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International Journal of Bioprinting Dual ions mixed GelMA for hair follicle regeneration

Figure 3. The proangiogenic effect of different concentrations of ions. (A) The typical images of tube formation of HUVECs with different treatments.
(B, C) Quantitative analysis of tube formation ability. *P < 0.05, **P < 0.01, ***P < 0.001. N = 3 for each group. All the analyses were performed with one-
way ANOVA. Scale bar = 200 μm.

pure GelMA hydrogel, GelMA-Zn/Si hydrogel showed no compared to pure GelMA and is still suitable for treatment
great changes in mechanical properties. Figure 4G presents application.
typical compressive stress-strain curves of different
hydrogels. The two curves almost coincide, and there is 3.5. Wound healing and regeneration of hair follicle
no difference in compressive modulus between the two in mice models
hydrogels (Figure 4H). To determine whether ions promote in situ hair follicle

The rheological properties of both hydrogels were regeneration in vivo, we introduced a mouse excisional
investigated by frequency sweeping. Storage modulus (G′) model. As shown in Figure 5, there was no significant
and loss modulus (G″) of hydrogels were tested by time difference between the two groups on day 0 in the wound
scanning. Figure 4I indicates that GelMA and GelMA- area. On day 7, the wound area of the control group
Zn/Si hydrogels have an identical point where G′ and greatly decreased, possibly due to the contraction of the
G″ intersected with each other. The viscosities of both wound without moisturizing, but the group showed more
hydrogels have the same tendency with the increasing shear significant scar formation. At the time-point, we found
rate (Figure 4J). Frequency scanning reveals that the value that the GelMA-Zn/Si group had moister and smoother
of G′ is higher than that of G″ within an angular frequency wounds without scar formation than other groups. Pure
range of 0.1–100 rad/s (Figure 4K). The ion release GelMA group also had relatively good wounds, which were
behavior of GelMA-Zn/Si hydrogel was evaluated by ICP. better than hydrocolloid group. On day 14, all the treated
The results showed that the cumulative release of Zn and Si groups almost achieved closure, while the control group
ions reached 0.363 μg/mL and 0.060 μg/mL, respectively, in still presented with detectable unhealed wounds. More
7 days (Figure 4L). For that, 1 mL GelMA-Zn/Si hydrogel interestingly, the GelMA-Zn/Si group had more significant
was soaked in 9 mL PBS, the ion concentration was within hair follicle reappearance in the center of the wound and
biologically active concentration range after conversion. less scar formation based on gross observation, which
Taken together, our results suggest that GelMA-Zn/Si indicates that GelMA-Zn/Si hydrogel can promote in situ
hydrogel has no changes in physicochemical properties hair follicle regeneration and reduce scar formation.

Volume 9 Issue 3 (2023) 206 https://doi.org/10.18063/ijb.703