Heart failure has long been an intractable disease, afflicting 25 million patients worldwide. Most have few options, other than a full heart transplant or surgery to insert a left ventricular assist device.
Now, several companies are advancing clinical trials to see whether stem cell therapy can provide some relief, and early results are promising.
The Australian biotech Mesoblast is conducting a trial in 159 patients who have already had a left ventricular assist device implanted. The therapy consists of millions of stem cells injected or infused via catheter into the heart’s left ventricle. Preliminary results were promising, and the U.S Food and Drug Administration (FDA) granted the therapy fast-track review status late last year.
In the UK, Celixir won approval earlier this year to push ahead with a mid-stage clinical trial for its stem cell therapy, dubbed Heartcel, which has shown strong results in earlier studies. The therapy consists of allogeneic immunomodulatory progenitor cells engineered to reduce scarring and regenerate tissue. So far, it’s been delivered only during bypass surgery, though Celixir is also working on a formulation that’s delivered via catheter. The company will likely seek FDA approval if the new trial succeeds.
Meanwhile, in the U.S., Cleveland-based Athersys is testing stem cell therapies to help patients recover from stroke, and a Belgium biotech, TiGenix, is working on a stem cell treatment to reduce scarring after a heart attack.
Scientists acknowledge that it’s not clear exactly how these treatments affect patients’ hearts. The stem cells seem to revitalize tissue and reduce inflammation, and may perhaps spur the formation of new blood vessels. They may also release cardio-protective proteins, known as paracrine factors.
Experts caution, however, that more rigorously controlled studies are needed before stem cell treatments can be widely recommended for cardiac patients. Though the companies developing the therapies are enthusiastic, clinical trials over the years have shown mixed results.
As a systematic review of clinical literature published in JAMA Cardiology last year concluded: “Despite over a decade of research, further investigation is still needed to determine whether stem cell regenerative therapy is clinically effective and can be routinely implemented in clinical practice.”