(516b) Surface Immobilization of P-Selectin Glycoprotein Ligand-1 On Mesenchymal Stem Cells Enables Selectin Mediated Cell Tethering and Rolling

Mesenchymal stem/stromal cells (MSCs) are an important candidate for cell-based therapy since they can be easily isolated and expanded, secrete beneficial paracrine factors, and differentiate into multiple lineages. Since the endothelium at sites of injury and inflammation often express adhesion molecules belonging to the selectin family, methods to endow MSCs with selectin-ligands can enhance the efficacy of cell delivery and tissue engraftment. Here, we describe a construct 19Fc[FUT7⁺], where the first 19 amino acids of the pan-selectin ligand PSGL-1 (P-selectin glycoprotein ligand-1) was fused to a human IgG1. When expressed in HEK293T cells over-expressing the α(1,3)fucosyltransferase FUT7, 19Fc[FUT7⁺] is decorated by a core-2 sialyl Lewis-X sialofucosylated O-glycan. The non-covalent coupling of this protein onto MSC surface using palmitated protein G (PPG) enhanced cell binding to E- and P-selectin under hydrodynamic shear, without altering MSC multipotency. MSCs functionalized with 19Fc[FUT7⁺] were captured/tethered onto stimulated endothelial cell monolayers at wall shear stresses up to 4 dyn/cm². Once captured, the cells rolled robustly up to the highest shear stress tested, 10 dyn/cm². Unlike previous work where MSCs could only be captured onto selectin-bearing substrates at low or no-flow conditions, the current work presents a robust strategy to enable leukocyte-like capture and rolling.