminergic neurons can be highly enriched, and cells that may proliferate after transplantation are removed during the enrichment process
- No tumor formation was observed after transplantation into immunosuppressed mice with no abnormalities in cancer-related genes
The trial will be conducted on 7 target patients and will be followed for 2 years. The goal is to reduce the number of bedridden patients with Parkinson's disease to zero by accumulating cases where cell transplantation is safe and effective.
3. Causes of developing Parkinson's disease
Parkinson's disease is a disease that causes motor dysfunction due to loss of dopamine neurons in the substantia nigra in the brain.
Although some gene mutations are related, the cause of degeneration and loss of dopaminergic neurons is unknown.
The striatum, to which dopamine is sent, is most involved in regulating movement, resulting in symptoms characteristic of Parkinson's disease such as tremor, rigidity, and akinesia.
Parkinson's disease is closely related to aging, and many studies have shown that an average of 10% of dopaminergic neurons degenerate and drop out over a period of 10 years.
In Japan, which has entered a super-aged society, the number of Parkinson's disease patients is expected to increase explosively in the future.
4. Common treatments for Parkinson's disease
There is no established fundamental treatment for Parkinson's disease, and the focus is on symptomatic treatment.
Current treatment mainly uses dopaminergic drugs. Due to the wide variety of symptoms, it is essential to use a combination of drugs.
Under such circumstances, regenerative medicine using iPSs cells is attracting attention. Recent studies have shown that it is also effective against Parkinson's disease.
In the not too distant future, it may be introduced into general use as an effective treatment for Parkinson's disease, which has been designated as an intractable disease.
5. Summary: Regenerative medicine is attracting attention as a treatment for Parkinson's disease, so expectations are high for future prospects
There is currently no established cure for Parkinson's disease.
The only general treatment is drug therapy, which mainly slows progression.
However, drugs can have side effects such as nausea, constipation, and hallucinations.
Among these, regenerative medicine is attracting attention.
If iPS cells reduce motor dysfunction, there is no need to worry about the side effects of drugs.
Even if you don't have to make detailed adjustments to your internal medicine, the burden on your life will be greatly reduced.
Family understanding and support are essential for patients with characteristic movement disorders due to Parkinson's disease to maintain their daily lives.
I hope that regenerative medicine treatment will be widely deployed in the future as an option for continuing support from both the physical and mental aspects.
Supervision: Dr. Yasushi Tsuda