Johan Ericson: Our Stem Cells may be 10 Times More Effective

Johan Ericson stands before five hundred people in a conference hall in Oslo. On the screen behind him is an image showing a cross-section of a brain.

“Look here!” he says enthusiastically. “The green marks the dopamine-producing nerve cells. Not just present, but also active. Alive, integrated, and connected.”

Ericson switches images. Another brain, but the same cross-section. Almost no green. The difference isn’t subtle. It’s brutal. One works. The other does not.

Ericson returns to the first image. Holds the pointer still for a moment: “That’s how we want it, lots of green!”

No rhetoric. No pause for effect. Yet it’s hard to hear it as anything other than a manifesto. In those few words lie both a method, a critique of the field, and a hope that treatment for Parkinson’s might one day mean more than just delaying the decline.

Later that evening, Ericson sits in the hotel’s lounge. Waiters glide between the tables with practiced discretion. Conversations are conducted in a way that suggests they are not meant to be overheard by others. Ericson orders a beer and describes his project with the sobriety that only researchers with truly grand ambitions seem to master.

What if Parkinson’s can not only be slowed down, but fully or partially repaired?

Ericson smiles slightly when it is put that way: “Yes, that’s the intuitive way to understand it. Cells are lost, and we’re trying to replace them. But it sounds simpler than it is.”

Simple premises

There are research ideas so complicated that they’re almost impossible to explain. And then there are ideas that are so simple in form that they seem almost overwhelming. Ericson’s project belongs to the latter category. Not because it’s actually simple, but because the premise is so pure simple it almost feels too good to be true.

In Parkinson’s disease, certain dopamine-producing nerve cells in the brain die. Ericson’s project aims to create new ones. Not in a metaphorical sense. Not as a vague vision of the future. Not as a marketed promise from the fringes of biotechnology. But quite concretely: growing new dopamine cells in the laboratory and implanting them into the brain, with the goal that they will survive, mature, produce dopamine, and integrate into the existing network.

Ericson is not the entrepreneur who speaks in slogans, nor is he one of those modern research figures who treats his own future as a personal brand. Not Silicon Valley. Not big talk about revolution. He is a professor, a stem cell researcher, and a lab person, with a background in basic research and a way of speaking that constantly leans toward precision. Perhaps that is precisely why it resonates.

For while much of Parkinson’s research today focuses on understanding disease mechanisms, identifying subgroups, slowing cell death, or alleviating symptoms, Ericson is working on an idea that is far easier to grasp, and therefore also far more remarkable in its scope. What he is attempting is not primarily to protect what remains. It is to replace what is already gone.

This is where Ericson takes a different path than many others.

“There is a lot of important research focused on slowing disease processes, better understanding the biology, or identifying which patients will benefit from various treatments.” says Ericson. “What we’re trying to do is something else. We’re trying to restore function.”

It’s a word he uses often: function. Not a miracle. Not a cure. Not a quick fix. Function.

“If this works as we hope, it’s not primarily about symptom relief in the traditional sense. It’s about giving something back. Replacing cells that have been lost, so that the brain’s own networks can function better again.”

How do one create new brain cells?

The explanation begins with a type of cell that in itself sounds like pure science fiction: pluripotent stem cells.

These are cells that can develop into any cell type in the body. In the laboratory, they function as a kind of biological blank slate, or building blocks that have not yet decided what they will become. But having such cells is not the same as being able to use them. The challenge lies in getting them to become exactly what is needed, neither more nor less.

“The challenge is not to create cells; the challenge is to create the right cell.”

In his laboratory, these stem cells are guided through a carefully controlled developmental program. Using signaling molecules, including retinoic acid, the researchers attempt to mimic the same biological processes that occur in the fetal brain when dopamine-producing nerve cells are formed.

The goal is not just to create neurons. The goal is to create a specific subtype: dopaminergic precursor cells of the type normally found in the embryonic midbrain, the cells that can later mature into precisely the dopamine-producing nerve cells that are lost in Parkinson’s.

"The key point is that we’re not just creating neurons in general. We have to create the right type. The cells lost in Parkinson’s disease are a very specific subtype of dopamine neurons. If you don’t achieve the correct cellular identity, you won’t get the effect you’re looking for."

This is where Ericson’s scientific signature lies. Not just in the idea of cell replacement, but in the precision. In the ability to guide the stem cells toward their intended fate. Not 'brain cells' in a loose sense, but precisely the subtype that is lost in Parkinson’s disease.

Once the cells are produced, they are further cultured and purified under controlled conditions. The goal is to obtain a cell product where the proportion of the correct cells is high, and the proportion of unwanted cells as low as possible. It may sound like a technical detail. In reality, much of the entire battle hinges on precisely this.

