TRIB3 Is Highly Expressed in the Adipose Tissue of Obese Patients and Is Associated With Insulin Resistance

CONTEXT

The upregulation of TRIB3 (Tribbles homolog 3), a stress-inducible gene encoding a pseudokinase, has been implicated in the development of insulin resistance in the skeletal muscle and liver of patients with obesity and type 2 diabetes. However, there is little information regarding TRIB3 expression in human adipose tissue.

OBJECTIVE

To investigate whether TRIB3 expression is dysregulated in human adipose tissue in the context of obesity and type 2 diabetes and whether TRIB3 expression in adipose tissues is associated with insulin resistance.

METHODS

We measured metabolic parameters and TRIB3 expression in abdominal subcutaneous and visceral adipose tissue in obese (with or without type 2 diabetes) and normal-weight women. Regulation of TRIB3 expression was studied in human adipocytes.

RESULTS

TRIB3 expression in both fat depots was higher in patients with obesity and/or type 2 diabetes; in addition, the expression level was significantly associated with insulin resistance. Incubating adipocytes under conditions mimicking the microenvironment of obese adipose tissue, including increased endoplasmic reticulum (ER) stress, induced TRIB3 expression. In human adipocytes, the overexpression of TRIB3 impaired insulin-stimulated protein kinase B (AKT) phosphorylation and caused dysregulation of the transcription of genes encoding bioactive molecules released from adipocytes, such as proinflammatory cytokines, adiponectin, and leptin. Pioglitazone, an insulin-sensitizing agent, reduced both these effects of TRIB3 and the ER stressor-induced expression of TRB3.

CONCLUSION

Our data indicate that TRIB3 expression in adipose tissue is enhanced in patients with obesity and suggest that increased TRIB3 dysregulates adipocyte function, which may contribute to the development of insulin resistance.

Proteomic Signatures of Human Visceral and Subcutaneous Adipocytes

CONTEXT

Adipose tissue distribution is a key factor influencing metabolic health and risk in obesity-associated comorbidities.

OBJECTIVE

Here we aim to compare the proteomic profiles of mature adipocytes from different depots.

METHODS

Abdominal subcutaneous (SA) and omental visceral adipocytes (VA) were isolated from paired adipose tissue biopsies obtained during bariatric surgery on 19 severely obese women (body mass index > 30 kg/m2) and analyzed using state-of-the-art mass spectrometry. Differential expression analysis and weighted gene co-expression network analysis (WGCNA) were performed to investigate proteome signature properties and to examine a possible association of the protein expression with the clinical data.

RESULTS

We identified 3686 protein groups and found 1140 differentially expressed proteins (adj. P value < 0.05), of which 576 proteins were upregulated in SA and 564 in VA samples. We provide a global protein profile of abdominal SA and omental VA, present the most differentially expressed pathways and processes distinguishing SA from VA, and correlate them with clinical and body composition data. We show that SA are significantly more active in processes linked to vesicular transport and secretion, and to increased lipid metabolism activity. Conversely, the expression of proteins involved in the mitochondrial energy metabolism and translational or biosynthetic activity is higher in VA.

CONCLUSION

Our analysis represents a valuable resource of protein expression profiles in abdominal SA and omental VA, highlighting key differences in their role in obesity.

Src family kinases involved in the differentiation of human preadipocytes

BACKGROUND

Obesity is characterized by the excess accumulation of white adipose tissue (WAT). Src family kinases (SFKs) are non-receptor tyrosine kinases consisting of eight members (SRC, FYN, YES1, HCK, LCK, LYN, FGR and BLK) that have been studied extensively in mammalian cells. Although individual members in murine cells provide some clues that are associated with the regulation of adipogenesis, the specific role of this family in adipocyte differentiation has rarely been assessed, especially in human adipocytes.

METHODS

Herein, we first explored the expression profiles of SFKs during human preadipocyte differentiation. Then, we used the pyrazolo-pyrimidinyl-amine compound PP1, a potent SFK inhibitor, to evaluate the function of SFKs during adipocyte differentiation. Furthermore, we adopted a loss-of-function strategy with siRNAs to determine the role of FGR in adipocyte differentiation.

RESULTS

Here, we found that SRC, FYN, YES1, LYN and FGR were expressed in human preadipocytes and induced after the initiation of differentiation. Furthermore, the SFK inhibitor PP1 suppressed adipocyte differentiation. We also found that PP1 significantly suppressed the SFK activity in preadipocytes and decreased the expression of adipogenic genes in early and late differentiation. Given that FGR exhibited the most expression enhancement in mature adipocytes, we focused on FGR and found that its knockdown reduced lipid accumulation and adipogenic gene expression.

CONCLUSIONS

Collectively, these findings suggest that SFKs, especially FGR, are involved in the differentiation of human preadipocytes. Our results lay a foundation for further understanding the role of SFKs in adipocyte differentiation and provide new clues for anti-obesity therapies.

14-3-3ε protein-immobilized PCL-HA electrospun scaffolds with enhanced osteogenicity

Adipose-derived mesenchymal stem cells (ASCs) accelerate the osteointegration of bone grafts and improve the efficiency in the formation of uniform bone tissue, providing a practical and clinically attractive approach in bone tissue regeneration. In this work, the effect of nanofibrous biomimetic matrices composed of poly(ε-caprolactone) (PCL), nanometric hydroxyapatite (nHA) particles and 14-3-3 protein isoform epsilon on the initial stages of human ASCs (hASCs) osteogenic differentiation was investigated. The cells were characterized by flow cytometry and induction to differentiation to adipogenic and osteogenic lineages. The isolated hASCs were induced to differentiate to osteoblasts over all scaffolds, and adhesion and viability of the hASCs were found to be similar. However, the activity of alkaline phosphatase (ALP) as early osteogenic marker in the PCL-nHA/protein scaffold was four times higher than in PCL-nHA and more than five times than the measured in neat PCL.

