Genome-wide analysis of gene expression during adipogenesis in human adipose-derived stromal cells reveals novel patterns of gene expression during adipocyte differentiation

We have undertaken an in-depth transcriptome analysis of adipogenesis in human adipose-derived stromal cells (ASCs) induced to differentiate into adipocytes in vitro. Gene expression was assessed on days 1, 7, 14 and 21 post-induction and genes differentially expressed numbered 128, 218, 253 and 240 respectively. Up-regulated genes were associated with blood vessel development, leukocyte migration, as well as tumor growth, invasion and metastasis. They also shared common pathways with certain obesity-related pathophysiological conditions. Down-regulated genes were enriched for immune response processes. KLF15, LMO3, FOXO1 and ZBTB16 transcription factors were up-regulated throughout the differentiation process. CEBPA, PPARG, ZNF117, MLXIPL, MMP3 and RORB were up-regulated only on days 14 and 21, which coincide with the maturation of adipocytes and could possibly serve as candidates for controlling fat accumulation and the size of mature adipocytes. In summary, we have identified genes that were up-regulated only on days 1 and 7 or days 14 and 21 that could serve as potential early and late-stage differentiation markers.The South African Medical Research Council in terms of the SAMRC's Flagship Award Project SAMRC-RFAUFSP- 01-2013/STEM CELLS, the SAMRC Extramural Stem Cell Research and Therapy Unit, the National Research Foundation of South Africa (grant no. 86942), the National Health Laboratory Services Research Trust (grant no. 94453) and the Institute for Cellular and Molecular Medicine of the University of Pretoria.http://www.elsevier.com/locate/scram2016African Language

Novel flow cytometric approach for the detection of adipocyte subpopulations during adipogenesis

The ability of mesenchymal stromal cells (MSCs) to differentiate into adipocytes provides a cellular model of human origin to study adipogenesis in vitro. One of the major challenges in studying adipogenesis is the lack of tools to identify and monitor the differentiation of various subpopulations within the heterogeneous pool of MSCs. Cluster of differentiation (CD)36 plays an important role in the formation of intracellular lipid droplets, a key characteristic of adipocyte differentiation/maturation. The objective of this study was to develop a reproducible quantitative method to study adipocyte differentiation by comparing two lipophilic dyes [Nile Red (NR) and Bodipy 493/503] in combination with CD36 surface marker staining. We identified a subpopulation of adiposederived stromal cells that express CD36 at intermediate/high levels and show that combining CD36 cell surface staining with neutral lipidspecific staining allows us to monitor differentiation of adiposederived stromal cells that express CD36 during adipocyte differentiation in vitro. The gradual increase of CD36 NR cells during the 21 day adipogenesis induction period correlated with upregulation of adipogenesisassociated gene expression.http://www.jlr.org2017-04-30hb2016Immunolog

Reference gene expression in adipose-derived stromal cells undergoing adipogenic differentiation

Adipose-derived stromal cells (ASCs) are becoming increasingly attractive as cellular therapy products. Their differentiation potential, the secretion of growth and differentiation factors, and the ability to cryopreserve the cells over extended periods are important features. Changes in experimental conditions result in changes in gene expression, and reverse-transcription quantitative polymerase chain reaction (RT-qPCR) has become an important tool for measuring these changes. There is, however, the potential to introduce technical bias in the process, which can be diminished through the selection of stable reference genes (RGs). Using geNorm software, in this in vitro study we explore the effects that adipogenic differentiation for a 21 day induction period, cryopreservation (freshly isolated ASCs or previously cryopreserved/frozen ASCs), and culture medium supplementation (fetal bovine serum vs. pooled human platelet lysate) have on the stability of 11 RGs. We found that RG stability is markedly affected by the different experimental conditions. Of the RGs assessed, YWHAZ, HPRT, TBP, andACTB were stably expressed genes under all experimental conditions. We recommend that a panel of stable RGs should be selected before studying gene expression during adipogenesis, and that this is based on the experimental condition(s) being investigated.https://www.liebertpub.com/tecpm2020Immunolog

Comparison of human platelet lysate alternatives using expired and freshly isolated platelet concentrates for adipose-derived stromal cell expansion

Pooled human platelet lysate (pHPL) has been used to expand adipose-derived stromal cells (ASCs) and can be formulated using fresh or expired buffy coats (BCs) which are then resuspended in either plasma or an additive solution. Not much is known about the effects that expired products and additive solutions have on ASC expansion, and the need for quality control and release criteria has been expressed. This pilot study compared proliferation, cell size, morphology and immunophenotype of ASCs expanded in the different pHPL alternatives versus foetal bovine serum (FBS). Quality control criteria were assessed prior to and during the manufacture of the pHPL alternatives. ASCs were then expanded in 1%, 2.5%, 5% or 10% of the different pHPL alternatives or in 10% FBS. Cell size, morphology, cell number and immunophenotype were measured using microscopy and flow cytometry. The majority of the pHPL alternatives were within the recommended ranges for the quality control criteria. ASCs expanded in the pHPL alternatives were smaller in size, displayed a tighter spindle-shaped morphology, increased cell growth and had a similar immunophenotype (with the exception of CD34 and CD36) when compared to ASCs expanded in FBS. Here we report on the effects that expired BC products and additive solutions have on ASC expansion. When taken together, our findings indicate that all of the pHPL alternatives can be considered to be suitable replacements for FBS for ASC expansion, and that expired BC products can be used as an alternative to fresh BC products.Grants from the South African Medical Research Council Flagship Awards Project SAMRC-RFA-UFSP- 01-2013/STEM CELLS, the SAMRC Extramural Unit for Stem Cell Research and Therapy and the Institute for Cellular and Molecular Medicine of the University of Pretoria. The National Research Foundation of South Africa also provided funding.http://www.tandfonline.com/loi/iplt20am2018Immunolog