*2.2. Evaluation of Cellular Viability*

Qualitative analysis of the cell spheroids for cellular viability was done using the Live/Dead assay kit (Molecular Probes, Eugene, OR, USA). These spheroids were washed twice with the growth media

before calcein acetoxymethyl (Molecular Probes) and ethidium homodimer-1 (Molecular Probes) were added for an incubation period of 30 min at room temperature. Then, the spheroids were evaluated using a fluorescence microscope (Axiovert 200; Zeiss, Oberkochen, Germany) on Days 3 and 7.

Quantitative analysis of cell viability was performed using the cell counting kit-8 (CCK-8; Dojindo, Tokyo, Japan) on Days 1, 3, 5, and 7. WST-8 solution was added to the stem cell spheroids, which were then cultured for 45 min at 37 ◦C. Absorbance was measured using a microplate reader at 450 nm (BioTek, Winooski, VT, USA).
