Figure 6.

Mechanical stimulation on epithelial cell behaviors by hydrogel‐based platforms. A) 3D bar graph of mechanical stimulation on epithelial cells for various cell activities and biomedical applications. The research conditions are evaluated based on h‐index of each field were calculated by paper publication and citation data from Scopus. B) Immunofluorescence images of podocytes cultured on polyacrylamide hydrogels which elasticity ranging between 0.6 and 44 kPa and have different actin cytoskeleton architecture and podocin levels. Cell nucleus, actin cytoskeleton, and podocin protein are stained by blue DAPI, green phalloidin, and red antipodocin dye, respectively. Reproduced with permission.^{[ 243 ]} Copyright 2019, American Chemical Society. C) Schematic illustration of dynamic irradiation stiffening/softening hydrogel. The nanorods generate heat under irradiation and result in calcium/chelator releasing from liposome. Adapted with permission.^{[ 248 ]} Copyright 2015, National Academy of Sciences. D) Mechanism illustration of matrix (gel) stiffness‐modulated mammary epithelial cell spreading through mechanotransduction (TGF‐β and YAP). Adapted with permission.^{[ 251 ]} Copyright 2019, National Academy of Sciences. E) Schematic illustration of hydrogel magnetic stiffening and representative immunofluorescence images of induced epithelial cell morphology switch. Reproduced with permission.^{[ 253 ]} Copyright 2021, American Chemical Society. F) Schematic illustration of internal fiber alignment modulation by external magnetic field, and transmitted light image of superparamagnetic iron oxide nanoparticles (red arrows) within electrospun dextran vinyl sulfone fibers. Reproduced with permission.^{[ 254 ]} Copyright 2021, Frontiers Media S.A. G) Schematic illustration of the protrusion/retraction activities during relaxation phase which cause cell reorientation in response to uniaxial cyclic stretching. Reproduced with permission.^{[ 258 ]} Copyright 2021, Springer Nature.