NEW DELHI — Stem cell therapies are a safe and effective way of treating
Parkinson's disease, according to results of two independent clinical trials.
The two papers, published in the journal Nature,
investigated the use of cells derived from human induced pluripotent stem cells
and human embryonic stem cells, respectively.
Parkinson's disease is a neurodegenerative disease
characterised by the progressive loss of neurons that produce dopamine, a
neurotransmitter.
Although current treatments, such as ʟ-dopa, can
alleviate symptoms in the early stages, their efficacy declines, and they are
often accompanied by side effects such as dyskinesia (involuntary movements).
However, the studies found that cell therapy could
replenish dopamine-producing (dopaminergic) neurons in the brain. This provided
a potentially more effective treatment with fewer adverse effects.
The first phase I/II trial led by researchers from Kyoto
University in Japan focussed on seven patients (aged from 50 to 69) who
received transplantation of dopaminergic progenitors derived from human induced
pluripotent stem cells into both sides of the brain.
No serious adverse events were reported during the study
period of 24 months, and the transplanted cells produced dopamine without
overgrowth or forming tumours -- a risk associated with stem cell therapy.
The researchers also observed a decrease in motor
symptoms associated with Parkinson's in four of the six participants who
continued the trial to efficacy evaluation while not taking their standard
medication, and in five while taking medication.
The second phase I clinical trial led by a team from the Memorial
Sloan Kettering Cancer Center in the US explored the safety of a dopaminergic
neuron progenitor cell product (bemdaneprocel) derived from human embryonic
stem cells.
Twelve patients with a median age of 67 received surgical
transplantation of bemdaneprocel to the putamen on both sides of the brain.
Five participants received a low dose and seven received
a high dose.
The cell product was generally well tolerated and no
severe adverse events related to the therapy were reported during the follow-up
period of 18 months.
There was no incidence of dyskinesia.
In addition, some improvement in motor function was also
observed in patients in both the low-dose and high-dose cohorts.
Even with limitations such as the small sample size, both
clinical trials establish the safety of allogeneic (non-self) transplantation
of stem cell-derived cell products for the treatment of Parkinson's.
While this can be “an important step towards the
establishment of this cell therapy for Parkinson's disease”, further research
is needed with a larger sample size to test the effectiveness and clinical
benefits of these therapies, the researchers said.