Early Changes in Adipose Tissue Morphology, Gene Expression, and Metabolism After RYGB in Patients With Obesity and T2D

CONTEXT

Roux-en-Y gastric bypass (RYGB) surgery effectively prevents or treats type 2 diabetes (T2D). Adipose tissue (AT) mechanisms may be of importance.

OBJECTIVE

To assess the relationship between early changes in whole-body and AT metabolism in surgically treated patients with T2D.

DESIGN AND SETTING

A randomized single-center study.

PATIENTS

Nineteen patients with T2D with body mass index 30 to 45 kg/m2.

INTERVENTIONS

Thirteen patients were assessed at baseline and 4 and 24 weeks after RYGB (preceded by a 4-week low-calorie diet) and compared with 6 control patients continuing standard medical treatment: oral glucose tolerance test, subcutaneous AT biopsies for gene expression, adipocyte size, glucose uptake, lipolysis, and insulin action.

RESULTS

At 4 and 24 weeks post-RYGB, all patients but one had stopped diabetes medication. Fasting glucose, HbA1c, and insulin levels decreased and the Matsuda index increased compared with baseline (P < 0.01 for all), indicating improved whole-body insulin sensitivity. Mean adipocyte size significantly reduced, more at 4 than at 24 weeks; at 4 weeks, glucose uptake per adipocyte was lowered, and isoproterenol-stimulated lipolysis tended to increase, whereas the fold insulin effects on glucose uptake and lipolysis were unchanged. Expression of genes involved in fatty acid oxidation, CPT1b and adiponectin, was increased at 4 weeks, whereas leptin and E2F1 (involved in cell proliferation) were reduced (P < 0.05 for all).

CONCLUSION

Glycemic control and in vivo insulin sensitivity improved 4 weeks after RYGB, but adipocyte insulin sensitivity did not change despite a marked reduction in adipocyte size. Thus, mechanisms for a rapid improvement of T2D after RYGB may occur mainly in other tissues than adipose.

Effects of administration of adipose-derived stromal vascular fraction and platelet-rich plasma to dogs with osteoarthritis of the hip joints

OBJECTIVE To evaluate effects of simultaneous intra-articular and IV injection of autologous adipose-derived stromal vascular fraction (SVF) and platelet-rich plasma (PRP) to dogs with osteoarthritis of the hip joints. ANIMALS 22 client-owned dogs (12 placebo-treated [control] dogs and 10 treated dogs). PROCEDURES Dogs with osteoarthritis of the hip joints that caused signs of lameness or discomfort were characterized on the basis of results of orthopedic examination, goniometry, lameness score, the Canine Brief Pain Inventory (CBPI), a visual analogue scale, and results obtained by use of a pressure-sensing walkway at week 0 (baseline). Dogs received a simultaneous intraarticular and IV injection of SVF and PRP or a placebo. Dogs were examined again 4, 8, 12, and 24 weeks after injection. RESULTS CBPI scores were significantly lower for the treatment group at week 24, compared with scores for the control group. Mean visual analogue scale score for the treatment group was significantly higher at week 0 than at weeks 4, 8, or 24. Dogs with baseline peak vertical force (PVF) in the lowest 25th percentile were compared, and the treatment group had a significantly higher PVF than did the control group. After the SVF-PRP injection, fewer dogs in the treated group than in the control group had lameness confirmed during examination. CONCLUSIONS AND CLINICAL RELEVANCE For dogs with osteoarthritis of the hip joints treated with SVF and PRP, improvements in CBPI and PVF were evident at some time points, compared with results for the control group.

Comparative analysis of three human adipocyte size measurement methods and their relevance for cardiometabolic risk

OBJECTIVE

To determine whether adipocyte diameters from three measurement methods are similarly associated with adiposity measurements and cardiometabolic variables.

METHODS

Surgical samples of omental and abdominal subcutaneous adipose tissue were obtained in a sample of 60 women (age 35-59 years; body mass index 20.3-41.1 kg/m² ). Median adipocyte diameter of the main cell population was determined by collagenase digestion, osmium tetroxide fixation, and histological analysis. Adiposity and cardiometabolic risk factors were assessed.

RESULTS

Adipocyte diameter was consistently smaller with formalin fixation than with collagenase digestion, whereas osmium-fixed cells were larger (P < 0.0001, for all). Median adipocyte diameters derived from all methods were intercorrelated (r = 0.46-0.83, P < 0.001 for all). Positive associations were found between adipocyte diameters from all techniques and regional or total adiposity measurements (P < 0.01 for all). Omental adipocyte diameter was positively associated with fasting glucose, insulin, and homeostatic model assessment of insulin resistance (r = 0.30-0.52, P < 0.05 for all), with osmium-fixed cell size as a stronger correlate. Osmium-fixed cell diameter was also a better correlate of plasma adiponectin and leptin.

CONCLUSIONS

Although measurement techniques generated systematic differences in adipocyte size, associations with adiposity were only slightly affected by the technique. Osmium fixation generated stronger associations with cardiometabolic risk factors than collagenase digestion and histological analysis.

Depot Dependent Effects of Dexamethasone on Gene Expression in Human Omental and Abdominal Subcutaneous Adipose Tissues from Obese Women

Glucocorticoids promote fat accumulation in visceral compared to subcutaneous depots, but the molecular mechanisms involved remain poorly understood. To identify long-term changes in gene expression that are differentially sensitive or responsive to glucocorticoids in these depots, paired samples of human omental (Om) and abdominal subcutaneous (Abdsc) adipose tissues obtained from obese women during elective surgery were cultured with the glucocorticoid receptor agonist dexamethasone (Dex, 0, 1, 10, 25 and 1000 nM) for 7 days. Dex regulated 32% of the 19,741 genes on the array, while 53% differed by Depot and 2.5% exhibited a Depot*Dex concentration interaction. Gene set enrichment analysis showed Dex regulation of the expected metabolic and inflammatory pathways in both depots. Cluster analysis of the 460 transcripts that exhibited an interaction of Depot and Dex concentration revealed sets of mRNAs for which the responses to Dex differed in magnitude, sensitivity or direction between the two depots as well as mRNAs that responded to Dex only in one depot. These transcripts were also clearly depot different in fresh adipose tissue and are implicated in processes that could affect adipose tissue distribution or functions (e.g. adipogenesis, triacylglycerol synthesis and storage, insulin action). Elucidation of the mechanisms underlying the depot differences in the effect of Dex on the expression of specific genes and pathways that regulate adipose function may offer novel insights into understanding the biology of visceral adipose tissues and their links to metabolic health.

