For patients with ischemic cardiomyopathy (ICM), transplanting sheets of autologous myoblasts onto the epicardial surface was safe and led to “marked” improvements in functional and laboratory measures, investigators reported.
However, cell sheet transplantation was much less effective for patients with dilated cardiomyopathy in this phase I trial, wrote Shigeru Miyagawa, MD, PhD, of Osaka (Japan) University, and his associates in the Journal of the American Heart Association. The findings merit additional follow-up in larger clinical studies, the investigators asserted.
Heart failure remains life threatening even with the best approved treatments. Previously, the researchers transplanted scaffold-free sheets of autologous myoblasts derived from skeletal muscle into small and large animals with heart failure and found that this approach healed severely damaged myocardium. Transplantation caused secreted cytokines to induce native regeneration through paracrine effects, Dr. Miyagawa noted in a prior review article (BioMed Research International. 2013. doi: 10.1155/2013/583912).
To evaluate this approach in humans, the researchers transplanted 15 patients with ischemic cardiomyopathy and 12 patients with dilated cardiomyopathy (DCM). Patients were 20-75 years old, had ejection fractions under 35% and New York Heart Association (NYHA) classifications of II or more, and were responding inadequately to standard treatment with a beta-blocker or ACE inhibitor and an angiotensin receptor blocker. The sole intervention was transplantation of the cell sheet over the left ventricular-free wall during left thoracotomy (J Am Heart Assoc. 2017 Apr 5. doi: 10.1161/JAHA.116.003918). There were no major procedure-related complications during follow-up, the researchers said. For patients with ICM, NYHA classifications dropped significantly at 6 months, from 2.9 at baseline to 2.1 at 6 months and 1.9 at 1 year. Six-Minute Walk Test scores improved significantly, from 416 m at baseline to 475 m at 6 months to 484 m at 1 year. Transplantation also led to significant drops in serum brain natriuretic peptide levels (baseline average, 308 pg/mL; 6 months, 191 pg/mL; 1 year, 182 pg/mL). Additionally, ICM patients improved significantly on measures of pulmonary artery pressure, pulmonary capillary wedge pressure, pulmonary vein resistance, and left ventricular wall stress.
In contrast, DCM patients did not significantly improve based on the 6-Minute Walk Test, NYHA classification, or brain natriuretic peptide serum levels. Of 12, 3 progressed to NYHA functional class IV by 1-year follow-up and there were five cardiac deaths. There were no cardiac deaths in the ICM group. “It has been reported that regeneration mechanisms in cell sheet mainly depend on angiogenesis induced by secreted cytokines, so cell-sheet implantation may be more suitable for ICM patients, compared with DCM patients, considering pathophysiological aspects,” the researchers wrote.
The study was funded by grants from Regenerative Medicine for Clinical Application, Health and Labor Sciences Research, and the Japan Agency for Medical Research and Development. The investigators disclosed laboratory funding from Terumo for cooperative research in cell sheet.