Stem Cell Therapy Mends Broken Hearts

Researchers gain a rare edge against America's most frequent killer.

Oct 10 2016, 3:00pm

Image: Africa Studio/Shutterstock

Heart disease, the thing that kills more Americans than any other cause, is a process. Hearts can fail suddenly and catastrophically—they do all the time—but the reality is more likely to be a slow accumulation of failure. Someone has a heart attack and recovers, but is left with scar tissue, the result of cell death due to temporary oxygen starvation resulting a blocked blood vessel. Scar tissue is kind of just filler. It doesn't help the heart beat. The rest of the heart compensates for a while, but as more heart attacks occur, and more and more heart disappears, it stops being able to keep up.

In time, the damaged heart just can't serve the circulatory needs of the body. Physical exertion becomes hard and then impossible. Eventually, so does living.

What makes heart disease a seemingly intractable problem is this fact that heart tissue doesn't regenerate. Damage to the heart is accumulative. This may not be the end of it, however. As described in a paper published Monday in Nature, researchers at Shinshu University have found that they can induce cardiac self-repair in primates via transplanted stem cells from other primates. The result is that most elusive thing: improved cardiac function. Human hearts may be unbroken after all.

Image: Shiba et al

This sort of stem cell transplant isn't a brand-new idea by any stretch, but it's come with the same caveat that plagues any sort of individual to individual transplant. Naturally, the recipient's immune system identifies the transplanted cells as foreign and goes on the attack. Consequently, the transplant may be rejected.

To get around this, the Shinshu researchers ensured that a key protein found on the cell surface of the donor stem cells—a protein that is used by the immune system for targeting invaders—matched that of the recipient. With this condition met, the recipient immune systems appeared to have been none the wiser about non-native cells. With the addition of a relatively mild immunosuppressant, the grafted cells were able to survive for 12 weeks while improving functioning in the damaged heart.

Compared to, say, cancer, the slow unwinding of heart failure doesn't have a whole lot of flash among post-boomer generations. Which makes sense because it doesn't really happen to young people, who may every now and again drop dead of cardiac arrest, but much less so suffer the kind of blockage that results from many years of arterial hardening. But it's a thing that's nonetheless there, waiting. Knowing that it may not be quite as final/irreversible then as it is today should be comforting.

In any case, cardiac regeneration via stem cell still has a ways to go. One thing the researchers behind the current study discovered is that hearts featuring grafted cells were more likely beat irregularly. It wasn't to the point of being dangerous, but it's still a cause for concern and also a bit of intrigue. What is it about the new cells that doesn't conform? Only further research will provide an answer.