UMBILICAL CORD-DERIVED MESENCHYMAL STROMAL CELLS AS AN ALTERNATIVE TO BONE MARROW IN IMMUNOSUPPRESSIVE THERAPY

Abstract

<h3>Background</h3> Due to their immunomodulatory characteristics, mesenchymal stromal cells (MSC) have become an option in immunosuppressive therapy. HLA-G expression appears to play a key role in immunomodulation, inhibiting proliferation of immune cells and inducing activation of regulatory cells, modulating host‘s immune response. Thus, identifying a source of MSC with high HLA-G expression can be a good strategy for future treatments. <h3>Methods</h3> MSC from umbilical cord tissue (UCT) (n=3) were compared to a sample of bone marrow (BM) (n=1) under the following growing conditions: (i) standard cultivation; (ii) stimulation of interferon-γ (IFN-γ); and (iii) hypoxia condition (2% O2). Expression of CD14, CD73, CD34, CD19, CD166, CD29, CD45, CD90, HLA-DR and CD105 markers and co-stimulatory CD40, CD80 and CD86 markers were analyzed. The analysis of CD152 molecule (intracellular isoform) and membrane HLA-G1 isoform was performed by flow cytometry to study the expression of immunosuppressive molecules. The analysis of soluble HLA-G5 isoform was performed by enzyme-linked immunosorbent assay (ELISA). For analysis of the immunosuppressive potential of MSCs, a lymphocyte (PBMCs) inhibition assay was performed in proportions 1:2 and 1:10 (MSC:PBMC). <h3>Results</h3> The expression of cellular markers was following that required by the International Society for Cell and Gene Therapy. All samples showed negative expression for co-stimulatory markers CD40, CD80 and CD86 and positive expression for CD152. CD152 and HLA-G1 molecules were more expressed by UC when grown under normal conditions (<i>p</i>=0.0018 and <i>p</i>=0.0003, respectively) or hypoxia (<i>p</i>=0.0057 and <i>p</i><0.0001, respectively), but were similar when grown with IFN-γ (<i>p</i>=0.2888 and <i>p</i>=0.2307, respectively). The expression of soluble isoform HLA-G5 was similar by UC and BM. UC and BM showed similar inhibition of PBMCs in standard culture or hypoxia. However, when stimulated with IFN-γ, BM showed greater inhibitory capacity in the proportion 1:2 (<i>p</i>=0.0011) and 1:10 (<i>p</i>=0.0177). IFN-γ increases inhibition of PBMC by BM in relation to standard culture (<i>p</i>=0.0219). <h3>Conclusion</h3> We observed that IFN-γ was able to trigger an increase in inhibitory capacity of BM MSC, but not in UCT-MSC, being indicated in cultivation of BM MSC used for immunosuppressive therapy. In addition, UCT-MSC proved to be an efficient alternative to BM MSC. UCT-MSC showed an advantage in the expression of immunosuppressive