| Abstract
| - Cell rolling is an important physiological and pathological process that is used to recruit specific cells in thebloodstream to a target tissue. This process may be exploited for biomedical applications to capture and separatespecific cell types. One of the most commonly studied proteins that regulate cell rolling is P-selectin. By coatingsurfaces with this protein, biofunctional surfaces that induce cell rolling can be prepared. Although most immobilizationmethods have relied on physisorption, chemical immobilization has obvious advantages, including longer functionalstability and better control over ligand density and orientation. Here we describe chemical methods to immobilizeP-selectin covalently on glass substrates. The chemistry was categorized on the basis of the functional groups onmodified glass substrates: amine, aldehyde, and epoxy. The prepared surfaces were first tested in a flow chamberby flowing microspheres functionalized with a cell surface carbohydrate (sialyl Lewis(x)) that binds to P-selectin.Adhesion bonds between P-selectin and sialyl Lewis(x) dissociate readily under shear forces, leading to cell rolling.P-selectin immobilized on the epoxy glass surfaces exhibited enhanced long-term stability of the function and betterhomogeneity as compared to that for surfaces prepared by other methods and physisorbed controls. The microsphererolling results were confirmed in vitro with isolated human neutrophils. This work is essential for the future developmentof devices for isolating specific cell types based on cell rolling, which may be useful for hematologic cancers andcertain metastatic cancer cells that are responsive to immobilized selectins.
|
