Mesenchymal Stromal Cells Differentiating to Adipocytes Accumulate Autophagic Vesicles Instead of Functional Lipid Droplets

Abstract

Adult bone marrow mesenchymal stromal cells (BMSCs) can easily be differentiated into a variety of cells. In vivo transplantation of BMSCs-differentiated cells has had limited success, suggesting that these cells may not be fully compatible with the cells they are intended to replace in vivo. We investigated the structural and functional features of BMSCs-derived adipocytes as compared with adipocytes from adipose tissue, and the structure and functionality of lipid vesicles formed during BMSCs differentiation to adipocytes. Gas chromatography-mass spectrometry showed fatty acid composition of BMSCs-derived adipocytes and adipocytes from the adipose tissue to be very different, as is the lipid rafts composition, caveolin-1 expression, caveolae distribution in their membranes, and the pattern of expression of fatty acid elongases. Confocal microscopy confirmed the absence from BMSCs-derived adipocytes of markers of lipid droplets. BMSCs-derived adipocytes cannot convert deuterated glucose into deuterated species of fatty acids and cannot uptake the deuterated fatty acid-bovine serum albumin complexes from the culture medium, suggesting that intra-cellular accumulation of lipids does not occur by lipogenesis. We noted that BMSCs differentiation to adipocytes is accompanied by an increase in autophagy. Autophagic vesicles accumulate in the cytoplasm of BMSCs-derived adipocytes and their size and distribution resembles that of Nile Red-stained lipid vesicles. Stimulation of autophagy in BMSCs triggers the intra-cellular accumulation of lipids, while inhibition of autophagy prevents this accumulation. In conclusion, differentiation of BMSCs-derived adipocytes leads to intra-cellular accumulation of autophagic vesicles rather than functional lipid droplets, suggesting that these cells are not authentic adipocytes. J. Cell. Physiol. 231: 863-875, 2016. © 2015 Wiley Periodicals, Inc.

Strontium ranelate-induced anti-adipocytic effects are involved in negative regulation of autophagy in rat bone marrow mesenchymal stem cells

“…In their studies, mouse models with a targeted deletion of Atg7 exhibited decreased white adipose mass and enhanced insulin sensitivity, while lipid accumulation and protein levels of adipocyte differentiation factors were inhibited. All these results suggested that adipocytic differentiation was attenuated after inhibition of autophagy [7,8], and revealed the phenomenon of the accumulation of autophagic vesicles and intracellular lipid-like vesicles [21]. The results of LC3 and P62 expression in our study (Fig.…”

Metabolomic Applications in Stem Cell Research: a Review

“…and indicated increased methionine and FAs levels (and non-detectable creatine) as characteristic of adipogenesis. Subsequent reports employed MS metabolomics, with hBMMSC lipid extracts unveiling changes in free FAs throughout adipogenesis [23,24]. MSC-differentiated preadipocytes (days 5-7) and adipocytes (day 21) lacked specific elongases (possibly hindering endogenous polyunsaturated FA, PUFA, synthesis) and differed from primary adipocytes in decreased levels of LA, -linolenic acid (ALA) and arachidonic acid (AA); and increased docosahexaenoic acid (DHA).…”

Endo- and Exometabolome Crosstalk in Mesenchymal Stem Cells Undergoing Osteogenic Differentiation

“…The increasing interest in SC lipidomics [8] has resulted in the majority of studies addressing MSCs (mostly using MS [3], along with one report using 1 H NMR [11]), followed by pluripotent SCs [13][14][15] and other SCs [16][17][18]. The main topics studied have comprised MSC differentiation (into adipogenic [19][20][21][22][23], osteogenic [19,[24][25][26][27], or chondrogenic lineages [24,28,29]) and senescence/aging [30][31][32], with most reports employing bone marrow MSCs (BMMSCs) [22,23,[25][26][27][28][29][30]32], followed by adipose tissue-derived MSCs (AMSCs) [19,20,24,[33][34][35][36][37] and other MSCs [11,31]. Initial differentiation studies using GC-MS found that rat BMMSCs exposed to adipogenic media experienced decreases in saturated/unsaturated fatty acid (FAs) ratios over time, while maintaining a fr...…”

“…The main topics studied have comprised MSC differentiation (into adipogenic [19][20][21][22][23], osteogenic [19,[24][25][26][27], or chondrogenic lineages [24,28,29]) and senescence/aging [30][31][32], with most reports employing bone marrow MSCs (BMMSCs) [22,23,[25][26][27][28][29][30]32], followed by adipose tissue-derived MSCs (AMSCs) [19,20,24,[33][34][35][36][37] and other MSCs [11,31]. Initial differentiation studies using GC-MS found that rat BMMSCs exposed to adipogenic media experienced decreases in saturated/unsaturated fatty acid (FAs) ratios over time, while maintaining a free fatty acid (FFA) profile similar to that of undifferentiated cells [22,23]. Interestingly, differences between differentiated and primary adipocytes could be partially explained by the lack of essential polyunsaturated fatty acids (PUFAs) in culture media [22].…”

“…Interestingly, differences between differentiated and primary adipocytes could be partially explained by the lack of essential polyunsaturated fatty acids (PUFAs) in culture media [22]. It was also suggested that the presence of the differentiation-inductor dexamethasone (Dexa) in the medium could lead to autophagy and consequent lipid accumulation, without adipogenesis occurring [23]. In addition, a shotgun tandem MS study found that the lipidome is significantly influenced by adipose tissue type and anatomical location.…”