Isolation of human peripheral blood mononuclear cells and monocytes

AT-MSC are studied as an alternative for BM-MSC for immunomodulatory treatment. In this study we systematically compared the immunomodulatory capacities of BM-MSC and AT-MSC, derived from age-matched donors. We found that BM-MSC and AT-MSC share a similar immunophenotype and capacity for in vitro multilineage differentiation. BM-MSC and AT-MSC showed comparable immunomodulatory effects as they were both capable to suppress proliferation of stimulated PBMC and to inhibit differentiation of monocyte-derived immature dendritic cells (iDC). However, at equal cell numbers, the AT-MSC showed more potent immunomodulatory effects in both assays as compared to BM-MSC. Moreover, AT-MSC showed a higher level of secretion of cytokines that have been implicated in the immunomodulatory modes of action of MSC, such as IL-6 and TGF-β1. This is correlated with higher metabolic activity of AT-MSC compared to BM-MSC. We conclude that the immunomodulatory capacities of BM-MSC and AT-MSC are similar, but that differences in cytokine secretion cause AT-MSC to have more potent immunomodulatory effects than BM-MSC. Therefore, lower numbers of AT-MSC evoke the same level of immunomodulation. These data indicate that AT-MSC can be considered as a good alternative to BM-MSC for immunomodulatory therapy. of MSC 24,25 and tissue collection is simple. Moreover, 400,000 liposuctions a year are performed in the US alone, where the aspirated adipose tissue is regarded as waste 26 , and could be collected without any additional burden or risk for the donor. Adipose tissue-derived MSC (AT-MSC) are already applied in clinical trials 21,22 , but a systematic comparative study of bone marrow-derived MSC (BM-MSC) and AT-MSC has not been performed. Studies that compared MSC derived from different sources focused on phenotype, transcription profiling and differentiation potential 27-33 . A few studies compared the immunomodulatory properties 30,32,34-36 and showed qualitative similarities between AT-MSC and BM-MSC. Quantitative analysis could not be performed in these studies, since different patient groups and different age groups were analyzed. Age is an important variable, since the composition of the MSC population and the functional properties of MSC change with aging 37,38 . In this study we systematically compared the in vitro immunomodulatory capacities of BM-MSC and AT-MSC, derived from age-matched donors, to further define the advantages and disadvantages related to the use of the different tissue sources for MSC therapy. We show that both AT-MSC and BM-MSC are capable to suppress proliferation of stimulated PBMC and to inhibit differentiation of monocyte-derived immature dendritic cells (iDC). However, AT-MSC show more potent immunomodulatory effects, which is related to higher levels of cytokine secretion. Our data show that BM-MSC and AT-MSC share a similar immunophenotype and capacity for in vitro multilineage differentiation. Also functionally, BM-MSC and AT-MSC show similar immunomodulatory effects, but with a different dose-response curve, in favor of AT-MSC. We show that the differences in immunomodulatory properties between BM-MSC and AT-MSC are primarily due to the quantitative aspects of the suppression, which are likely related to their respective metabolic activity. These data support the notion that AT-MSC could be a promising alternative for BM-MSC for future clinical immunomodulatory applications.