Reprogrammed stem cell therapy shows promise in Parkinson's

By Dr. Ananya Mandal, MDAug 30 2017

Japanese investigators have found that their experimental stem cell therapy for Parkinson’s disease actually works. In their experimental therapy, the team of researchers “reprogrammed” stem cells to make them neurons and implanted them into the brain of monkeys with a version of Parkinson’s disease. Stem cell therapy showed improvement of symptoms in these patients and was found to be safe. The study was published yesterday, 30th August 2017 in Nature.

Stem cell therapies have been tried for various degenerative and difficult to treat diseases with some success. This team of researchers led by a stem-cell scientist at Kyoto University in Japan Jun Takahashi, found that these stem cells that have been modified to form the neurons and then implanted into the monkey brains seemed to survive in the brain for at least two years with no harm to the animal. Takahashi said that their team is gearing up to begin transplanting neurons that have been created from stem cells or induced pluripotent stem (iPS) cells into people who are suffering from Parkinson’s disease as a next step of this research work. Other approaches to treatment of Parkinson’s disease using stem cells are also on the cards in several research labs.

Parkinson’s Disease

Parkinson's disease is a degenerative disease of the brain. It affects parts of the brain that are associated with normal movement and balance. It is mainly caused by the death of the cells called dopaminergic neurons. These normally make a neurotransmitter called dopamine in certain areas of the brain that deal with movement and balance.

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The classic symptoms of this condition are a tremor or shaking of the hand or other limbs while at rest. Another classic symptom is rigidity and increased tone in the body's muscles. The movements of the body are slowed (this is termed bradykinesia) and the patient often finds difficulty in maintaining balance.

The problems are usually at the beginning of a new activity like getting up and walking. Once they begin the patients usually moves too fast, ending up almost running or out of control. The disease is commonly diagnosed at the age of 60 but around 1 in 20 patients may be diagnosed earlier (less than 40 years of age). Men are one-and-half times more likely to get Parkinson’s disease than women.

Parkinson’s disease can be controlled initially with several groups of drugs but the disease is a progressive one and has no cure.

Stem Cell Therapy

Stem cells or pluripotent cells are those that can be programmed to form any cell type in the body. These are the cells that are the precursors or beginning cells of all the different types of cells in the body. These cells can be obtained from embryos. This has been under fire from research ethics point of view because of the likelihood of unethical practices in collecting these cells. Nowadays adult cells are being induced to become emybronic-like stem cells. These are called induced pluripotent stem (iPS) cells. They have the same capacity as the embryonic stem cells – i.e. to form any cell – but do not carry the risk of ethical misdemeanors.

Stem Cell Therapy and Parkinson’s Disease

The stem cells are coaxed into forming dopamine-making neurons by the research team. Once they turn into these neurons, they can be implanted in the brain to replace the dead dopaminergic neurons. Most medications for Parkinson’s disease work by increasing the levels of dopamine and this do not treat the actual cause of the disease providing only symptomatic relief. Using these stem cells that replace the dead neurons can address the underlying cause of the disease. This could potentially halt or even reverse the progression of the disease.

Takahashi’s team used these iPS cells coming from healthy people and those with Parkinson’s disease. They made the cells become dopamine-producing neurons. They then transplanted these newly made neurons into the brains of macaque monkeys. These experimental monkeys had been made to develop Parkinson’s disease by giving them a neuron-killing toxin.

The transplanted brain cells lived without damage or any harm for at least two years and formed connecting networks with the monkey’s brain cells. This made the monkey’s more active and a 40 to 55 percent improvement was noted in the monkeys. None of the implanted cells turned into tumours. One of the main concerns about stem cell therapy is their turning into tumours. These new cells also did not trigger the immune responses whih could not be controlled by the use of immune-suppressing drugs.