Cell deformability is an important emerging bio-marker for a number of disease states. Deformability is indicative of underlying membrane, cytoskeletal or nuclear changes associated with a wide range of cell functional changes, such as differentiation or mitosis, or disease processes (e.g. cancer). Dr David Holmes (a Principal Engineer at Sphere Fluidics) and collaborators at University College London, University of Cambridge, University of Erlangen and the Technical University Dresden have just published a paper in the Royal Society’s journal Interface Focus ( Separation of Blood Cells with Differing Deformability Using Deterministic Lateral Displacement, http://bit.ly/1tcceUB, Published on October 24th 2014 doi: 10.1098/rsfs.2014.0011).
This work demonstrates a method for separating cells based on differences in their mechanical phenotype (i.e. stiffness). Cell stiffness was independently measured using optical stretching techniques and was demonstrated to correlate with cell separation in the microfluidic device. This work, taken together with recent numerical modelling work, will contribute to the development of devices for deformability-based separations for disease diagnostics and biological sample preparation.
Fig.1 Schematic showing the fluid streamlines (at low Reynolds number) through an array of pillars. Each column is shifted vertically by ɛλ relative to the previous column, where λ is the inter-pillar distance, ɛ is the column shift fraction and g the gap between the pillars. The flow between the pillars is assumed to be parabolic with streamlines being divided by stall lines which begin and terminate on the pillars. The horizontal flow velocity is indicated by the colour intensity.
Fig.2 (a) shows a schematic of the optical stretcher set-up and a cell undergoing stretching. Treatment of cells with different concentrations of glutaraldehyde resulted in well-defined increases in cell stiffness. Fig.2 (b) shows images from the cell stretching experiments for a range of different concentrations of glutaraldehyde. The optical stretcher data showed a monotonic increase in cell stiffness with increasing glutaraldehyde concentration up to concentrations of approximately 0.02%. Fig. 2(c) shows stretch data up to 0.003% glutaraldehyde concentration.
Source from: Spherefluidics