Snake Venom-Containing Hydrogels To Control Bleeding

Rice University scientists have developed a nanofiber hydrogel containing snake venom, as a procoagulant to be used to control bleeding. While the solution starts as a liquid, once it is applied to a wound it quickly thickens into a gel and induces blood clotting within a few seconds.

The hydrogel – named SB50 – is infused with batroxobin, which is made by two distinct species of the South American pit viper. According to the researchers, the hydrogel may have an important role in controlling bleeding during surgical procedures, particularly in those patients taking blood thinners.

Jeffrey Hartgerink and Vivek Kumar, both chemists at Rice University, published their work in the American Chemical Society journal, ACS Biomaterials Science and Engineering. “It’s interesting that you can take something so deadly and turn it into something that has the potential to save lives,” said Hartgerink.

This newly-developed hydrogel is hardly the first medical tool to take advantage of batroxobin’s coagulant properties; the venom was first discovered in 1936. Since then, batroxobin has been used as a topical hemostat to control bleeding during surgery, and as a treatment for thrombosis by removal of unnecessary fibrin proteins from the blood.

Batroxobin has also been used to study the blood clotting time in the presence of the anticoagulant drug, heparin. “From a clinical perspective, that’s far and away the most important issue here,” said Hartgerink. “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.”

According to the researchers, the batroxobin used in the hydrogel – along with most other medical applications of the coagulant – isn’t harvested from the pit vipers. Instead, the compound is produced in and extracted from genetically engineered bacteria, preventing any contamination from other substances produced by the snakes.

“Heparin blocks the function of thrombin, an enzyme that begins a cascade of reactions that lead to the clotting of blood,” said Hartgerink. “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 hydrogel – combined with the lab’s synthetic, self-assembling nanofibers which promote gel formation once the solution has been applied to the wound – is capable of stopping bleeding in as few as 6 seconds. Comparing this result with a number of combinations of the three-ingredient gel – including the batroxobin on its own and the hydrogel without the batroxobin – the researchers found that none were as effective at promoting clotting as the hydrogel, nanofibers and batroxobin mix.

This batroxobin-containing hydrogel was even more effective than the commercially-available hemostats, GelFoam and Puramatrix. “To be clear, we did not discover nor do any of the initial investigations of batroxobin,” said Hartgerink. “Its properties have been well-known for many decades. What we did was combine it with the hydrogel we’ve been working on for a long time.”

“We think SB50 has great potential to stop surgical bleeding, particularly in difficult cases in which the patient is taking heparin or other anti-coagulants,” said Hartgerink. “SB50 takes the powerful clotting ability of this snake venom and makes it far more effective by delivering it in an easily localized hydrogel that prevents possible unwanted systemic effects from using batroxobin alone.”

Before the hydrogel can be used in a clinical setting, it must be approved for use by the Food and Drug Administration (FDA). While batroxobin on its own is currently approved by regulators, the researchers believe they have a few more years of testing before the batroxobin-containing hydrogel will be ready to submit for approval.

Sources:

• Snake venom helps hydrogels stop the bleeding – http://news.rice.edu/2015/10/26/snake-venom-helps-hydrogels-stop-the-bleeding/
• Kumar, V., Wickremasinghe, N., Shi, S., Hartgerink, J. (2015). Nanofibrous Snake Venom Hemostat. ACS Biomater Sci Eng.