Ultra-fast transient cell adhesion and its application for high-throughput microfluidic cell sorting

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Biological cells use various adhesion molecules on their surfaces to interact with each other and their environment. The type, amount, and combination of these adhesion molecules, which carry important information about specific cell conditions, can be used to characterize cells and diagnose disease. Sorting and separating cells based on their expressions of adhesion molecules are critical steps in many biomedical assays. Current cell sorting approaches use tags that bind to cells expressing specific adhesion molecules. These attached tags enable high purity sorting, but the tags can alter cell state and can lead to unwanted cell activation preventing further use of the labeled cells. This project will develop a microfluidic technology that enables rapid and efficient sorting of biological cells based on the expression of adhesion molecules without the use of any tags or labels. The technology utilizes a microfluidic channel with periodic constrictions coated with molecules that briefly interact adhesion molecules on the cells' surfaces. The interaction causes a change in the trajectories of the cells of interest without inducing unwanted activation. The project will investigate the mechanics of cell interactions within the microchannel and will probe the use of this microfluidic separation technique to isolate lymphocytes with highly specific adhesion molecules that can be used in cancer therapies. The research will involve undergraduate and graduate students, and the team will conduct several outreach activities to students at all levels, including developing projects for science and engineering competitions.This project will develop a microfluidic approach for high-throughput, label-free cell sorting and separation based on the affinity of molecular surface markers for target ligands. Identifying and isolating cells that express desired molecular surface markers are required in a variety of applications in the biological sciences, cell therapy, and medical diagnostics. The project will integrate microfluidic experiments and computer simulations to examine transient adhesion of biological cells at ultrafast time scales that have not yet been explored. Cells will be propelled through a microfluidic channel decorated with diagonal ridges that slightly compress the cells to promote binding between adhesion molecules and ligands covering the microchannel surfaces. The binding events alter cell trajectories in the microchannel characterizing cell adhesion. The short contact time between cells and microchannel surfaces will prevent unwanted cell activation. The project will systematically probe effects of confinement on transient cell adhesion for a wide range of time scales. Furthermore, the project will employ the microfluidic cell sorting technique to examine T cell selectivity to target antigens, which is important in clinical applications, without activating the cells. Positive and negative selection to T cell neoantigens will be investigated to identify disease-selective T cells. The results of this research project, a new microfluidic method for high-throughput label-free cell separation, will have broad implications in medical diagnostics, therapeutics, cell engineering, and cell manufacturing. Furthermore, the microfluidic method can enable direct measurements of transient interactions between important physiological ligands and adhesive cell molecules that will benefit the development of novel diagnostic methods.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.