3D bioprinting brought several advances to regenerative medicine, which emerged as a way out of the growing demand for functional human tissues and organs. Among different existing techniques, the in situ bioprinting method has been on the rise. It facilitates the repair and reconstruction of defective tissues, directly producing bioprinted constructs at the sites of defective tissues in a clinical setting. 1
Figure 1: Schematic diagram illustrating the concept of a handheld bioprinter. 1
Several other techniques derived from in situ bioprinting are already being developed, such as handheld bioprinters. In this approach, the operator can hold the bioprinter to directly deposit the bioink in place, providing greater freedom to adjust the deposition of the bioink into the tissue. For example, researchers at the University of Toronto have successfully tested a portable 3D skin printer, which treats severe burns by bioprinting new skin cells directly onto a wound. 1 2
Removing damaged tissue and replacing it with skin taken from another area of the patient's body is a standard treatment for severe burns. Still, in cases of extensive burns, there is not always enough healthy skin to use. To solve this problem, the handheld bioprinter developed by Canadian researchers deposits directly into wounds a fibrin-based bioink infused with mesenchymal stromal cells (MSCs), which can support local cell growth and assist in the body's immune response. The results indicated that wounds treated with MSC heal exceptionally well and show a reduction in inflammation. 2 3 4
Figure 2: The handheld 3D skin printer developed by University of Toronto researchers. 3
In addition to the skin, several studies have shown the potential of manual bioprinting in intraoperative dressing applications and muscle, cartilage, and bone healing. As an alternative to cartilage healing, Di Bella et al. (2018) created a portable 3D printing device that allows the simultaneous coaxial extrusion of bioscaffold and cultured cells directly into a cartilage defect in vivo in a single surgical session. In this approach, the deposition of live cells and biomaterials is done manually and directly, integrating a multiple-inlet extruder nozzle and a light source to catalyze the phase transformation of the paint and a motorized extrusion system. This handheld bioprinter enabled early cartilage regeneration, providing a feasible strategy to regenerate articular cartilage. 5
REFERENCES
1. Ying, G. et al. An open-source handheld extruder loaded with pore-forming bioink for in situ wound dressing. Mater Today Bio 8, 100074 (2020).
2. Davies, S. New handheld bioprinter holds promise for treating serious burns. https://ioppublishing.org/news/new-handheld-bioprinter-holds-promise-for-treating-serious-burns/ (2020).
3. U of T researchers’ handheld 3D skin printer helps heal large, severe burns, study finds. https://www.utoronto.ca/news/u-t-researchers-handheld-3d-skin-printer-helps-heal-large-severe-burns-study-finds.
4. Hakimi, N. et al. Handheld skin printer: in situ formation of planar biomaterials and tissues. Lab Chip 18, 1440–1451 (2018).
5. Bella, C. D. et al. In situ handheld three‐dimensional bioprinting for cartilage regeneration. Journal of Tissue Engineering and Regenerative Medicine vol. 12 611–621 (2018).