Proteomics analyses of subcutaneous adipocytes reveal novel abnormalities in human insulin resistance

OBJECTIVE

To provide a more global view of adipocyte changes in human insulin resistance by proteomics analyses.

METHODS

Baseline biopsies of abdominal subcutaneous adipose tissue were obtained from 23 subjects without diabetes. Euglycemic clamps were used to divide subjects into an insulin-resistant group (IR, N = 10) and an insulin-sensitive (IS, N = 13) group, which were of similar age and gender but unequal adiposity (greater in IR). Proteins of isolated adipocytes were quantified by mass spectrometry using normalized spectral abundance factors.

RESULTS

Of 1,245 proteins assigned, 30 were detected in at least 12 of the 23 subjects that differed significantly in abundance ≥1.5-fold between IR and IS. IR displayed a pattern of increased cytoskeletal proteins and decreased mitochondrial proteins and FABP4 and FABP5. In subgroup analyses of adiposity-matched subjects, several of these changes were less pronounced in IR, but the abundance of proteins related to lipid metabolism and the unfolded/misfolded protein response were significantly and unfavorably altered.

CONCLUSIONS

These results confirm lower abundance of mitochondrial proteins and suggest increased cytoskeletal proteins and decreased FABP4 and FABP5 in subcutaneous adipocytes of typical IR individuals. Changes in proteins related to lipid metabolism and the unfolded/misfolded protein may discriminate IR and IS individuals of equal adiposity.

Adipokines and Vascular Endothelial Growth Factor in Normal Human Breast Tissue in Vivo - Correlations and Attenuation by Dietary Flaxseed

Exposure to sex steroids increases the risk of breast cancer but the exact mechanisms are yet to be elucidated. Events in the microenvironment are important for carcinogenesis. Diet containing phytoestrogens can affect the breast microenvironment and alter the risk of breast cancer. It has previously been shown that estrogen regulates extracellular levels of leptin, adiponectin, and VEGF in normal breast tissue in vivo. Whether these proteins correlate in breast tissue in vivo or if diet addition of flaxseed, a major source of phytoestrogens in Western diets, alters adipokine levels in breast tissue are unknown. We used microdialysis to sample proteins of normal human breast tissue and abdominal subcutaneous fat in situ in 34 pre-and postmenopausal women. In vitro, co-culture of breast cancer cells and primary human adipocytes was used. In vivo, in normal breast tissue, a significant positive correlation between VEGF and leptin was detected. No correlations were found in fat tissue. Co-culture of adipocytes and breast cancer cells per se increased the secretion of VEGF and leptin and enhanced the effects of estradiol compared to culture of either cell type alone. In vitro, inhibition of VEGF diminished the release of leptin while inhibition of leptin had no influence on VEGF secretion. The levels of leptin decreased and adiponectin increased after a dietary addition of 25 g of flaxseed/day for one menstrual cycle. We conclude that VEGF and leptin correlate significantly in normal human breast tissue in vivo and that dietary addition of flaxseed affect adipokine levels in the breast.

Retinoic Acid Mediates Visceral-Specific Adipogenic Defects of Human Adipose-Derived Stem Cells

Increased visceral fat, rather than subcutaneous fat, during the onset of obesity is associated with a higher risk of developing metabolic diseases. The inherent adipogenic properties of human adipose-derived stem cells (ASCs) from visceral depots are compromised compared with those of ASCs from subcutaneous depots, but little is known about the underlying mechanisms. Using ontological analysis of global gene expression studies, we demonstrate that many genes involved in retinoic acid (RA) synthesis or regulated by RA are differentially expressed in human tissues and ASCs from subcutaneous and visceral fat. The endogenous level of RA is higher in visceral ASCs; this is associated with upregulation of the RA synthesis gene through the visceral-specific developmental factor WT1. Excessive RA-mediated activity impedes the adipogenic capability of ASCs at early but not late stages of adipogenesis, which can be reversed by antagonism of RA receptors or knockdown of WT1. Our results reveal the developmental origin of adipocytic properties and the pathophysiological contributions of visceral fat depots.

Advanced Properties of Urine Derived Stem Cells Compared to Adipose Tissue Derived Stem Cells in Terms of Cell Proliferation, Immune Modulation and Multi Differentiation

Adipose tissue stem cells (ADSCs) would be an attractive autologous cell source. However, ADSCs require invasive procedures, and has potential complications. Recently, urine stem cells (USCs) have been proposed as an alternative stem cell source. In this study, we compared USCs and ADSCs collected from the same patients on stem cell characteristics and capacity to differentiate into various cell lineages to provide a useful guideline for selecting the appropriate type of cell source for use in clinical application. The urine samples were collected via urethral catheterization, and adipose tissue was obtained from subcutaneous fat tissue during elective laparoscopic kidney surgery from the same patient (n = 10). Both cells were plated for primary culture. Cell proliferation, colony formation, cell surface markers, immune modulation, chromosome stability and multi-lineage differentiation were analyzed for each USCs and ADSCs at cell passage 3, 5, and 7. USCs showed high cell proliferation rate, enhanced colony forming ability, strong positive for stem cell markers expression, high efficiency for inhibition of immune cell activation compared to ADSCs at cell passage 3, 5, and 7. In chromosome stability analysis, both cells showed normal karyotype through all passages. In analysis of multi-lineage capability, USCs showed higher myogenic, neurogenic, and endogenic differentiation rate, and lower osteogenic, adipogenic, and chondrogenic differentiation rate compared to ADSCs. Therefore, we expect that USC can be an alternative autologous stem cell source for muscle, neuron and endothelial tissue reconstruction instead of ADSCs.

