How much promise is there today for stem cell therapy for heart disease? Where do things stand with the clinical research?
Patients regularly ask me these kinds of questions.
The goal of today’s post is to update you on where things stand.
What’s in this post
Stem cell therapy for heart disease: where we are today
Unfortunately, I don’t know of any current stem cell-based treatments for heart disease that are going to give a good chance of a clear benefit and low risk. That’s the reality today. I go over the idea of stem cells for heart disease on our YouTube channel in a video below.
The better news is that there are hundreds of clinical trials ongoing.
There have been some hints of efficacy in some trials too, but we need to get more data from late-stage trials. Also, some trial results have been discouraging. More below in the next section.
Also, see my post Can Hearts Repair Themselves Via Stem Cells.
Clinical trials and types of stem cells
Overall, I found 391 listings on Clinicaltrials.gov for a search for stem cells for heart disease.
The types of cells being used vary substantially in these trials. For example, BioCardia is using autologous bone marrow mononuclear cells.
In contrast, Josh Hare at the University of Miami is using allogeneic MSCs in his trial in collaboration with the NHLBI.
Some researchers are studying using actual heart cells as a therapy rather than directly using stem cells.
Trying different types of cells increases the chance that some may work but in each case, there should be a solid rationale for how a particular type of cell might be effective.
An example of an encouraging study of stem cell therapy for heart disease was a well-controlled clinical trial on more than 500 patients with heart failure using Mesoblast cells.
This JAMA review gives an overview of the more discouraging side of clinic studies in this space.
Delivery is a challenge for stem cell therapy for heart disease
How does one safely get a meaningful number of stem cells into the heart tissue itself?
From what I’ve seen, a simple infusion of stem cells into the bloodstream is unlikely to get enough of the cells into the heart muscle or the walls of the coronary arteries.
Direct injection of stem cells into the heart tissue seems riskier and so far it’s unclear if there’s any benefit. However, at least in that case, you’re getting the cells directly into a place where they may be needed.
Heart organoids. Stem cells could also help in an indirect way not even involving transplantation at all. For example, researchers can make heart organoids from stem cells in the lab and study them. They can even screen drugs on hundreds or thousands of organoids to look for new drugs that are effective for certain kinds of heart disease. Organoids may also help understand heart disease better.
How might stem cells help the heart?
Let’s say you do get enough stem cells in there somewhere to possibly do something, what would the stem cells do that is useful?
- Regrow heart muscle?
- Unclog coronary arteries?
- Stop arrhythmia?
These clinical goals are complicated.
They also point to the reality that there are many kinds of heart disease so there’s not going to be a one-size-fits-all cell therapy for heart issues.
In the first example above of a goal of regrowing heart muscle, this could be in patients who have already had heart attacks. They have damaged muscle that needs replacing. Such patients could also have heart failure, although heart failure can also be caused by other things than a heart attack.
Next we have a target group of people with heart disease and the goal is maybe trying to prevent a first (or second) heart attack.
In the third example, you may be using stem cells to produce heart pacemaker cells for implanting to stop or lessen arrhythmia.
In other instances, it may be more challenging to use cells to help diseased hearts. For instance, those patients with congenital heart defects including especially due to genetic causes could be harder to help with cell therapies. Much would depend on the specifics of the condition.
CRISPR gene-editing might be used on stem cells to correct a genetic defect and then after those cells are differentiated into heart cells they could be transplanted into a diseased heart.
Any kind of cell therapy will pose risks too. If stem cells end up in the wrong place they could cause problems. For instance, we now know that too much growth of cells in coronary arteries (those vessels that supply the heart itself with blood) can contribute to blockages. Stem cells ending up in the wrong place or doing the wrong thing could clog such arteries.
Abnormal new heart muscle growth such as in the wrong place could disrupt the beating or electrical system of the heart.
These are just two examples of possible risks.
It’s important to be aware of and cautious about stem cell clinics too.
The stem cell clinics out there both in the U.S. and elsewhere are generally in it for the money in my view. They should not be selling stem cell therapy for heart disease because so far there aren’t clear data that it works or is safe.
If this general area interests you, talk to your cardiologist about what they think of the idea of using stem cells. They can help you think about risks too. Also, note that I’m not a physician and this post is not meant as medical advice.