If there’s anything Star Trek taught us about futuristic health care in space, it would be that a hypospray is a doctor’s best friend. A needleless way to deliver life-saving medicines — and, at one point, help Captain James Kirk (William Shatner) fake his own death — through a gentle spurt of pressurized air or liquid, the hypospray gets deployed routinely in Federation sickbays, away missions, and humanitarian excursions.
While the medical device is a work of fiction, the inspiration behind it has roots in scientific reality. Jet injectors were first developed in the 1960s and used successfully in mass vaccination efforts around the world to inoculate military service members and the public against pathogens like the flu, smallpox, cholera, and typhoid. But unlike the gentle hiss, we hear in Star Trek, jet injectors were hella painful and not exactly hygienic.
“[Jet injectors] that shoot liquids into people have been around for a long time, but those have pretty much been pulled because of cross-contamination issues,” Jeremiah Gassensmith, associate professor of chemistry and biochemistry at the University of Texas at Dallas, tells Inverse. “Basically, people’s bodily fluids splashing up onto the injector and being spread around [to others].”
But those pitfalls haven’t stopped scientists like Gassensmith from the pursuit of forging a functional hypospray for all of us who hate being poked and prodded. In a study presented this month at a meeting of the American Chemical Society, Gassensmith and fellow researchers at the University of Texas at Dallas unveiled a jet injector that’s no more painful than getting hit by a Nerf dart and doesn’t require shooting pressurized liquid through the skin, rather a puff of air carrying a powdered drug.
While still a prototype, Gassensmith hopes his team’s jet injector, dubbed a “MOF-Jet” for the specialized metal-organic “bullets” the device uses, will one day be used to deliver vaccines (mostly livestock but humans as well), chemotherapeutics, or other medicinal treatments.
So how does it work?
Unlike needles which puncture through the skin, nerves, and other bodily tissues, this jet injector propels crystalline structures called metal-organic frameworks (the MOF in MOF-Jet) loaded with a compound through the microscopic crevices between individual cells, kind of like a tiny nuclear warhead.
“These things are thinner than the width of a human hair, essentially. They go so fast [that] they slip through the cells on the skin, [which] are all dead,” says Gassensmith. “It doesn’t tear any tissue. You do make holes, they’re just so small you can’t see them. They’re so small, blood can’t come out [because] red blood cells are way bigger than these particles.”
Once the payload is delivered, both the MOF and the cargo get absorbed by the body. How fast this absorption happens, Yalini Wijesundara, a doctoral student in Gassensmith’s lab and the paper’s first author, found depends on the kind of gas inside the MOF. If the MOF is loaded with regular air, then it takes about four or five days for the body to absorb the cargo. But if the MOF is loaded with carbon dioxide, that turns into carbonic acid in the body (our bodies ordinarily make carbonic acid), which breaks up the MOF more efficiently and allows the body to absorb the cargo faster.
In the lab, the researchers tested out their MOF-Jet by injecting a gene for fluorescence in onion cells and albumin, a protein that ferries nutrients and other proteins, into BALB/c mice, a common mouse strain that’s often used in immunological research. The device appeared to be successful in delivering its genetic and protein payloads into both organisms without any major side effects.
If you’re curious exactly how much pressure the MOF-Jet uses, Wijesundara says it’s around 500 pound-force per square inch, or psi (compared to 2,000 to 5,000 psi for some earlier jet injectors). This pressure was optimized for mice but proved forceful enough for the particles to lodge in the subcutaneous layer of the animal’s skin.
Could vaccine needles become a thing of the past?
Many Trekkies (and folks who hate shots) probably will rejoice at the thought of hypodermic needles becoming an ancient relic. Unfortunately, the MOF-Jet is still very much a prototype that Gassensmith and his colleagues are continuing to tweak and test.
Right now, they’re investigating its potential use in treating melanoma, the most serious form of skin cancer that begins in the cells that control skin pigment, called melanocytes.
“A lot of people are under the impression that melanoma is not as dangerous of cancer, but that’s not true. It’s a significant public health issue,” says Gassensmith. “[The MOF-Jet] can shoot drugs essentially over a controlled area. Penetration depth isn’t really infinite, so it has to be something that’s on the surface, and melanomas fit the bill.”
Results are yet forthcoming, and may take many years before anything upgrades from lab bench to bedside. But another application with a potential quicker timeline is vaccine delivery. Gassensmith says that from an immunological standpoint, this method could be very promising as you can control the absorption of the MOF and its cargo — in this case, an antigen (the bit of a pathogen the immune system attacks and produces antibodies against) — such that it happens slowly over a period of time. This pace would allow the immune system to mount a stronger, more robust response and possibly lead to more long-lasting immunity.
The only caveat is that the payload has to be powdered, which may limit what kinds of vaccines can be delivered through the MOF-Jet, at least for humans but maybe not so much for animals.
“I think it’s a wonderful way to vaccinate livestock, so that’s what we’re really aiming for,” says Gassensmith. “Realistically, getting it into a human, there’s a much higher barrier than getting it into farm animals.”
Until then, there’s no avoiding needles, dear reader.
