Micro glass ball embedded gels to study cell mechanobiological responses to substrate curvatures

The effects of substrate stiffness on cell behaviors have been extensively studied; however, the effects of substrate curvature are not well documented. The curvature of the surface to which cells adhere can have profound effects on cell behaviors. To reveal these cell mechanobiological responses to substrate curvatures, here we introduce a novel, unique, simple, and flexible class of substrates, polyacrylamide gels embedded with micro glass balls ranging in diameter from 5 μm to 2 mm, to culture cells. NIH-3T3 fibroblasts were cultured on these glass ball embedded gels. Morphologies of cells growing on glass balls were analyzed by using an optical microscope and a 3D confocal laser scanning microscope. The cell behaviors on micro cylindrical glass tubes having similar diameters to the glass balls were also compared. It is observed that the fibroblasts were sensitive to the curvatures of the glass balls. Significant differences in cell attachment rate, migration speed, and morphology were noted for cells cultured on glass balls of diameters at or below 500 μm, compared to those on glass balls of larger diameters. Cell spread area increased as a function of the ball diameter with three different slopes in the three distinct regions depending on the ball diameter. To the best of our knowledge, this is the first experimental attempt to study cell responses to spherically shaped substrates. These cell culture experiments imply that this class of substrates, micro glass ball embedded gels, can be useful tools to study cell mechanobiological responses to substrate curvatures, related cell and tissue engineering researches, and biomedical applications.