Meeting Abstract
Increasing evidence suggests that mechanical forces play critical roles in development, physiology, and diseases. Reports have implicated stresses to be important in regulating cell and tissue functions in embryogenesis and in tumors. However, no methods exist that can quantify compressive stresses between living cells or in living tissues in situ. Using self-designed microfluidic channels, we generated cell-sized, fluorescent nanoparticles-labeled, mono-disperse elastic microspheres made of Arg-Gly-Asp conjugated alginate hydrogels (elastic round microgels, ERMs). Using confocal fluorescence microscopy to image ERMs after they were trapped between cell layers or in a cell colony, we generated 3D displacement maps with fast iterative digital volume correlation and calculated strains, normal and shear tractions exerted on the ERMs. We found that average compressive tractions are ~570 Pa between cell layers and are ~360 Pa in a cell colony of tumor-repopulating cells (TRCs) grown in a fibrin gel of 400 Pa in elastic stiffness. Surprisingly, the compressive stresses were substantially heterogeneous on the ERMs within a seemingly uniform melanoma colony and did not increase with the colony size of the TRCs. Substantial local compressive, tensile, and shear stresses were exerted to an ERM by cells of developing zebrafish embryos several hours post fertilization. Our findings suggest that this ERM method is useful for quantifying stresses (compressive, tensile, and shear) between living cell layers and in living tissues.
