Page 146 - IJB-9-5

International Journal of Bioprinting 3D printed PEEK scaffold mediates macrophages to affect osseointegration

Figure 6. Effects of conditioned medium on in vitro HUVECs migration and angiogenesis-related gene expression. Conditioned medium is the supernatant
of the medium produced after co-culture of macrophages and scaffolds for 3 days. (A) Representative images showing HUVECs migration (scratch assay)
after cell cultivation in conditioned medium for 0 (baseline), 12, and 24 h. (B) Quantitative analysis of the scratch confluence of migrated cells following
cell cultivation in conditioned medium for 12 and 24 h. (C) Expression of angiogenesis-related genes (Angiogenin, FGF-2, and SDF) in HUVECs cultured
in conditioned medium for 3 days. Data are shown as the mean ± SD for n ≥ 3; *p < 0.05, **p < 0.01, and ***p < 0.001 indicate significant differences when
compared to the PEEK0; p < 0.05, p < 0.01, and p < 0.001 indicate significant differences when compared to the PEEK200.
#
##
###
group, only PEEK scaffolds can be seen in the defect area, had a significant difference compared with other groups,
and no new bone tissue, cartilage tissue, and calcium salt which indicated that the PEEK400 scaffold had the best
deposition were found. For PEEK200 scaffold, new bone osseointegration ability and biomechanical properties.
matrix and cartilage tissue transformed into bone tissue,
which was embedded at the edge of the scaffold, and 4. Discussion
calcium deposition also appeared in the scaffold, indicating The host immune response is an important factor affecting
that bone integration has occurred between the PEEK200 the fate of bone repair materials, and previous studies have
scaffold and the host bone. For the PEEK400 scaffold, minimized the host immune response to improve the effect
more new bone matrix and cartilage tissue appeared in the of implantation [30,31] . However, it is now generally believed
scaffold, and the results of von Kossa staining showed that that the immune system has a positive effect on bone
the calcium salt deposition degree inside the scaffold was regeneration, and the responses generated by immune
similar to that in the host bone, which may suggest that cells not only produce foreign body responses to bone
there is a greater amount of new and more mature bone in repair materials, but also participate in and mediate the
the PEEK400 scaffold. The results of histological staining process of angiogenesis and osteogenesis [12,32-34] . As core
showed that the scaffold with large pore size could promote cells of the bone immune system, diversity, and plasticity
the growth of new bone, thereby enhancing the integration are typical of macrophages, their ability to alter phenotype
of bone and scaffold interface.
through subtle changes in the microenvironment has
Biomechanical properties are a key indicator for been widely described. The polarization of macrophages
evaluating the osseointegration of materials with host bone. to different phenotypes may have different functions,
To examine the osseointegration properties of 3D-printed which in turn trigger completely different effects on
PEEK scaffolds with different pore sizes, biomechanical bone repair. Thus, favorable macrophage phenotypic
tests were performed on the specimens after 12 weeks of polarization modulated by bone repair materials will
implantation, as shown in Figure 9. The results showed ensure vascularization of the material and integration of
that the maximum load and stiffness gradually increased the material with host bone. The importance of pore size
with the increase of pore size, and the PEEK400 group on bone repair materials for angiogenesis and new bone

Volume 9 Issue 5 (2023) 138 https://doi.org/10.18063/ijb.755