Scientists have created a quarter-sized microneedle patch that can painlessly pull immune cells and signals from the skin in minutes. The device could transform how doctors track responses to vaccines, infections, cancer therapies and skin diseases.
A bandage-like skin patch about the size of a quarter could soon make it possible to track the body’s immune defenses without needles, blood draws or surgical biopsies.
Researchers at The Jackson Laboratory, working with the Massachusetts Institute of Technology and collaborators at the University of Massachusetts Chan Medical School, have developed the first microneedle patch that can painlessly sample live immune cells directly from human skin. The device detects inflammatory signals within minutes and collects specialized immune cells within hours.
The team’s findings, published in Nature Biomedical Engineering, point to a future in which monitoring immune health could be as simple as applying a patch for a short time at home or in a clinic.
Sasan Jalili, a biomedical engineer and immunologist at The Jackson Laboratory and joint faculty member at UConn School of Medicine, noted the new technology is designed to replace some of the most invasive parts of immune monitoring.
“Traditionally, studying some of the most important immune cells in the body requires a skin biopsy or blood draws. Because many of these cells live and respond in tissues like the skin, accessing them has meant invasive procedures,” Jalili said in a news release. “We’ve shown we can capture them painlessly and noninvasively instead. This is especially important in sensitive or visible areas like the face or neck, where people often don’t want biopsies because of scarring, as well as for older adults, frail patients, and very young children or infants.”
The patch is already being used in research on aging and autoimmune skin conditions such as vitiligo and psoriasis. In the long run, it could complement traditional blood tests and biopsies to help doctors follow how people respond to vaccines, infections and cancer therapies, while putting far less burden on patients.
A new way to tap the skin’s immune “alarm”
Most current tests for immune health rely on bloodwork. But many of the immune cells that recognize specific infections, vaccines or autoimmune triggers spend much of their time in tissues like the skin, not in circulation. That makes them hard to study without cutting into tissue.
The new patch takes advantage of a powerful but localized system: resident memory T cells. These long-lived immune sentinels sit in the skin and other barrier tissues, waiting for threats they have seen before, such as viruses, allergens or other antigens. When they recognize a familiar target, they rapidly “sound the alarm,” calling in reinforcements from the bloodstream.
By briefly reactivating these resident memory T cells with a small amount of antigen placed in the skin, the researchers can trigger that natural alarm response on demand. Immune cells and signaling molecules then concentrate in the area under the patch, where they can be absorbed and later analyzed in the lab.
“In this study, we used antigen-specific T cells as a proof of concept, but the patch also captures other immune cells and inflammatory biomarkers,” Jalili added.
In mouse vaccination models, the patch dramatically increased the number of antigen-specific T cells that could be recovered, pulling many of them in from the blood rather than just sampling what was already in the skin. In an initial human test at UMass Chan, the device collected a rich mix of immune cells and signaling proteins, including resident memory T cells.
“This study marks the first demonstration of live human immune cell sampling using a microneedle patch,” added Jalili. “This opens the door to a new way of monitoring immune responses that’s practical, painless, and clinically feasible.”
How the microneedle patch works
The patch looks like a small adhesive bandage, but its surface is studded with hundreds of microscopic needles made from an FDA-approved polymer. These microneedles are coated with a seaweed-derived hydrogel that is also considered safe by the FDA.
When pressed onto the skin, the microneedles penetrate only the upper layers, staying shallow enough to avoid nerves and blood vessels. That minimizes pain and tissue damage while allowing the hydrogel coating to soak up immune cells and signaling proteins from the fluid between skin cells.
After a short application time, the patch is removed and the absorbed material is processed. Researchers can then measure which immune cells are present, how many there are and what chemical signals they are sending. That offers a dynamic snapshot of how the immune system is responding to a specific disease, vaccine or trigger.
Expanding the immune monitoring toolbox
The scientists emphasize that blood tests and biopsies will still be essential for many diagnoses and treatments. But they see the microneedle patch as a powerful addition to the immune monitoring toolkit, especially for conditions where skin plays a central role.
The patch may be particularly useful for skin diseases such as allergic dermatitis, psoriasis and vitiligo, where the key immune cells already live in the tissue. Jalili is using the technology to study how age-related changes in skin contribute to chronic inflammation and frailty in older adults, through the Pepper Scholars Program at the UConn School of Medicine and UConn Center on Aging.
The device could also make it easier to study how the immune system responds over time, since it is far less invasive than repeated biopsies. That could be critical for tracking unpredictable flare-ups in chronic skin conditions or following how patients respond to new therapies.
Co-author Darrell Irvine, an immunologist and bioengineer who began the work at MIT and is now at Scripps Research, noted how quickly the technology has moved from the lab toward human testing.
“Not only did we run extensive preclinical experiments, we were able to carry out an initial test in humans,” Irvine said in the news release. “That’s exciting because it almost never happens with brand-new technologies. Moving new technologies from the lab to testing on patients often takes years.”
Toward at-home immune checkups
Looking ahead, the researchers envision a future where patients could use similar patches at home to monitor their immune health between clinic visits. People with chronic skin conditions might apply a patch when they feel a flare-up coming on, then send it in or bring it to a doctor to see what is happening at the cellular level.
The same basic idea could be adapted for other parts of the body. The team notes that versions of the technology might one day be used in the mouth or nose to monitor immune responses at mucosal surfaces, which are critical front lines against respiratory and gastrointestinal infections.
“People wouldn’t need hours of sampling. Even 15 to 30 minutes can be enough to detect inflammatory signals and get a sense of what’s happening in the tissue,” Jalili added.
Before the patch can be widely used in clinics, researchers will need to test how it performs in larger and more diverse groups of patients and across different diseases. The team has submitted a patent application related to the technology.
If future studies confirm its promise, a simple, painless patch could turn the skin into an accessible window on the immune system, making it easier to catch problems early, personalize treatments and understand how the body fights disease over a lifetime.
Source: The Jackson Laboratory