Page 475 - IJB-10-4

International Journal of Bioprinting 3D-bioprinted peripheral nerve scaffold

ensure scaffold shape and integrity. Furthermore, the viscosity. In the context of extrusion-based 3D bioprinting,
augmented strength of the hydrogel-PCL composite these results highlighted the highly thixotropic nature of
scaffolds addressed the inherent brittleness of hydrogels hydrogels (Figure 3D–F).
that pose a challenge in suturing. The FTIR spectra of the hydrogels are depicted in
To ensure the integrity of the printing scaffold and Figure 3C. For both hydrogels, a SA hydroxyl bond (O-H)
-1
cell protection, a shear thinning feature should be added was reported at 3291 cm . The prominent peak at 1241
-1
to allow smooth passage of the printing nozzle with cm corresponded to the C=O bond of GelMA. For RGD-
-1
44
reduced shear viscosity. Temperature plays a vital role in Alg, a spectral peak was observed at 1510 cm , which
hydrogel application during 3D bioprinting. Our findings corresponded to the amide II band, thereby indicating that
indicated that as the shear rate increased, the viscosity the RGD peptide was successfully grafted. These findings
of our hydrogel decreased. Similarly, an increase in collectively demonstrated that the intrinsic properties of
temperature also decreased the viscosity. Thixotropic tests the materials remained unaltered upon the addition of
revealed that the viscosity closely approximated 50 Pa·s, at RGD peptide and the 3D-bioprinting process.
an adequate temperature of 20 C and shear rate of 0.1 s . 3.3. In vitro analysis of 3D-printed scSHEDs
-1
o
When the shear rate was increased to 100 s , there was a The hydrogel extract did not exhibit any prominent effect
-1
significant reduction in viscosity. Upon restoring the shear on the propagation of scSHEDs (Figure 4C), indicating
rate to 0.1 s , the hydrogel essentially returned to its initial the absence of hydrogel-associated cytotoxicity. We used
-1

Figure 4. Growth status and functional assessment of Schwann-like stem cells from human-exfoliated deciduous teeth (scSHEDs) cultured in 2D
environment or 3D-bioprinted scaffolds. (A) Live/dead staining of scSHEDs on scaffolds, displaying live and dead cells and merged live and dead cell
images on days 1, 4, and 7. Scale bar: 1 mm. (B) Immunostaining of S-100β marker with S-100β (green) and DAPI staining (blue), with a merged staining
image. (C) Proliferation assessment of scSHEDs cultured in normal conditions and in hydrogel extracts. (D) Cell viability on days 1, 4, and 7. (E) NGF
release of scSHEDs cultured in a 2D environment or 3D-bioprinted scaffolds on day 7. (F and G) Day 4 quantitative comparison of (F) BDNF and (G)
S100B gene expressions of 2D-cultured scSHEDs and 3D-bioprinted scSHEDs. (H) Solid merged image of immunostained S-100β marker with S-100β
(green) and DAPI staining (blue). (I) Solid merged image of cytoskeleton staining (red) and DAPI staining (blue). Scale bars: (B) 50 μm; (H and I) 100 μm.
**p < 0.01; ns: no statistical difference.

Volume 10 Issue 4 (2024) 467 doi: 10.36922/ijb.2908