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Stanford University School of Medicine

Changeling cells source of coronary arteries

During my lunchtime run today, I was thinking a lot about coronary arteries. Mostly because mine were working so hard. I'm a relatively new runner, and my huffing and puffing were signs that my heart was working hard to supply my muscles with the fuel they needed to keep me sprinting (well, ok, it's really more like shuffling) down the road.

Coronary arteries are part of a particularly important class of blood vessels. They encircle and burrow into the heart muscle itself to deliver oxygen and nutrients to support the regular contractions that pump our blood to the rest of the body. As you might expect, any blockage in these vessels can be catastrophic. If it doesn't kill you, you will probably need coronary bypass surgery, in which surgeons use arteries or veins from other parts of the body to create a detour around the clog. This works pretty well, but these substitutions - particularly veins - don't perform as well as the real thing.

Now post-doctoral fellow Kristy Red Horse, PhD, and her supervisor, developmental biologist Mark Krasnow, PhD, have reported a surprising finding in the journal Nature that may one day lead to more reliable bypasses-or even eliminate the need for them altogether.

They discovered that the cells that make up the arteries started out their lives as veins in an embryonic heart structure called the sinus venosus. The finding was surprising because veins and arteries function very differently in the body, and because cells don't usually change their career choices so dramatically.

Red Horse didn't start out thinking about better bypasses. She simply wanted to identify, once and for all, the source of the cells that form the heart's coronary arteries during development. Developmental biologists had been pondering two main possibilities-each supported by various lines of research. The answer seemed like a foregone conclusion: they'd either come from column A, or from column B.

It has interesting implications for bypass surgery, said Krasnow:

This is a beautiful example of natural reprogramming. The heart is somehow telling these venous cells to leave the sinus venosus and convert into coronary arteries. If we can identify these molecular signals, we might be able to use them to construct coronary arteries for bypass surgery, which could be very important therapeutically.

In other words, it might one day be possible to take a vein, or even just cells from a vein, and induce them in the laboratory dish to become bona fide coronary arteries that could then be transplanted into the patient. Even better would be the possibility of bypassing the bypass surgery altogether by applying factors to the heart to coax existing vessels to make a career change and become coronary arteries.

Of course, much more work remains to be done. But the possibilities are exciting to think about. I suppose in the meantime, though, I'd better keep trotting along. But at least research like this gives me something to ponder while I suffer.

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