HS-5 and HS-27A Stromal Cell Lines to Study Bone Marrow Mesenchymal Stromal Cell-Mediated Support to Cancer Development.

Annalisa Adamo,Pietro Delfino,Alessandro Gatti,Mauro Krampera,Angela Mercuri,Alice Bonato,Stefano Ugel,Riccardo Bazzoni,Simone Caligola,Paul Takam Kamga

doi:10.3389/fcell.2020.584232

Abstract

In this study, we compared the overall gene and pathway expression profiles of HS-5 and HS-27A stromal cell lines with those of primary bone marrow MSCs to verify if they can be considered a reliable alternative tool for evaluating the contribution of MSCs in tumor development and immunomodulation. Indeed, due to their easier manipulation in vitro as compared to primary MSC cultures, several published studies took advantage of stromal cell lines to assess the biological mechanisms mediated by stromal cells in influencing tumor biology and immune responses. However, the process carried out to obtain immortalized cell lines could profoundly alter gene expression profile, and consequently their biological characteristics, leading to debatable results. Here, we evaluated the still undisclosed similarities and differences between HS-5, HS-27A cell lines and primary bone marrow MSCs in the context of tumor development and immunomodulation. Furthermore, we assessed by standardized immunological assays the capability of the cell lines to reproduce the general mechanisms of MSC immunoregulation. We found that only HS-5 cell line could be suitable to reproduce not only the MSC capacity to influence tumor biology, but also to evaluate the molecular mechanisms underlying tumor immune escape mediated by stroma cells. However, HS-5 pre-treatment with inflammatory cytokines, that normally enhances the immunosuppressive activity of primary MSCs, did not reproduce the same MSCs behavior, highlighting the necessity to accurately set up in vitro assays when HS-5 cell line is used instead of its primary counterpart.

Highlights

Mesenchymal stromal cells (MSCs) are a heterogeneous cell population representing the progenitors of stromal tissues and containing multipotent cells capable of differentiating in vitro and in vivo into mesodermal tissues, such as osteoblasts, chondrocytes, and adipocytes (Campagnoli et al, 2001; Im et al, 2005; da Silva Meirelles et al, 2006)
According to the minimal criteria for defining MSCs established by the International Society for Cellular and Gene Therapy (ISCT), primary bone marrow MSCs and HS-5 and HS-27A cell lines were positive for CD73, CD90, CD105, and HLA-ABC, with no expression of CD14, CD31, CD34, CD45, and HLADR surface molecules (Figures 1A,B)
These data confirm the preservation of the well-defined MSCs immunophenotypic profile in HS-5 and HS-27A cell lines

Summary

Introduction

Mesenchymal stromal cells (MSCs) are a heterogeneous cell population representing the progenitors of stromal tissues and containing multipotent cells capable of differentiating in vitro and in vivo into mesodermal tissues, such as osteoblasts, chondrocytes, and adipocytes (Campagnoli et al, 2001; Im et al, 2005; da Silva Meirelles et al, 2006). MSC in Cancer Development with immunomodulatory functions that are elicited by the presence of an inflammatory microenvironment. This phenomenon, called “MSCs licensing,” induces MSCs to become strongly inhibitory towards different immune effector cells (IECs) of both innate immunity, such as neutrophils, monocytes and natural killer (NK) cells, and adaptive immunity, such as T cells, B cells and dendritic cells (Krampera, 2011; Di Trapani et al, 2016). The wellknown molecular mechanisms involved in MSC-mediated immunosuppression are represented by the up-regulation of several immunosuppressive molecules, including IDO1 and PD-L1 (Krampera, 2011; Di Trapani et al, 2016). The role of FasL expression on MSCs cell surface has been recently reported to induce Fas-mediated T cell apoptosis (Akiyama et al, 2012)

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