Stem cells may potentially offer a new treatment route for patients with heart failure.
When the heart is no longer capable of pumping enough blood and oxygen to the body, it is referred to as heart failure.
Around 5.7 million adults in the United States are experiencing heart failure, and 1 in 9 deaths in 2009 was caused by the condition.
Heart failure can occur due to illnesses such as coronary heart disease, diabetes, and high blood pressure. It can also be brought on by certain behaviors, including smoking, eating a high-fat diet, not exercising enough, or being obese.
Current treatments are available for heart failure, but they are far from ideal. Initial interventions aim to treat the condition's underlying cause - high blood pressure, for instance. They also aim to reduce symptoms, prevent further damage, increase lifespan, and improve quality of life.
Certain medical procedures are available if lifestyle changes and medications are not adequate. These include a pacemaker, which can help both sides of the heart to contract in unison, or an implantable cardioverter defibrillator, which corrects the heart's rhythm if it starts to go off track.
In some cases, a heart transplant is the only option, but the shortage of donors and the gravity of the operation makes this the last port of call.
Using stem cells to repair the heart
Treatment options for heart failure are not ideal, and there is no good long-term solution. Even with the best care, heart failure can often be fatal. Of course, regenerating the heart tissue itself would be an ideal option. Although far-fetched, this may one day be possible if the results of the current study are confirmed.
Published this week in the Journal of the American Heart Association, the study investigates the use of muscle stem cells in repairing damaged hearts. The Japanese team had previously shown the technique's potential benefits in a rat model, so now was the time to move into humans.
In total, the team chose 27 patients with heart failure who had limited exercise capacity and were not responding to other treatments. Fifteen had ischemic cardiomyopathy, and 12 had dilated cardiomyopathy.
This phase I trial involved making patches of cells from the patients' own thigh muscles (the vastus medialis, specifically). These patches of so-called autologous somatic tissue-derived cells were then surgically glued onto the surface of the heart's left ventricle.
Stem cells are sometimes used to entirely replace the body's failing tissues. However, stem cells can also help to regenerate tissue in a second way - using the paracrine effect. The implanted tissue secretes factors that encourage the old tissue to behave differently, which is what happened in the current study. The implant helped the existing tissue to perform better, rather than taking over from it.
Following the operation, the patients experienced no significant complications and, a year after the procedure, there were measurable improvements in their exercise capacity and heart function. The authors conclude:
"This phase I study found cell-sheet transplantation as a sole therapy to be a feasible treatment for cardiomyopathy. The promising results in the safety and functional recovery seen in this study warrant further clinical follow-up and larger studies to confirm the therapeutic efficacy of autologous skeletal stem-cell sheets for severe congestive heart failure."
Although larger trials are needed and, according to the authors, "the therapeutic effects are modest," this study demonstrates the intervention's safety and future potential.