Advances in the treatment of neurodegenerative diseases through stem cells

The potential of stem cells to repair brain injuries and advance the treatment of all types of neurodegenerative diseases, such as Alzheimer's or Parkinson's, is yielding important results in recent years. But it is as complex an area as the brain itself and ensuring the results of each research is fundamental.

This is how one of the world's pioneers in this field understands it, José Ramón Alonso, professor of Cell Biology at the University of Salamanca, who, despite his prudence, has obtained "unprecedented" results with the transplantation of stem cells into mice with genetic brain damage by achieving "significant improvements at the motor level and also at the sensory level," according to the head of research at the University of Salamanca Communication.

Advances in the treatment of neurodegenerative diseases through stem cells

In the first case, as explained by Alonso, director of the laboratory "Neuronal Plasticity and Neurorepair" of the Institute of Neurosciences of Castilla y León (INCyL), animals were used with a genetic problem affected by a neurodegeneration that made them paralytic and begin to stagger a few days after birth. To evaluate the efficacy of the new cells in his brain, coming from the bone marrow of a donor, a measuring protocol was designed using a device with a bar that spins faster and faster where the mice must adapt to movement and, if they do not succeed, fall. Five stopwatches are installed below to measure exactly how well they work. "In a very striking way, we saw that they improved significantly, with high statistical significance; there was a very important motor improvement," explains the researcher.

With a second group, we wanted to respond to sensory problems that are also behind the brain damage. "We have many diseases in which the problem is not motor, but you lose sight, hearing or smell, which is precisely the most important sense of mice and a field in which we have always worked," explains José Ramón Alonso.

Thus, not only did they manage to demonstrate that "there was also an important sensory improvement in animals", but they also designed a new device, an olfactometer "that we are going to patent now, because we believe it could be a relevant economic entry for the University of Salamanca". It is a system of tubes and valves that releases a certain amount of aroma and, by means of a computer connection, measures the cerebral response to odours. "We encourage the mouse to collaborate by giving it a prize when it does well and the results are really very good," he says.

Since adult neurogenesis. The origins of pioneering research

In order to get here, "with such impressive data" that have attracted international attention both in congresses and in journals, the research of this group from the University of Salamanca has gone through different phases that have, in turn, yielded important discoveries.

The first experiments on mice did not give the desired results, but they represented a significant advance in understanding the functioning of the new cells. Subsequently, cell transplants were performed on monkeys with a lesion similar to Alzheimer's, and "we had a mixture of good news and bad news, as is usually the case with research".

The cells survived, the brain, "we don't know very well why, it doesn't reject a transplant; however, we weren't able to reconstruct the damaged brain circuits. On the contrary, what they did was to "connect with each other, which is logical if you think about it. They were very young cells and, instead of going to look for the mature ones, they would get together and make microbrain. The problem is that we don't have a guidance system to take them to the place where we need them," explains the professor.

The following strategy led them to resort to a donor animal, extract cells, not from the brain, but from the bone marrow, and transplant them. A decisive step, since, as Alonso comments, "you recently told this and nobody believed it. It has already been demonstrated by different groups, including ours, that these cells are generating new cell types and some reach the brain, although we do not know how they cross the blood-brain barrier. Finding out is also an exciting topic.

In order to be able to track these cells and "prove that they really were there," especially to validate results in scientific journals, the researchers used several mechanisms. One was to place cells from a male animal into a female receptor, and if they had a Y chromosome, they could be followed with a specific probe. They also used green fluorescent mice, with all their green fluorescent cells, "so we took them from the bone marrow and we were able to follow them in the receptor even if they divide or differentiate," he says.

In both cases, they found that they reached the brain, but in very small numbers and not all areas. "How can we increase their presence, guide them and take them where we need them?" is the big question this group is working on.

The future of research

So far, they have already achieved real results in the motor and sensory improvement of paralytic mice. Now they are trying to find out why such a low number of cells, 20, 40 or 60 in some cases, cause so much functional improvement. They are also studying possibilities for the number of cells to increase, making the blood-brain barrier more permeable. "When there is inflammation it is more permeable and in some experiments we have already managed to multiply the number of cells that enter by ten, but we are exploring other paths," according to the biologist.

In addition, they are perfecting the inclusion of cells, moving from intraperitoneal mode to intravenous injection and studying other pathways, for example, through the olfactory epithelium.

However, the professor assures that "we have really achieved very attractive results, but with many lines of research open to consolidate the results, and many variables".

Parallel lines of research: autism

One of these parallel investigations has also had very encouraging results for people with Autism Spectrum Disorder (ASD), as one of the most striking findings of the few autopsies performed in this field shows that Purkinje cells are lost with this disease. People with autism have up to 40% less of these neurons, which are closely related to emotions and movement.

"We are getting, in an animal that loses these cells, that they do not die, which is arousing much interest, because there is increasing awareness that autism is a neurobiological problem, and we are closer to having that biomarker that we have always pursued, "says Alonso.

The stem cells that have been implanted in the animals in this laboratory have managed to reach those of Purkinje and have fused like two soap bubbles; when they carry a new gene, they no longer die. "If their destiny was to disappear, they do not disappear. If the development of autism finally has something to do with these lost cells, we can prevent it in the laboratory. But a lot of previous research is needed before reaching the clinic, we have to be sure to have the best procedure", in the words of the researcher.

International collaboration and training

The Neuronal Plasticity and Neurorepair group of the Institute of Neurosciences of Castilla y León (INCyL) directed by José Ramón Alonso is made up of three biologists and six doctoral students and maintains constant collaboration with other international laboratories, in France or the United States, as well as with different Spanish universities and institutes in Seville, Barcelona or Madrid, because "there is no other way in today's science, it is necessary to share techniques, apparatus and results".

In addition, it has stable and competitive funding from both the central government and the Junta de Castilla y León and private foundations. "We are a small group, but we train people very well; in the end they are hired from the best places and we give a lot of importance to the relationship with society, especially in the dissemination of science and health education," adds Alonso.

As a result of these premises, one of the students is doing a doctoral thesis using precisely the olfactometer, about to achieve the patent. In addition, in collaboration with the Otorhinolaryngology Service of the University Hospital of Salamanca, he is measuring the causes and variables of anosmia -or loss of the sense of smell- with tests on citizens throughout the province.