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International Journal of Bioprinting Expanding 3D cell proliferation with DLP bioprinting

characteristics. 41,59 These characteristics allow the cells at day 1 following incubation. Cell viability continued
encapsulated in the F-GelMA hydrogel to exhibit better to increase at days 3 and 5, reaching 94.56 ± 3.34% and
diffusion, movement, and proliferation. Therefore, the 96.84 ± 4.33%, respectively, and 99.39 ± 0.66% at day 7, a
layered structure within the F-GelMA hydrogel printed statistically significant difference from the group at day 1
by the DLP printing method was observed, and the pores (p < 0.01) (Figure 3C). Since 2D cultures grow by adhering
within each layer were predicted to serve as pathways for to cross-section, there is limited space for cell adhesion
the transport of oxygen and nutrients necessary for cell and proliferation during long-term culture compared
attachment and proliferation, providing a space for cell to 3D cultures. However, the printed GelMA hydrogels
60
attachment and proliferation. are predicted to promote cell adhesion by providing a
microcellular environment for cell culture. 51
3.3. Cell viability analysis on F-GelMA hydrogel
printed by DLP Difficulties in distributing cells arise evenly using
In this study, cell viability on F-GelMA hydrogels printed extrusion-based 3D printing methods due to the
by DLP was analyzed and evaluated. A Live/Dead assay accumulation of cells at the bottom caused by gravity. 61
was performed on the control group of cells cultured in Therefore, in this study, we utilized the advantages of DLP
2D culture (Figure 3A). Cell viability was 75.49 ± 9.58% printing to encapsulate cells in a hydrogel and achieve

Figure 3. Cell viability on printed F-GelMA hydrogel by digital light processing (DLP). (A, B) Fluorescence images of a Live/Dead assay of fibroblasts
on 2D culture for 1, 3, 5, and 7 days and the surface of printed hydrogel for 1, 3, 5, 7, 14, 21, 28, and 35 days. Live cells produce green fluorescence, and
dead cells show red fluorescence. Scale bars: 500 µm. (C) Cell viability of 2D culture was determined using Live/Dead assay. Data are shown as means ± SD
(n = 3). *p < 0.05, **p < 0.01 vs. time course 1 day, and data are analyzed by one-way ANOVA followed by Tukey’s post-hoc test. (D) Using the Live/Dead
assay, 2D cell viability is determined on printed hydrogels. Data are shown as means ± SD (n = 3). *p < 0.05, **p < 0.01, ***p < 0.001 vs. time course 1 day
and between the indicated groups. Data are analyzed by a one-way ANOVA followed by Tukey’s post-hoc test.

Volume 10 Issue 3 (2024) 415 doi: 10.36922/ijb.2219