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REVIEW ARTICLE

3D Bioprinting Photo-Crosslinkable Hydrogels for Bone

and Cartilage Repair

Quanjing Mei , Jingdong Rao , Ho Pan Bei , Yaxiong Liu , Xin Zhao *
1,†
1
1,†
1
2
1 Department of Biomedical Engineering, The Hong Kong Polytechnic University, Hung Hom, Hong Kong, China
2 Jihua Laboratory, Foshan, Guangdong, China
† These authors contributed equally to this work
Abstract: Three-dimensional (3D) bioprinting has become a promising strategy for bone manufacturing, with excellent
control over geometry and microarchitectures of the scaffolds. The bioprinting ink for bone and cartilage engineering has
thus become the key to developing 3D constructs for bone and cartilage defect repair. Maintaining the balance of cellular
viability, drugs or cytokines’ function, and mechanical integrity is critical for constructing 3D bone and/or cartilage scaffolds.
Photo-crosslinkable hydrogel is one of the most promising materials in tissue engineering; it can respond to light and
induce structural or morphological transition. The biocompatibility, easy fabrication, as well as controllable mechanical and
degradation properties of photo-crosslinkable hydrogel can meet various requirements of the bone and cartilage scaffolds,
which enable it to serve as an effective bio-ink for 3D bioprinting. Here, in this review, we first introduce commonly used
photo-crosslinkable hydrogel materials and additives (such as nanomaterials, functional cells, and drugs/cytokine), and then
discuss the applications of the 3D bioprinted photo-crosslinkable hydrogel scaffolds for bone and cartilage engineering.
Finally, we conclude the review with future perspectives about the development of 3D bioprinting photo-crosslinkable
hydrogels in bone and cartilage engineering.
Keywords: Bone and cartilage engineering; Hydrogel; Photo-crosslinking; Three-dimensional printing

*Correpondence to: Xin Zhao, Department of Biomedical Engineering, The Hong Kong Polytechnic University, Hung Hom, Hong Kong, China;
xin.zhao@polyu.edu.hk
Received: April 1, 2021; Accepted: May 31, 2021; Published Online: June 24, 2021
(This Article Belongs To The Special Section: Bioprinting of 3D Functional Tissue Constructs)
Citation: Mei Q, Rao J, Bei HP, Liu X, Zhao X, et al., 2021, 3D Bioprinting Photo-crosslinkable Hydrogels for Bone and
Cartilage Repair. Int J Bioprint, 7(3):367. http://doi.org/10.18063/ijb.v7i3.367

1. Introduction of native tissue-mimicking structure and the inability to
establish a three-dimensional (3D) niche for different
The incidence of skeletal disorders involving both bone cell types (osteoblasts, osteoclasts, and endothelial cells
and cartilage caused by trauma, injuries, and dysfunction [EC]) . Bone and cartilage are highly complex anisotropic
[4]
has significantly increased in recent decades, creating a tissues with distinctive structures, various compositions,
demand for more effective treatment . Despite decades and excellent mechanical properties. The repair of bone
[1]
of study, the treatments for large bone and cartilage and cartilage involves cell migration, extracellular
defects remain a significant clinical problem . Although matrix (ECM) remodeling, and tissue regeneration, of
[2]
traditional methods such as autografts, allografts and which both functional details and structures should be
xenografts have been developed for repairing these carefully considered when developing bone and cartilage
defects, they all suffer corresponding restrictions, constructs .
[5]
including limited supply, insufficient function, and 3D bioprinting, which not only provides
immune response . Hence, synthetic biomaterials are adjustable 3D organizational structures but also
[3]
developed as alternatives; however, they often fail to be encapsulates cells and growth factors, brings forth a new
properly integrated into the recipient sites due to the lack strategy to design biomimetic scaffolds for bone and

© 2021 Mei, et al. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons. org/
licenses/by/4.0/), permitting distribution and reproduction in any medium, provided the original work is cited.
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