Injections of a heart patient’s own stem cells can significantly reduce exercise tolerance and symptoms of angina pectoris, which is crushing chest pain that heart patients suffer when their level of exertion exceeds the oxygen delivery to the heart. This new research, which was published online in Circulation Research, showed that injections of adult patients’ own CD34+ stem cells from bone marrow aided patients who did not respond to other therapeutic options.
This research was part of a phase II prospective, double-blind, randomized, controlled clinical trial that was conducted at 26 centers in the United States. This research project is part of a long-term collaboration between scientists at Northwestern University Feinberg School of Medicine and a private company, Baxter International Inc. The objective of the trial is to determine if delivery of autologous (meaning one’s own) CD34+ stem cells directly into multiple targeted sites in the heart can reduce the frequency of angina episodes in patients suffering from chronic severe refractory angina. It is possible that CD34+ stem cells might help make new blood vessels and, therefore, increase tissue perfusion.
Lead investigator Douglas W. Losordo, MD, director, Feinberg Cardiovascular Research Institute said, “Early research across multiple disease categories suggests that stem cells generated within the body in adults may have therapeutic benefit. This is the first controlled trial treating chronic myocardial ischemia (CMI) patients with their own stem cells to achieve significant reductions in angina frequency and improvement in exercise tolerance…While we need to validate these results in phase III studies before definitive conclusions can be drawn, we believe this is an important milestone in considering whether the body’s own stem cells may one day be used to treat chronic cardiovascular conditions.”
Losordo and his team mobilized and extracted stem cells from all participants, and then randomized them to one of three treatment groups: low- or high-dose cell concentrations, or placebo, and administered the regimens in 10 distinct sites in the heart tissue through a multi-point injection catheter.
Six months after treatment, patients in the low-dose treatment group reported significantly fewer episodes of angina than patients in the control group (6.8 vs. 10.9 episodes per week), and maintained lower episodes at one year after treatment (6.3 vs. 11 episodes per week). Patients in the low-dose treatment group were also able to exercise (on a treadmill) significantly longer at six months after treatment, as compared with those in the control group (139 seconds vs. 69 seconds, on average). Angina episodes and exercise tolerance rates were also improved in the high-dose treated group at six months and at one year post treatment compared to the control group.
Norbert Riedel, Ph.D., Baxter’s chief scientific officer noted, “The concept of using one’s own stem cells to treat disease is highly attractive to the medical community and this research is consistent with Baxter’s commitment to driving scientific advances that can lead to promising new treatments for critically ill patients. These results provide important insights into the potential for these cells to be used in larger scale settings, and we look forward to moving into phase III studies in the near future to hopefully substantiate these results.”
There was no evidence of complications related to the autologous stem cells. Three deaths occurred during the trial, one from procedural complications due to the inherent risks of cardiac surgery, the others unrelated to the treatment (all in the control group). There were seven myocardial infarctions (heart attacks) in seven of the control group patients, and there were three MIs each in the low-dose and high-dose patient groups.
Previous preclinical studies of autologous CD34+ stem cells have shown an increase in capillary density and improved cardiac function in models of acute and chronic myocardial ischemia. This phase II study is based on a phase I/II study, which provided early evidence of the feasibility, safety and bioactivity of these autologous stem cells in a similar setting.