Researchers at the Swedish Center for Disaster Medicine and Traumatology, in collaboration with Linköping University, have developed “skin in a syringe”—a gel infused with live cells that can be 3D printed into functional skin grafts. Successfully tested in mouse models, this innovation could offer new avenues for treating severe burns and large, complex wounds.
The research received support from the Perling-Persson Foundation, the European Research Council (ERC), the Swedish Research Council, and the Knut and Alice Wallenberg Foundation.
Understanding the Role of Skin
Current treatments for severe burns typically involve transplanting only the epidermis, the skin’s outermost layer composed primarily of a single cell type. While this can cover the wound, it often results in significant scarring. Beneath the epidermis lies the dermis—a more complex layer containing blood vessels, nerves, hair follicles, and other structures essential for function and elasticity. Transplanting the dermis is rarely an option, as it would leave a donor wound as large as the original injury.
“The dermis is so complicated that we can’t grow it in a lab. We don’t even know what all its components are. That’s why we, and many others, think that we could possibly transplant the building blocks and then let the body make the dermis itself,” says Johan Junker, researcher at the Swedish Center for Disaster Medicine and Traumatology and docent in plastic surgery at Linköping University, who led the study published in Advanced Healthcare Materials.
Innovating Skin Regeneration
To address this challenge, the team used fibroblasts—the most common dermal cells—grown on tiny porous gelatin beads, a material similar to skin collagen. These are easy to extract from the body and grow in the lab. They can also differentiate into specialized cell types as needed. To support their growth, researchers use tiny porous gelatin beads, which act as a scaffold similar to skin collagen. However, a simple liquid containing these beads cannot stay on a wound.
To solve this, the team mixed the gelatin beads with a gel made of hyaluronic acid, another naturally occurring substance in the body. The beads and gel are linked using click chemistry, producing a material that can be described, in simplified terms, as skin in a syringe.
“The gel has a special feature that means that it becomes liquid when exposed to light pressure. You can use a syringe to apply it to a wound, for example, and once applied it becomes gel-like again. This also makes it possible to 3D print the gel with the cells in it,” said Daniel Aili, professor of molecular physics at Linköping University, who co-led the study.
3D Printed Grafts and Vascular Support
In the study, researchers 3D printed small puck-shaped grafts containing patient-derived cells and implanted them under mouse skin. The cells survived, produced substances required for dermis formation, and supported blood vessel growth—essential for tissue survival.
Blood vessel development is a key limitation in bioengineered tissues. While scientists can grow cells in three-dimensional scaffolds to create organoids—miniature organ models—these structures lack vessels to supply oxygen and nutrients, restricting their size and viability.
The Linköping University team may be addressing this challenge. In a separate study, they produced elastic hydrogel threads made of 98% water. These threads can be tied into knots or formed into tiny tubes that support fluid flow or the growth of blood vessel cells. These “perfusable channels” could enable vascular networks in organoids and other lab-grown tissues, expanding possibilities for engineered tissue research and applications.
Artificial Skin Development
In recent years, there has been growing interest and development in 3D bioprinted skin models and grafts. For instance, the NOVOPLASM consortium has developed cold plasma technology to treat infected burns and skin grafts, while the University of Birmingham and the University of Huddersfield developed the SLAM 3D bioprinting for treating chronic skin wounds.
Even in space, the potential of 3D printed skin is being explored. Back in 2022, astronauts aboard the International Space Station (ISS) developed bioprinted bandages from their own cells. These innovative bandages hold promise for improving the healing of flesh wounds during space missions. Elsewhere, Cornell University researchers developed a biomaterial for 3D printing artificial skin mimicking natural human tissues. Combining collagen with a ‘zwitterionic’ hydrogel, this biohybrid composite offers softness, biocompatibility, and flexibility.
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Featured image shows Researchers collaborating to develop a gel containing living cells that can be 3D printed into a transplant. Photo via Linköping University.
