Hemophilia: stopping the bleeding

Download the audio version.
Get my science column weekly as a podcast.

To receive these columns weekly by email, just provide me with an email address at edward(at)edwardwillett.com or in comments.

***

A few years ago, I wrote a children’s book on hemophilia, an inherited condition in which the blood fails to clot properly.

Which meant a news item this week about a successful cure in mice for the most common form of the disease really caught my attention.

First, a little background. Whenever blood vessels are damaged, the body undertakes a three-step process to stop the bleeding.

First comes vasoconstriction, the narrowing of blood vessels in the injured area. Next comes platelet plug formation, in which a series of chemical reactions causes particles in the blood called platelets to rush to the site of the injury and attach themselves to the walls of the blood vessel and to other platelets.

The final step is fibrin clot formation, in which a sticky, thread-like substance called fibrin forms a tight mesh over the platelet plug, binding it together.

Fibrin is formed by the interaction of at least 12 special proteins called clotting factors. If just one factor is missing, clotting doesn’t happen.

Which is exactly what happens with hemophilia.

It doesn’t take an actual cut or wound to make a lack of clotting a problem, because we damage blood vessels all the time inside our bodies.

Thus, people with hemophilia bruise easily. Bleeding into their joints can cause pain and swelling and, over time, cause the joints to become arthritic and deformed. Bleeding into muscles causes swelling and pain and can damage nerves and blood vessels. And bleeding inside the head can be fatal: untreated, it’s one of the most common causes of death in people with hemophilia.

That’s probably what killed the first “celebrity” with hemophilia: Prince Leopold, youngest son of Queen Victoria, who died at age 31 after a fall at Cannes.

Victoria appears to have become a carrier of the hemophilia gene through a spontaneous mutation, since it doesn’t appear in her family before her time. Because her daughters were carriers, and married other royals around the continent, hemophilia became known as the “royal disease,” most famously afflicting her great-grandson Alexis, son of Czar Nicholas of Russia and Victoria’s granddaughter Alexi. (Alas, Alexis didn’t live long enough to either die of hemophilia or ascend to the throne, since he was murdered along with the rest of his family in the Russian Revolution in 1917.)

Because the genes that cause hemophilia are sex-linked, the vast majority of sufferers are male. According to a 1998 study, one out of every 5,000 boys, of all races, born in the United States has some form of hemophilia.

Right now, hemophilia is treated by replacing the deficient blood clotting factor through injection. At one time, all clotting factor was prepared from the plasma collected from blood donors–and as a result, from the late 1970s to the mid-1980s, about half of all people with hemophilia contracted the HIV virus, and later died of AIDS. Many others contracted hepatitis.

The blood supply is more carefully screened these days, and clotting factor can be produced by genetically modified bacteria, but obviously the best solution of all would be a treatment that doesn’t involve injection: which is where the news from the Albert Eisnstein College of Medicine of Yeshiva University comes in.

Scientists there have successfully cured Hemophilia A by transplanting healthy liver endothelial cells from donor mice into mice with a mouse version of the disease. They’ve also shown that Factor VIII is produced by these special cells, which line the blood-filled spaces in the liver called sinusoids. Up until now, most scientists have assumed that clotting factors were being produced by the cells that make up most of the liver’s bulk.

Of course, as always, there are caveats about assuming a cure in mice can be applied to humans. For example, the hemophiliac mice had to be given a toxic chemical called monocrotaline to deplete their own endothelial cells before the new ones were transplanted. On the plus side, there are several drugs already available for clinical use that might be able to do the trick more safely.

Hemophilia has plagued humanity for millennia. If we can cure it…well, that will be proof, once again, that the true age of miracles and wonders is today.

Permanent link to this article: https://edwardwillett.com/2008/03/hemophilia-stopping-the-bleeding/

Leave a Reply

Your email address will not be published.

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Easy AdSense Pro by Unreal