Researchers Create Portable Bioprinter for Deep Skin Wound Repair

While portable 3D printers do exist, the majority of them are not handheld, and generally use readily available materials, like PLA. But an innovative team of researchers from the University of Toronto have created a 3D printer that’s not only handheld, but it also prints skin tissue.

The portable 3D bioprinter, a bit reminiscent of the BioPen for cartilage drawing, deposits even layers of skin to cover and repair deep wounds, and the researchers say that it’s likely the first device of its kind to form and deposit tissue in situ in under two minutes. As you can well imagine, the potential benefits for patients such as burn victims are tremendous.

The epidermis, dermis, and hypodermis layers could all be potentially damaged in patients with deep skin wounds, and the typical treatment for this is known as split-thickness skin grafting. Healthy donor skin can be grafted onto the surface epidermis and part of the underlying dermis, but doctors need enough healthy donor tissue to cover all three layers, which is not always available when it comes to larger wounds. Unfortunately, if there’s not enough graft skin, parts of the area are left uncovered, which can lead to unsuccessful healing.

This is why the handheld skin 3D bioprinter is so important – in situ formation of skin tissue sheets and biomaterials could ensure proper repair and healing of deep wounds.

The team was led by PhD student Navid Hakimi in collaboration with Dr. Marc G. Jeschke, a professor of Immunology from the university’s Faculty of Medicine as well as the Director of the Ross Tilley Burn Centre at Sunnybrook Hospital; Associate Professor Axel Guenther from the university’s Faculty of Applied Science & Engineering, supervised the research project.

The handheld 3D skin bioprinter, which weighs less than a kilogram, is roughly the same size as a small shoe box, and does not require much in the way of operator training. It kind of looks like a white-out tape dispenser, but with the tape roll replaced by a microdevice that forms tissue sheets.

Recently, the team published a paper on their handheld bioprinter research, titled “Handheld skin printer: in situ formation of planar biomaterials and tissues,” in the journal Lab on a Chip.

The abstract reads, “When manually positioned above a target surface, the compact instrument (weight <0.8 kg) conformally deposits a biomaterial or tissue sheet from a microfluidic cartridge. Consistent sheet formation is achieved by coordinating the flow rates at which bioink and cross-linker solution are delivered, with the speed at which a pair of rollers actively translate the cartridge along the surface. We demonstrate compatibility with dermal and epidermal cells embedded in ionically cross-linkable biomaterials (e.g., alginate), and enzymatically cross-linkable proteins (e.g., fibrin), as well as their mixtures with collagen type I and hyaluronic acid. Upon rapid crosslinking, biomaterial and skin cell-laden sheets of consistent thickness, width and composition were obtained. Sheets deposited onto horizontal, agarose-coated surfaces were used for physical and in vitro characterization. Proof-of-principle demonstrations for the in situ formation of biomaterial sheets in murine and porcine excisional wound models illustrate the capacity of depositing onto inclined and compliant wound surfaces that are subject to respiratory motion.”

While there are already tissue-engineered skin substitutes, adoption is not widespread in clinical settings, for various reasons.

Guenther said, “Most current 3D bioprinters are bulky, work at low speeds, are expensive and are incompatible with clinical application.”

The researchers think that their new in situ 3D skin bioprinter could be a big step in the right direction of getting past these issues, while also improving the process for healing skin. Vertical stripes of bioink made from fibrin, a protein involved in wound healing, and collagen, the most abundant protein in the dermis, run up and down the inside of each tissue sheet.

“Our skin printer promises to tailor tissues to specific patients and wound characteristics. And it’s very portable,” said Hakimi.

Not only does the team’s skin printer get rid of the washing and incubation stages that are necessary for many other bioprinters, but the researchers also plan to add several new capabilities to it, including making the size of coverable wound areas bigger.

The University of Toronto researchers will continue to work with Dr. Jeschke’s team at Sunnybrook Hospital to perform more in vivo studies, with the hopes of someday beginning human clinical trials.

Co-authors of the paper include Hakimi, Richard Cheng, Lian Leng, Mohammad Sotoudehfar, Phoenix Qing Ba, Nazihah Bakhtyar from the Ross Tilley Burn Centre, Saeid Amini-Nik, Dr. Jeschke, and Guenther.

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[Source/Images: University of Toronto]