Microfluidic platforms for multi-protein crosstalk and its application on cell sorting
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This thesis describes the development of two platforms for cell receptor crosstalk study and their applications to several problems in cellular engineering. The first platform of an auto-alignment protein patterning approach allows moving cells to interact with spatially separated ligands sequentially, thus dissecting the crosstalk between different receptors by detangling the ligand interactions and the effect of triggering. This system was applied to provide independent evidence for the presence of an intermediate state of the major integrins on platelets and leukocytes. An intermediate state of integrin αIIbβ3 was demonstrated by triggering GPIb on one zone and measuring platelet adhesion to FN or antibodies on another zone. Furthermore, the increased αIIbβ3 binding upon triggering was suggested in diabetic platelets. The intermediate state of integrin LFA-1 was similarly studied on human neutrophils and mouse T lymphocytes. The second system is to sort antigen-specific T cells based on TCR triggering. The sorting chip first triggers T cells by specific pMHC and then allows activated T cells to move laterally on a patterned ICAM-1 surface to separate cells. The approach for studying cell multi-receptor crosstalk is generalizable to various receptor mechanobiology and can be applied to mechanistic studies to potential clinical applications. The platform for functional antigen-specific T cell sorting should be valuable in clinical diagnoses and functional immunotherapies.