Aggregation of cells dispersed in packed microgels

Mixtures of different types of living cells within cultured spheroids segregate in space, sometimes forming core-shell distributions. One long-standing potential mechanism behind this process is described by the differential adhesion hypotheses, which states that cells having differing levels of adhesivity will separate into groups. While this hypothesis has been tested in many ways, alternative driving forces have been proposed. To investigate an extreme limit of cell clustering and segregation, we perform studies using only one cell-type at a time, replacing all other cells with passive, non-adhesive microgel particles. Multiple cell types with tunable cadherin densities are dispersed in polyacrylamide microgels at different volume fractions and monitored over time. In this talk, we will present data on the kinetics of aggregation, the physical characteristics of clusters including fractal dimension, and the role of adhesion energy density on aggregates. By treating microgels as passive, non-adhesive “surrogate” cells, we envision testing theoretical models of active matter designed to study cell-cell phase separation, but in this case setting the appropriate parameters to zero.