Motility-based cell sorting by planar cell chromatography

Shape of scaffold controlling the direction of cell migration

Cell migration plays an important role in the development and maintenance of multicellular organisms. Factors that induce cell migration and mechanisms controlling their expression are important for determining the mechanisms of factor-induced cell migration. Despite progress in the study of factor-induced cytotaxis, including chemotaxis and haptotaxis, precise control of the direction of cell migration over a wide area has not yet been achieved. Success in this area would update the cell migration assays, superior cell separation technologies, and artificial organs with high biocompatibility. The present study therefore sought to control the direction of cell migration over a wide area by adjusting the three-dimensional shape of the cell scaffold. The direction of cell migration was influenced by the shape of the cell scaffold, thereby optimizing cell adhesion and protrusion. Anisotropic arrangement of these three-dimensional shapes into a periodic structure induced unidirectional cell migration. Three factors were required for unidirectional cell migration: 1) the sizes of the anisotropic periodic structures had to be equal to or lower than the size of the spreading cells, 2) cell migration was restricted to a runway approximately the width of the cell, and 3) cells had to be prone to extension of long protrusions in one direction. Because the first two factors had been identified previously in studies of cell migration in one direction using two-dimensional shaped patterns, these three factors are likely important for the mechanism by which cell scaffold shapes regulate cell migration.

Directed cell migration in co-cultures by topographic curvature for heterogeneous tissue engineering

Placing cells in the proper position is important for tissue engineering. Previous works addressed this subject in the way of controlling cell migration by micro- or nano-patterning the substrates. However, the problem of changing spatial cell density freely under co-culture conditions is remaining. To solve this problem, in this work, we report that C2C12 spatial cell density changes by the patterning geometric boundary of the topographical structures. In 48 h after seeding cells, at the linear boundary (ridge-groove) structures, C2C12 Groove/Ridge ratio was under 0.70 both under monoculture conditions and under co-culture conditions. In contrast, at the combining the linear boundary and the round boundary (ridge-groove + hole) structures, the ratio was over 0.89 under both culture conditions. This our finding will provide a new device which enables to manipulate spatial cell density under co-culture conditions for heterogeneous tissue engineering.

Ratchetaxis: Long-Range Directed Cell Migration by Local Cues

Directed cell migration is usually thought to depend on the presence of long-range gradients of either chemoattractants or physical properties such as stiffness or adhesion. However, in vivo, chemical or mechanical gradients have not systematically been observed. Here we review recent in vitro experiments, which show that other types of spatial guidance cues can bias cell motility. Introducing local geometrical or mechanical anisotropy in the cell environment, such as adhesive/topographical microratchets or tilted micropillars, show that local and periodic external cues can direct cell motion. Together with modeling, these experiments suggest that cell motility can be viewed as a stochastic phenomenon, which can be biased by various types of local cues, leading to directional migration.

Gradient-free directional cell migration in continuous microchannels

Directing cell movements within 3D channels is a key challenge in biomedical devices and tissue engineering. In two dimensions, closely spaced arrays of asymmetric teardrop islands can intermittently polarize cells and sustain their autonomous directional migration with no gradients. However, in 3D microchannels composed of linearly connected teardrop segments, negligibly low directional bias is observed. Rather than adopt teardrop shapes, cells evade morphological polarization by spreading across multiple teardrop segments, only partly filling each. We demonstrate here that cells can be forced to adopt the shape of individual segments by connecting the segments at an angle to minimize cell spreading across multiple segments. The resulting rhythmic polarization leads to significant directional bias for NIH3T3 fibroblasts, epithelial cells, and even cells whose intracellular signalling have been purposely altered to affect lamellipodia extension (Rac1) and cell polarity (Cdc42). This gradient-free approach to directing cell migration in 3D microchannels may find significant applications in tissue scaffolds and cell on a chip devices.