Sialyl-N-acetyllactosamine (sLN)

Cell-surface sialyl Lewis X (sLeX) precursor glycans, specifically sialyl-N-acetyllactosamine (sLN), are carbohydrate structures that serve as the essential substrate for the synthesis of functional sLeX (CD15s) (Sackstein, 2009, Nature Medicine). These precursors are widely expressed on the surface of various therapeutic cells, including Mesenchymal Stem Cells (MSCs) and certain T cell subsets, but they lack the fucose modification required for binding to E-selectin (Abdi et al., 2011, Blood). E-selectin is a vascular adhesion molecule upregulated at sites of inflammation and in the bone marrow microenvironment. Because many therapeutic cell types lack the endogenous fucosyltransferases (e.g., FUT6 or FUT7) to complete the sLeX structure, their ability to home to target tissues is often severely limited (Dykstra et al., 2016, Stem Cells). By targeting these precursor glycans through ex vivo enzymatic fucosylation—a process known as Glycosyltransferase Programmed Stereosubstitution (GPS)—the cells can be engineered to express high levels of functional sLeX (Sackstein, 2011, JBC). This modification enhances the rolling and tethering steps of the adhesion cascade, significantly improving the delivery and engraftment of cell therapies in inflammatory and regenerative medicine contexts (Xia et al., 2004, Nature Medicine).

Other names

Sialyl Lewis X precursorCD15s precursorNeu5Ac-alpha-2,3-Gal-beta-1,4-GlcNAcType 2 lactosamine precursorSialylated N-acetyllactosamine

Enzymatic alpha-1,3-fucosylation of terminal sialyl-N-acetyllactosamine to create functional sialyl Lewis X (sLeX) ligands for E-selectin binding.