The properties of multipotent mesenchymal stromal cells samples vary depending on their ability to induce HLA-DR expression on T-cells co-cultured with them

Abstract

Interactions between lymphocytes and multipotent mesenchymal stromal cells (MSCs) in vitro sometimes increase HLA-DR expression on T-cells. On lymphocytes derived from one donor the elevation of HLA-DR was observed after co-cultivation with part of MSCs samples (group A), on the others the HLA-DR expression level did not change (group B). Study of T-cell subpopulations after interactions with MSCs could explain ineffectiveness of some MSCs, as an immunomodulating agent in clinical applications. The aim of the study was to discriminate variations in T-cell subpopulations, co-cultured with MSCs from groups A and B. MSCs were isolated from bone marrow of 13 donors for allogeneic hematopoietic cells and cultured by a standard method. MSCs were seeded 100000 cells per flask, and then 1000000 allogeneic lymphocytes from single donor were added to all MSCs cultures. Lymphocytes and MSCs were immunophenotyped separately during 4 days of co-cultivation. The expression of HLA-DR, activation markers CD25, CD38, CD69, HLA-DR and PD-1 and the distribution of naïve and effector T-cells were studied by flow cytometry. Expression of HLA-DR on lymphocytes after 4 days of cultivation without MSCs did not change compared to 1st day. HLA-DR expression on lymphocytes co-cultured with MSCs from group A was 3 times greater than from group B. In lymphocytes co-cultured with MSCs there were higher number of naïve cells compared to control, p < 0.001. Group B showed lower number of EM and TM cells. Differences between groups were more pronounced when lymphocytes were activated. In group B proportion of HLA-DR CD4+ and CD8+ cells was significantly lower, compared to group A and control samples. At the same time the number of CM and PD-1+ CD4+ cells was lower in group A, but number of TE was increased. These data indicate that MSCs from group A became more immunogenic after interaction with lymphocytes and could not show immunomodulating properties in the same way as MSCs from group B. Data obtained can explain why administration of MSCs is not always successful. Preliminary study of MSCs prior to their administration may be used to predict their efficiency in the future.