Page 340 - IJB-10-5

International Journal of Bioprinting Immunomodulatory bone repair by MBG/PCL

Figure 9. RAW264.7 cell polarization and immunomodulation of osteogenic properties promoted by F300, F500, and F800 scaffolds. (A) Levels of
RAW264.7 cell polarization gene expression induced by the scaffolds. (B1, B2) Staining and quantification plots of F300, F500, and F800 in MP-conditioned
medium, which mediated the expression of ALP in BMSCs. (C) Expression levels of osteogenic genes (Alp, Opn, Runx2, Bmp2, Col1) in F300, F500, and
F800 scaffolds in MP-conditioned medium.

ALP secretion (Figure 9B-1 and B-2). Overall, the levels M2 phenotype at a greater extent. Compared with P200,
of immunomodulatory osteogenic properties of these P500 and P800 significantly upregulated the expression of
three scaffolds were in this order: F500 > F300 > F800. CD206 and Arg. Meanwhile, the expression of Arg on the
first day was higher in P500 than in P800, while there was
3.7. Effect of pore size on the immunomodulatory no significant difference in Arg expression between P500
osteogenic properties of MBG/PCL scaffolds and P800. P200 induced the expression of inflammatory
In this subsection, we continued to evaluate the effect genes (Tnfa, Il1b) the most significantly, followed by P800,
of pore size on the performance of the scaffolds. The while P500 exhibited a significant inhibitory effect on the
scaffolds were co-cultured with BMSCs, and on the first expression of these inflammatory genes. Mediated by MP-
day of proliferation, P800 had the highest OD, and there conditioned medium, P500 significantly upregulated the
was no significant difference between P200 and P500. On expression of osteogenic genes at all time points, and the in
days 3 and 7, the cell proliferative activity of P500 was vitro immuno-osteogenic properties of P800 were superior
significantly enhanced. Overall, the BMSCs proliferative to those of P200 (Figure 11C). Similarly, P500 had the
activity for these scaffolds is in this order: P500 > P800 highest staining and levels of ALP, followed by P800, while
> P200, and the results are demonstrated in Figure 10C. P200 had the lowest levels in these parameters (Figure
In the fluorescence staining after 3 days of co-culture, 11B-1 and B-2). Overall, the levels of immunomodulatory
we observed the similar trend. The fluorescence intensity osteogenic properties of these scaffolds are in this order:
of P500 was the strongest, followed by that of P800, and P500 > P800 > P200.
P200 had the weakest fluorescence intensity (Figure 10A).
According to the ALP staining and quantification on day 4. Discussion
7, we could see that P500 had the most significant ALP
expression effect, and the ALP expression was higher in Three-dimensional printing allows for the direct layer-
by-layer fabrication of highly accurate 3D solids based
P200 than in P800 (Figure 10B and D). However, in the
expression of Alp, Opn, Runx2, Bmp2, and Col1, P800 was on the structure of the bone as well as the type of bone
defect, with the assistance of imaging data and computer-
superior to P200, with the most significant upregulation aided design models, which are widely used in bone tissue
performance noted in P500 (Figure 10E).
engineering. 34-36 The performance requirements of bone
The effect of pore size on the scaffold’s performance in tissue-engineered scaffolds can be easily met by 3D-printed
promoting MP polarization is shown in Figure 11A. Large composite materials (e.g., polymers and bioceramics), and
pore size seems to promote MPs polarization toward the thus, 3D printing of these materials is currently a hot research

Volume 10 Issue 5 (2024) 332 doi: 10.36922/ijb.3551