Funnel-web spider venom may help save the lives of heart transplant patients
Funnel-web spider venom may one day help save the lives of heart transplant patients
Striding along a sandy track, a group of scientists is doing something kids are warned not to do: looking for funnel-web spiders. Leading the pack, known as the "bugs-and-drugs squad", is biochemist Glenn King from the University of Queensland, who has built a career unpicking the chemical composition of Australia's venomous creatures.He and his team have come to K'gari — the place you may know as Fraser Island — looking for a special kind of treasure in funnel-web venom: a miracle molecule.It's called Hi1a and it contains neurotoxins that act on the nervous system of the recipient.But the scientists aren't interested in how it harms humans, but how it could help them.'One of the most complex venoms' ever discoveredScientists need to be careful where they tread when searching for funnel-webs. (ABC Catalyst)Venom is a chemical weapon used by all kinds of animals, from snakes and spiders to jellyfishes, octopuses and even platypuses. It can help an animal to subdue prey they want to eat, or protect them from predation.Inevitably, humans also occasionally get envenomated, most commonly by things like bees and wasps. And although the producer of the venom might have no intention of consuming us, their venom can still cause us pain, suffering, psychosis and even death.Venom is made up of microscopic proteins all bound together, each of which might have a different impact on the recipient (or none at all).For example, the Irukandji jellyfish causes incredibly strong pain, psychosis and even a desire for death, whereas the coastal taipan snake can cause internal bleeding and emptying of your bowels.If you were bitten by one of the funnel-web spiders that the scientists are searching for on K'gari, you might get tingling around the lips, start sweating profusely, vomit, find your blood pressure skyrocketing and eventually, have your lungs fill with fluid.These are terrifying and potentially deadly impacts, but in the right context, some of the reactions caused by venom could be life saving.In some medical situations, doctors want to make blood coagulate or to thin, or they want to inhibit movement or stimulate some other chemical process in the body.And so scientists like Professor King want to isolate proteins in funnel-web venom and see if they can be used in human therapeutics."We're interested in trying to develop drugs that target the nervous system," says Professor King, while searching for spider holes on K'gari.Funnel-webs on K'gari have been genetically isolated from the mainland for a long time, and their venom has developed a unique peptide profile with a labyrinthine chemical composition, according to Professor King."It is one of the most complex venoms that has ever been seen. There are up to 3,000 [different] molecules in the venom of a single spider."Finding spiders using a spaghetti spoonFunnel-web spiders sit at the entrance to their lairs at night. (ABC Science: Hannah Draper)Scientists scour the Butchulla people's sand island, moving across a hillside while carefully watching where they put their feet.The species of funnel-web they're looking for is known as Hadronyche infensa."You can usually spot the funnel-webs fairly easily because they've got these distinctive holes with web trip lines," says Sam Nixon, a PhD candidate at UQ.The sticky silken lines that fan out from the "funnel" are like the sensors on the local milk bar door, setting off an alert that someone has entered the area.But instead of a "ding dong" sound, the female funnel-web, deep in her burrow, feels vibrations along the thread.As the scientists arrive on the scene she'll know they're there, inspecting the log she shelters under.The term "funnel web" comes from the fact that the spiders live in a burrow which, from the surface, looks as if it is a silk-lined funnel.But that's an illusion and when extracted from the earth, the whole silk-lined home ends up looking like a ratty old footy sock the dog buried years ago.Every night, the hairy legs of the spider can be seen as she sits at the entrance like a hulking bouncer at a laneway nightclub.But those are not the moments when the scientists can grab the spiders. Funnel-webs are too canny for that.Instead, this group of elite scientists dig the spider out in the daytime using a spaghetti spoon.Researchers use spaghetti spoons to dig out the "funnel" part of the web, which actually resembles an old sock. (ABC Catalyst)And when she is finally exposed from her silken cavern, they coax her into a container in which she will travel back to the lab in Brisbane.At the lab, she'll be spoiled with as much food as a spider can reasonably handle, and the researchers will harvest her venom in the hopes that it may save a life, rather than end one.'Like a telephone exchange operator'The Hi1a molecule was discovered by 'accident'. (ABC Science: Hannah Draper)As with so many leaps of scientific knowledge, it was an accident which led to the "drugs and bugs squad" finding Hi1a — the miracle molecule — within their collection of 700 venoms and tens-of-thousands of peptides. Natalie Saez, a postdoctoral researcher, had previously worked on the potential medical uses of a molecule from a Trinidadian tarantula, Psalmopoeus cambridgei.But when a colleague of Dr Saez was looking at the molecules of the K'gari spider venom, she says something clicked."One of [the molecules] really stood out. It was very similar to a peptide I'd worked on during my PhD," Dr Saez says."We had an idea that it could have potentially amazing therapeutic applications."This molecule acts on the ion channels in neurons. Sort of like a telephone exchange operator, it can start and stop messages from getting through.The scientists suspected that this molecule could buy time against cell death, especially where cell death is caused by lack of oxygen when circulation has stopped."In rat models of stroke, we can give the peptide [to a rat] post-stroke, and we've shown that it actually prevents further brain damage from occurring," Dr Saez says.Scientists are hoping the spider's venom can help, not hinder. (ABC Catalyst)Essentially, the molecule stops a cell from absorbing too much calcium, which sets off a chain reaction that results in our cells dying, Professor King says."What we're trying to develop it for is to treat conditions of ischemia," he says."This is where a tissue is exposed to low-oxygen conditions for some period of time. The classic examples are a heart that's been taken out ready for heart transplant."From heart stopper to show stopperTechnology is able to keep a donor heart alive outside the body during a transplant. (ABC Catalyst)And that's where Sarah Scheuer from the Victor Chang Cardiac Research Institute enters the story.She speaks next to a heart inside a container that looks like it could be a lunch box, hooked up to technology that keeps it beating.Most hearts put up for donation never make it to the stage to have a second chance at life, because even the fittest of donors have one final battle against time."Once that heart has stopped in that donor, we have a pretty narrow timeframe to actually get it out," Dr Scheuer says."It's about 30 minutes at the moment." And 30 minutes is a very short amount of time when you think of the hospital mechanics and even just the time it takes to open a human chest.If the teams can't scramble quickly enough, the heart cells start to deteriorate, and the heart cannot be used for a transplant."We're hoping that by adding in this Hi1a — the venom peptide — to the preservation flush we give the heart, that it might extend that time out even up to 60 minutes," Dr Scheuer says."That could really significantly increase the number of donors we can use."Although the research has been a collaborative effort between the Victor Chang Cardiac Research Institute and the University of Queensland, all the pieces are starting to come together, she says."Hopefully it's something we can then get into the clinic in the next couple of years and make it even easier for us to do these transplants."This venom, once a heart stopper, could soon be coming to a live, beating heart near you. Watch Catalyst's Kill or Cure: The Story Of Venom on iview now.