"One of the major problems in the field has been that the yield of the cells we actually need is often quite low. If the transplant contains too few of the therapeutically relevant dopamine cells and too many other cells, both efficacy and safety suffer." He says it almost laconically, as if describing something that should be obvious. But therein also lies part of his criticism of the field as it has developed. For too long, as he sees it, people have accepted too low a yield of the right cells.

This is a sentence to keep in mind when trying to understand the entire project:

"If this works, it is because they have solved the cell quality issue, not because the idea it self is new."

Ericson’s implicit criticism of the rest of the field is simple: The problem has not primarily been that researchers have thought incorrectly. The problem has been that they have produced cells of insufficient quality: "If you look at many of the earlier methods, you get relatively few of the dopamine cells you’re actually after.Then the question becomes: how well can this actually work in patients?"

In his presentation earlier that day, he had demonstrated this visually.

First, a series of diagrams: Stem cells guided through a developmental pathway, via signaling molecules, to what he calls dopaminergic progenitor cells. Then transplantation. Then, after some time: The same image as on the screen.

Green.

Not just as an illustration, but as a measurement point.

“What we want is the highest possible proportion of the right cells. That’s where much of the difference lies.”

Some of the slides compare methods. In certain transplants, the signal is barely visible. In others, there is a dense green network.

The difference is not theoretical.

It is visible.

An idea with historical baggage

Cell therapy for Parkinson’s is not a new idea. On the contrary, the entire field rests on a long and complicated history.

As early as the 1980s and 1990s, transplantation trials were conducted using fetal tissue from aborted fetuses to replace lost dopamine cells. The results were mixed, but in some cases remarkable. Some patients experienced significant improvement, and in the most successful cases, people with severe Parkinson’s symptoms were able to return to a much more normal life.

"There are patients from those studies who experienced significant improvement. In some cases, they were able to stop symptomatic treatment and return to a more normal working life." says Ericson.

This is important, he emphasizes, because it means one thing: "We actually have a 'proof of concept' in humans. We know that the principle, that is, replacing lost dopamine cells, can work."

The problem was that this approach could never become a large-scale treatment. The supply of tissue was limited. The biology was difficult to standardize. The model was both practically and ethically challenging.

Ericson's Stem cells change that.

In principle, they make it possible to produce large quantities of cells under controlled conditions, with defined quality and a higher degree of standardization. That is why this field is now once again seen as vibrant.

But this is not the same as saying that every stem cell-based approach will succeed: "The crucial question is whether the cells we create actually meet the required quality standards. Do they behave like the body’s own dopamine neurons? Do they survive? Do they mature properly? Do they integrate into the network? That is what we are trying to document."

His own claim is that they come closer than others. Not because the idea is new, but because the quality of the cell product is higher. He believes their method yields a significantly higher proportion of therapeutically useful dopamine cells than previous approaches; in interviews, he speaks of up to ten to twenty times higher yields of relevant cells.

If that’s true, it’s not a minor detail. It’s the whole difference.

What the field has struggled with

It’s rare for researchers to speak so bluntly about one another in public contexts, but there is a clear conflict in Ericsson’s account.

The field has, as he sees it, long used methods that are similar to one another. The basic idea has been the same. But the yield of the cells one actually needs, the dopamine neurons, has often been low. In practice, it can be as low as 2 to 10 percent.
The rest are other cells. Immature cells. Irrelevant cells. Cells that take up space without providing the desired therapeutic effect.

"If the product consists mainly of other cell types, they take up space in the brain without providing the desired therapeutic effect. In the worst case, an oversized graft can cause tissue damage, even if it doesn’t result in cancer or tumor formation."

It is this part of the presentation that makes the strongest impression. Not the grandest promises, but the dry logic: If you are going to replace lost dopamine neurons, you actually need to have enough of them. Not just a vague cocktail of cells that might do something useful.

Thus, his project is less about a spectacular idea than about strict quality control.

Quality over quantity

This is also how he explains the dosage issue. Most clinical trials currently underway have, roughly speaking, given patients between 2 and 15 million cells in total. But, he points out, the decisive factor is not just the number. If the quality is high, you don’t necessarily need enormous quantities.

"There are approximately 300,000 dopamine cells per hemisphere in the relevant system, so in theory you don’t need enormous quantities if you actually have the right cells. In addition, there are different subtypes of dopamine neurons, and the A9 subtype in particular is important for the motor symptoms of Parkinson’s. This makes it even more complicated."

So it’s not just about how many cells you implant.

It’s about what kind of cells they are.

The toughest questions

This is where journalistic instinct must kick in. Because it’s easy to get carried away by the narrative: dead cells are replaced with new ones. The brain is repaired. The future is brought forward.

But biology is full of elegant ideas that have run aground between rats and humans.

