Comparing the immunosuppressive potency of naïve marrow stromal cells and Notch-transfected marrow stromal cells

Mo A Dao,Ciara C Tate,Michael Mcgrogan,Casey C Case,Irina Aizman

doi:10.1186/1742-2094-8-133

Abstract

BackgroundSB623 cells are expanded from marrow stromal cells (MSCs) transfected with a Notch intracellular domain (NICD)-expressing plasmid. In stroke-induced animals, these cells reduce infarct size and promote functional recovery. SB623 cells resemble the parental MSCs with respect to morphology and cell surface markers despite having been in extended culture. MSCs are known to have immunosuppressive properties; whether long-term culture of MSCs impact their immunomodulatory activity has not been addressed.MethodsTo assess the possible senescent properties of SB623 cells, we performed cell cycle related assays and beta-galactosidase staining. To assess the immunomodulatory activity of these expanded NICD-transfected MSCs, we performed co-cultures of SB623 cells or MSCs with either enriched human T cells or monocytes and assessed cytokine production by flow cytometry. In addition, we monitored the immunosuppressive activity of SB623 cells in both allogenic and xenogenic mixed lymphocyte reaction (MLR).ResultsCompared to MSCs, we showed that a small number of senescent-like cells appear in each lot of SB623 cells. Nevertheless, we demonstrated that these cells suppress human T cell proliferation in both the allogeneic and xenogeneic mixed lymphocyte reaction (MLR) in a manner comparable to MSCs. IL-10 producing T cells were generated and monocyte-dendritic cell differentiation was dampened by co-culture with SB623 cells. Compared to the parental MSCs, SB623 cells appear to exert a greater inhibitory impact on the maturation of dendritic cells as demonstrated by a greater reduction in the surface expression of the co-stimulatory molecule, CD86.ConclusionThe results demonstrated that the immunosuppressive activity of the expanded NICD-transfected MSCs is comparable to the parental MSCs, in spite of the appearance of a small number of senescent-like cells.

Highlights

There is an important need for stromal cell lines that support neural cells and the mesenchymal stem cell (MSC) line SB623, transfected with the Notch-intracellular domain (NICD), appear to meet these criteria
In each tested culture of SB623 cells, the frequency of beta-galactosidase-positive cells was higher than the parental MSC cultures, suggesting the presence of senescent cells in SB623 cell culture (Additional File 1B). qRT-PCR for the exogenous NICD1 gene and Hes1, a downstream target of Notch signaling, validated the high expression of exogenous NICD1 DNA and the induction of endogenous Hes1 transcript after transfection (Additional File 1C)
The results showed a higher number of viable cell counts for MSC culture than for SB623 cell culture, suggesting a lower proliferative index for SB623 cells

Summary

Introduction

There is an important need for stromal cell lines that support neural cells and the mesenchymal stem cell (MSC) line SB623, transfected with the Notch-intracellular domain (NICD), appear to meet these criteria. As SB623 cells are derived from MSCs that have undergone gene transfection and cell expansion in culture, we initiated the current study to determine whether SB623 cells display senescent-like properties. We compare the immunomodulatory activity between SB623 cells and the corresponding parental MSCs. We demonstrate that SB623 cells, currently in a clinical trial for stable stroke Gov/ct2/show/NCT01287936), retain the immunosuppressive activity of standard MSCs despite the appearance of a small number of senescent-like cells. SB623 cells are expanded from marrow stromal cells (MSCs) transfected with a Notch intracellular domain (NICD)-expressing plasmid. MSCs are known to have immunosuppressive properties; whether longterm culture of MSCs impact their immunomodulatory activity has not been addressed

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Conclusion