Variation
in microsphere size and stiffness over time. (A–L)
Phase-contrast images of breast cancer cells encapsulated within PF
microspheres demonstrate variations in size distribution and cellular
appearance of MCF7 and MDA-MB-231 cells. (A,C,E,G,I,K: scale bar =
1000 μm; B,D,F,H,J,L: scale bar = 200 μm). (M) Quantification
of the microsphere diameter reveals a significant reduction in size
for both cell types over 14 days in culture (*p <
0.05, n = minimum of 50 microspheres). Red circles
denote individual microspheres, blue diamonds denote the mean, while
rectangular boxes represent lower quartiles, medians, and upper quartiles
of the respective groups. (N) Quantification of the elastic modulus
reveals a significant increase in MCF7 microsphere stiffness but no
variation in MDA-MB-231 microsphere stiffness over time. The acellular
microsphere stiffness is significantly low compared to that of the
cell-laden microspheres for both cell types. (*,#p < 0.05, n = 3 microspheres per group).