Two new published studies provide further evidence for the effectiveness of adult stem cells in repairing heart damage, and suggest possible mechanisms for how the cells work.

A Brazil-Florida collaboration found that adult stem cells injected directly into the heart could relieve angina. The researchers used injection directly into the heart based on previous results showing higher uptake of cells administered in this way. All eight of the angina patients in the study benefitted. Lead author Dr. Nelson Americo Hossne, Jr. said:

"For our patients, angina symptom relief began as early as three months post-procedure with continuing improvement through the twelfth month and sustained improvement past 18 months. Symptom relief improved in all patients, suggesting that the effect is sustained, not transitory."

The authors conclude that their results show the procedure to be safe and effective, and suggest neoangiogenesis, the stimulation of new blood vessel growth, as the main stem cell mechanism of action in these patients.

A separate published study by Chinese scientists suggests that a small protein called apelin, which affects the strength of muscle contraction, may play a role in adult stem cell repair of heart. Twenty patients experiencing severe heart failure were treated with their own bone marrow adult stem cells, while another twenty heart failure patients were treated with standard medications; both groups were compared against twenty healthy adults. All twenty of the heart failure patients treated with adult stem cells showed significant improvement in cardiac function within 21 days of treatment, while the standard medication patients showed no improvement. Interestingly, the adult stem cell-treated patients showed a large increase in levels of apelin, correlated with the improvement in cardiac function. They postulate that the secretion of apelin is induced by the grafted adult stem cells.

Both studies were published in the journal Cell Transplantation. Dr. Amit Patel of the University of Utah School of Medicine and an Editor of the journal said:

"Both studies demonstrate a possible mechanistic approach in a clinical trial either. These important findings further enhance the understanding of the use of bone marrow derived cell therapy for the treatment of cardiovascular disease."