Engineering amount of cell-cell contact demonstrates biphasic proliferative regulation through RhoA and the actin cytoskeleton.

Endothelial cell-cell contact via VE-cadherin plays an important role in regulating numerous cell functions, including proliferation. However, using different experimental approaches to manipulate cell-cell contact, investigators have observed both inhibition and stimulation of proliferation depending on the adhesive context. In this study, we used micropatterned wells combined with active positioning of cells by dielectrophoresis in order to investigate whether the number of contacting neighbors affected the proliferative response.

Assembly of multicellular constructs and microarrays of cells using magnetic nanowires.

An approach is described for controlling the spatial organization of mammalian cells using ferromagnetic nanowires in conjunction with patterned micromagnet arrays. The nanowires are fabricated by electrodeposition in nanoporous templates, which allows for precise control of their size and magnetic properties. The high aspect ratio and large remanent magnetization of the nanowires enable suspensions of cells bound to Ni nanowires to be controlled with low magnetic fields.

Characterization of the nuclear deformation caused by changes in endothelial cell shape.

We investigated the mechanotransduction pathway in endothelial cells between their nucleus and adhesions to the extracellular matrix. First, we measured nuclear deformations in response to alterations of cell shape as cells detach from a flat surface. We found that the nuclear deformation appeared to be in direct and immediate response to alterations of the cell adhesion area.

Dielectrophoretic registration of living cells to a microelectrode array.

We present a novel microfabricated device to simultaneously and actively trap thousands of single mammalian cells in alignment with a planar microelectrode array. Thousands of 3 Ipm diameter trapping electrodes were fabricated within the bottom of a parallel-plate flow chamber. Cells were trapped on the electrodes and held against destabilizing fluid flows by dielectrophoretic forces generated in the device.

Dielectrophoretic registration of living cells to a microelectrode array.

We present a novel microfabricated device to simultaneously and actively trap thousands of single mammalian cells in alignment with a planar microelectrode array. Thousands of 3 micromdiameter trapping electrodes were fabricated within the bottom of a parallel-plate flow chamber. Cells were trapped on the electrodes and held against destabilizing fluid flows by dielectrophoretic forces generated in the device.

Repositioning of cells by mechanotaxis on surfaces with micropatterned Young's modulus.

Adherent cells are strongly influenced by the mechanical aspects of biomaterials, but little is known about the cellular effects of spatial variations in these properties. This work describes a novel method to produce polymeric cell culture surfaces containing micrometer-scale regions of variable stiffness. Substrates made of acrylamide or poly(dimethylsiloxane) were patterned with 100- or 10-microm resolution, respectively.

Cells lying on a bed of microneedles: an approach to isolate mechanical force.

We describe an approach to manipulate and measure mechanical interactions between cells and their underlying substrates by using microfabricated arrays of elastomeric, microneedle-like posts. By controlling the geometry of the posts, we varied the compliance of the substrate while holding other surface properties constant. Cells attached to, spread across, and deflected multiple posts.