Diabetic human adipose tissue-derived mesenchymal stem cells fail to differentiate in functional adipocytes

Abstract

Adipose tissue dysfunction represents a hallmark of diabetic patients and is a consequence of the altered homeostasis of this tissue. Mesenchymal stem cells (MSCs) and their differentiation into adipocytes contribute significantly in maintaining the mass and function of adult adipose tissue. The aim of this study was to evaluate the differentiation of MSCs from patients suffering type 2 diabetes (dASC) and how such process results in hyperplasia or rather a stop of adipocyte turnover resulting in hypertrophy of mature adipocytes. Our results showed that gene profile of all adipogenic markers is not expressed in diabetic cells after differentiation indicating that diabetic cells fail to differentiate into adipocytes. Interestingly, delta like 1, peroxisome proliferator-activated receptor alpha, and interleukin 1β were upregulated whereas Sirtuin 1 and insulin receptor substrate 1 gene expression were found downregulated in dASC compared to cells obtained from healthy subjects. Taken together our data indicate that dASC lose their ability to differentiate into mature and functional adipocytes. In conclusion, our in vitro study is the first to suggest that diabetic patients might develop obesity through a hypertrophy of existing mature adipocytes due to failure turnover of adipose tissue. Impact statement In the present manuscript, we evaluated the differentiative potential of mesenchymal stem cells (MSCs) in adipocytes obtained from healthy and diabetic patients. This finding could be of great potential interest for the field of obesity in order to exploit such results to further understand the pathophysiological processes underlying metabolic syndrome. In particular, inflammation in diabetic patients causes a dysfunction in MSCs differentiation and a decrease in adipocytes turnover leading to insulin resistance.

Keywords: Adipocyte; diabetes; differentiation; metabolic syndrome; obesity; stem cells.

Figure 1

hASC (healthy) (a) and dASC (diabetes) (b) cells after 21 days of adipogenic differentiation viewed by light microscopy. Lipid droplets accumulation measured by Oil Red staining in hASC (c) and in dASC (d) after 21 days of adipogenic differentiation. ASC: adipose stem cell. (A color version of this figure is available in the online journal.)

Figure 2

Analysis of gene expression by real-time PCR of CEBPα, FAS, FABP4, DGAT1, SCD-1, SREBP-1c, and DLK-1 of hASC (healthy) and dASC (diabetes) before and after 21 days of adipogenic differentiation. All values are expressed as mean ± SEM of four experiments (n = 4) in duplicate. (^#p < 0.05 versus hASC at 0 day; *p < 0.05 versus dASC at 0 day.) ASC: adipose stem cell; CEBPα: CCAAT/enhancer-binding protein alpha; DGAT1: diacylglycerol O-acyltransferase 1; DLK-1: delta like non-canonical Notch ligand 1; FAS: fatty acid synthase; FABP4: fatty acid binding protein 4; hASC: healthy adipose stem cell; PCR: polymerase chain reaction; SCD-1: stearoyl-CoA desaturase-1; SREBP-1c: sterol regulatory element-binding protein 1c.

Figure 3

Analysis of gene expression by real-time PCR of cytokines IL-1β, IL-6, and TNFα of hASC (healthy) and dASC (diabetes) before and after 21 days of adipogenic differentiation. All values are expressed as mean ± SEM of four experiments (n = 4) in duplicate. (^#p < 0.05 versus hASC at 0 day; *p < 0.05 versus dASC at 0 day.). ASC: adipose stem cell; IL: interleukin; PCR: polymerase chain reaction; SEM: mean standard error; TNFα: tumor necrosis factor alpha.

Figure 4

Analysis of gene expression of PPARα, PPARδ, and PPARγ by real-time PCR of hASC (healthy) and dASC (diabetes) before and after 21 days of adipogenic differentiation. All values are expressed as mean ± SEM of four experiments (n = 4) in duplicate. (^#p < 0.05 versus hASC at 0 day.). ASC: adipose stem cell; PCR: polymerase chain reaction; PPAR: peroxisome proliferator-activated receptor.

Figure 5

Analysis of gene expression by real-time PCR of IRS-1 and SIRT1 of hASC (healthy) and dASC (diabetes) before and after 21 days of adipogenic differentiation. All values are expressed as mean ± SEM of four experiments (n = 4) in duplicate. (^#p < 0.05 versus hASC at 0 day.). ASC: adipose stem cell; IRS-1: insulin receptor substrate 1; PCR: polymerase chain reaction; SIRT-1: sirtuin 1.