Oxidative activity of 17β-hydroxysteroid dehydrogenase on testosterone in male abdominal adipose tissues and cellular localization of 17β-HSD type 2

Testosterone can be converted into androstenedione (4-dione) by 17β-hydroxysteroid dehydrogenase (HSD) activity likely performed by 17β-HSD type 2. Our objective was to evaluate the rate of testosterone conversion to 4-dione as well as expression and localization of 17β-HSD type 2 in omental (OM) vs. subcutaneous (SC) adipose tissues of men. Formation of 4-dione from testosterone was significantly higher in homogenates (p ≤ 0.001) and explants (p ≤ 0.01) of OM than SC tissue. Microscopy analyses and biochemical assays in cell fractions localized the enzyme in the vasculature/endothelial cells of adipose tissues. Conversion of testosterone to 4-dione was weakly detected in most OM and/or SC preadipocyte cultures. Positive correlations were found between 17β-HSD type 2 activity in whole tissue and BMI or SC adipocyte diameter. We conclude that conversion of testosterone to 4-dione detected in abdominal adipose tissue is caused by 17β-HSD type 2 which is localized in the vasculature of the adipose compartment.

The Association Between Subcutaneous Fat Density and the Propensity to Store Fat Viscerally

BACKGROUND

Alterations in the cellular characteristics of subcutaneous adipose tissue (SAT) may reduce its ability to expand in times of caloric excess, increasing the propensity to store excess calories viscerally (visceral adipose tissue [VAT]). We hypothesized (1) that increased SAT density, an indirect marker of fat quality, would be associated with an increased VAT/SAT ratio and increased cardiovascular disease (CVD) risk and (2) that these associations would be independent of the absolute volume of SAT.

METHODS

We investigated the association of SAT density with the VAT/SAT ratio and CVD risk in 3212 participants (48% women, mean age, 50.7 years) from the Framingham Heart Study. Adipose tissue depot density and volume were quantified by computed tomography; traditional CVD risk factors were quantified.

RESULTS

Higher SAT density was correlated with a higher VAT/SAT ratio in men (r = 0.17; P < .0001) but not in women (r = 0.04; P ≥ .05). More adverse levels of CVD risk factors were observed in the high SAT density/high VAT/SAT ratio group than in the referent group (low density/low ratio). For example, women had an increased risk of diabetes (odds ratio [OR], 6.7; 95% confidence interval [CI], 2.6-17.6; P = .0001) and hypertension (OR, 1.6; 95% CI, 1.1-2.4; P = .009). Additional adjustment for SAT volume generally strengthened these associations (diabetes OR, 10.8; 95% CI, 4.1-29.0; hypertension OR, 2.5; 95% CI, 1.7-3.7; all P < .0001). These trends were similar but generally weaker in men.

CONCLUSION

High fat density, an indirect marker of fat quality, is associated with the propensity to store fat viscerally vs subcutaneously and is jointly characterized by an increased burden of CVD risk factors.

Mature adipocyte proteome reveals differentially altered protein abundances between lean, overweight and morbidly obese human subjects

Overweight (OW) and obese individuals are considered to be graded parts of the scale having increasing weight as a common feature. They may not, however, be part of the same continuum and may differ metabolically. In this study we applied an untargeted proteomic approach to compare protein abundances in mature adipocytes derived from the subcutaneous adipose tissue of overweight and morbidly obese female subjects to those of lean age matched controls. Mature adipocytes were isolated from liposuction samples of abdominal subcutaneous adipose tissue collected from both lean (L; n = 7, 23.3 ± 0.4 kg/m(2); mean BMI ± SD), overweight (OW; n = 8, 27.9 ± 0.6 kg/m(2); mean BMI ± SD) and morbidly obese (MOB; n = 7, 44.8 ± 3.8 kg/m(2); mean BMI ± SD) individuals. Total protein extracts were then compared by two-dimensional difference in gel electrophoresis (2D DIGE). One hundred and ten differentially expressed protein spots (i.e., fitting the statistical criteria ANOVA test, p < 0.05; fold-change ≥1.5) were detected, and of these, 89 were identified by MALDI-TOF mass spectrometry. Of these, 66 protein spots were common to both groups whereas 23 were unique to the MOB group. Significant differences were evident in the abundances of key proteins involved in glucose and lipid metabolism, energy regulation, cytoskeletal structure and redox control signaling pathways. Differences in the abundance of some chaperones were also evident. The differentially abundant proteins were investigated using Ingenuity Pathway Analysis (IPA) to establish their associations with known biological functions. The network identified in the OW group with the highest score relates to-: cell-to-cell signaling and interaction; in contrast, in the MOB group the major interacting pathways are associated with lipid metabolism, small molecule biochemistry and cancer. The differences in abundance of the differentially regulated proteins were validated by immunoblotting. These findings provide insights into metabolic differences in OW and MOB individuals.

Human adipose tissue-derived mesenchymal stem cells inhibit melanoma growth in vitro and in vivo

BACKGROUND/AIM

The effects of adipose tissue-derived mesenchymal stem cells (AT-MSCs) on the growth of human malignancies, including melanoma, are controversial and the underlying mechanisms are not yet-well understood. The aim of the present study was to investigate the in vitro and in vivo anti-tumor effects of human AT-MSCs on human melanoma.

MATERIALS AND METHODS

The inhibitory effect of AT-MSC-conditioned medium (AT-MSC-CM) on the growth of A375SM and A375P (human melanoma) cells was evaluated using a cell viability assay. Cell-cycle arrest and apoptosis in melanoma cells were investigated by flow cytometry and western blot analysis. To evaluate the in vivo anti-tumor effect of AT-MSCs, CM-DiI-labeled AT-MSCs were circumtumorally injected in tumor-bearing athymic mice and tumor size was measured.

