Differences in Gene Expression and Cytokine Release Profiles Highlight the Heterogeneity of Distinct Subsets of Adipose Tissue-Derived Stem Cells in the Subcutaneous and Visceral Adipose Tissue in Humans

Sebastio Perrini,Romina Ficarella,Massimo Carella,Maria Barbaro,Annalisa Natalicchio,Michele De Fazio,Alessandro Peschechera,Angelo Cignarelli,Ernesto Picardi,Pasquale Nigro,Francesco Giorgino,Graziano Pesole,Orazio Palumbo,Luigi Laviola,Andrea Vergani

doi:10.1371/journal.pone.0057892

Abstract

Differences in the inherent properties of adipose tissue-derived stem cells (ASC) may contribute to the biological specificity of the subcutaneous (Sc) and visceral (V) adipose tissue depots. In this study, three distinct subpopulations of ASC, i.e. ASCSVF, ASCBottom, and ASCCeiling, were isolated from Sc and V fat biopsies of non-obese subjects, and their gene expression and functional characteristics were investigated. Genome-wide mRNA expression profiles of ASCSVF, ASCBottom and ASCCeiling from Sc fat were significantly different as compared to their homologous subsets of V-ASCs. Furthermore, ASCSVF, ASCCeiling and ASCBottom from the same fat depot were also distinct from each other. In this respect, both principal component analysis and hierarchical clusters analysis showed that ASCCeiling and ASCSVF shared a similar pattern of closely related genes, which was highly different when compared to that of ASCBottom. However, larger variations in gene expression were found in inter-depot than in intra-depot comparisons. The analysis of connectivity of genes differently expressed in each ASC subset demonstrated that, although there was some overlap, there was also a clear distinction between each Sc-ASC and their corresponding V-ASC subsets, and among ASCSVF, ASCBottom, and ASCCeiling of Sc or V fat depots in regard to networks associated with regulation of cell cycle, cell organization and development, inflammation and metabolic responses. Finally, the release of several cytokines and growth factors in the ASC cultured medium also showed both inter- and intra-depot differences. Thus, ASCCeiling and ASCBottom can be identified as two genetically and functionally heterogeneous ASC populations in addition to the ASCSVF, with ASCBottom showing the highest degree of unmatched gene expression. On the other hand, inter-depot seem to prevail over intra-depot differences in the ASC gene expression assets and network functions, contributing to the high degree of specificity of Sc and V adipose tissue in humans.

Highlights

The biological diversity of adipose tissue depots has become a fundamental issue in recent years, in light of its potential impact on human health [1]; [2]
The qualitative histochemical evaluation of functional outcomes indicated that ASCSVF, ASCCeiling and ASCBottom from both adipose tissue depots underwent differentiation along the adipogenic, osteogenic and chondrogenic lineages, respectively (Fig. S1)
The mRNA levels of fat cellspecific gene markers, including GLUT4, PPARc2 and adiponectin, were increased several-fold with adipocyte differentiation (p,0.001 vs. adipose tissue-derived stem cells (ASC)), and found to be expressed in the distinct ASC populations (Fig. S2). These results indicate that the differentiation process into mature adipocytes was completed in an apparently equal manner in all ASC populations

Summary

Introduction

The biological diversity of adipose tissue depots has become a fundamental issue in recent years, in light of its potential impact on human health [1]; [2]. Variations in the inherent properties of undifferentiated fat cell progenitors may dictate the biological specificity between the two fat depots bringing about the innate characteristics of Sc and V adipose cells. We have shown that depot-related differences in gene expression, adiponectin secretion, and insulin signaling and action were still evident when precursor cells isolated from bioptic adipose tissue fragments were differentiated in vitro [11]. These findings support the concept that there could be an early commitment of fat precursor stromal cells able to influence the biological responses of the resulting adipocytes, independently of extrinsic influences deriving from tissue microenvironment. Little is known about the identity, localization, or specific characteristics of endogenous adipocyte progenitors

Results

Discussion

Conclusion