Using the male chromosome as a marker, researchers studying eight cross-gender heart transplants from New York Medical College have discovered that the body can actively reshape the heart after injury. The research explodes the long-standing belief that the heart cannot repair itself and the finding has implications for heart disease treatment.
The realization that the body works to repair a damaged heart much as it does other organs came after Dr. Federico Quaini and his colleagues examined tissue from eight men who had received heart transplants from women. Because female cells lack the Y chromosome that carries the genetic code for male characteristics, the researchers were able to determine which cells came from the female donor and which belonged to the male recipient.
But the researchers found cells throughout the female heart that contained a Y chromosome. In some samples from the heart, more than 45 percent of the cells carried the Y chromosome. It is unclear whether those cells came from remnants of the old male heart and migrated to the new one, or whether they were originally highly versatile stem cells from the men's bone marrow and moved to the heart in an attempt to repair the damage from the heart surgery.
Many of the male cells that had found a home in the transplanted heart had characteristics of stem cells. Even in the one patient who died four days after his transplant, the researchers found plenty of evidence in his heart that Y-containing cells had moved in and started work.