Page 131 - IJB-9-5

International Journal of Bioprinting DLP-printed scaffold for bone regeneration

Figure 8. Histological and immunohistochemistry evaluation of the new blood vessels in the defect site at week 4. (A) Fluorescent staining (CD31 and
OPN) of newly formed bone at week 4. (B) The mean fluorescent intensity of CD31. (C) Hematoxylin–eosin staining of newly formed bone at week 4.
Data were analyzed using one-way ANOVA and are shown as mean ± standard deviation (*p < 0.05, **p < 0.01, ***p < 0.001, n = 3). (NB, new bone; IM,
implanted materials; BM, bone marrow; BV, blood vessel.)

Therefore, it has become an attractive strategy to induce progression of ECO. Furthermore, owing to their excellent
ECO in situ through the properties of the material itself . structure, the 3D-printed scaffold also supported the access
[50]
Sun et al. prepared an injectable, poly (glycerol sebacate)- of bone tissue and blood vessels, providing a novel material
co-poly (ethylene glycol)/polyacrylic acid (PEGS/PAA) design for ECO-based bone regeneration.
hydrogels to induce a hypoxia-mimicking environment and The GelMA/PMAA scaffold possessed better elasticity
subsequently recapitulate ECO via in situ iron chelation . and compression strength compared to the conventional
[37]
However, injectable hydrogels cannot be prepared directly GelMA scaffold, increasing early mechanical stability and
as pre-designed macroscopic structures.
meeting the mechanical requirements of inclusive bone
In our study, GelMA/PMAA scaffolds promoted the defects. In terms of surface structure, the 3D printing
expression of HIF-1α by chelating iron ions with the carboxyl technology could help the scaffold to achieve the co-
group of PMAA, thus reducing the consumption of HIF-1α existence of macropores and micropores, as compared to
by PHD and allowing for better chondrocyte differentiation only micropores in the conventional injectable hydrogel,
and vascular regeneration. The scaffolds also overcame the which is essential for the occurrence of osteoconductivity.
disadvantages of exogenous factors and allowed smooth In addition, the introduction of PMAA not only improved

Volume 9 Issue 5 (2023) 123 https://doi.org/10.18063/ijb.754