Page 83 - IJB-10-6

International Journal of Bioprinting 3D bioprinting techniques & hydrogels materials

combination with bioceramics in integrated osteochondral Chen et al. combined a thixotropic magnesium
repair are as follows: phosphate-based hydrogel material with gellan/
(i) Hydroxyapatite (HAP): HAP, the most widely alginate to produce bioink, and the printed scaffold
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used bioactive material in calcium carbonate exhibited outstanding osteogenic activity.
ceramics, has outstanding biocompatibility and (iii) The combination of bioceramics and hydrogels as
mechanical properties, which can compensate bioinks holds significant potential for 3D printing in
for the deficiencies in the mechanical properties osteochondral repair. However, the current number
of hydrogels. In addition, its porous structure of studies is rather limited, warranting further
is conducive to the growth of bone tissue and research to derive more precise conclusions.
vessels. Recently, researchers have endeavored
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to print scaffolds appropriate for osteochondral 3.2.2. Synthetic polymer-reinforced hydrogels
repair through the combination of hydrogels and Synthetic polymers, such as polycaprolactone (PCL)
HAP. You et al. compared the biological properties and polylactic acid (PLA), are extensively employed as
of pure alginate hydrogel scaffolds and alginate tissue engineering materials due to their plasticity and
hydrogels combined with HAP composite scaffolds. controllable degradation rate. These polymers are often
They discovered that chondrocytes exhibited a combined with hydrogels to develop composite materials.
higher survival rate and proliferation efficiency in Gao et al. combined poly(N-acryloyl 2-glycine) (PACG)
the composite scaffolds, as well as a higher level and GelMA to develop a biodegradable, high-strength
of mineralized matrix, revealing their potential in molecular polymer-reinforced biohybrid gradient
the integrated repair of osteochondral tissues. scaffold that promoted the simultaneous regeneration
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Liu et al. employed a composite material consisting of cartilage and subchondral bone in rats (Figure 2ii).
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of GelMA and nanoHAP (nHAP) to fabricate N-acryloyl glycinamide (NAGA) is also compounded
a three-layer scaffold for repairing OCDs in into a GelMA hydrogel and printed as a scaffold,
rabbits and demonstrated a favorable therapeutic which has great potential for treating OCDs under
effect (Figure 2ii). Furthermore, Wang et al. OA conditions and exhibits excellent antifatigue and
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reported that HAP content and hypoxia are antioxidation properties, as well as printability. In
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important factors for osteogenic differentiation, addition, Antich et al. utilized HA and PLA to print a
hypertrophy, and endochondrosis of adipose composite scaffold with excellent mechanical properties
MSCs (ADMSCs), but the optimal HAP content that can promote cartilage regeneration by increasing the
has not yet been determined. HAP and hydrogel expression of chondrogenic gene markers and specific
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composite scaffolds demonstrate great potential matrix deposition. 165
in osteochondral repair, but the optimal ratio of
mixing is still uncertain, and further studies are Due to the large amount of equipment required,
warranted to determine whether this combination difficulties with bioink crosslinking, and other issues,
can enhance efficacy. traditional 3D bioprinting methods are generally printed
in vitro before implantation in the body to repair the
(ii) β-Tricalcium phosphate (TCP) and magnesium damaged area. Its long waiting time without treatment
phosphate: The most commonly utilized calcium makes it a major flaw. As an emerging technology, in situ
phosphate derivative is TCP. Among its forms, β-TCP, 3D printing can be implemented to greatly reduce the
which has an inorganic composition similar to that waiting time. Ma et al. 3D printed a four-arm pegylated
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of the bone matrix, is widely used in biomaterials hydrogel hybrid scaffold in situ with robotic assistance, and
due to its ability to effectively bind to bone and OCDs could be repaired in approximately 60 s. 167
ensure normal cell growth and differentiation. In
osteochondral repair, Kosik-Kozioł et al. designed Although many studies have explored the use of
a 3D hydrogel scaffold containing β-TCP that can polymer hydrogel composites in osteochondral integrative
promote the proliferation and differentiation of bone repair, many problems remain in their clinical application.
marrow-derived MSCs (BMSCs) and reported that For example, further extensive and clinical translational
0.5% w/v TCP was the optimal concentration for research is required to determine how to better control
the formation of a stable scaffold. Approximately the degradation rate to match bone growth and identify
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60% of magnesium in the human body is found in optimal porosity. Furthermore, while in situ 3D printing
the bone matrix, where it facilitates cell adhesion, technology has begun to be applied, more relevant research
proliferation, and differentiation; induces bone and better technology are needed to improve repair results
mineral deposition; and promotes bone formation. in the future.
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Volume 10 Issue 6 (2024) 75 doi: 10.36922/ijb.4472