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
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. The hydrogel may be most useful for surgeries, particularly for patients who take anti-coagulant drugs to thin their blood.
Batroxobin was recognized for its properties as a coagulant 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.
“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. They 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.
Tests showed the new material stopped a wound from bleeding in as little as 6 seconds, and further prodding of the wound minutes later did not reopen it. The researchers also tested several other options: the hydrogel without batroxobin, the batroxobin without the hydrogel, a current clinical hemostat known as GelFoam and an alternative self-assembling hemostat known as Puramatrix and found that none were as effective, especially in the presence of anti-coagulants.
The new work builds upon the Rice lab’s extensive development of injectable hydrogel scaffolds that help wounds heal and grow natural tissue. The synthetic scaffolds are built from the peptide sequences to mimic natural processes. SB50 will require FDA approval before clinical use, Hartgerink said. While batroxobin is already approved, the Rice lab’s hydrogel has not yet won approval, a process he expects will take several more years of testing. http://news.rice.edu/2015/10/26/snake-venom-helps-hydrogels-stop-the-bleeding-2/
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