ABSTRACT: Differences in the inherent properties of undifferentiated fat cell progenitors may contribute to the biological specificity of the abdominal subcutaneous (Sc) and visceral omental (V) fat depots. In this study, the biological characteristics of three distinct subpopulations of adipose tissue-derived stem cells (ASC), i.e. ASCSVF, ASCBottom and ASCCeiling isolated from Sc and V adipose tissue biopsies of non-obese subjects, were investigated. Genome-wide differential gene expression analysis followed by quantitative RT-PCR and analysis of cytokines in the ASC-derived conditioned medium were performed. By analysis of 28,869 annotated genes, 1,019 genes resulted differentially expressed between Sc-ASC and V-ASC. Within the Sc-ASC and V-ASC populations, 546 and 1,222, respectively, were the genes differentially expressed among ASCSVF, ASCBottom and ASCCeiling. A far more striking difference was found when the hierarchical clusters analysis was performed comparing each Sc-ASC with its own homologous V-ASC subset. mRNA levels of HoxA5, Tbx15, PI16, PITPNC1, FABP5, IL-6, IL-8, MCP-1, VEGF, MMP3, TFPI2, and ANXA10 were significantly different between Sc-ASC and V-ASC. Of the 27 cytokines measured, 14 (IL-2, IL-4, IL-5 IL-7, IL-9, IL-10, IL12, IL13, MIP1-α, MIP1-β, PDGF-ΒΒ, FGFbasic, GM-CSF, IP-10) were not released, whereas 13 were expressed (IL-1beta, IL-1ra, IL-15, IL-17, G-CSF, IFNγ, RANTES, TNF-α, Eotaxin, IL-8, MCP-1, VEGF, IL-6), and of these, MCP-1, Eotaxin, IL-1ra, FGFbasic, IL-6, IL-8, G-CSF, and VEGF were significantly different among ASCSVF, ASCCeiling and ASCBottom of the two adipose tissue depots. These results demonstrate the existence of genetically and functionally heterogeneous fat-derived ASC populations, which may add to the complexity and specificity of Sc and V adipose tissue in humans.
