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  • Huttala, Outi; Mysore, R.; Sarkanen, J. R.; Heinonen, T.; Olkkonen, Vesa; Ylikomi, T. (2016)
    Adipose tissue-related diseases such as obesity and type 2 diabetes are worldwide epidemics. In order to develop adipose tissue cultures in vitro that mimic more faithfully the in vivo physiology, new well-characterized and publicly accepted differentiation methods of human adipose stem cells are needed. The aims of this study are (1) to improve the existing natural adipose tissue extract (ATE)-based induction method and (2) to study the effects of a differentiation method on insulin responsiveness of the resulting adipocytes. Different induction media were applied on human adipose stromal cell (hASC) monocultures to study the differentiation capacity of the induction media and the functionality of the differentiated adipocytes. Cells were differentiated for 14 days to assess triglyceride accumulation per cell and adipocyte-specific gene expression (PPAR gamma, adiponectin, AP2, leptin, Glut4, Prdm16, CIDEA, PGC1-alpha, RIP140, UCP and ADCY5). Insulin response was studied by measuring glucose uptake and inhibition of lipolysis after incubation with 100 or 500 nM insulin. The selected differentiation method included a 3-day induction with ATE, 6 days in serum-free medium supplemented with 1.15 mu M insulin and 9.06 mu M Troglitazone, followed by 4 days in a defined serum- and insulin-free stimulation medium. This protocol induced prominent general adipocyte gene expression, including markers for both brown and white adipocytes and triglyceride accumulation. Moreover, the cells were sensitive to insulin as observed from increased glucose uptake and inhibition of lipolysis. This differentiation protocol provides a promising approach for the induction of hASC adipogenesis to obtain functional and mature human adipocytes.
  • Tolkachov, Alexander; Fischer, Cornelius; Ambrosi, Thomas H.; Bothe, Melissa; Han, Chung-Ting; Muenzner, Matthias; Mathia, Susanne; Salminen, Marjo; Seifert, Georg; Thiele, Mario; Duda, Georg N.; Meijsing, Sebastiaan H.; Sauer, Sascha; Schulz, Tim J.; Schupp, Michael (2018)
    The transcription factor GATA2 is required for expansion and differentiation of hematopoietic stem cells (HSCs). In mesenchymal stem cells (MSCs), GATA2 blocks adipogenesis, but its biological relevance and underlying genomic events are unknown. We report a dual function of GATA2 in bone homeostasis. GATA2 in MSCs binds near genes involved in skeletal system development and colocalizes with motifs for FOX and HOX transcription factors, known regulators of skeletal development. Ectopic GATA2 blocks osteoblastogenesis by interfering with SMAD1/5/8 activation. MSC-specific deletion of GATA2 in mice increases the numbers and differentiation capacity of bone-derived precursors, resulting in elevated bone formation. Surprisingly, MSC-specific GATA2 deficiency impairs the trabecularization and mechanical strength of bone, involving reduced MSC expression of the osteoclast inhibitor osteoprotegerin and increased osteoclast numbers. Thus, GATA2 affects bone turnover via MSC-autonomous and indirect effects. By regulating bone trabecularization, GATA2 expression in the osteogenic lineage may contribute to the anatomical and cellular microenvironment of the HSC niche required for hematopoiesis.
  • Herbers, Elena; Patrikoski, Mimmi; Jokinen, Riikka; Wagner, Anita; Hassinen, Antti; Heinonen, Sini; Miettinen, Susanna; Peltoniemi, Hilkka; Pirinen, Eija; Pietiläinen, Kirsi H. (2022)
    Mitochondrial dysfunction in white adipose tissue is strongly associated with obesity and its metabolic complications, which are important health challenges worldwide. Human adipose-derived stromal/stem cells (hASCs) are a promising tool to investigate the underlying mechanisms of such mitochondrial dysfunction and to subsequently provide knowledge for the development of treatments for obesity-related pathologies. A substantial obstacle in using hASCs is that the key compounds for adipogenic differentiation in vitro increase mitochondrial uncoupling, biogenesis, and activity, which are the signature features of brown adipocytes, thus altering the white adipocyte phenotype towards brown-like cells. Additionally, commonly used protocols for hASC adipogenic differentiation exhibit high variation in their composition of media, and a systematic comparison of their effect on mitochondria is missing. Here, we compared the five widely used adipogenic differentiation protocols for their effect on metabolic and mitochondrial phenotypes to identify a protocol that enables in vitro differentiation of white adipocytes and can more faithfully recapitulate the white adipocyte phenotype observed in human adipose tissue. We developed a workflow that included functional assays and morphological analysis of mitochondria and lipid droplets. We observed that triiodothyronine- or indomethacin-containing media and commercially available adipogenic media induced browning during in vitro differentiation of white adipocytes. However, the differentiation protocol containing 1 mu M of the peroxisome proliferator-activated receptor gamma (PPAR gamma) agonist rosiglitazone prevented the browning effect and would be proposed for adipogenic differentiation protocol for hASCs to induce a white adipocyte phenotype. Preserving the white adipocyte phenotype in vitro is a crucial step for the study of obesity and associated metabolic diseases, adipose tissue pathologies, such as lipodystrophies, possible therapeutic compounds, and basic adipose tissue physiology.
  • Stalin, Antony; Kandhasamy, Subramani; Kannan, Balakrishnan Senthamarai; Verma, Rama Shanker; Ignacimuthu, Savarimuthu; Kim, Yrjala; Shao Qingsong; Chen, Yuan; Palani, Perumal (2020)
    The embelin derivative 2a was synthesized with the 1,2,3-bistriazole and spectral data confirmed its structural identity. Anti-diabetic and anti-lipidemic effects were evaluated using HFD-STZ induced type 2 diabetic rats. The derivative 2a (30 mg/kg b wt.) supplementation significantly (P