Determination of spheroid growth kinetics
During the spheroid culture process, the growth of MTSs was assessed and
recorded using electron microscopy (Life Technology, Carlsbad, CA, USA)
every 24 h, and the diameter and roundness of MTSs were calculated by
Image Pro Plus 6.0. To determine
the active cell number in the spheroid, 3 cell spheroids were taken
every 24 h, the supernatant discarded, and then digested with Accutase™
cell digestive solution (40506ES60, Yesen, Shanghai, CN) at 37 ℃ for 30
min to form single cell suspension. The suspension was stained by trypan
blue and then counted using
Countstar.