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International Journal of Bioprinting dECM bioink for 3D musculoskeletal tissue reg.

The muscle-tendon interface plays a crucial effectively integrate with surrounding natural bone tissues.
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physiological function by transmitting the force generated 3D bioprinting of artificial bones holds great promise for
by muscles through tendons to the bone via the muscle- bone TE. The bdECM bioink is highly biocompatible,
tendon junction (MTJ) to guide movement. However, capable of stimulating osteogenesis differentiation, and
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there is limited research on the use of 3D bioprinting can mimic the intricate microenvironment of natural bone
technology to repair the muscle-tendon interface. Kim et tissue. However, this biomaterial faces challenges such as its
al. utilized core collagen hydrogel, collagen bioink, muscle insufficient mechanical strength, limited vascularization,
and tendon-derived dECM, and hASC bioinks to fabricate and susceptibility to degradation, which can result in
in vitro MTJ constructs via modified core-sheath nozzles tissue collapse. 64,130,131,175,176
for 3D bioprinting (Figure 7C). The in vitro 3D MTJ models Parthiban et al. developed a photo-crosslinked
displayed good morphological structure and biochemical
characteristics, warranting subsequent developments of methacrylate bone ECM hydrogel-derived biomaterial
MTJ tissue interfaces in vivo. 171 (boneMA), which has the ability to promote endothelial
cell vasculogenesis, enhance the vascularization function
The bone–cartilage interface is often damaged in for bone regeneration, and improve bioprintability and
osteochondral defects, and osteochondral tissue has poor mechanical strength. These attributes highlight the
regenerative capacity and is difficult to repair. 40,131,172,173 potential of boneMA as a promising bioink for 3D printing
Yang et al. used decellularized cartilage ECM (cdECM)/ applications. Lee et al. prepared an alginate (Alg)/MA-
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alginate and alginate/hydroxyapatite bioinks to reproduce dECM composite bioink and optimized its printability
a biphasic graft consisting of cartilage and subchondral and capacity to support cell viability. Compared with pure
bone. In vitro tests have reported good fusion between Alg bioink, the expression levels of the cells loaded with
the cartilage and subchondral bone layers for a complete structural osteogenic genes (ALP, BMP2, OCN, and OPN)
structure. However, the efficacy of in vivo implantation has printed by the composite bioink were markedly increased
not been verified, and the anisotropic structural properties (Figure 8A). However, its mechanical strength (90.4 ± 14.9
are lacking. Zhang et al. developed a double-layer MPa) is still lower than that of natural bone tissue. To
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scaffold printed from TGF-β1-loaded cartilage dECM/SF address this issue, the researchers combined bdECM with
(silk fibroin) and BMP-2-loaded bone dECM/SF bioinks. various reinforcement substances (e.g., gelatin [GEL],
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The scaffold reportedly promoted the differentiation of PCL, PLLA, nano-hydroxyapatite [nHAP] ) for
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bone marrow MSCs and osteochondral regeneration in 3D printing to prepare reinforced composite scaffolds
rabbit knee joint models (Figure 7D), addressing most (Figure 8B–D).
of the aforementioned issues except the low mechanical
strength. Since the osteochondral interface contains To improve osteogenic performance, Kang et al.
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vascularized and avascular zones, the directional utilized extrusion-based 3D printing to design a hybrid
establishment of vascularization remains a challenge in scaffold rich in microchannel network, consisting of
osteochondral defect repair. To tackle this issue, Terpstra dECM, gelatin (Gel), quaternized chitosan (QCS), and
et al. developed human umbilical vein endothelial nHAP (the scaffold hereafter termed as dGQH). Exosomes
cell (HUVEC)-loaded pro-angiogenic and meniscal (Exos) isolated from human ADSCs were subsequently
progenitor cell (MPC)-loaded anti-angiogenic bioinks loaded into the scaffold. The researchers verified the
combined with cartilage dECM and other microfibers biocompatibility and osteogenic characteristics of the
(MFs), partitioned through 3D printing, to achieve spatial scaffolds with various amounts of nHAP (0%, 20%, 30%,
confinement of new blood vessels. This approach provides and 40%). The dGQH scaffold significantly increased the
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a new perspective on anisotropic vascular repair of the expression of ALP, RUNX2, and OCN. In addition, the
osteochondral interface. 174 dGQH @Exo group also displayed a stronger angiogenic
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effect than other groups and had good bacteriostatic
6.5. Bone activity. The dGQH20@Exo scaffold also demonstrated
Bone tissue is composed of different cells, such as bone good bone regeneration and vascularization levels in rat
progenitors, osteoblasts, osteocytes, and osteoclasts. It also models of skull defects. These findings indicate that the
contains a rich ECM that provides excellent tensile strength composite scaffold has great potential to treat craniofacial
and elasticity to support the body’s mechanical activities. In bone defects.
recent years, surgical procedures, such as bone resection,
bone grafting, and fracture repair, have made bone tissue 6.6. Cartilage
the second most transplanted tissue. Bone tissue grafts Cartilage is a type of tissue that lacks blood vessels,
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must possess mechanical strength and biocompatibility to lymphatics, and nerves. It is mainly composed of

Volume 10 Issue 5 (2024) 81 doi: 10.36922/ijb.3418