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International Journal of Bioprinting 3D-Printed GelMA biomaterials in cartilage repair

Figure 5. Synthesis process of GelMA.

4. Modification of GelMA in cartilage tissue important. This is a vital aspect of successful tissue
engineering engineering and regenerative medicine strategies.

The preparation of GelMA can be affected by many In this section, we summarize the related researches on
parameters, such as gelatin source, reaction condition (e.g., the modifications of GelMA for better articular cartilage
pH), methacrylate group donor, and so on. Therefore, the repair (Figure 6 and Table 1).
reaction can be controlled to adjust these parameters. The
adjustable physical and chemical properties of GelMA 4.1. Mechanical properties
are great advantages of GelMA that make it suitable for Cartilage in the joint experiences complex mechanical
[14]
articular cartilage tissue engineering . loads in vivo, and therefore, it is essential to develop
hydrogels with sufficient mechanical strength to withstand
On the one hand, articular cartilage is a load-bearing these loads and maintain their structural integrity over
tissue which plays a pivotal role in maintaining joint health time. Hydrogels with inadequate mechanical strength may
and stability. The restoration of its mechanical properties deform, fracture, or collapse under physiological loads,
following injury remains a significant challenge. To achieve leading to implant failure and the inability to support the
optimal recovery of function of joints, modifications of growth and differentiation of chondrocytes. Therefore,
biomaterials to bestow them with enhanced mechanical improving the mechanical strength of hydrogels is crucial
strength are essential. Evaluating the efficacy of cartilage for the successful engineering of functional cartilage tissue.
repair necessitates the assessment of mechanical strength,
which serves as a crucial parameter. However, employing Normally, increasing the concentration of GelMA
pure GelMA hydrogels for cartilage regeneration proves to or extending the UV irradiation time improves the
be inadequate due to their weak mechanical properties and mechanical properties of the hydrogels . However,
[15]
brittleness, which restrict their overall utility. Therefore, researchers have also modified GelMA hydrogels to
modification of GelMA hydrogels can optimize the improve their mechanical properties by introducing other
hydrogel properties, leading to improved outcomes of materials. These modifications have resulted in enhanced
articular cartilage regeneration. toughness and resilience, controlled degradation rate,
continued protein release, and promoted chondrocyte
On the other hand, fostering seamless integration adhesion and proliferation, as well as good cartilage repair
between GelMA hydrogels and in situ tissues is also a abilities in vitro and in vivo. Gan et al. introduced the
[16]
challenge for optimal articular cartilage repair. Effective oligomer of dopamine methacrylate (ODMA) to GelMA
integration of GelMA with the native cartilage tissue hydrogels, resulting in improved toughness and resilience
can yield several benefits, including enhanced cell without affecting compatibility or hindering neocartilage
adhesion and proliferation as well as cell migration regeneration. Lim et al. introduced tyrosine (Tyr)
[17]
from the surrounding tissues, efficient transmission groups into GelMA to develop a visible-light responsive
of mechanical loads, and improved nutrient and waste bioink. Tyrosine residues can be used to create crosslinks
exchange. between polymer chains through photocrosslinking.
In addition, the physical cues provided by scaffolds The crosslinked network can enhance the mechanical
can also control multiple aspects of cell behavior, notably strength and stability of the hydrogel, and also improve
differentiation. As articular cartilage tissues comprise adhesion to the surrounding tissue, thus improving the
different types of cells in different layers, the modifications lateral integration of neocartilage. Wang et al. made
[18]
targeting to regulate cell differentiation lineage are a 3D-printed biological scaffold with high mechanical

Volume 9 Issue 6 (2023) 243 https://doi.org/10.36922/ijb.0116