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Liang, et al.
Table 1. Summary of different 3D-printing technologies in cartilage tissue repair and their bioinks.
3D‑printing Advantages Disadvantages Bioink requirements Bioink Reference
technique examples
Extrusion-based Support cell-laden bioinks Slow printing speed High viscosity GelMA [21,22,25,26]
Moderate-resolution Inferior cell viability Shear-thinning HA
Improved shape fidelity (40-80%) characteristics for Collagen
Expensive cost cell-laden bioinks
Digital-light Superior vertical structure Separating force Photocrosslinkable GelMA [21,25,27]
processing fidelity between the platform Viscosity maintained PEGDA
Hight resolution and the printed surface within a specific range Silk-fibrin
Fast printing speed May need the
Mild condition for cells addition of cytotoxic
(viability: 85-95%) photoinitiator
Drop-on-demand Medium printing speed Poor structure fidelity Thermoplastic Alginate [21,25]
inkjet High cell viability (>85%) Low cell density (<106 Viscosity maintained PEGDA
cells mL − 1) within a specific range Collagen

Table 2. HA derivatives, their fabrication and gelation methods.
HA derivatives Fabrication Gelation method Reference
Thiol-modified HA Modifying the carboxylate groups of Difunctional electrophiles [33,34]
GAGs and polypeptides with hydrazide
reagents
Haloacetate-modified HA Using excessive bromoacetic anhydride Crosslinker-free when combined with [35]
to synthesize HA bromoacetic with a thiol-modified HA
substitution of 18%
Dihydrazide-modified HA Addition of adipic dihydrazide and Ketones and aldehydes; can also [36]
other hydrazides acylhydrazide with acylating agents
Tyramine-modified HA Coupling tyramine to a small Addition of horseradish peroxidase and [37]
percentage of HA carboxylates hydrogenperoxide

A B

C D E

Figure 4. The structure of (A) hyaluronic acid, (B) type II collagen, (C) gelatin methacryloyl, (D) polyethylene glycol, and (E) alginate.

of MeHA concentration was needed for this photosensitive stem cells (hMSCs) (Table 4) . The GelMA-MeHA
[41]
bioink . Currently, MeHA has been combined with hydrogel exhibited benign cell viability through 8 weeks of
[40]
GelMA to build a scaffold carrying human mesenchymal culture and it also improved regeneration of both cartilage
International Journal of Bioprinting (2022)–Volume 8, Issue 3 19