Ex vivo glycan engineering of CD44 programs human multipotent mesenchymal stromal cell trafficking to bone

Abstract

The capacity to direct migration ('homing') of blood-borne cells to a predetermined anatomic compartment is vital to stem cell-based tissue engineering and other adoptive cellular therapies. Although multipotent mesenchymal stromal cells (MSCs, also termed 'mesenchymal stem cells') hold the potential for curing generalized skeletal diseases, their clinical effectiveness is constrained by the poor osteotropism of infused MSCs (refs. 1-3). Cellular recruitment to bone occurs within specialized marrow vessels that constitutively express vascular E-selectin, a lectin that recognizes sialofucosylated determinants on its various ligands. We show here that human MSCs do not express E-selectin ligands, but express a CD44 glycoform bearing alpha-2,3-sialyl modifications. Using an alpha-1,3-fucosyltransferase preparation and enzymatic conditions specifically designed for treating live cells, we converted the native CD44 glycoform on MSCs into hematopoietic cell E-selectin/L-selectin ligand (HCELL), which conferred potent E-selectin binding without effects on cell viability or multipotency. Real-time intravital microscopy in immunocompromised (NOD/SCID) mice showed that intravenously infused HCELL(+) MSCs infiltrated marrow within hours of infusion, with ensuing rare foci of endosteally localized cells and human osteoid generation. These findings establish that the HCELL glycoform of CD44 confers tropism to bone and unveil a readily translatable roadmap for programming cellular trafficking by chemical engineering of glycans on a distinct membrane glycoprotein.

Multipotent mesenchymal stromal cells for autoimmune diseases: teaching new dogs old tricks

“…infused HCELL( þ ) MSCs infiltrated marrow within hours of infusion, with ensuing rare foci of endosteally localized cells and human osteoid generation. 51 MSC homing to tumors is of concern as shown by human MSC localization to a murine xenogenic breast cancer SCID mouse model through monocyte chemotactic protein-1 (MCP-1), 52 which while being a potential therapeutic delivery system for cancer therapy, may pose long-term safety issues in AD treatment. MSCs concentrate in radiation-damaged and ischemic tissue, 53 but as yet active homing mechanisms have not been shown.…”

Enforced hematopoietic cell E- and L-selectin ligand (HCELL) expression primes transendothelial migration of human mesenchymal stem cells

“…Although MSCs have shown therapeutic potential in skeletal diseases (10), myocardial injury, and immunologic disorders (11,12), a critical limitation to the therapeutic use of MSCs is their modest tissue colonization upon systemic administration (13)(14)(15). Importantly, human MSCs (hMSCs) lack expression of various adhesion receptors that mediate step 1 interactions, particularly E-selectin ligands (16). Moreover, in contrast to hematopoietic cells, hMSCs display a rather limited repertoire of chemokine receptors, with variable evidence of functional receptors (17), particularly CXCR4 (16).…”

Mesenchymal stromal cells: a novel and effective strategy for facilitating engraftment and accelerating hematopoietic recovery after transplantation?

“…A possible strategy to facilitate homing of MSCs involves the modification of surface structures that have a role in migration to specific tissues, as suggested by Sackstein et al 44 These authors converted the native CD44 glycoform expressed on MSCs into E-selectin/L-selectin ligand (HCELL) (expressed on HCs) using fucosyltransferase. Intravital micro- Table 2 MSC potential mechanisms that can be hypothesized to be at the basis of their capacity to enhance engraftment/accelerate hematopoietic recovery…”