Cell Surface Engineering of Mesenchymal Stem Cells

Abstract

By leveraging the capacity to promote regeneration, stem cell therapies offer enormous hope for solving some of the most tragic illnesses, diseases, and tissue defects world-wide. However, a significant barrier to the effective implementation of cell therapies is the inability to target a large quantity of viable cells with high efficiency to tissues of interest. Systemic infusion is desired as it minimizes the invasiveness of cell therapy, and maximizes practical aspects of repeated doses. However, cell types such as mesenchymal stem cells exhibit a poor homing capability or lose their capacity to home following culture expansion (i.e. FASEB J 21:3197-3207, 2007; Circulation 108:863-868, 2003; Stroke: A Journal of Cerebral Circulation 32:1005-1011; Blood 104:3581-3587, 2004). To address this challenge, we have developed a simple platform technology to chemically attach cell adhesion molecules to the cell surface to improve the homing efficiency to specific tissues. This chemical approach involves a stepwise process including (1) treatment of cells with sulfonated biotinyl-N-hydroxy-succinimide to introduce biotin groups on the cell surface, (2) addition of streptavidin that binds to the biotin on the cell surface and presents unoccupied binding sites, and (3) attachment of biotinylated targeting ligands that promote adhesive interactions with vascular endothelium. Specifically, in our model system, a biotinylated cell rolling ligand, sialyl Lewisx (SLeX), found on the surface of leukocytes (i.e., the active site of the P-selectin glycoprotein ligand (PSGL-1)), is conjugated on MSC surface. The SLeX engineered MSCs exhibit a rolling response on a P-selectin coated substrate under shear stress conditions. This indicates that this approach can be used to potentially target P-selectin expressing endothelium in the more marrow or at sites of inflammation. Importantly, the surface modification has no adverse impact on MSCs' native phenotype including their multilineage differentiation capacity, viability, proliferation, and adhesion kinetics. We anticipate that the present approach to covalently modify the cell surface and immobilize required ligands is not limited to MSCs or the SLeX ligand. Therefore, this technology should have broad implications on cell therapies that utilize systemic administration and require targeting of cells to specific tissues. The approach may also be useful to promote specific cell-cell interactions. In this protocol, we describe the conjugation of SLeX on MSC surface and methods to study cell rolling behaviors of SLeX-modified MSCs on a P-selectin coated substrate using an in vitro flow chamber assay. We also provide a brief description of cell characterization assays that can be used to examine the impact of the chemical modification regimen.

Synapse-directed delivery of immunomodulators using T-cell-conjugated nanoparticles

“…In contrast, stable chemical conjugation of drug-loaded NPs to the surface of T-cells provides a means for synapse-directed delivery of compounds, where tiny doses of drug can be bioactive and thereby limiting exposure of healthy tissue to toxic side effects. Beyond adoptive T-cell therapy for cancer, our studies hold promise to in vivo modulate synapse-driven cell fate decision of other cell types used to treat autoimmunity and transplant rejection, such as regulatory T cells or iNKT cells [66, 67], and may be applicable in other cell therapies in preclinical and clinical development [68, 69]. …”

Protective effect of ad-vegf-bone mesenchymal stem cells on cerebral infarction

“…This process contributed to the formation and growth of new capillaries in ischemic tissue, which reduced neuronal apoptosis and infarct size as well as promoted recovery of neurological function. Meanwhile, some nutritional factors and cytokines (such as brain-derived neurotrophic factor, nerve growth factor) were secreted in the surrounding brain tissue through paracrine and autocrine (17), which promoted stem cells to differentiate into neural-like and glial-like cells (15), instead of damaged nerve cells, thereby increasing recovery of neurological function.…”

Engineering mesenchymal stem cells for regenerative medicine and drug delivery

“…Biotinylated lipid vesicles intercalate and fuse to the cell membrane of MSC and display biotin on its surface, offering a docking site for subsequent conjugation with biotinylated SLe X after treating MSC with streptavidin. MSC modified with SLe X using this method resulted in promoted cell rolling, adhesion, and migration [121]. …”