Engineered ridge and micropillar array detectors to quantify the directional migration of fibroblasts

Abstract

Cell migrations on substrates are important in diverse processes such as wound healing, embryogenesis, and pathologies like cancer metastasis. An understanding of the cellular mechanobiology during migration requires development of suitable engineering platforms to better represent the anisotropic in vivo cellular environment and measure traction forces due to cell adhesion. We fabricated a custom elastomeric micropillar array detector (mPAD), comprised of alternate ridge and pillar topographical features, using a lithographic fabrication method that creates an anisotropic microenvironment and also permits the measurement of traction forces. We used the finite element method to compare predictions of calculated tractions for pillar geometries with different aspect ratios using linear and nonlinear constitutive models. These simulations showed the importance of pillar aspect ratios and constitutive models in computing resulting tractions. We cultured 3T3 fibroblasts on the engineered mPAD and characterized cellular migrations over a three hour period. Our results show highly elongated cellular and nuclear morphologies on the mPAD substrates as compared to cells cultured on control elastomeric substrates. Cells on mPADs demonstrated persistent directional motion along ridges as compared to random movements on control substrates. These results showed the importance of substrate anisotropy in the alignment of fibroblasts on mPAD. We also measured differences in the cellular tractions along the length of the cell on mPAD substrates. Engineered mPADs are hence useful in directing cellular motions and in delineating mechanobiological processes during adhesion and migration.