Stem cells are a hot topic, not only for us but for the scientific community. Breakthroughs are being made every day in many different fields, including stroke. That’s why we set out to learn more from a leading expert on this topic. Recently, a team from Strokemark met with Prof. Benedikt Berninger from The Center for Developmental Neurobiology at King’s College in London. As we continue to explore this topic, we wanted to learn from Prof. Berninger how he views the current status of this field and specifically about the research he’s conducting.
We actually learned so much that we divided our interview with him into two parts. This is the first part that focuses on the general state of stem cells research. Prof. Berninger explains more about the theory of how stem cells are supposed to work, offers his insights about clinical trials, and warns why we must be cautious about clinics that already offer stem cell therapy.
Learning more about the field of stem cell research
Strokemark: How are stem cells supposed to work?
Prof. Berninger: First, let me cover what stem cells are supposed to do. Most people expect that they are replacing something, like in the case of stroke. Stem cells could integrate into the brain and differentiate there, meaning they turn into the cell types that are missing. I think, overall, we are not there. But that is one of the hopes.
The other thing that stem cells could do is that they could have a modulatory effect, or a bystander effect, on the stem cells that are still there. So their role is not to replace the cells that have died but to support the ones that still exist. For example, they could secrete growth factors for the healthy cells remaining. They could also help positively suppress the immune response. It is thought that mesenchymal stem cells (MSCs) have exactly this effect (for further explanation, please see our stem cell glossary and part III of our stem cell report where we describe clinical trials that use MSCs).
Strokemark: Do you think at one point it would be possible that stem cells replace dead cells in the brain?
Prof. Berninger: The main problem with the brain is that it is extremely complex. When you have a stroke, complex tissue consisting of many cell types dies. And to reconstitute something that is so complex is a challenge.
In other fields, we see the potential to replace damaged cells. For example, there is quite some hope to be able to replace cells in a damaged heart. There are experimental trials where human heart muscle cells are grafted into the hearts of primates and have yielded some recovery effects. The important takeaway here is that there is healing. The difference to the nervous system is that heart muscle cells need to be replaced with cells that take over for them.
It’s a little more complicated when it comes to using stem cells in the brain because here the attempt is to replace one type of damaged cell with another cell type. There are complex circuits in the brain. And we don’t actually know how the circuits are composed or the ratio of all the components and how the circuits are arranged. If we had to program all this information, it would be a challenge. The hope is that, to some degree, there are self-organizing processes that happen. And the processes can take over and then the complexity would take care of itself.
Strokemark: What are the main obstacles for clinical trials?
Prof. Berninger: I think many trials have been using mesenchymal stem cells (stem cells from an adult source that can change into some types of other cells, but not all types, see glossary) with the idea of a bystander effect. I don’t think this can solve all problems. However, researchers have embraced this approach and are assessing their potential to restore function.
It is likely, the cells themselves don’t cause any harm. So then some researchers think, “why don’t we just try it and see what happens?” But there is evidence that it could be working because of growth factors or other molecules excreted that could help. But I don’t think this will profoundly transform treatments in the case of neurological degenerative diseases (such as Parkinson’s Disease).
Strokemark: Do you think that this is a problem with the type of cell, and would other types be more effective?
Prof. Berninger: It depends on your intention. If you plan to take advantage of a bystander effect in a sample population that by chance, purely by chance, has a positive effect, then there might be hope. It’s like if you find a new antibiotic that you didn’t know before and it works.
Originally, the idea was the mesenchymal stem cells also could replace diseased neurons, but I don’t think there is any evidence that this can be the case. There were reports at one time, but nobody takes these reports seriously anymore. So the hope that these cells will be making neurons or any other part that is relevant for promoting brain function has died entirely.
It is possible that someday we understand more what these cells are doing. And if we know what these cells are secreting in terms of growth factors or if we know what the positive effect is on the immune system, then instead of using the cells, we could use some compounds that would replace their functions.
So, I think that using mesenchymal stem cells is like just taking a chance on something. We hope that these cells can do something, but we still don’t’ know what exactly it would be. And we hope that this could benefit the tissue and thereby, the patient.
The other big expectation is that at one point we would really be able to replace the damaged cells. For this, I don’t think we can start with the famous mesenchymal stem cells. Instead, we need to develop other systems.
Strokemark: Are you familiar with the results of Steinberg’s research? He implanted stem cells and reported results where people started to feel better the next day. What is your take on results like this?
Prof. Berninger: Frankly speaking, it is impossible to see results in a day. The neurons in our nervous system, even in a fetus, take months to mature. To reconstitute neurons within hours is not possible. There could be some immediate benefit because of some collateral effects. Bystander effects might be possible, and they can be more rapid. But I have a difficult time believing that we could really see results in one day. Recovery will always take substantially more time.
Strokemark: Would you recommend people to take part in clinical trials that are happening now?
Prof. Berninger: If it is approved, I would say, of course. Why not? I think people have to be careful that it is a real clinical trial. I think if it is approved, then it was analyzed and designed carefully. If you hear of one that you would like to try, it would make sense to join.
Strokemark: There are clinics out there that offer treatments. Would you recommend these?
Prof. Berninger: The scientific community is absolutely opposed to this. These clinics often have one stem cell for everything, and that is clearly bogus. These clinics only exist to extract money from patients.
Strokemark: Does the therapy offered in these clinics pose a danger?
Prof. Berninger: Even if there would be no danger, it is clear that they have no benefit. It would not even evoke a bystander effect. Somebody just wants to have the patients’ money. There is no rationale behind the treatment. There might be side effects, but the biggest concern is that it doesn’t work and only plays with the patients’ hope.
Researchers continue to look into stem cells
So, as we conclude the first part of our interview, we would like to leave you with the hope that many exciting things are happening in the field of stem cell research. Although researchers have not quite yet discovered the best way to use stem cells, they are working hard to uncover the possibilities. And as this field is growing, they are testing different types of stem cells and different ways to unlock their potential through clinical trials.