First litmus test demonstrates the potential of artificial neurons against serious diseases

In a landmark trial of medical research into the use of stem cells to treat serious illnesses, Massachusetts-based BlueRock Therapeutics showed that implanting laboratory neurons into the brains of 12 people with Parkinson’s appears safe and may reduce symptoms in some patients. .

The main issue is that the added cells must produce the neurotransmitter dopamine, the lack of which causes the devastating symptoms of the disease, including problems with movement. “The goal is for the implanted neurons to form synapses and connect with the host neurons as if they belonged to the same person,” explains Claire Hencliffe, a neuroscientist at the University of California.

The study stands out as one of the largest and most expensive trials to date of embryonic stem cell technology, a controversial and highly publicized method that uses stem cells taken from fertilized embryos. in vitro produce in tissues.

The primary purpose of the study was to demonstrate the safety of the method, and it was sponsored by BlueRock Therapeutics, a subsidiary of pharmaceutical giant Bayer. The neurons were created from powerful stem cells obtained from a human embryo created through a fertilization procedure. in vitro.

According to the results presented by the team that brought together Hencliffe at the latest International Congress on Parkinson’s and Movement Disorders, there are also indications that the added cells survived and, as a result, reduced symptoms in patients a year after starting treatment. increase in the number of dopamine-producing cells.

The data also indicates a reduction in “off time”; that is, the number of hours per day during which volunteers felt incapacitated due to symptoms of Parkinson’s disease. Experts, however, are cautious in interpreting the results as they seem to show conflicting effects. Some of these may be due to the placebo effect rather than the treatment.

“What is reassuring about the study is that it did not lead to any safety issues and at the same time has some advantages,” says Roger Barker, a scientist who studies Parkinson’s disease at the University of Cambridge in the United Kingdom. Barker, however, describes the experience as “a little disappointing” because the results did not conclusively show that the transplanted cells survived.

Because researchers cannot see the cells immediately after implantation, they have to track their presence with a radioactive precursor. They then monitor its absorption in the brain with a scanner. For Barker, the results are not as convincing. “It is still too early to say whether the transplanted cells have taken root and rebuilt the brain,” says the researcher.

Embryonic stem cells are not without controversy. They were first isolated in 1998 at the University of Wisconsin from embryos obtained from reproductive medicine clinics. Their usefulness to scientists stems from the fact that they can be grown in the lab and theoretically made to form any of the nearly 200 cell types in the human body.

This possibility, although theoretical, has spurred hundreds of attempts to restore vision, cure diabetes, and reverse spinal cord injuries. However, there is still no treatment based on embryonic stem cells, despite the billions of dollars invested in research by governments and companies since the late 1990s.

Moreover, stem cells continue to raise burning questions. In Germany, where the multinational company Bayer is headquartered, for example, according to the country’s embryo protection law, which experts consider one of the strictest, receiving cells is a crime punishable by imprisonment.

They can only be obtained under certain circumstances. For example, if those that are used are obtained from abroad, if they were created before 2007. Seth Ettenberg, BlueRock’s president and CEO, says the company manufactures neurons in the US and uses embryonic stem cells from original supplies to do so. from Wisconsin.

The idea of ​​replacing dopamine-producing cells to treat Parkinson’s disease dates back to the 1980s, when doctors tried it with fetal neurons from miscarriages. Research has been mixed. Some people have benefited from this. However, the experiments generated disturbing headlines. Reason: There were patients who developed side effects such as uncontrollable twitching and twitching.

The use of embryonic brain cells was not only ethically dubious. The researchers were also convinced that this tissue was so variable and difficult to obtain that it could not be used for treatment. “Not a single experience has brought results. I believe that there was not enough understanding of the mechanism of action and a sufficient number of cells with controlled quality, ”asses Hencliffe.

However, there was evidence that the transplanted cells could live. Autopsies of some patients who received fetal cells showed that the grafts were still present years after they were completed.

“Many people are involved in embryonic cell transplantation. They always wanted to see if they could work,” recalls Jean Loring, co-founder of Aspen Neuroscience, a stem cell company that plans to launch its own tests to treat Parkinson’s disease.

The discovery of embryonic stem cells has made more controlled research possible. These cells can multiply and grow into billions of dopamine-producing cells. The original work was done by Lorenz Studer at Columbia University in New York. In 2016, Studer became the scientific founder of BlueRock, which was originally created as a joint venture between Bayer and investment fund Versant Ventures.

In Parkinson’s disease, dopamine-producing cells die, leading to a lack of this substance, which can lead to tremors, stiffness of the limbs, and a general decrease in mobility. The disease usually progresses slowly, and levodopa can control symptoms for many years. However, the disease progresses, and eventually the effect of levodopa stops.

Cellular therapy promises that doctors will no longer simply treat symptoms, but can replace damaged brain networks by adding new neurons.

“The potential of regenerative medicine lies not only in delaying disease. The challenge is to restore brain functionality,” explains Ettenberg, who says BlueRock plans to start a larger study with more patients to determine if the treatment is working and how effective it is.

(with agency information)

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