The common counterargument is that there is a big difference between rats and humans. Many things look promising in preclinical trials and fall apart in clinical studies.

"That’s absolutely right, and that’s why we have to be cautious. But here we have an extra point of reference, because there is already historical data in humans showing that cell transplantation can work. The question is whether the stem cell product is good enough."

This is the point where most promising ideas in medicine face their toughest test: the transition from model to human. "The biggest uncertainty is always what happens when the cells do what we hope they will after they enter the human brain; they must survive, mature, produce dopamine, and integrate into the system in a meaningful way. And they must do so without causing problems."

On one of the last slides is a single word:

Safety.

Below it: a short list. Wrong cell types. Overgrowth. Undesirable effects. Tumor formation. Space issues in the brain.

"The brain is already full. If one introduce cells that not only do their job but also take up space they shouldn’t, that in itself can become a problem."

It’s a reminder of what makes this research so demanding. Not only must you create the right cells, but those right cells must behave correctly, in the right place, in the right numbers, over a long period of time, within one of the body’s most complex organs. This is not a treatment that can be turned off or adjusted afterward. It is a surgical intervention.

And even though many of Parkinson’s most well-known symptoms are linked to dopamine, Parkinson’s is more than a dopamine disorder. It is also a disease with non-motor symptoms, various subtypes, and a biology that has not yet been fully mapped. Even if we succeed in replacing dopamine cells, that does not necessarily mean that all aspects of the disease will disappear.

"I don’t think a single treatment will solve everything about Parkinson’s. The disease is more complex than that. But if we can restore the dopamine system that has been lost, we can push the boundaries of what is possible quite significantly."

Human trials that make the field hard to dismiss

Clinical studies are already underway globally. The field is no longer in the conceptual stage. Both embryonic stem cells and iPS cells are being used in projects that have entered the early clinical phase.

Ericson isn’t first in line. He knows that. He emphasizes it himself: “We are by no means the first on the scene. But we believe we may have a better method.”

He points in particular to a study from South Korea, which he describes as very promising.

“When their preclinical study came out, I saw right away that the grafts looked better than what you usually see.” They have now evaluated the first year in twelve transplanted patients, and all twelve have shown symptomatic improvement. The group that received the most cells appears to have had an even better clinical effect. This is an important signal that this type of therapy may actually work in a significant proportion of patients.

It is not definitive proof. But it is enough to make it difficult to dismiss the entire field as wishful thinking. The principle can work. The question is how well, how safely, and for whom.

This is also where Ericsson’s claim to be 'best in class' makes some sense. He isn’t saying they are first. He is saying they can be better.

Who will be able to benefit from this treatment?

Another question naturally follows: Who is this treatment actually intended for?

Not necessarily the very sickest patients. Not necessarily those who have only had mild symptoms for a short time. Rather, somewhere in between: "As it stands now, likely patients in the middle of the disease course. Previous results suggest that it may be best to treat relatively early. If you wait too long, the response may be poorer."

At the same time, the first clinical trials will always be cautious, precisely because you have to measure both efficacy and assess safety.

"The first studies are always conservative, because it can be dangerous; it can go wrong. You need to know if tumors, overgrowth, or other unwanted effects occur. That’s why you don’t start with the very sickest patients."

This makes the project less straightforward than the immediate narrative suggests. This is not “one operation and the problem is solved” kind of thing. It is more accurate to say that he is attempting to make it biologically possible to restore some function to selected patients—initially, likely in carefully defined groups.

Nevertheless, it is difficult to escape the underlying drama. For in a field of medicine where so much revolves around delaying, slowing down, adjusting, and managing, this carries a different kind of promise.

Not that time will be stopped.

But that something lost can be rebuilt.

When asked whether this can, at best, make patients “almost healthy,” he weighs his words before answering:

"People are often cautious about using the word “cure,” and that’s understandable. But in the most successful historical transplant trials, there were indeed patients who improved so much that they could stop symptomatic treatment and return to a normal working life. So in an optimal scenario, you can go very far."

He stops there. Not because he doesn’t see the greatness of what he’s working on. But because he’s a scientist enough to know the difference between hope, a principle, and a treatment.

What will the future bring

Outside, Oslo carries on at its own pace. Trams, taxis, people with shopping bags, office workers on their way home, tourists stopping at the entrance to take a picture of the facade.

Inside the conference rooms, a portrait interview has focused on something that just a few decades ago would have been pure speculation: cultivating new brain cells and implanting them into a damaged nervous system, not to alleviate symptoms from the outside, but to rebuild some of what has been destroyed.

No one knows yet how far this will go. Not even Ericson. He is too much of a researcher for that.

But if he succeeds, Parkinson’s will no longer be just a disease one tries to live with for as long as possible.

Then it will also be a disease where some of what has been destroyed can actually be rebuilt.