Mesenchymal Stromal Cells Regulate Sialylations of N-Glycans, Affecting Cell Migration and Survival.

Kayla Templeton,Meiby Ramos,Amin Cressman,Carlito B Lebrilla,Bryan Le,Qingwen Zhou,Stephanie Ferreyra,Fernando Antonio Fierro,Jacqueline Rose

doi:10.3390/ijms22136868

Abstract

N-Glycosylations are an important post-translational modification of proteins that can significantly impact cell function. Terminal sialic acid in hybrid or complex N-glycans has been shown to be relevant in various types of cancer, but its role in non-malignant cells remains poorly understood. We have previously shown that the motility of human bone marrow derived mesenchymal stromal cells (MSCs) can be modified by altering N-glycoforms. The goal of this study was to determine the role of sialylated N-glycans in MSCs. Here, we show that IFN-gamma or exposure to culture media low in fetal bovine serum (FBS) increases sialylated N-glycans, while PDGF-BB reduces them. These stimuli alter mRNA levels of sialyltransferases such as ST3Gal1, ST6Gal1, or ST3Gal4, suggesting that sialylation of N-glycans is regulated by transcriptional control of sialyltransferases. We next show that 2,4,7,8,9-pentaacetyl-3Fax-Neu5Ac-CO2Me (3F-Neu5Ac) effectively inhibits sialylations in MSCs. Supplementation with 3F-Neu5Ac increases adhesion and migration of MSCs, as assessed by both videomicroscopy and wound/scratch assays. Interestingly, pre-treatment with 3F-Neu5Ac also increases the survival of MSCs in an in vitro ischemia model. We also show that pre-treatment or continuous treatment with 3F-Neu5Ac inhibits both osteogenic and adipogenic differentiation of MSCs. Finally, secretion of key trophic factors by MSCs is variably affected upon exposure to 3F-Neu5Ac. Altogether, our experiments suggest that sialylation of N-glycans is tightly regulated in response to environmental cues and that glycoengineering MSCs to reduce sialylated N-glycans could be beneficial to increase both cell migration and survival, which may positively impact the therapeutic potential of the cells.

Highlights

Mesenchymal Stromal Cells (MSCs) have been widely recognized as a key cell type in regenerative medicine [1]
We have shown that inducing N-glycan core-fucosylations or high mannose N-glycans promote migration of MSCs [13,16]
Based on our previous observation that N-glycan fucosylations were increased in response to basic fibroblast growth factor (bFGF) [16], we aimed to identify conditions that would alter sialylations in MSCs

Summary

Introduction

Mesenchymal Stromal Cells (MSCs) have been widely recognized as a key cell type in regenerative medicine [1]. Over one thousand clinical trials have tested MSCs as therapeutics to promote wound healing, tissue regeneration, and to reduce inflammation, among others [2]. MSCs have a remarkable safety profile because they can evade the immune system, while most human cells are rarely tolerated in allogeneic settings [3]. Despite this attention, very few clinical trials have met therapeutic expectations and led to commercialization of MSCs [4]. MSCs require active cell motility to reach their intended sites, but current approaches to improve cell motility have been only modestly successful, with no clear impact on the cell’s therapeutic effect [7]. Improving MSC migration should result in less invasive delivery methods [8]

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Methods

Results