Lateral view flow system for studies of cell adhesion and deformation under flow conditions

Physical interactions between circulating cells and the vascular wall play a central role in inflammation, metastasis, atherosclerosis, and therapeuti c cell delivery. Unfortunately, traditional in vitro flow assays cannot be used to visualize the details of cell-surface interactions in blood flow be cause of inappropriate geometry and the poor penetration of light in erythr ocyte solutions. To overcome these obstacles, we have developed an agarose- cast cylindrical vessel system to examine the profiles of cells interacting with surfaces under flow conditions. This design allows observation and qu antification of cell deformations as cells adhere to surfaces under dynamic flow conditions without modifying the microscope or optical path. Furtherm ore, our flow system is uniquely suited for monitoring the profiles of adhe rent leukocytes deforming in response to erythrocyte suspension flow. We ha ve used this flow system to study the role of erythrocytes in leukocyte-sub strate interactions. Our results show that the cell deformation index (the ratio of the cell length of cell height) is higher in erythrocyte solutions compared to erythrocyte-free saline. This novel lateral view flow system p rovides a powerful technique for visualizing and quantifying the morphologi cal changes of cells in contact with substrates exposed to shear stress.