For the first time, neurons manufactured in the laboratory have been grafted into the brain of Parkinson patients, with clear signs of dopamine production. Two distinct clinical trials, conducted in Japan and the United States, draw a very promising therapeutic path.
Parkinson: a movement disease with deep neural roots
Parkinson’s disease affects more than 10 million people worldwide. This neurodegenerative pathology is caused by the progressive destruction of Dopaminergic neurons In a region of the brain called black substance. Dopamine, which they produce, plays a central role in the control of movements. Result: patients suffer from tremors, muscle rigidity and increasing motor slowness.
Current treatments, such as L-dopatemporarily relieve symptoms but do not slow down the progression of the disease. For several decades, researchers have been wondering: and if we could Replace destroyed neurons ? The idea of using reprogrammed stem cells to create new neurons is making its way. It remains to demonstrate that these cells can survive, integrate into the brain, produce dopamine … and improve the condition of patients.
This is precisely what the last clinical trials have just started to prove.
Two clinical trials, two approaches, spectacular results
Two independent teams-one led by the University of Kyoto in Japan, the other by the Weill Cornell Medical College in the United States-have conducted clinical trials in humans with results deemed very encouraging.
Led to New York, the first trial focused on 12 patients aged 50 to 78, with Parkinson at a moderate stage. Researchers have transplanted into the brain of Dopaminergic neurons from human embryonic stem cellscultivated in the laboratory according to strict protocols. The results are up to hopes: grafted neurons survived more than a year and began to produce dopamine, confirmed by brain imaging. No serious immune reaction or major side effects have been observed. It should be noted that some patients have found stabilization or improvement of their symptoms.
“”Our results show that stem cell therapy can be carried out safely and could potentially replace lost neurons“declares the Dr Claire Henchcliffe, neurologist, Weill Cornell Medicine. And his colleague, Dr. Lorenz Studer, director of the Center for Stem Cell Biology, Sloan Kettering Institute S “Enthusiasm:”It’s a pivotal moment for regenerative medicine. This is the First proof in humans that neurons derived from stem cells can survive, integrate, operate in the human brain, and produce dopamine“.
For their part, researchers from the Center for IPS Cell Research and Application launched a phase I/II test in seven Japanese patients aged 50 to 69, suffering from advanced and refractory forms of Parkinson. This time, the cells used are Multipotent induced stem cells (IPS)reprogrammed from adult cells. In one of the patients, the results are particularly spectacular: doctors have observed a notable improvement in motor functionswithout appearance of serious side effects. MRI examinations have confirmed that the transplanted cells were still present several months after the transplant.
In total, the two trials converge: the implanted neurons survive, integrate, produce dopamine, and – in some cases – improve the motor symptoms.
And now ? Next stages and scientific prudence
Despite the enthusiasm aroused by these results, researchers call for caution. The number of patients remains very limited, and the effects should be confirmed in the long term. Japanese and American teams already announce New test phaseswith more participants, to refine the protocols, precisely dose the number of transplanted cells, and better assess the potential side effects.
The next steps will be to determine The optimal dose of cells to be implanted, sore long -term side effectsin particular the risk of development of tumors and standardize the production of stem cellsto guarantee their quality and security. It will take several years to confirm that this approach is safe and effective in the long term.
The challenge is now as biological as logistics. But the essential is there: the proof of concept is validated, and with it the opening of a new chapter in the fight against Parkinson.