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REVIEW ARTICLE

3D bioprinting for tissue engineering: Stem cells in

hydrogels

2*
1
1
Nazia Mehrban , Gui Zhen Teoh and Martin Anthony Birchall
1 Department of General Surgery, University College London, London, WC1E 6BT, United Kingdom
2 Ear Institute, University College London, London, WC1X 8DA, United Kingdom

Abstract: Surgical limitations require alternative methods of repairing and replacing diseased and damaged tissue. Re-
generative medicine is a growing area of research with engineered tissues already being used successfully in patients.
However, the demand for such tissues greatly outweighs the supply and a fast and accurate method of production is still
required.
3D bioprinting offers precision control as well as the ability to incorporate biological cues and cells directly into the
material as it is being fabricated. Having precise control over scaffold morphology and chemistry is a significant step
towards controlling cellular behaviour, particularly where undifferentiated cells, i.e., stem cells, are used. This level of
control in the early stages of tissue development is crucial in building more complex systems that morphologically and
functionally mimic in vivo tissue.
Here we review 3D printing hydrogel materials for tissue engineering purposes and the incorporation of cells within
them. Hydrogels are ideal materials for cell culture. They are structurally similar to native extracellular matrix, have a
high nutrient retention capacity, allow cells to migrate and can be formed under mild conditions. The techniques used to
produce these materials, as well as their benefits and limitations, are outlined.
Keywords: 3D bioprinting, hydrogels, stem cells, polymers, tissue engineering

*Correspondence to: Martin Anthony Birchall, Ear Institute, University College London, London, WC1X 8DA, United Kingdom; Email:
m.birchall@ucl.ac.uk

Received: September 17, 2015; Accepted: November 27, 2015; Published Online: December 9, 2015
Citation: Mehrban N, Teoh G Z and Birchall M A, 2016, 3D bioprinting for tissue engineering: Stem cells in hydrogels. Interna-
tional Journal of Bioprinting, vol.2(1): 6–19. http://dx.doi.org/10.18063/IJB.2016.01.006.

1. Introduction for cell growth but combining engineering, materials
W of specific dimensions. That material must then inte-
science and cell biology to create a bespoke material
hilst 2D printing has had a big influence on
everyday living, the advent of additive
grate well with the patient’s healthy tissue and restore
[1]
processing technology in 1986 has seen
an explosion in innovative ways of producing 3D functionality to an acceptable level. In the pursuit of
developing materials that meet such criteria, manu-
[3]
[2]
structures, such as electronic devices , aircraft parts , facturing techniques have also become more complex.
[4]
medical devices and tissue mimics [5–7] . For clinical 3D bioprinting is the spatial control of the original
applications, early designs based on creating sacrifi- scaffold preparation techniques with integration of
[8]
cial moulds as templates for the biomaterials were chemical cues and living cells [12] . Printing sensitive
quickly superseded by aqueous systems that could biological materials presents new challenges, such as
directly print biological materials [9−11] . Today, the fo- maintaining cell viability throughout the manufactur-
cus is no longer just on providing a suitable platform ing process and preventing denaturation of proteins.

3D bioprinting for tissue engineering: Stem cells in hydrogels. © 2016 Nazia Mehrban, et al. This is an Open Access article distributed under the
terms of the Creative Commons Attribution-NonCommercial 4.0 International License (http://creativecommons.org/licenses/by-nc/4.0/), permitting
all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
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