BLOOD VESSEL REGENERATION - 3D Bioprinting and Nanotechnology in Tissue Engineering and Regenerative Medicine - page 161

Investigations utilizing these methods, both cell-free scaffolds and cell-laden scaffolds, will yield the
necessary insight into some of these problems. Furthermore, the developed materials and technologies
must progress in order to have the desired mechanical and surface properties while at the same time
steps must be taken to address the necessary regulatory requirements for clinical applications. As such,
these technologies stand poised to provide insight into the direction that future research must follow to
successfully develop 3D printed vasculature for therapeutic applications.
7.2 FUTURE DIRECTIONS
This research is not just limited to simple replacement of existing vascular tissue. It also has a much
broader impact on the vascularization of 3D printed implants discussed throughout this topic. All of
these tissues require integration into the vascular system and by understanding the complex process
of angiogenesis and developing mimetic tissue that can provide sufficient nutrient exchange, these ar-
tificial tissues can be further developed to make a significant impact on the field of tissue engineering
and regenerative medicine.
Again, the predominant challenge that needs to be addressed for 3D printing of vasculature and
its application to tissue-engineered constructs is the heterogeneous nature of the desired tissues. It is
important that the printed implants not only mimic the natural shape of the organs and tissues, but that
the implants recapitulate the complex, heterogeneous nature of those tissues. For vascular implants,
future directions must address the need to have distinct layers with different mechanical properties to
best mimic the native vasculature. Cell-laden constructs need to take this one step further by addressing
the heterogeneous mechanical properties as well as scaffold materials for the different cell types being
incorporated into the vascular implant.
The future of 3D printed blood vessel implants will need to address the aforementioned challenges
as well as improve upon the rapid fabrication techniques such that the technologies developed in a
laboratory setting can be translated into clinical settings by allowing for the scale up required for mass
production. As such, the next several years will see advances in the materials used in the 3D printing
application and in the ease of preparation of these materials for use with the various 3D printing tech-
nologies. Additionally, the use of stem cells, either obtained directly from the patient or induced from
other cells, will have a significant impact on the design of blood vessel implants. These stem cells can
be used to determine the best material environment for in vitro and in vivo population of the blood ves-
sel implants, which will give additional insight into the critical parameters for the design of biomimetic
niches within the 3D printed implants.
ACKNOWLEDGMENTS
The authors would like to thank Amanda F. Levy for help with the illustrations. This work was funded by the
National Science Foundation with support from the Instrument Development for Biological Research (IDBR) Pro-
gram and the Division of Chemical, Bioengineering, Environmental, and Transport Systems (CBET 1264517), and
by the National Institute of Arthritis and Musculoskeletal and Skin Diseases of the National Institutes of Health
(R01 AR061460).