RESULTS

AT-MSC-CM inhibited melanoma growth by altering cell-cycle distribution and inducing apoptosis in vitro. AT-MSCs suppressed tumor growth in tumor-bearing athymic mice and fluorescence analysis showed that AT-MSCs migrated efficiently to tumor tissues.

CONCLUSION

AT-MSCs inhibit the growth of melanoma suggesting promise as a novel therapeutic agent for melanoma.

Therapeutic potential of human adipose-derived stem cells (ADSCs) from cancer patients: a pilot study

Mesenchymal stem cells from adipose tissue (ADSCs) are an important source of cells for regenerative medicine. The therapeutic effect of culture-expanded adipose derived stem cells has been shown; however, optimal xeno-free culture conditions remain to be determined. Cancer patients, specifically those undergoing invasive surgery, constitute a subgroup of patients who could benefit from autologous stem cell transplantation. Although regenerative potential of their ADSCs could be affected by the disease and/or treatment, we are not aware of any study that has evaluated the therapeutic potential of ADSCs isolated from cancer patients in reference to that of ADSCs derived from healthy subjects. Here we report that ADSCs isolated from subabdominal adipose tissue of patients with urological neoplasms yielded similar growth kinetics, presented equivalent mesenchymal surface markers and showed similar differentiation potential into distinct mesodermal cell lineages: adipocytes, chondroblasts and osteoblasts than ADSCs isolated from adipose tissue of age-matched non-oncogenic participants, all under xeno-free growth culture conditions. Molecular karyotyping of patient expanded ADSCs genomes showed no disease-related alterations indicating their safety. In addition, vesicles <100 nm identified as exosomes (EXOs) which may be at least partly responsible for the attributed therapeutic paracrine effects of the ADSCs were effectively isolated from ADSCs and showed equivalent miRNA content regardless they were derived from cancer patients or non-oncogenic participants indicating that the repair capabilities of xeno-free expanded ADSCs are not compromised by patient condition and therefore their xeno-free culture expanded ADSCs should be suitable for autologous stem cell transplantation in a clinical setting.

Inducible brown adipocytes in subcutaneous inguinal white fat: the role of continuous sympathetic stimulation

Brown adipocytes (BA) generate heat in response to sympathetic activation and are the main site of nonshivering thermogenesis in mammals. Although most BA are located in classic brown adipose tissue depots, BA are also abundant in the inguinal white adipose tissue (iWAT) before weaning. The number of BA is correlated with the density of sympathetic innervation in iWAT; however, the role of continuous sympathetic tone in the establishment and maintenance of BA in WAT has not been investigated. BA marker expression in iWAT was abundant in weaning mice but was greatly reduced by 8 wk of age. Nonetheless, BA phenotype could be rapidly reinstated by acute β₃-adrenergic stimulation with CL-316,243 (CL). Genetic tagging of adipocytes with adiponectin-CreER(T2) demonstrated that CL reinstates uncoupling protein 1 (UCP1) expression in adipocytes that were present before weaning. Chronic surgical denervation dramatically reduced the ability of CL to induce the expression of UCP1 and other BA markers in the tissue as a whole, and this loss of responsiveness was prevented by concurrent treatment with CL. These results indicate that ongoing sympathetic activity is critical to preserve the ability of iWAT fat cells to express a BA phenotype upon adrenergic stimulation.

Plasticity of human dedifferentiated adipocytes toward endothelial cells

The process of cellular differentiation in terminally differentiated cells is thought to be irreversible, and these cells are thought to be incapable of differentiating into distinct cell lineages. Our previous study showed that mature adipocytes represent an alternative source of mesenchymal stem cells. Here, results showed the capacity of mature adipocytes to differentiate into endothelial-like cells, using the ability of these cells to revert into an immature phase without any relievable chromosomal alterations. Mature adipocytes were isolated from human omental and subcutaneous fat and were dedifferentiated in vitro. The resulting cells were subcultivated for endothelial differentiation and were analyzed for their expression of specific genes and proteins. Endothelial-like cells were harvested from the differentiation medium and were traditionally cultured to evaluate the endothelial markers and the karyotype. Cells cultured in specific medium formed tube-like structures and expressed several endothelial marker genes and proteins. The endothelial-like cells expressed significantly higher levels of vascular endothelium growth factor receptor 2, vascular endothelial cadherin, Von Willebrand factor, and CD133 than the untreated cells. These cells were positively stained for CD31 and vascular endothelial cadherin, markers of mature endothelial cells. Moreover, the low-density lipoprotein-uptake assay demonstrated a functionally endothelial differentiation of these cells. When these cells were harvested and reseeded in basal medium, they lost the endothelial markers and reacquired the typical mesenchymal stem cell markers and the ability to expand in a short time period. Moreover, karyotype analysis showed that these cells reverted into an immature phase without any karyotype alterations. In conclusion, the results showed that adipocytes exhibited a great plasticity toward the endothelial lineage, suggesting their possible use in cell therapy applications for vascular disease.

FKBP5 expression in human adipose tissue increases following dexamethasone exposure and is associated with insulin resistance

OBJECTIVE

To study effects of dexamethasone on gene expression in human adipose tissue aiming to identify potential novel mechanisms for glucocorticoid-induced insulin resistance.

MATERIALS/METHODS

Subcutaneous and omental adipose tissue, obtained from non-diabetic donors (10 M/15 F; age: 28-60 years; BMI: 20.7-30.6 kg/m²), was incubated with or without dexamethasone (0.003-3 μmol/L) for 24 h. Gene expression was assessed by microarray and real time-PCR and protein expression by immunoblotting.

