Device and method for conducting cellular assays using multiple fluid flow

A method for detecting cell-cell interactions comprising:

• (a) providing a substrate having a surface containing a contiguous target region;
• (b) immobilizing a plurality of cells in the contiguous target region;
• (c) placing at least one partitioning wall in contact with the contiguous target region, thereby defining a plurality of distinct exposure zones on the target region;
• (d) maintaining a plurality of fluids each in contiguous laminar flow over the target region, wherein each fluid conveys a cell over a distinct exposure zone, thereby exposing any immobilized cells in the distinct exposure zone to the cell conveyed by the fluid;
• and
• (e) detecting a cell-cell interaction, if present, in any of the distinct exposure zones as a result of the contact or proximity between a cell conveyed by a fluid and an immobilized cell.

A method for exposing a substrate surface to a plurality of fluids, comprising:

• (a) providing
• a substrate having a surface containing a contiguous target region,
• a cover plate having a surface capable of fluid-tight contact with the substrate surface,
• a plurality of fluid-transporting features present in the cover plate surface, the fluid-transporting features separated by at least one partitioning wall representing an integral portion of the cover plate,
• a plurality of inlets, wherein each inlet is in fluid communication with a fluid-transporting feature, and
• at least one outlet associated with the plurality of fluid-transporting features,
• (b) positioning the cover plate surface in fluid-tight contact with the substrate surface such that the at least one partitioning wall contacts the contiguous target region at a location and that each fluid-transporting feature, in combination with the substrate surface, forms a flow passage containing a distinct exposure zone on the target region such that each distinct exposure zone is downstream from the inlet in fluid communication therewith and upstream from the at least one outlet;
• and
• (c) maintaining one or more fluids in laminar flow from one or more sources through the inlets over the target region such that the one or more fluids contact the exposure zones on the target region.