Lab-grown heart cells improve function in phase 2 trial

Patients with advanced heart failure can struggle to walk even a few steps without losing their breath, and some cannot lie flat to sleep. At Nanjing Drum Tower Hospital, Dongjin Wang’s team has now paired bypass surgery with injections of lab-grown heart muscle cells in an early-stage randomized trial. Nine of the 10 treated patients showed better cardiac function after 12 months, according to the trial results.

The phase 2 HEAL-CHF trial enrolled 20 patients. All underwent coronary artery bypass grafting, the standard operation used to restore blood flow to the heart. Researchers randomly assigned 10 patients to receive roughly 100 million cardiomyocytes—heart muscle cells—directly into damaged tissue at several sites during that same operation; the other 10 received surgery alone.

The cells were made from induced pluripotent stem cells, or adult cells reprogrammed in a laboratory to behave like embryonic stem cells. Researchers then coaxed them into becoming functioning cardiomyocytes. The idea, Wang said, is to combine restored blood flow from bypass surgery with the possibility of regenerating damaged muscle.

Safety was the trial’s primary goal. During one year of follow-up, neither sustained ventricular tachycardia, a dangerous irregular rhythm, nor tumor growth appeared in either group. Some patients who received the cells developed accelerated idioventricular rhythm during the first month, but researchers described the change as mild, short-lived and not a serious safety concern.

So what changes in practice? Not yet a new standard treatment: the trial had only 20 participants, and the team plans to test the approach in a larger patient group. But for people with severe heart failure and no readily available donor heart, the result supplies early clinical evidence that an operation already used to restore circulation might also be combined with an attempt to replace damaged heart muscle.