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Li, et al.
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I J

Figure 5. (A-J) 3D printing of human lungs. Republished with permission of American Association for the Advancement of Science, from
Multivascular networks and functional intra vascular topologies within biocompatible hydrogels., Grigoryan B, Paulsen SJ, Corbett DC,
et al, Vol. 364 No. 6439, 2019 ; permission conveyed through Copyright Clearance Center, Inc.

traditionally glass transition) temperatures between 1°C The control of the double-nozzle 3D printer parameters
and 10°C. To overcome this shortcoming, Professor can provide a strong connection between the different
Wang has explored several series of low-temperature polymer systems, such as the PLGA solution-gelatin
deposition manufacturing technologies equipped with hydrogel and PU solution/cell-laden gelatin-based hydrogel.
one, two, or more extrusion nozzles [50,100-104] . Under the The supportive synthetic polymers, such as PLGA and
low-temperature conditions, such as minus 20 – 30°C, PU, and the ECM-like gelatin-based hydrogels can be
both natural and synthetic polymers are frozen and adjusted to degrade at different time points during the organ
distributed into predefined space to form elaborated 3D construction and maturation stages. With proper selection of
constructs (Figure 8). natural and synthetic polymer components, the 3D-printed

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