Ultra-structural morphology of long-term cultivated white adipose tissue-derived stem cells

Abstract

White adipose tissue was long perceived as a passive lipid storage depot but it is now considered as an active and important endocrine organ. It also harbours not only adipocytes and vascular cells but also a wide array of immunologically active cells, including macrophages and lymphocytes, which may induce obesity-related inflammation. Recently, adipose tissue has been reported as a source of adult mesenchymal stem cells with wide use in regenerative medicine and tissue engineering. Their relatively non-complicated procurement and collection (often performed as liposuction during aesthetic surgery) and grand plasticity support this idea even more. We focused our research on exploring the issues of isolation and long-term cultivation of mesenchymal stem cells obtained from adipose tissue. Ultra-structural morphology of the cells cultivated in vitro has been studied and analysed in several cultivation time periods and following serial passages--up to 30 passages. In the first passages they had ultra-structural characteristics of cells with high proteosynthetic activity. Within the cytoplasm, big number of small lipid droplets and between them, sparsely placed, small and inconspicuous, electron-dense, lamellar bodies, which resembled myelin figures were observed. The cells from the later passages contained high number of lamellar electron-dense structures, which filled out almost the entire cytoplasm. In between, mitochondria were often found. These bodies were sometimes small and resembled myelin figures, but several of them reached huge dimensions (more than 1 µm) and their lamellar structure was not distinguishable. We did not have an answer to the question about their function, but they probably represented the evidence of active metabolism of lipids present in the cytoplasm of these cells or represented residual bodies, which arise after the breakdown of cellular organelles, notably mitochondria during long-term cultivation.

Human adipose mesenchymal stromal cells growing into PCL‐nHA electrospun scaffolds undergo hypoxia adaptive ultrastructural changes

“…Pasquinelly et al proposed that the peripheral aspect of hBM-MSCs cells could probably mean that the cell membrane is deeply invaginated. [26] These characteristics are similar to those of hUC-MSCs, [27] hAD-MSC described earlier, [24,25] and observed here.…”

“…Pasquinelly et al proposed that the peripheral aspect of hBM‐MSCs cells could probably mean that the cell membrane is deeply invaginated. [ 26 ] These characteristics are similar to those of hUC‐MSCs, [ 27 ] hAD‐MSC described earlier, [ 24,25 ] and observed here. Nevertheless, not all MSCs show exclusively these mesenchymal characters, that is, hAM‐MSCs also retain some epithelial features, such as surface non‐intestinal‐type microvilli, intracytoplasmic lumina lined with microvilli, and intercellular junctions between adjacent cell membranes and processes.…”

“…Also, a polymorphous nucleus with deep clefts and prominent nucleolus, lipid droplets, and small lamellar bodies were observed in the cytoplasm of hAD‐MSCs. [ 25 ]…”

“…Also, a polymorphous nucleus with deep clefts and prominent nucleolus, lipid droplets, and small lamellar bodies were observed in the cytoplasm of hAD-MSCs. [25] Ultrastructural differences and similarities have been observed in hMSCs deriving from different sources. By TEM, hBM-MSC showed two distinct cytoplasmic features: the presence of dilated cisternae of ER and a multiloculated peripheral appearance.…”

Effect of Serial Passaging on the Morphology and Biological Characteristics of Human Adipose Tissue-derived Stem Cells

“…Only in last passage they contained a small amount of lamellar bodies, s.c. endosomes in the cytoplasm. In our previous morphological study we identify these structures in higher passages (about passage 30) but they were present in significantly higher quantities (they filled out almost whole cytoplasm) (Varga et al, 2015). These structures represent late stage of endosome maturation with partial electron dense areas prior to final breakdown by lysosomes (Huotari and Helenius, 2011).…”