A blister on the heel. A small cut that catches on a sock. For most of us these are nothing, gone in a week and forgotten. For someone with diabetes, the same small breach in the skin can sit open for months, refuse to close, turn septic, and end in an amputation. The grim arithmetic is well documented: roughly four in ten of these foot ulcers come back within a year, and the five-year mortality for people with diabetic foot complications is worse than for most cancers, beaten only by lung cancer. The wounds themselves are not exotic. What makes them lethal is that the blood simply will not arrive.
That is the gap a team spread across the University of New Mexico, Texas A&M, and a small Oregon company called Exhalix has been trying to close, and their answer is a little strange. They want to treat these wounds with a poison.
Hydrogen sulfide is the gas that gives rotten eggs their smell, and in any quantity it is dangerous. But the body makes tiny amounts of it on purpose, and at those vanishing concentrations it turns out to be a rather elegant signaling molecule. It relaxes blood vessels so they widen (vasodilation, if you want the proper word), and it nudges the tissue into growing fresh vessels of its own. More vessels, wider vessels, more blood. In diabetes, the body’s own production of the gas falls off, which is part of why the circulation to a wounded foot is so poor in the first place.
So the logic writes itself: put the gas back. The trouble has always been how. Send hydrogen sulfide through the whole body and you create exactly the problem you were trying to avoid, only everywhere at once.
The danger is the whole point
“If that effect happened throughout the entire body, your blood pressure would drop too much because your vessels would all widen at once,” says Dr. Cristine Heaps, interim head of the Department of Physiology and Pharmacology at Texas A&M’s College of Veterinary Medicine and Biomedical Sciences. “By keeping it localized, we can target the wound without affecting the rest of the body.” Open the vessels everywhere and the blood drains away from the organs that need it, the brain included. Systemic delivery also carries a tail of nastier risks, cytotoxicity and liver damage among them. The gas that heals the foot could stop the heart.
The device the team has built, which they call H2EALS, gets around this by not carrying any gas at all. Instead it carries a coating of silver sulfide, a stable, shelf-friendly solid that sits there doing nothing until it is asked. When a small electric current passes through it (under a single volt, the kind a coin battery supplies), the coating gives up its sulfur, and hydrogen sulfide is born right there inside the dressing, on demand, molecule by counted molecule. The cartridge runs off a 2032 battery, the same flat disc that powers a car key fob, and it is controlled by tapping a phone against it. A clinician could, in principle, dial in a slow trickle of five nanomoles an hour, or a single measured dose once a day, for a fortnight.
That control is the part that matters, and the benchtop numbers back it up: across repeated runs the delivered dose tracked the target with a correlation of 0.998, the kind of agreement that makes engineers pleased. The gas is fragile, mind you. In the warm, damp, oxygen-rich pocket of a dressing it oxidizes and degrades within minutes, and the absorbent wound padding itself eats into the dose, more so when wet. None of which is fatal to the idea, but it does mean the thing has to be metered carefully rather than simply switched on.
Staying put
The real test was whether the gas would stay where it was put. In rats, doses between 25 and 100 nanomoles were soaked up by the wound bed quickly, and blood flow rose in step with the dose, the higher amounts producing a clear, measurable lift in perfusion. Male and female animals responded alike. Then the team moved to pigs, whose skin is a far better stand-in for ours, and built deliberately starved, low-circulation wounds to mimic the human problem. Here they pushed doses as high as 500 nanomoles and went looking for the gas everywhere it should not be: in the animals’ breath, and at patches of skin away from the wound. They found nothing. No detectable rise, even at the top dose. The poison, it seems, knows how to stay home.
There is a nice second act to the work, too. One of the standard tools for difficult wounds is negative pressure therapy, the controlled suction that draws out fluid and coaxes tissue to knit. The team is now trying to marry the two, letting the gas do its work for a spell before the suction kicks back in. “We’re using our device in combination with negative pressure wound therapy to see if we can improve outcomes beyond what either approach can do on its own,” Heaps says. The hope is not to replace what already works but to slot in underneath it, addressing the one thing the dressings and the suction never touch: the missing blood.
It would be easy to oversell this. The work is preclinical, no human has yet been treated, and the questions of how much and how often remain open. “We’re still working to understand the best dosing and how often it should be delivered to get the greatest benefit,” Heaps says. An efficacy study, the one that asks whether wounds actually close faster, is still to come. And the most striking promise of the gas, that it grows new vessels over weeks rather than just widening old ones for an hour, sits beyond what this paper measured.
Still. If the approach holds up, the people it could reach extend well past diabetes. Heaps has said the device might suit anyone with slow-healing wounds, surgical patients among them, not just those whose problem starts with blood sugar. A bandage that brews a controlled dose of rotten-egg gas and persuades the body to plumb itself anew is an odd thing to root for. But for a wound that has stopped trying, an odd idea that arrives where the blood cannot may be exactly the right one.
DOI / Source: https://doi.org/10.1186/s13036-026-00654-9
Frequently Asked Questions
Why would anyone treat a wound with hydrogen sulfide, a toxic gas?
Because in tiny, controlled amounts the body already makes it on purpose, using it as a signal that widens blood vessels and encourages new ones to form. In people with diabetes that natural production drops, starving wounds of the blood they need to heal. The trick is delivering just enough of the gas, in just the right place, to restore that signal without the dangers that come with toxic doses.
How does the device avoid dropping someone’s blood pressure dangerously?
It keeps the gas local. The dressing generates hydrogen sulfide on the spot from a stable coating, so it acts on the wound rather than circulating through the whole body. In pig studies the researchers checked the animals’ breath and distant skin and found no detectable gas escaping, even at the highest doses tested.
How does a bandage actually make gas on demand?
The dressing holds a coating of silver sulfide, a stable solid, that releases hydrogen sulfide only when a small electric current passes through it. The current comes from a coin-cell battery, and the dose is controlled by tapping a phone against the cartridge. That lets a clinician meter out a slow trickle or timed doses over roughly two weeks.
Could this replace existing wound treatments?
Not replace, but possibly add to them. Current care cleans the wound and manages infection but does little about poor circulation, which is the actual barrier to healing. The team is testing the device alongside negative pressure therapy, a common suction-based treatment, to see whether the combination beats either one alone.
What’s stopping this from reaching patients now?
It is still preclinical, tested only in rats and pigs, with no human trials yet. The researchers also have not pinned down the best dose or timing, and the key question of whether treated wounds truly close faster awaits a follow-up study. The early safety signals are encouraging, but the gap between a promising device and an approved treatment is a long one.