LOS ANGELES — Dr. Eduardo Marban, director of the Cedars-Sinai Heart Institute in Los Angeles, and his wife Linda Marban, research manager for Cedars-Sinai’s Board of Governors Heart Stem Cell Center, are blazing a new trail in adult cardiac stem-cell research.

In a first-ever clinical trial, a small sample of a patient’s own heart tissue is used to grow specialized heart stem cells. The stem cells are then injected back into the patient’s heart in an effort to repair and re-grow healthy muscle in a heart that has been injured by heart attack.

The trial could start a new era of treating heart disease, which is the No. 1 killer of men and women in the United States. If cardiac regeneration is possible, then people who suffer heart attacks might be able to achieve greater post-heart-attack productivity and health and, for the most extreme cases, not require heart transplants.

The moral implications of the trial are also profound; no embryo is involved at any stage of the process.

“I come from a culture that’s deeply Catholic,” said Eduardo Marban, who came to the United States from Cuba with his parents when he was 6 years old. “For me, that we could develop a treatment that was not ethically problematic, that was consistent with the Hippocratic Oath and the tenets of Catholicism, was very gratifying. We not only get a unique chance to do good, but we do it without trampling on anyone’s ethical principles.”

Linda Marban’s faith also threads throughout her life as a scientist.

“I am a strongly believing and practicing Catholic,” she said. “When I believe in God the most is when I look at a chart of cell signaling. When you see all those millions and billions of processes that we don’t even begin to really understand, there is no way some higher power didn’t generate that.”

Eduardo Marban holds a medical degree and doctorate from Yale. Before coming to Cedars-Sinai, he spent 25 years at Johns Hopkins University School of Medicine in Baltimore, where he served as chief of cardiology. His numerous discoveries include developing some techniques used in his current cardiac stem-cell work.

Linda Marban received her doctorate in cardiac physiology from Case Western Reserve University in Cleveland. During her graduate studies, she learned of Eduardo Marban’s work. After earning her degree, she was hired by him as a postdoctoral fellow at Johns Hopkins.

Catholicism drew them together personally.

“My desk at Johns Hopkins was covered with religious medals, crosses and varieties of prayer cards,” said Linda Marban. “One day, Eduardo’s mother saw all those things, and we had a wonderful chat. She was a larger-than-life person and an incredibly devout Catholic. I admired Eduardo tremendously professionally, but I didn’t like him at all. But I thought, ‘there is no way that that cold fish could come from this warm and wonderful woman.’”

Eduardo Marban said he was “a lapsed Catholic at the time. When Linda and I got together, she got me involved as an active, churchgoing member in the church again.”

In 2007, the Marbans and their then-2-year-old daughter, Cristina, attended an audience at which Pope Benedict reaffirmed his earlier encouragement of research involving adult stem cells. Linda Marban keeps in her purse a rosary that the pope blessed that day.

“Prayer keeps me centered,” she said. “What I pray about most is to be a good and productive person and to use gifts I might have to make the world a better place.”

When the Marbans began their scientific journeys, the prevailing thought was that cardiac tissue could not be regenerated once it was damaged or destroyed by heart failure. The current trial, with 24 patients enrolled at Cedars-Sinai and seven at Johns Hopkins, could result in a completely new way of thinking and, possibly, new treatments in several years.

“By the end of 2011, we’ll release the results of the trial,” said Eduardo Marban. “What we’re doing is still in clinical testing. We’re not ready for prime time yet, and we don’t want to raise false hopes. But we’re onto something. We’re very optimistic.”

“I believe very strongly that God has provided us with many gifts, one of which is coming to understand what can heal and what can make people better,” said Linda Marban. “These adult stem cells are a gift that we hope will lead to long and happy lives for those living with heart disease.”