RESULTS

FKBP5 (FK506-binding protein 5) and CNR1 (cannabinoid receptor 1) were the most responsive genes to dexamethasone in both subcutaneous and omental adipose tissue (~7-fold). Dexamethasone increased FKBP5 gene and protein expression in a dose-dependent manner in both depots. The gene product, FKBP51 protein, was 10-fold higher in the omental than in the subcutaneous depot, whereas the mRNA levels were similar. Higher FKBP5 gene expression in omental adipose tissue was associated with reduced insulin effects on glucose uptake in both depots. Furthermore, FKBP5 gene expression in subcutaneous adipose tissue was positively correlated with serum insulin, HOMA-IR and subcutaneous adipocyte diameter and negatively with plasma HDL-cholesterol. FKBP5 SNPs were found to be associated with type 2 diabetes and diabetes-related phenotypes in large population-based samples.

CONCLUSIONS

Dexamethasone exposure promotes expression of FKBP5 in adipose tissue, a gene that may be implicated in glucocorticoid-induced insulin resistance.

TSH signaling pathways that regulate MCP-1 in human differentiated adipocytes

OBJECTIVE

Adipose tissue is an extra-thyroidal thyroid-stimulating hormone (TSH) target. Increases in lipolysis and in expression and release of interleukin-6 (IL-6) occur in TSH-stimulated adipocytes, and levels of circulating free fatty acids and IL-6 rise following TSH administration to patients with previous thyroidectomy and radioablation for thyroid cancer. Our first objective was to compare how TSH stimulates protein kinase A (PKA) and inhibitor of κB (IκB) kinase (IKK)-β. Our second objective was to investigate whether TSH induces other cytokines besides IL-6.

METHODS

TSH stimulation of either CHO cells expressing human TSH receptor or human abdominal subcutaneous differentiated adipocytes.

RESULTS

Signaling studies showed TSH increased NADPH oxidase activity, and either diphenyleneiodonium (oxidase inhibitor) or N-acetyl cysteine (scavenger of reactive oxygen species) reduced IKKβ phosphorylation. Phosphorylation of protein kinase C-δ, an upstream regulator of NADPH oxidase, was increased by TSH, and rottlerin (PKCδ inhibitor) reduced TSH-stimulated IKKβ phosphorylation. TSH upregulated monocyte chemoattractant protein-1 (MCP-1) mRNA expression and the release of MCP-1 protein in human abdominal differentiated adipocytes. H89 (PKA inhibitor) and sc-514 (IKKβ inhibitor) each blocked TSH-stimulated MCP-1 mRNA expression and protein release, suggesting PKA and IKKβ participate in this pathway.

CONCLUSIONS

These data provide new information about TSH signaling in human differentiated adipocytes, and add to the evidence that TSH is a pro-inflammatory stimulus of adipocytes.

White, brown and pink adipocytes: the extraordinary plasticity of the adipose organ

In mammals, adipocytes are lipid-laden cells making up the parenchyma of the multi-depot adipose organ. White adipocytes store lipids for release as free fatty acids during fasting periods; brown adipocytes burn glucose and lipids to maintain thermal homeostasis. A third type of adipocyte, the pink adipocyte, has recently been characterised in mouse subcutaneous fat depots during pregnancy and lactation. Pink adipocytes are mammary gland alveolar epithelial cells whose role is to produce and secrete milk. Emerging evidence suggests that they derive from the transdifferentiation of subcutaneous white adipocytes. The functional response of the adipose organ to a range of metabolic and environmental challenges highlights its extraordinary plasticity. Cold exposure induces an increase in the 'brown' component of the organ to meet the increased thermal demand; in states of positive energy balance, the 'white' component expands to store excess nutrients; finally, the 'pink' component develops in subcutaneous depots during pregnancy to ensure litter feeding. At the cell level, plasticity is provided not only by stem cell proliferation and differentiation but also, distinctively, by direct transdifferentiation of fully differentiated adipocytes by the stimuli that induce genetic expression reprogramming and through it a change in phenotype and, consequently function. A greater understanding of adipocyte transdifferentiation mechanisms would have the potential to shed light on their biology as well as inspire novel therapeutic strategies against metabolic syndrome (browning) and breast cancer (pinking).

Permanent activation of HMGA2 in lipomas mimics its temporal physiological activation linked to the gain of adipose tissue

OBJECTIVE

In this study the activation of HMGA2 and overexpression by FGF1-driven stimulation of adipose tissue derived stem cells (ADSCs) in adipose tissue tumors were analyzed. In addition, the expression of HMGA2 and PPAR-gamma mRNA were quantified in canine subcutaneous abdominal adipose tissue from normal and overweight purebred dogs.

DESIGN AND METHODS

ADSCs and adipose tissue explants stimulated with FGF1 followed by gene expression analyses of HMGA2 and p14(Arf) using Western-blot and qRT-PCR. Furthermore, canine subcutaneous white adipose tissue (WAT) were analyzed by qRT-PCR for their expression of HMGA2 and PPAR-gamma.

RESULTS

ADSCs and adipose tissue explants are able to execute a HMGA2 response upon FGF1 stimulation. FGF1 enhances proliferation of ADSCs by a HMGA2-dependent mechanism. In lipomas increase of HMGA2 is accompanied by increased expression of p14(Arf) . Furthermore, a significantly elevated level of HMGA2 in overweight dogs and a negative correlation between the expression of HMGA2 and PPAR-gamma in subcutaneous cWAT were noted.

CONCLUSIONS

These results suggest that WAT contains cells that as essential part of adipogenesis up-regulate HMGA2 resulting from growth factor stimulation. In subgroups of lipoma, constitutive activation of HMGA2 due to rearrangements replaces the temporal response triggered by growth factors.

