A new device that resembles a glue gun is 3D printing skin, and researchers hope that it can one day be used to heal very deep wounds.
The device — which weighs less than 2 lbs. (0.9 kilograms) — leaves behind a slime of "bio-ink" when dragged across a surface. This ink contains materials normally present in the skin, including collagen, a protein that allows cells to grow and thrive; and fibrin, a protein that aids in blood clotting to help heal wounds.
In a new study, published in April in the journal Lab on a Chip, researchers tested the device on small wounds made on pigs and mice, and found that it was safe. However, the device hasn't yet been tested on humans. [How to Fix 9 Common Skin Problems]
The device is a proof of concept, and more research is needed before it's used on patients, said co-senior study author Saeid Amini Nik, a stem-cell biologist at the University of Toronto. But "as we move toward precision medicine … I think the 3D printer has the potential to really spot the [necessary] cells and specially distribute them to make organs," Amini Nik said.
Skin may look simple, but there's much more than meets the eye. It's the body's largest organ and consists of three main layers. The outermost layer, called the epidermis, is made up mainly of dead cells called keratinocytes and serves as a barrier against water loss, according to the paper. This layer also has immune cells called lymphocytes, which are tasked with carrying germs to lymph nodes for waste disposal, and Merkel cells, which give us the ability to sense light touches, according to the U.S. National Library of Medicine. The middle layer, called the dermis, contains a matrix of collagen fibers (and the cells that make them called fibroblasts), which give the skin both its elasticity and its strength. The bottom layer, called the hypodermis or the subcutaneous layer, is made mostly of fat.
This complicated network of cells, blood vessels, nerves and hairs serves to protect us from the world of germs we live in. But some kinds of wounds — such as burns — can wipe out all three layers of skin, creating portals into our body for thirsty pathogens.
The printed skin that the researchers tested didn't replicate all of these elements, however. Rather, the device deposited only certain cells, including keratinocytes and fibroblasts — but the scientists hope that one day it will be able to leave behind the "perfect skin," complete with stem cells that can grow into hair follicles, blood vessels and various types of cells in the correct configuration, Amini Nik said.
This isn't the first "skin-printing" device out there. For example, a group of Spanish researchers created such a device in 2016. But it is the first device that could potentially allow doctors to immediately deposit skin onto a wound without going through a lab or other donors first: Doctors could potentially take stem cells from the patient (for example, from fat tissue or bone marrow) and feed them into the device at the time of the procedure, Amini Nik told Live Science.
Currently, treatment for deep burns includes covering the affected areas with a collagen-based material and waiting for the body to do the rest of the work, including creating all of the necessary skin cells.
But "a person with a really large burn on their body can't respond efficiently," Amini Nik said. Other treatments include covering the wound in cells that mimic skin, but these grafts have to be created in the lab in advance.
"It takes a long time; it's very expensive," Amini Nik said. What's more, this type of procedure also introduces opportunities for contamination, because it wouldn't be done right there in the operating room, he added. Skin can also be taken from donors, but this could lead to adverse effects, including tissue rejection, and rarely is there enough donor tissue available to cover extensive burns, according to a press release.
Originally published on Live Science.
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Yasemin is a staff writer at Live Science, covering health, neuroscience and biology. Her work has appeared in Scientific American, Science and the San Jose Mercury News. She has a bachelor's degree in biomedical engineering from the University of Connecticut and a graduate certificate in science communication from the University of California, Santa Cruz.