Analysis of in vitro secretion profiles from adipose-derived cell populations

Abstract

BackgroundAdipose tissue is an attractive source of cells for therapeutic purposes because of the ease of harvest and the high frequency of mesenchymal stem cells (MSCs). Whilst it is clear that MSCs have significant therapeutic potential via their ability to secrete immuno-modulatory and trophic cytokines, the therapeutic use of mixed cell populations from the adipose stromal vascular fraction (SVF) is becoming increasingly common.MethodsIn this study we have measured a panel of 27 cytokines and growth factors secreted by various combinations of human adipose-derived cell populations. These were 1. co-culture of freshly isolated SVF with adipocytes, 2. freshly isolated SVF cultured alone, 3. freshly isolated adipocytes alone and 4. adherent adipose-derived mesenchymal stem cells (ADSCs) at passage 2. In addition, we produced an ‘in silico’ dataset by combining the individual secretion profiles obtained from culturing the SVF with that of the adipocytes. This was compared to the secretion profile of co-cultured SVF and adipocytes. Two-tailed t-tests were performed on the secretion profiles obtained from the SVF, adipocytes, ADSCs and the ‘in silico’ dataset and compared to the secretion profiles obtained from the co-culture of the SVF with adipocytes. A p-value of < 0.05 was considered statistically different. To assess the overall changes that may occur as a result of co-culture we compared the proteomes of SVF and SVF co-cultured with adipocytes using iTRAQ quantitative mass spectrometry.ResultsA co-culture of SVF and adipocytes results in a distinct secretion profile when compared to all other adipose-derived cell populations studied. This illustrates that cellular crosstalk during co-culture of the SVF with adipocytes modulates the production of cytokines by one or more cell types. No biologically relevant differences were detected in the proteomes of SVF cultured alone or co-cultured with adipocytes.ConclusionsThe use of mixed adipose cell populations does not appear to induce cellular stress and results in enhanced secretion profiles. Given the importance of secreted cytokines in cell therapy, the use of a mixed cell population such as the SVF with adipocytes may be considered as an alternative to MSCs or fresh SVF alone.

Secretion of immunoregulatory cytokines by mesenchymal stem cells

“…Nevertheless, the published data demonstrating the secretion of IL-10 by MSCs are quite contradictory. Almost half of the papers discussed in the present review report positive secretion of IL-10 by MSCs [62,66,[81][82][83][84] , while the other half and our own experimental results reject such a possibility [60,64,69,78,[85][86][87][88] . It is quite logical to support the concept proposed by some authors claiming that MSCs secrete IL-10 under specific conditions with the inflammatory environment and presence of cytokines (IFNγ, IL-1b and TNFα) which activate certain Toll-like receptors on MSCs [63,65,67] .…”

“…Contrary to IL-10, there is no doubt that IL-6 is secreted by MSCs and almost all authors agree with this statement [69,78,82,84,86,87] . Its secretion by MSCs has been demonstrated both in mice and in humans [62,66] and is detected either after induction with TNFα, IL-1b and IFNγ or spontaneously [37,[61][62][63]72,95] .…”

“…Some authors believe that the effect of IL-6 mediated by trans-signaling (IL-6/sIL-6R) is related to a pro-inflammatory effect, while the "classical" pathway (IL-6/mIL-6R) of activation is connected to the antiinflammatory action of the cytokine [94] . Such an assumption sounds quite logical, keeping in mind the dual nature of IL-6 because of its pro-inflammatory and/or antiinflammatory effects [75,82] . IL-6 is routinely described as a classical pro-inflammatory cytokine based on well proven effects of this cytokine.…”

Treatment of a mouse model of collagen antibody-induced arthritis with human adipose-derived secretions

“…We have previously demonstrated that unique secretion profiles can be obtained from different adipose-derived cell populations [8]. In particular, we demonstrated that the co-culture of adipocytes with the SVF results in the cells acting in a synergistic manner and consequently increasing the production of 9 cytokines when compared to culturing the SVF alone [8]. For example, IL-1Ra was produced in significantly increased levels by the co-culture of SVF with adipocytes versus the SVF alone.…”

“…This communication between the cells is essential for the normal functioning of adipose tissue and this complex-reciprocal signaling has been demonstrated by in vitro co-culture experiments [5][6][7]. We have previously demonstrated that unique secretion profiles can be obtained from different adipose-derived cell populations [8]. In particular, we demonstrated that the co-culture of adipocytes with the SVF results in the cells acting in a synergistic manner and consequently increasing the production of 9 cytokines when compared to culturing the SVF alone [8].…”