THE IMMUNOMODULATORY EFFECT OF UMBILICAL CORD MESENCHYMAL STEM CELLS PRODUCED UNDER XENO-FREE CONDITIONS

Background Mesenchymal stem cells (MSC) are promising in cell therapy especially for their paracrine action and immunomodulatory and anti-inflammatory functions. However, for clinical application, these cells need to expand in vitro to achieve enough number for therapy. Most of the studies for MSC expansion use xenogeneic products. In order to provide a safe therapy, using animal protein-free products have been considered. In this study it was evaluated the immunomodulatory potential of umbilical cord MSC (UC-MSC) using xeno-free expansion conditions compared with UC-MSC expansion using animal derived components. Methods Six samples of UC-MSC were isolated and expanded until passage 3 (P3), under xeno-free conditions and with animal derived components. Immunomodulation was evaluated by lymphocyte proliferation assay where MSC suppress peripheral blood mononuclear cell (PBMC) proliferation. Results UC-MSC cultured under the xeno-free conditions, were able to inhibit 37.69% of T lymphocyte proliferation, in the ratio 1:2 (PBMC:MSC), 65.33% in 1:5 and 78.04% in 1:10. In the protocol using animal derived components, the MSC inhibitory capacity was 74.33% in the ratio 1:2, 74.60% in 1:5 and 79.61% in 1:10. The inhibitory capacity of UC-MSC in the ratio 1:2, was statistically significantly lower in xeno-free conditions than in the protocol using animal derived components (p=0.004). In ratios 1:5 and 1:10, the inhibitory capacity was similar, with no statistical difference (p=0.238 and p=0.792, respectively). Conclusion The inhibitory capacity of UC-MSC in the ratio 1:2 was insufficient in the xeno-free conditions, because UC-MSC inhibit less than 50% of T cells, that is under the criteria established for clinical use, which must be ≥ 50%. The T lymphocyte proliferation assay showed that a greater number of MSC in xeno-free conditions is necessary for an effective immunosuppression. The study showed that UC-MSC culture under xeno-free conditions reduced the immunomodulatory potential of these cells.