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International Journal of Bioprinting Skin bioprinting: Keratinocytes and stem cells

Figure 14. Storage modulus and complex modulus of printed constructs on days (d) 1, 7, and 14 at 37°C (n = 3). Data are represented as mean ± standard
deviation. Abbreviations: ADSC, adipose-derived stem cell; Alg, alginate; Gel, gelatin; GelMA, gelatin methacryloyl; HA, hyaluronic acid.

living cells strongly correlated with the metabolic activity Two-way ANOVA revealed a significant difference
of cells at the well bottom (i.e., correlation coefficient of 1 in cell viability between the hydrogels. The viability of
for both hydrogels). cells within GelMA constructs was significantly higher
The bioprinted constructs containing HaCaT and compared to those in Alg/HA/Gel constructs on days 7
ADSCs displayed a steady increase in living cells over the and 14. Moreover, the cell type significantly affected the
experimental period (Figure 12A). Experimental groups results. The ratio of living cells within the constructs was
containing both HaCaT and ADSCs revealed significantly higher for ADSCs compared to that of HaCaT. On days 1
higher cell viability on days 7 and 14 compared to day 1. and 4, the ratio of living cells within GelMA constructs was
Figure 13 features the cell viability within the biofabricated significantly higher for ADSCs than for HaCaT. On days
constructs of all experimental groups. Within the 7 and 14, the survival of ADSCs was significantly higher
constructs, two-way ANOVA revealed a significant role than that of HaCaT for the constructs of both hydrogel
of time for the total number of cells and number of living types. Cell viability and metabolic activity of cells within
cells per region of interest (ROI). Furthermore, on days the biofabricated constructs indicate a strong correlation
7 and 14, the total number of cells and number of living for Alg/HA/Gel (correlation coefficient: 0.75) and GelMA
cells per ROI within GelMA constructs with HaCaT was (correlation coefficient: 0.98).
significantly higher than that of day 1. On day 14, the total
number of cells per ROI within the GelMA constructs 3.3.4. Stiffness analysis
with HaCaT was significantly higher compared with The rheological behavior of the bioprinted constructs
the respective Alg/HA/Gel constructs. In contrast to the was measured on days (d) 1, 7, and 14. All biofabricated
constructs containing only HaCaT, constructs containing constructs had a higher storage modulus than loss modulus
HaCaT and ADSC in co-culture displayed an increasing on all days, confirming the gel-like behavior of the
trend in live cell count over the 14 days. hydrogels. Figure 14 features the viscoelastic properties of

Volume 10 Issue 6 (2024) 276 doi: 10.36922/ijb.3925