The Brazilian
lancehead is one of several South American pit vipers that produce
venom that has
proven to be a powerful blood coagulant. Scientists at Rice University
have combined a
derivative of the venom with their injectable hydrogels to create a
material that can
quickly stop bleeding and protect wounds, even in patients who take
anti-coagulant
medications. (Credit: Photo by Greg Hume via Wikipedia)
(October 26, 2015) Rice
University lab employs clotting powers of viper-derived drug, even in presence
of anti-coagulants
A nanofiber hydrogel infused with snake venom may be the
best material to stop bleeding quickly, according to Rice University
scientists.
The hydrogel called SB50 incorporates batroxobin, a venom
produced by two species of South American pit viper. It can be injected as a
liquid and quickly turns into a gel that conforms to the site of a wound,
keeping it closed, and promotes clotting within seconds.
Rice chemist Jeffrey Hartgerink, lead author Vivek Kumar and
their colleagues reported their discovery in the American Chemical Society
journal ACS Biomaterials Science and Engineering. The hydrogel may be most
useful for surgeries, particularly for patients who take anti-coagulant drugs
to thin their blood.
“It’s interesting that you can take something so deadly and
turn it into something that has the potential to save lives,” Hartgerink said.
Batroxobin was recognized for its properties as a coagulant
– a substance that encourages blood to clot – in 1936. It has been used in
various therapies as a way to remove excess fibrin proteins from the blood to
treat thrombosis and as a topical hemostat. It has also been used as a
diagnostic tool to determine blood-clotting time in the presence of heparin, an
anti-coagulant drug.
Rice University
researchers Jeffrey Hartgerink, left, and Vivek Kumar led research that
combines a
derivative of snake venom with their nanofiber hydrogel to help encourage
blood clotting in
wounds, even for patients who take anti-coagulant medications.
(Credit: Jeff
Fitlow/Rice University)
“From a clinical perspective, that’s far and away the most
important issue here,” Hartgerink said. “There’s a lot of different things that
can trigger blood coagulation, but when you’re on heparin, most of them don’t
work, or they work slowly or poorly. That obviously causes problems if you’re
bleeding.
“Heparin blocks the function of thrombin, an enzyme that
begins a cascade of reactions that lead to the clotting of blood,” he said.
“Batroxobin is also an enzyme with similar function to thrombin, but its
function is not blocked by heparin. This is important because surgical bleeding
in patients taking heparin can be a serious problem. The use of batroxobin
allows us to get around this problem because it can immediately start the
clotting process, regardless of whether heparin is there or not.”
The batroxobin combined with the Rice lab’s hydrogels isn’t
taken directly from snakes, Hartgerink said. The substance used for medicine is
produced by genetically modified bacteria and then purified, avoiding the risk
of other contaminant toxins.
The Rice researchers combined batroxobin with their
synthetic, self-assembling nanofibers, which can be loaded into a syringe and
injected at the site of a wound, where they reassemble themselves into a gel.