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International Journal of Bioprinting Exosome-based bioink for bioprinting

Figure 8. The applications of biomedical engineering for nerve injury repair. (A) 3D-printed collagen/silk fibroin/hypoxia-pretreated human umbilical
cord mesenchymal stem cells (HUCMSCs)-derived exosomes scaffolds (3D-CS-HMExos) and implanted in the injured brain of the small hunting dog,
which used to treat traumatic brain injury (TBI). Adapted with permission from ref. . Copyright 2022 Frontiers Media S. A. (B) The controllable three-
[75]
dimensional exterior hydrogel mixed microneedle array patch to achieve the repair of spinal cord injury. Adapted with permission from ref. . Copyright
[76]
2022 American Chemical Society. (C) The exogenous body derived from human MSC was fixed in an exo-PGEL (Exo-PGEL) that promoted spinal cord
regeneration and recovery of hind limbs. Adapted with permission from ref. . Copyright 2020 American Chemical Society.
[77]
(traumatic optic neuropathy[TON]) . It overcame the scaffold and found that it not only had good effects on
[81]
shortcomings of low tissue penetration and a short half-life wound closure, but also promoted a high degree of re-
period and improved the transfer efficiency of neurogenic epithelialization [46] . They characterized the physical
peptides. and biochemical properties of the hydrogel and found
Bioprinting technology with exosomes is an innovative that the prepared exosome-hydrogel had excellent
strategy for treating nerve damage. Compared with other biodegradability and biocompatibility. The exosome-
bioink, exosomes can effectively improve bioactivity. The hydrogel significantly improved wound closure, collagen
potential of exosomes in treating neural diseases, including synthesis, and angiogenesis in the wound area. The results
those related to neurotransmitters, is evident from their of this study also provided a cell-free therapeutic strategy
nature discussed in the first chapter and this section. for wound healing treatments using composite structures
of exosomes-encapsulated alginate hydrogels, showing its
4.4. Skin regeneration great potential for application in bioprinting.
Conventional means of skin repair include topical One of the common complications of diabetes is
application of relevant drugs, exposure to lasers, and skin impaired wound healing, characterized by inadequate
grafting [82,83] . In recent years, researchers have discovered angiogenesis and susceptibility to infections, which can
the linkage between exosomes and skin diseases [84,85] . They lead to non-healing chronic diabetic ulcers . Wang et al.
[89]
found that exosomes can participate in the physiological prepared a polysaccharide-based dressing (FEP) exosome-
and pathological processes of the skin, such as regulating contained scaffold dressing with heat-sensitive, injectable,
the secretion of pro-inflammatory cytokines in the adhesive, self-healing, antibacterial, hemostatic, and UV
microenvironment of skin, promoting vascularization and shielding properties to stimulate early angiogenesis in
collagen deposition in some skin defect diseases, as well diabetic wounds . It has been demonstrated that the
[90]
as regulating the proliferation and differentiation of skin system thus promoted skin healing and reconstruction.
fibroblasts [86-88] . Most importantly, people have discovered The scaffold can chronically release exosomes from
that exosomes positively affect skin regeneration and adipose stem cells, enhancing the proliferation, migration,
repair.
and tubular formation of stimulated HUVECs, and
Shafei et al. used an alginate hydrogel loaded with promoting diabetic wound healing. The synergistic effects
adipose stem cell-derived exosomes as a bioactive of these stimulatory responses promoted granulation tissue

Volume 9 Issue 6 (2023) 120 https://doi.org/10.36922/ijb.0114