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Manyi Wang, Jiankang He, Yaxiong Liu, et al.

[9]
Figure 1. A laser induced forward transfer (LIFT)-based bioprinting system that Keriquel et al. developed for in vivo repair of
[9]
mouse calvaria defects. (The images are reused with permission from © IOP Publishing. All rights reserved.)

Figure 2. The robocasting nozzle-based bioprinting system developed on the basis of a Fab@Home open-source, open-architecture
AM system. The laser highlighted in the left image was used for measuring the geometric fidelity of printed constructs. Images of
resultant print geometry: (A) CT image of the bovine femur with an osteochondral defect (cartilage defect highlighted in red, bone
defect in yellow); (B) Photo of the femur with an osteochondral defect; (C) Bone portion has been printed; (D) Alginate hydrogel has
been printed on the bone portion as a cartilage cap. (Image [10] courtesy of Daniel Cohen, Cornell University and reproduced from
with permission from © IOP Publishing. All rights reserved.)

defects with a cell-free injectable hydrogel comprising regenerative medicine using an in situ formable
dextran-tyramine conjugates (Dex-TA) [11] . A handheld hydrogel [13] . It is understandably arguable whether
device named “BioPen”, has recently been developed some of the aforementioned in situ tissue repair tech-
in the laboratories of the University of Wollongong for niques based on handheld syringes can be properly
in vivo repair of osteochondral defects. By combina- categorized as bioprinting since the “precise 3D print-
tion of nozzle-based material delivery system and a ing” feature is diluted. However, advances in these
low-powered ultraviolet light curing system, this endoscopy-compatible techniques for in situ tissue
technique allows operators to control the deposition of organ repair will undoubtedly be part of the founda-
stem cell-loaded materials to create customized im- tions of in vivo bioprinting.
plants as they work [12] . In vivo reconstruction of To date there is still no printed tissue that can satis-
biological tissue has also been achieved in corneal factorily mimic full hierarchical structures and func-
International Journal of Bioprinting (2015)–Volume 1, Issue 1 17