FTO deficiency induces UCP-1 expression and mitochondrial uncoupling in adipocytes

Variants in the fat mass- and obesity-associated (FTO) gene are associated with obesity and body fat mass in genome-wide association studies. However, the mechanism by which FTO predisposes individuals to obesity is not clear so far. First mechanistic evidence was shown in Fto-negative mice. These mice are resistant to obesity due to enhanced energy expenditure, whereas the mass of brown adipose tissue remains unchanged. We hypothesize that FTO is involved in the induction of white adipose tissue browning, which leads to mitochondrial uncoupling and increases energy expenditure. Uncoupling protein 1 (Ucp-1) was significantly higher expressed in both gonadal and inguinal adipose depots of Fto(-/-) compared with Fto(+/+) littermates accompanied by the appearance of multivacuolar, Ucp-1-positive adipocytes in these tissues. By using lentiviral short hairpin RNA constructs, we established FTO-deficient human preadipocytes and adipocytes and analyzed key metabolic processes. FTO-deficient adipocytes showed an adipogenic differentiation rate comparable with control cells but exhibited a reduced de novo lipogenesis despite unchanged glucose uptake. In agreement with the mouse data, FTO-deficient adipocytes exhibited 4-fold higher expression of UCP-1 in mitochondria compared with control cells. The up-regulation of UCP-1 in FTO-deficient adipocytes resulted in enhanced mitochondrial uncoupling. We conclude that FTO deficiency leads to the induction of a brown adipocyte phenotype, thereby enhancing energy expenditure. Further understanding of the signaling pathway connecting FTO with UCP-1 expression might lead to new options for obesity and overweight treatment.

Awakened by cellular stress: isolation and characterization of a novel population of pluripotent stem cells derived from human adipose tissue

Advances in stem cell therapy face major clinical limitations, particularly challenged by low rates of post-transplant cell survival. Hostile host factors of the engraftment microenvironment such as hypoxia, nutrition deprivation, pro-inflammatory cytokines, and reactive oxygen species can each contribute to unwanted differentiation or apoptosis. In this report, we describe the isolation and characterization of a new population of adipose tissue (AT) derived pluripotent stem cells, termed Multilineage Differentiating Stress-Enduring (Muse) Cells, which are isolated using severe cellular stress conditions, including long-term exposure to the proteolytic enzyme collagenase, serum deprivation, low temperatures and hypoxia. Under these conditions, a highly purified population of Muse-AT cells is isolated without the utilization of cell sorting methods. Muse-AT cells grow in suspension as cell spheres reminiscent of embryonic stem cell clusters. Muse-AT cells are positive for the pluripotency markers SSEA3, TR-1-60, Oct3/4, Nanog and Sox2, and can spontaneously differentiate into mesenchymal, endodermal and ectodermal cell lineages with an efficiency of 23%, 20% and 22%, respectively. When using specific differentiation media, differentiation efficiency is greatly enhanced in Muse-AT cells (82% for mesenchymal, 75% for endodermal and 78% for ectodermal). When compared to adipose stem cells (ASCs), microarray data indicate a substantial up-regulation of Sox2, Oct3/4, and Rex1. Muse-ATs also exhibit gene expression patterns associated with the down-regulation of genes involved in cell death and survival, embryonic development, DNA replication and repair, cell cycle and potential factors related to oncogenecity. Gene expression analysis indicates that Muse-ATs and ASCs are mesenchymal in origin; however, Muse-ATs also express numerous lymphocytic and hematopoietic genes, such as CCR1 and CXCL2, encoding chemokine receptors and ligands involved in stem cell homing. Being highly resistant to severe cellular stress, Muse-AT cells have the potential to make a critical impact on the field of regenerative medicine and cell-based therapy.

Adipocyte fatty acid storage factors enhance subcutaneous fat storage in postmenopausal women

Increases in weight have been associated with corresponding increases in insulin resistance in postmenopausal women. Although estrogen has significant impact on body fat and body fat distribution, the cellular mechanisms that influence this process are not yet known. We measured adipose tissue fatty acid (FA) storage and FA storage factors in 12 premenopausal and 11 postmenopausal women matched for age and body composition. Postmenopausal women had lower postprandial FA oxidation (indirect calorimetry), greater meal FA, and direct free FA (FFA) storage than premenopausal women, including two-fold greater meal FA storage in the femoral depot. The fed/fasted activities of adipose tissue lipoprotein lipase were not significantly different between premenopausal and postmenopausal women. In contrast, adipocyte acyl-CoA synthetase and diacylglycerol acyltransferase activities in postmenopausal women were significantly upregulated and were positively correlated with direct FFA storage rates. These findings suggest that the propensity for subcutaneous adipose tissue FA storage is increased in postmenopausal women, more so from changes in adipocyte FA storage factors than from adipose tissue lipoprotein lipase activity. Our results suggest that female sex steroids, most likely estrogen, have important effects on adipose tissue FA storage and FA oxidation that could promote fat gain in postmenopausal women.

The immunosuppressive agents rapamycin, cyclosporin A and tacrolimus increase lipolysis, inhibit lipid storage and alter expression of genes involved in lipid metabolism in human adipose tissue

Cyclosporin A (CsA), tacrolimus and rapamycin are immunosuppressive agents (IAs) associated with insulin resistance and dyslipidemia, although their molecular effects on lipid metabolism in adipose tissue are unknown. We explored IAs effects on lipolysis, lipid storage and expression of genes involved on lipid metabolism in isolated human adipocytes and/or adipose tissue obtained via subcutaneous and omental fat biopsies. CsA, tacrolimus and rapamycin increased isoproterenol-stimulated lipolysis and inhibited lipid storage by 20-35% and enhanced isoproterenol-stimulated hormone-sensitive lipase Ser552 phosphorylation. Rapamycin also increased basal lipolysis (~20%) and impaired insulin's antilipolytic effect. Rapamycin, down-regulated the gene expression of perilipin, sterol regulatory element-binding protein 1 (SREBP1) and lipin 1, while tacrolimus down-regulated CD36 and aP2 gene expression. All three IAs increased IL-6 gene expression and secretion, but not expression and secretion of TNF-α or adiponectin. These findings suggest that CsA, tacrolimus and rapamycin enhance lipolysis, inhibit lipid storage and expression of lipogenic genes in adipose tissue, which may contribute to the development of dyslipidemia and insulin resistance associated with immunosuppressive therapy.

