(CNN) – Dr. Roberto Bolli’s face lights up when he talks about his true love: the human heart.

“The heart is really a miraculous organ. It beats 72 times a minute throughout our life, which means billions of times in our lifetime. And it never gets tired,” Bolli says.

Stem cells were taken from patients with severe heart failure and multiplied in a laboratory run by Dr. Piero Anversa at Brigham & Women’s Hospital in Boston. A few months later, each patient was re-infused with a million of his or her own stem cells.

The results were dramatic. Patients saw scar tissue replaced by working heart muscle and a significant improvement in their hearts’ ability to pump blood.  Dr. Bolli is hoping to start a larger trial by the fall of 2013.