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Original Research ARTICLE Provisionally accepted The full-text will be published soon. Notify me

Front. Immunol. | doi: 10.3389/fimmu.2019.01716

Enhanced immunomodulation in inflammatory environments favors human cardiac mesenchymal stromal-like cells for allogeneic cell therapies

 Falk Diedrichs1, 2, Meaghan Stolk1,  Karsten Jürchott1, 3, Marion Haag1, 4, Michael Sittinger1, 4 and  Martina Seifert1, 3*
  • 1Berlin-Brandenburg Center for Regenerative Therapies, Charité Medical University of Berlin, Germany
  • 2Berlin Institute of Health Research (BIH), Germany
  • 3Institute for Medical Immunology, Charité Medical University of Berlin, Germany
  • 4Tissue Engineering Labor, Charité Medizinische Universität Berlin, Germany

Rising numbers of patients with cardiovascular diseases and limited availability of donor hearts require new and improved therapy strategies. Human atrial appendage-derived cells (hAACs) are promising candidates for an allogeneic cell-based treatment. In this study, we evaluated their inductive and modulatory capacity regarding immune responses and underlying key mechanisms in vitro.
For this, cryopreserved hAACs were either cultured in the presence of interferon-gamma (IFNγ) or left unstimulated. The expression of characteristic mesenchymal stromal cell markers (CD29, CD44, CD73, CD105, CD166) was revealed by flow cytometry that also highlighted a predominant negativity for CD90. A low immunogeneic phenotype in an inflammatory milieu was shown by lacking expression of co-stimulatory molecules and upregulation of the inhibitory ligands PD-L1 and PD-L2, despite de novo expression of HLA-DR. Co-cultures of hAACs with allogeneic peripheral blood mononuclear cells, proved their low immunogeneic state by absence of induced T cell proliferation and activation. Additionally, elevated levels of IL-1β, IL-33 and IL-10 were detectable in those cell culture supernatants. Furthermore, the immunomodulatory potential of hAACs was assessed in co-cultures with αCD3/αCD28-activated peripheral blood mononuclear cells. Here, a strong inhibition of T cell proliferation and reduction of pro-inflammatory cytokines (IFNγ, TNFα, TNFβ, IL-17A, IL-2) were observable after pre-stimulation of hAACs with IFNγ. Transwell experiments confirmed that mostly soluble factors are responsible for these suppressive effects. We were able to identify indolamin-2,3-dioxygenase (IDO) as a potential key player through a genome-wide gene expression analysis and could demonstrate its involvement in the observed immunological responses. While the application of blocking antibodies against both PD-1 ligands did not affect the immunomodulation by hAACs, 1-methyl-L-tryptophan as specific inhibitor of IDO was able to restore proliferation and to lower apoptosis of T cells.
In conclusion, hAACs represent a cardiac-derived mesenchymal stromal-like cell type with a high potential for the application in an allogeneic settings, since they do not trigger T cell responses and even increase their immunomodulatory potential in inflammatory environments.

Keywords: cardiac-derived cells, Immunogenicity, Immunomodulation, Inflammation, IFN-gamma, IDO - Indoleamine 2,3-dioxygenase

Received: 14 Feb 2019; Accepted: 09 Jul 2019.

Edited by:

Martin J. Hoogduijn, Erasmus University Rotterdam, Netherlands

Reviewed by:

Ralf Dressel, University Medical Center Göttingen, Germany
Mehdi Najar, Free University of Brussels, Belgium
Lagneaux Laurence, Free University of Brussels, Belgium  

Copyright: © 2019 Diedrichs, Stolk, Jürchott, Haag, Sittinger and Seifert. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Prof. Martina Seifert, Berlin-Brandenburg Center for Regenerative Therapies, Charité Medical University of Berlin, Berlin, 13353, Baden-Wurttemberg, Germany, martina.seifert@charite.de