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

room. Even the most experienced surgeons cannot ments are imposed on surgical techniques, such as
match a robot in terms of precision, which is a pre- temporary generation of a printing-friendly environ-
requisite from the perspective of nano- or micro-fab- ment. An example of such surgical techniques can be
rication. Robot-assisted surgery, which has been labe- seen in some arthroscopic cartilage repair surgeries
lled as a major step up in precision and surgical quali- when surgeons use carbon dioxide or normal air insuf-
ty, seems to be an integral part of in vivo bioprinting flation to facilitate the application of the gel under dry
devices. Currently, a few commercially available conditions [61] . Moreover, advanced real-time imaging
robot-assisted surgical systems, such as the MAKO- or geometric feedback modalities, along with compu-
®
®
plasty Knee Replacement System and the da Vinci tational modeling and analysis techniques, are of equal
Surgical System, have demonstrated their ability to importance in the success of in vivo bioprinting, for
make surgery much easier with perfect accuracy and fast and accurate morphological assessment of defects
repeatability achieved. and newly fabricated constructs [62–65] .
Another significant trend in surgical technology In summary, although the currently prevalent in vi-
innovations is minimally invasive surgery. Compared tro bioprinting strategies are promising in tissue/organ
to traditional open surgery, minimally invasive surgery fabrication, particularly for the repair and transplanta-
has demonstrated less post-operation pain, less reha- tion of vital organs such as the ones in cardiovascular
bilitation time, and higher quality of life scores [59] . system, in vivo bioprinting will have its own inherent
Since patients are better educated and informed thanks advantages over the in vitro systems that include but
to the Internet and television, demand for services are not limited to: in vivo tissue culture starting from
such as minimally invasive surgeries is mounting. the biofabrication stage to maximize the role of the
Back in the early 2000s, Burg and Boland already human body in the regeneration of tissues and organs;
pointed out the significance of combining injectable real-time, on-site, and precise building of biological
biomaterials with tissue-printing technologies in mi- constructs to minimize the morphological mismatch
nimally invasive tissue engineering applications [60] . between constructs and defects, and to eliminate the
However, most of the currently-developed bioprinting influence of physical implantation procedures on the
systems require open surgeries that fully expose the integration of the delicate construct structures; “one
organs, due to oversized printing units or intrinsic li- stop” fabrication and therapy to be delivered to pa-
mitations of their working principles. Therefore, fur- tients in the operating room, to ultimately reduce op-
ther miniaturizing of device combined with novel eration time as well as risks of contaminations and
working principles for minimally invasive in vivo bi- occurrence of errors due to transportation, manual
oprinting would be an interesting direction (Figure 5). implantation, etc. To date, although significant ad-
To bring bioprinting inside the body, more require- vances have occurred since the pilot studies on in situ
repair of superficial tissues/organs were performed, in
vivo bioprinting technology is still largely conceptual.
As previously mentioned, several core issues such as
establishing sufficient vascularization in the newly
fabricated tissues/organs, particularly the ones of large
sizes, must be addressed synergistically through mul-
tidisciplinary development in optimizing bioinks and
novel in vivo printing systems. With continuous and
increasing investments on seeking answers to the
global organ shortage crisis, technical advances in cell
biology, medicine, materials science, mechatronics,
computer science, and robotics have been immensely
expedited to benefit interdisciplinary innovations in
tissue engineering. It is safe to predict that in vivo bio-
printing will become realistic in the near future thanks
Figure 5. A conceptual vision of a simplified robot-assisted in
vivo bioprinting system which is compatible with minimally to accelerated growth and sophistication of interdis-
invasive surgeries. ciplinary knowledge and technologies.
International Journal of Bioprinting (2015)–Volume 1, Issue 1 23