Of all the creatures in our world, the vampire bat has one of the worst reputations. For centuries, stories and films have painted a grotesque picture of these nocturnal mammals as symbols of disease, death, and malevolence.
In fact, vampire bats rarely bite human. They are the only mammals that feed exclusively on blood primarily from domestic livestock and to a lesser degree on wild mammals and birds. These bats are very small, with wingspans of about 12-15 inches, and weigh less than 2 ounces.
In the tropical forests of Central and South America, medical researchers are looking at the common vampire bat. To these scientists, this tiny flying mammal isn’t a monster; it is the architect of a medicine that could soon save human stroke victims from permanent brain damage.
To appreciate the vampire bat biology, it is important to understand how they feed. Unlike a predator that kills its prey, a vampire bat makes a microscopic, painless incision on a sleeping animal—usually a cow or a bird—and laps up the blood. Gross.
If the bat’s bite clotted normally, it would get nothing more than a single sip. The vampire bat’s saliva has a highly specialized formula of anticoagulants. When the bat salivates into the wound, its spit systematically dismantles the prey’s ability to form blood clots, allowing the blood to flow freely. Grosser.
When scientists isolated the primary enzyme responsible, they gave it an amusing name, Draculin. While Draculin is an evolutionary trick for the bat to get its meal, it could be a profound breakthrough for human emergency neurology.
The majority of human strokes are ischemic strokes, which occur when a blood clot travels to the brain and lodges itself in an artery. This blocks the flow of blood to brain tissue. In the world of neurology, the mantra is “time is brain.” Every minute an artery remains blocked, an estimated 1.9 million brain cells die. If the clot isn’t dissolved immediately, the patient faces permanent paralysis, loss of speech, or death.
Currently, emergency rooms have a frontline weapon called tPA (tissue plasminogen activator), a synthetic drug designed to break up clots. But tPA has a very narrow clinical window. If it isn’t administered within 4.5 hours of the onset of stroke symptoms, the risk of causing catastrophic, fatal bleeding in the brain skyrockets. Because many stroke victims don’t make it to the hospital in time, only a fraction of patients can safely receive it.
Draculin operates entirely differently from human tPA.
While tPA aggressively attacks clots everywhere in the body simultaneously, Draculin is a precision laser. It targets a highly specific clotting factor (Factor IX and X) and only activates when it comes into direct contact with a fresh, existing clot.
Because of this targeted molecular design, Draculin dissolves the dangerous obstruction in the brain without destabilizing the rest of the body’s circulatory system. Researchers estimate that Draculin could be safely administered up to 9 hours after a stroke begins—double the window of current treatments. Because it doesn’t cause systemic bleeding, the risk of secondary brain hemorrhages is lower.
The drug has successfully passed several phases of testing and is being evaluated in clinical studies. However, scientists have found its effectiveness is dependent on its chemical structure, which requires further research before it can become a widely available treatment.
The story of Draculin is another lesson in ecological humility. Our first instinct when encountering a creature like the vampire bat to eradicate it. But wrapped inside the biology of this maligned little creature is a molecular blueprint that human scientists, with all our advanced supercomputers and laboratories, could never have engineered.
It turns out that the rainforest’s most famous bloodsucker might actually hold the key to restoring human life, proving once again that nature’s best secrets are often hidden in nature.
