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International Journal of Bioprinting 3D bioprinting techniques & hydrogels materials

Table 1. Advantages and disadvantages of current clinical treatments for osteochondral defects (OCD).
Treatments Mechanism Advantages Disadvantages Complications Ref.
ACI Induce the Promote cartilage Cannot repair the osteochondral Graft hypertrophy; 19-22
formation of regeneration interface; lack of chondrocyte arthrofibrosis; graft
hyaline-like source; long acquisition time breakdown; etc.
cartilage and of chondrocytes; difficult to fix
restore the integrity chondrocyte solution; young adults
of cartilage lesions have better efficacy
MACI Induce the Chondrocytes evenly Cannot repair the osteochondral Graft breakdown; wound 23,24
formation of distributed; low risk interface; lack of chondrocyte complications
hyaline-like associated with implants; source; long acquisition time
cartilage and relatively minor trauma of chondrocytes; difficult to fix
restore the integrity chondrocyte solution; different effects
of cartilage lesions in various people
Osteochondral Fill the defect Defects can be filled High surgical difficulty; donor site Donor site pain; donor 25
autografts directly immediately with mature, complications; uneven joint surface site infection; etc.
hyaline articular cartilage
Osteochondral Fill the defect Defects can be filled Limited tissue source; immune Immune rejection; 26
allografts directly immediately with mature, rejection; insufficient integration; low transplantation failure;
hyaline articular cartilage cell viability; disease transmission disease transmission
Microfracture Increase blood flow Simple Possibility of less functional Worse joint function; 27
and bone marrow fibrocartilage formation; young adults wound complications
supply to the defect have better efficacy
site
Total articular Prostheses replace Excellent joint function; Young adults need more than Periprosthetic infection; 14
replacement damaged joints high long-term survival one revision for total articular prosthesis loosening
rate replacement
Abbreviations: ACI: Autologous chondrocyte implantation; MACI: Matrix-induced autologous chondrocyte implantation.

of multiple materials. It can be tailored by combining ECM, ensuring cell proliferation, differentiation, and
different materials to fulfill the specific requirements of the even delivery of biomolecules, such as growth factors,
scaffold. 40,41 Additionally, various cells and bioactive factors drugs, and cells. In addition, its composition, structure,
can be loaded in the scaffold and even form gradients, mechanical properties, and biochemical properties can
which can better promote regeneration. 42,43 Therefore, 3D be easily adjusted to meet the specific requirements of
printing technology has brought a new dawn to bone and osteochondral tissue engineering. 46-49 These properties
cartilage tissue engineering. combined with 3D bioprinting technology facilitate a
homogeneous distribution of biological components
Bioinks are the most critical component in 3D within the biomaterial matrix and spatial complexity,
bioprinting. The ideal 3D bioink for osteochondral rendering them highly suitable for tissue engineering.
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engineering should be capable of supporting cell Depending on their source, hydrogels can be further
growth and proliferation, maintaining the phenotype of divided into natural and synthetic hydrogels. Natural
chondrocytes and osteoblasts, facilitating the osteogenic hydrogels derived from biological sources, such as alginate
and chondrogenic differentiation of stem cells, and and hyaluronic acid (HA), have excellent biocompatibility
replicating the osteochondral interface or cartilage and biodegradability and are often used as biomaterials for
tissue. Moreover, it must possess mechanical strength OCD tissue engineering. 50,51 Nevertheless, their mechanical
analogous to that of natural tissues. Hydrogels, which properties typically do not satisfy the requirements of OCD
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are composed of highly hydrated, natural extracellular therapy; thus, various strategies are adopted to increase
matrix (ECM)-mimicking polymeric networks, are their strength and toughness. Synthetic hydrogels are
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multifunctional biomaterials that play important roles hydrated networks of polymers synthesized via chemical
in 3D bioprinting. 44,45 Their unique properties, such as methods and can be tailored according to specific
outstanding water retention, biodegradability, porous physical and chemical properties, ensuring they meet the
3D grid structure, and biocompatibility, enable them requirements of their intended applications. Crosslinking
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to provide a 3D environment similar to that of the is a key step in controlling the properties of the printed

Volume 10 Issue 6 (2024) 69 doi: 10.36922/ijb.4472