Xds 3fl

The viability of the cells encapsulated in microgels were evaluated using LIVE/DEAD Cell Viability Assay kit (Thermo Fisher), following the manufacturer’s instructions. Briefly, the cell-laden microgels were treated with calcein-AM and ethidium homodimer-1 to fluorescently label live (green) and dead (red) cells. The cells were visualized with a fluorescent microscope (XDS-3FL, Optika, Ponteranica, BG, Italy) and counted. The viability was reported as the percentage of live cells from the total number of cells. The viability was measured at various time points.
The proliferation rate (k) of encapsulated cells was determined by counting the number of live cells at various time points, and the plot of the normalized number of viable cells (N_t/N₀) vs. time (t) was fitted with the following power-law equation,
$\frac{N_t}{N_0}\hspace{0.17em}=\hspace{0.17em}{2}^{k·t}$
N_t was the number of viable cells at time, t, and N₀ was the initial number of viable cells at t = 0 [23 (link),37 (link)].

Primary human adult dermal fibroblasts (NHDF-Ad, Lonza) were used in this study. The cells were cultured in Dulbecco,s modified Eagle,s medium supplemented with 1% penicillin/streptomycin and 10% fetal bovine serum (Thermo Fisher). The fibroblasts were dispersed in the precursor solution (1 × 10⁶ cells ml^–1) and incubated for 2 h with gentle shaking to induce cell adhesion to nanofibers prior to hydrogel formation. The precursor solution was then exposed to an external magnetic field, as described above, to induce the nanofiber alignment. After hydrogel was made by photocrosslinking, the cell-laden hydrogels were immersed in the cell culture medium and continuously cultured at 37 °C under 5% CO₂.
To evaluate the viability of encapsulated cells, the cells were fluorescently labeled with calcein-AM and ethidium homodimer-1 to distinguish live (green) and red (dead) cells, respectively (LIVE/DEAD Cell Viability/Cytotoxicity Kit, Thermo Fisher) [44 ]. The cells were visualized under a fluorescence microscope (XDS-3FL, Optika).