Researchers have developed a 3D-printed ‘skin in a syringe’, using a patient’s own cells to create functional dermis that could change the way we treat severe burns.
Large burns are often treated by transplanting a thin layer from the skin’s surface – the epidermis – which is mainly composed of a single cell type. However, replacing only this layer results in severe scarring.
Under the epidermis there is a thicker and more advanced layer of skin called the dermis. It has blood vessels, nerves, hair follicles and other structures necessary for skin function and elasticity. However, transplanting only the dermis is rarely an option, as the procedure leaves a wound as large as the wound that needs to be healed.
The trick is to create new skin that does not become scar tissue, but a functioning dermis.
Transplanting the building blocks of dermis
“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, who led the study published in Advanced Healthcare Materials.
The most common cell type in the dermis – the connective tissue cell or fibroblast – is easy to remove from the body and grow in a lab. The connective tissue cells can also develop into more specialised cell types. In the study, researchers provided a scaffold by growing the cells on tiny, porous beads of gelatine – a substance similar to skin collagen. However, a liquid containing these beads will not stay in place when poured onto a wound.
‘Skin in a syringe’
The researchers’ solved this problem by mixing the gelatine beads with a gel consisting of another body-specific substance – hyaluronic acid. The beads and gel are then mixed using a process known as click chemistry. The result is a gel that can effectively be called ‘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,” says Daniel Aili, professor of molecular physics at Linköping University.
Promising results in mice
In the current study, the researchers 3D-printed small pucks and implanted them under the skin of mice. The results suggest this technology could grow the patient’s own cells from a minimal skin biopsy – which can then be 3D-printed into a graft and applied to the wound.
“We see that the cells survive and it’s clear that they produce different substances that are needed to create new dermis. In addition, blood vessels are formed in the grafts, which is important for the tissue to survive in the body. We find this material very promising,” says Johan Junker.
Tackling the blood vessel limitation
Blood vessels are essential for many applications of engineered tissue-like materials. Scientists can grow cells in three-dimensional structures to create organoids, but these models lack the vessels needed to transport oxygen and nutrients to the cells. As a result, their size is limited – cells at the centre die once deprived of oxygen and nutrients.
Scientists can grow cells in three-dimensional structures to create organoids, but these models lack the vessels needed to transport oxygen and nutrients to the cells.
The LiU researchers may be closer to solving this problem, describing a method for making threads from materials composed of 98 percent water, known as hydrogels.
“The hydrogel threads become quite elastic, so we can tie knots on them. We also show that they can be formed into mini tubes, which we can pump fluid through or have blood vessel cells grow in,” says Daniel Aili.
The mini-tubes or the ‘perfusable channels’, as the researchers call them, enable the development of blood vessels in organoids.
Going forward
The development of “skin in a syringe” marks an important step toward effective burn treatments that restore both the form and function of damaged skin. By combining patient-derived cells with advanced biomaterials, researchers have created a 3D-printable gel that supports dermis formation and blood vessel growth – two key factors in long-term healing. Beyond burn care, the technology’s potential to overcome the blood vessel limitations could accelerate progress in organoid research and other regenerative medicine applications, bringing science closer to creating fully functional, lab-grown tissues.