A Glycovariant of Human CD44 is Characteristically Expressed on Human Mesenchymal Stem Cells

Abstract

The clinical effectiveness of systemically-administered human mesenchymal stem cells (hMSCs) depends on their capacity to engage vascular endothelium. hMSCs derived from bone marrow (BM-hMSCs) natively lack endothelial binding capacity but express a CD44 glycovariant containing N-linked sialyllactosamines that can be α(1,3)-fucosylated using fucosyltransferase-VI (FTVI) to enforce sLeX decorations, thereby creating hematopoietic cell E-/L-selectin ligand (HCELL). HCELL expression programs potent shear-resistant adhesion of circulating cells to endothelial beds expressing E-selectin. An alternative source of hMSCs is adipose tissue (A-hMSCs), and we assessed whether A-hMSCs bind E-selectin and/or possess sialyllactosamine-decorated CD44 accessible to α(1,3)-fucosylation. Similar to BM-hMSCs, we found that A-hMSCs natively lack E-selectin ligands, but FTVI-mediated cell surface α(1,3)-fucosylation induces sLeX expression and robust E-selectin binding secondary to conversion of CD44 into HCELL. Moreover, treatment with the α(1,3)-fucosyltransferase FTVII also generated expression of HCELL on both BM-hMSCs and A-hMSCs, with sLeX decorations created on N-linked glycans of the "standard" CD44 (CD44s) isoform. The finding that hMSCs from both source tissues each lack native E-selectin ligand expression prompted examination of the expression of glycosyltransferases that direct lactosaminyl glycan synthesis. These studies reveal that both types of hMSCs conspicuously lack transcripts encoding α(1,3)-fucosyltransferases but equally express glycosyltransferases critical to creation of sialyllactosamines. Collectively, these data indicate that assembly of a sialyllactosaminyl-decorated CD44s glycovariant is a conserved feature of hMSCs derived from adipose tissue and marrow, thus identifying a CD44 glycosignature of these cells and supporting the applicability of cell surface α(1,3)-fucosylation in programming migration of systemically-administered A-hMSCs to sites of tissue injury/inflammation.

Multiple Roles of Glycans in Hematological Malignancies

“…A CD44 glycoform expressed on primitive CD34 + human hematopoietic progenitor cells is the ligand of both E-selectin ( 86 ) and L-selectin ( 87 ), through sialylated, fucosylated binding determinants on N-glycans. Ex vivo glycan engineering of mesenchymal stromal cell CD44, derived from adipose tissue or marrow ( 88 ), confering the native CD44 glycoform tropism to bone, which is essential for stem cell-based tissue engineering and other adoptive cellular therapies ( 89 ).…”

Cost-Effective, Safe, and Personalized Cell Therapy for Critical Limb Ischemia in Type 2 Diabetes Mellitus

“…Biodistribution and long-term follow-up of these cells in animal models have shown that only a few cells persist after long periods of transplantation. This phenomenon supports the idea that most of the effects of MSCs are probably based on a “ hit and run effect .” To increase the implantation of an ATMP in the injured tissue, Sackstein et al (113), developed a method to transiently modify the CD44 antigen present in the MSC cell membrane by enzymatic fucosylation, converting this molecule into HCELL glycoform and thus favoring the migration of MSCs to the inflamed tissues (111, 115, 116). This method, called glycosyltransferase-programmed stereosubstitution (GPS) to custom modify cell surface glycans without affecting cell viability, has been optimized for its clinical application using an alpha-1,3-fucosyltransferase preparation and enzymatic conditions specifically designed to treat live cells and formulated to preserve the cell viability and phenotype.…”

Post-surgery fluids promote transition of cancer stem cell-to-endothelial and AKT/mTOR activity, contributing to relapse of giant cell tumors of bone

“…In addition, WF pool enriched the expression of CD117 + /CD44 ++ antigens, which become 30% and 75% of cell population, respectively. A high level of CD44 ++ antigen was previously described expressed in MSCs [ 28 ] and was associated with degree of malignancy of GCTB [ 29 ]. Similar results were reported for antigen CD117 + , although detected at very low level (1% of cells) in human biopsies [ 12 ].…”