Abstract
We introduce a microfluidic device for chemical manipulation and mechanical investigation of circulating cells. The device consists of two crossing microfluidic channels separated by a porous membrane. A chemical compound is flown through the upper “stimulus channel”, which diffuses through the membrane into the lower “cell analysis channel”, in which cells are mechanically deformed in two sequential narrow constrictions, one before and one after crossing the stimulus channel. Thus, this system permits to measure cell deformability before and after chemical cues are delivered to the cells within one single chip. The validity of the device was tested with monocytic cells stimulated with an actin-disrupting agent (Cytochalasin-D). Furthermore, as proof of principle of the device application, the effect of an anti-inflammatory drug (Pentoxifylline) was tested on monocytic cells activated with Lipopolysaccharides and on monocytes from patients affected by atherosclerosis. The results show that the system can detect differences in cell mechanical deformation after chemical cues are delivered to the cells through the porous membrane. Diffusion of Cytochalasin-D resulted in a considerable decrease in entry time in the narrow constriction and an evident increase in the velocity within the constriction. Pentoxifylline showed to decrease the entry time but not to affect the transit time within the constriction for monocytic cells. Monocytes from patients affected by atherosclerosis were difficult to test in the device due to increased adhesion to the walls of the microfluidic channel. Overall, this analysis shows that the device has potential applications as a cellular assay for analyzing cell-drug interaction.
Highlights
Blood cell deformability can affect vascular flow and can play a significant role in cardiovascular diseases, such as chronic inflammatory diseases
While flowing only the buffer in the upper stimulus channel, we observed that cells recovered completely in the serpentine channel from the deformation in the first constriction, and that, upon complete cell recovery, entry time and cell velocity in the second constriction were not affected by cell transit in the first constriction at any analyzed flow rates
We have introduced and characterized a microfluidic device that permits the investigation of cellular mechanical response to biochemical stimuli at single cell level in a physiologically relevant microenvironment
Summary
Blood cell deformability can affect vascular flow and can play a significant role in cardiovascular diseases, such as chronic inflammatory diseases. It is of significant importance to study mechano-biological changes of diseased circulating cells in the development of a new treatment. Microfluidics is being regarded as an excellent platform for cellbased assays since it enables analysis at the single cell level in an in vivo-like environment, allowing for controlled cell and biomolecule manipulation and interrogation, while still offering the perspective to analyze many cells within a short time. Controlling diffusion of chemical agents in a microfluidic device permits to realize a stable chemical gradient that can be maintained for prolonged periods of time, or create stable concentration levels of chemicals relevant for cellular assays. Microfluidic-based cell platforms can be used to generate biomolecular gradients mimicking biological signaling occurring in vivo, and to test concentration-dependent cellular response to chemical treatments
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