Researchers have introduced a safe and effective new stem cell therapy to restore heart function in pediatric patients
Dilation of the heart muscle (DCM) is a condition caused by a weakening of the heart muscle, affecting the ventricles (chambers in the heart that push blood around the body as it contracts). If allowed to progress unchecked, DCM can lead to heart failure and death, especially in children. The only treatment, at present, is heart transplantation, which comes with its own challenges: long waiting times to secure a suitable donor heart, the possibility of organ rejection, prolonged hospitalization, and recovery times, among others.
In recent decades, stem cells have become the cornerstone of regenerative medicine, allowing medical professionals to treat damaged organs and reverse many diseases that were previously deemed irreversible. Scientists have turned to “heart-derived cells” (CDCs), a type of heart stem cell known to have beneficial effects on adults with certain heart conditions. By developing (“differentiating”) heart tissue, the Centers for Disease Control and Prevention can reverse the damage that diseases cause. However, not much is known about its safety and therapeutic benefits in children.
To address this problem, Professor Hidemasa Oh led a cross-sectional team of scientists at Okayama University, Japan, to launch the first steps to evaluate this treatment in children with DCM. In a study published in Science Translational Medicine, the team not only showed the CDC’s effectiveness in regenerating damaged DCM tissue, but also revealed how it happens. Professor Oh explains Motivation, “I’ve been working on a cardiac regeneration therapy since 2001. In this study, my team and I evaluated the safety and efficacy of using the CDC to treat DCM in children.”
The first step in any trial when testing a new drug or treatment is to use animal models that interact similarly to humans, showing us whether the treatment is safe and has the intended effect. Thus, at first, the researchers tested this method on pigs, causing cardiac symptoms similar to DCM and treating them with different doses of CDC or a placebo. Scientists have noticed rapid improvement in heart function in those who undergo stem cell therapy. The heart muscle thickens, which allows more blood to be pumped throughout the body. This effectively reversed the damage done to the pigs’ hearts, an encouraging finding that led them to progress to small, controlled human trials.
The first phase of their trial included five young patients with DCM. Scientists now have a better idea of the appropriate dose from the Centers for Disease Control and Prevention to give their young patients, thanks to preclinical animal trials. One year after the injection, the patients showed no sign of severe side effects from the treatment, but most importantly, there were encouraging signs of improved heart function. The authors are cautious: judging by the small population size of their study, they cannot come to a robust conclusion. However, they are satisfied that the CDC treatment appears safe and effective enough to advance to a larger clinical trial. As Professor Oh explains, “We intend to transfer these results to a randomized phase II trial to obtain pharmaceutical approval for this treatment in Japan.”
Another important finding was the mechanism by which the Centers for Disease Control (CDCs) actually improve heart function. In fact, their analyzes revealed that the cultured cells secrete small vesicles called “exosomes,” which are rich in proteins called “microRNAs” that start a whole chain of molecular reactions. These microRNA-enriched exosomes have two effects. First, it prevents the damaging cells from causing further damage to the heart tissue. Second, it stimulates the differentiation of stem cells into fully functional heart cells (“cardiac muscle cells”), and initiates the regenerative process. This generates hope that injecting these exosomes alone may be sufficient to reverse this type of heart damage in patients, bypassing the need for the CDC in the first place.
Looking at their research, the scientists hope the Phase 2 trial will confirm their suspicions – and what this might mean for patients in the future. Prospective transplant patients sometimes wait for years for a donor heart to become available. This type of treatment can allow them to lead a relatively normal life and even completely prevent the need for a transplant for patients who have not yet reached this critical stage.