(237a) Mechano-Evolution Results in Novel Cellular Phenotypes

The fact that cellular properties and functions are governed by mechanical properties of the substrate has been well established in literature. Cells attain distinct set of phenotypes (like cell spreading area, focal adhesion area, nuclear height, YAP localization) and functions (like growth rate, migration speed, traction) on substrates of different rigidity and it is termed as ‘phenotypic plasticity’ by evolutionary biologists. Our hypothesis is that cause of this phenotypic plasticity could be natural selection by the mechanical properties of the substrate, i.e., the substrate selects for the phenotype that has higher fitness than the alternate phenotype. To test this hypothesis, we performed sustained culture of a genetically variable cell population on soft (E= 1kPa) and stiff (E= 308 kPa) polyacrylamide gels. We chose NIH 3T3 fibroblasts which have been cultured on tissue culture plastic (stiff substrate) for decades and are expected to be well-adapted on stiff substrate. As per our hypothesis, when we expose the genetically variable fibroblast populations to a novel soft substrate for a long time, the soft substrate should select for the phenotype that is optimal for survival of the population on that stiffness. This would open the possibility of engineering cells with novel properties by allowing them to evolve on biomaterials of different stiffness.