Abstract
The stromal vascular cell fraction (SVF) of visceral and subcutaneous adipose tissue (VAT and SAT) has increasingly come into focus in stem cell research, since these compartments represent a rich source of multipotent adipose-derived stem cells (ASCs). ASCs exhibit a self-renewal potential and differentiation capacity. Our aim was to study the different expression of the embryonic stem cell markers NANOG (homeobox protein NANOG), SOX2 (SRY (sex determining region Y)-box 2) and OCT4 (octamer-binding transcription factor 4) and to evaluate if there exists a hierarchal role in this network in ASCs derived from both SAT and VAT. ASCs were isolated from SAT and VAT biopsies of 72 consenting patients (23 men, 47 women; age 45 ± 10; BMI between 25 ± 5 and 30 ± 5 range) undergoing elective open-abdominal surgery. Sphere-forming capability was evaluated by plating cells in low adhesion plastic. Stem cell markers CD90, CD105, CD29, CD31, CD45 and CD146 were analyzed by flow cytometry, and the stem cell transcription factors NANOG, SOX2 and OCT4 were detected by immunoblotting and real-time PCR. NANOG, SOX2 and OCT4 interplay was explored by gene silencing. ASCs from VAT and SAT confirmed their mesenchymal stem cell (MSC) phenotype expressing the specific MSC markers CD90, CD105, NANOG, SOX2 and OCT4. NANOG silencing induced a significant OCT4 (70 ± 0.05%) and SOX2 (75 ± 0.03%) downregulation, whereas SOX2 silencing did not affect NANOG gene expression. Adipose tissue is an important source of MSC, and siRNA experiments endorse a hierarchical role of NANOG in the complex transcription network that regulates pluripotency.
Highlights
Both visceral (VAT) and subcutaneous adipose tissues (SAT) represent an alternative source of mesenchymal stem cells (MSCs)
Our aim was to study the expression of NANOG, SOX2 and OCT3/4 in Adipose-derived stem cells (ASCs) derived from SAT and VAT and to evaluate whether there exists a transcription factor with a more prominent role in this network
MSCs derived from visceral adipose tissue (V-ASCs) were characterized by large nuclei and elongated cytoplasms (Figure 1D) and those derived from subcutaneous adipose tissue (S-ASCs) by large nuclei and globular cytoplasms (Figure 1E)
Summary
Both visceral (VAT) and subcutaneous adipose tissues (SAT) represent an alternative source of mesenchymal stem cells (MSCs). There is great interest in understanding more in detail the cellular and molecular mechanisms of ASCs, which are known to modulate self-renewal and differentiation properties. The latter characteristics have made it possible to consider them as the preferable candidate for employment in regenerative medicine [6]. Boyer et al showed that OCT4 (octamer-binding transcription factor 4), NANOG (homeobox protein NANOG) and SOX2 (SRY (sex determining region Y)-box 2) work as a trio to support each other’s expression and that of other self-renewal genes repressing differentiation genes [8], while other studies suggested that only OCT4 and NANOG are co-regulated in embryonic stem cells [7]. As regards hASCs, the single components of the trio have been described separately, but the possible interplay among the principal transcription factors has not been fully explored
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