01 March 2019 P.M.Fornasari

While the advent of 3D printers is commonly thought of as a revolution for manufacturing, it could have huge benefits for medicine as well. To help patch up large wounds that might normally require a skin graft, researchers at Wake Forest Institute for Regenerative Medicine (WFIRM) have developed a new bioprinter that can print dual layers of a patient’s own skin directly into a wound.

The idea of 3D printing skin has been in development for a few years. In 2014, a prototype machine was unveiled that could print large sheets of human skin that could then be cut to size and grafted onto a patient. The tech evolved over the years into more detailed machines and eventually a handheld device that works like a tape dispenser for skin.

The new machine looks like a cross between those last two. It’s much larger than the handheld device, but it’s still relatively portable in a hospital setting. The machine can be wheeled to a bedside, and a patient lies underneath the printer nozzle while it goes to work.

Like earlier devices, the new printer uses an “ink” made up of a patient’s own cells, to minimize the risk of rejection. First a small biopsy of healthy skin is taken, and from that two types of skin cells can be isolated: fibroblasts, the cells that help build the structure to heal wounds, and keratinocytes, which are the main cells found in the outermost layer of skin.

Larger amounts of these cells are grown from the biopsy sample, then mixed into a hydrogel to form the bioprinter ink. And here’s where it differs from previous bioprinters – rather than just applying the new skin over the injury, the new machine first uses a 3D laser scanner to build a picture of the topology of the wound. Using that image, the device then fills in the deepest parts with the fibroblasts, before layering keratinocytes over the top.

That technique mimics the natural structure of skin cells, allowing the injury to heal faster. The team demonstrated that it works using mouse models, observing that new skin began to form outward from the center of the wound. Notably, it only worked when the ink was made using the patient’s own cells – in other experiments the tissue was rejected by the body.

“If you deliver the patient’s own cells, they do actively contribute to wound healing by organizing up front to start the healing process much faster,” says James Yoo, co-author of the paper. “While there are other types of wound healing products available to treat wounds and help them close, those products don’t actually contribute directly to the creation of skin.”

The researchers say that the next steps involve conducting clinical trials in humans. Eventually, the new device could be put to work treating burn victims, patients with diabetic ulcers and other large wounds that have trouble healing on their own.

The research was published in the journal Scientific Reports. https://www.nature.com/articles/s41598-018-38366-w