Adipose tissue plays a role in energy storage and metabolic balance and is composed of different cell types. The metabolic activity of the tissue itself has been a matter of research for a long time, but comparative data about the energy metabolism of different cell types of human subcutaneous adipose tissue are sparse. Therefore, we compared the activity of major energy metabolic pathways of adipocytes and CD34+ cells from the stromal vascular fraction (SVF) separated from the same tissue. This CD34+ cell fraction is enriched with adipose tissue-derived mesenchymal progenitors, as they account for the largest proportion of CD34+ cells of the SVF. Adipocytes displayed significantly higher mitochondrial enzyme capacities compared to CD34+ SVF-cells, as shown by the higher activities of isocitrate dehydrogenase and ß-hydroxyacyl-CoA dehydrogenase. Inversely, the CD34+ SVF-cells showed higher capacities for cytosolic carbohydrate metabolism, represented by the activity of glycolysis and the pentose phosphate pathway. Thus, the CD34+ SVF-cells may ensure the provision of pentose phosphates and reduction equivalents for the replication of DNA during proliferation. The data indicate that these two cell fractions of the human adipose tissue vary in their metabolic configuration adapted to their physiological demands regarding proliferation and differentiation in vivo.
Keywords: Adipocytes; Adipose tissue; Adipose tissue-derived mesenchymal stem/stroma cells; Dehydrogenases; Energy metabolism; Fatty acid oxidation; Gluconeogenesis; Glycolysis; Pentose phosphate pathway.
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