Glucocorticoids antagonize tumor necrosis factor-α-stimulated lipolysis and resistance to the antilipolytic effect of insulin in human adipocytes

High concentrations of TNF within obese adipose tissue increase basal lipolysis and antagonize insulin signaling. Adipocytes of the obese are also exposed to elevated levels of glucocorticoids (GCs), which antagonize TNF actions in many cell types. We tested the hypothesis that TNF decreases sensitivity to the antilipolytic effect of insulin and that GCs antagonize this effect in differentiated human adipocytes. Lipolysis and expression levels of lipolytic proteins were measured after treating adipocytes with TNF, dexamethasone (DEX), or DEX + TNF for up to 48 h. TNF not only increased basal lipolysis, it caused resistance to the antilipolytic effects of insulin in human adipocytes. DEX alone did not significantly affect lipolysis. Cotreatment with DEX blocked TNF induction of basal lipolysis and insulin resistance by antagonizing TNF stimulation of PKA-mediated phosphorylation of hormone-sensitive lipase (HSL) at Ser⁵⁶³ and Ser⁶⁶⁰ and perilipin. TNF did not affect perilipin, HSL, or phosphodiesterase-3B mass but paradoxically suppressed adipose tissue triglyceride lipase expression, and this effect was blocked by DEX. The extent to which GCs can restrain the lipolytic actions of TNF may both diminish the potentially deleterious effects of excess lipolysis and contribute to fat accumulation in obesity.

In vitro osteogenic potential of canine adipose derived stem cells

Stem cells based tissue engineering is a promising approach for the regenerative treatment of various tissue disorders. Adipose tissue is an abundant source of cells which are competent of multipotential differentiation, called adipose-derived stem cells (ADSCs). The present study was contemplated with the objective of assessing the osteogenic differentiation potential of the canine ADSCs in vitro. The canine ADSCs were isolated from adipose tissue around falciform ligament and abdominal subcutaneous fat. Yield of viable ADSCs from both the tissue sources was found to be nearly equivalent. Tissue subjected to trypsinization yielded more viable, but lesser number of cells as compared to collagenase treatment. The stemness of ADSCs was affirmed by reverse transcriptase PCR which exhibited the expression of stem cell specific genes, OCT4 and NANOG.The monolayer of ADSCs was subjected to differentiation into adipogenic and osteogenic lineages. Assessment of the osteogenic potential of ADSCs in vitro opens a new therapeutic horizon for development of in vivo strategies employing autologous stem cell based tissue regeneration in orthopedics.

Elevated serum 25(OH)D concentrations, vitamin D, and calcium intakes are associated with reduced adipocyte size in women

Recent studies have suggested a beneficial effect of vitamin D and calcium on adipocyte metabolism and the metabolic profile. Our objective was to examine associations of vitamin D intake, calcium and dairy products as well as serum 25(OH)D concentration with adiposity measures and adipocyte size in women. Omental and subcutaneous adipose tissue samples were obtained from 43 women undergoing gynecological surgeries. Adipocyte size was measured using adipocyte suspensions from collagenase-digested fat tissues. Total and visceral adiposity were assessed by dual-energy X-ray absorptiometry and computed tomography, respectively. Serum 25(OH)D was measured by radioimmmunoassay. Dietary intakes were assessed using a food frequency questionnaire. Women consuming two or more dairy product portions daily had smaller adipocytes in the omental depot compared to women consuming less than two portions daily (79 ± 12 vs. 94 ± 16 µm, P ≤ 0.01). Dietary intakes of calcium (r = -0.55) and vitamin D (r = -0.43) as well as serum 25(OH)D (r = -0.35) were also inversely and significantly associated with omental adipocyte size (P ≤ 0.05 for all). Dietary vitamin D intake was inversely associated with visceral adipose tissue area (r = -0.34, P ≤ 0.05). Serum 25(OH)D was also inversely associated with visceral adipose tissue area (r = -0.32) as well as with total adipose tissue area (r = -0.44), subcutaneous adipose tissue area (r = -0.36), BMI (r =-0.43) and total body fat mass (r = -0.41, P ≤ 0.05 for all). In conclusion, elevated dietary vitamin D intake and serum 25(OH)D values are related to lower visceral adiposity and omental adipocyte size in women.

Visfatin is regulated by rosiglitazone in type 2 diabetes mellitus and influenced by NFκB and JNK in human abdominal subcutaneous adipocytes

Visfatin has been proposed as an insulin-mimicking adipocytokine, predominantly secreted from adipose tissue and correlated with obesity. However, recent studies suggest visfatin may act as a proinflammatory cytokine. Our studies sought to determine the significance of this adipocytokine and its potential role in the pathogenesis of T2DM. Firstly, we examined the effects of diabetic status on circulating visfatin levels, and several other adipocytokines, demonstrating that diabetic status increased visfatin*, TNF-α*** and IL-6*** compared with non-diabetic subjects (*p<0.05, **p<0.01, ***p<0.001, respectively). We then assessed the effects of an insulin sensitizer, rosiglitazone (RSG), in treatment naïve T2DM subjects, on circulating visfatin levels. Our findings showed that visfatin was reduced post-RSG treatment [vs. pre-treatment (*p<0.05)] accompanied by a reduction in HOMA-IR**, thus implicating a role for insulin in visfatin regulation. Further studies addressed the intracellular mechanisms by which visfatin may be regulated, and may exert pro-inflammatory effects, in human abdominal subcutaneous (Abd Sc) adipocytes. Following insulin (Ins) and RSG treatment, our in vitro findings highlighted that insulin (100 nM), alone, upregulated visfatin protein expression whereas, in combination with RSG (10 nM), it reduced visfatin*, IKKβ** and p-JNK1/2*. Furthermore, inhibition of JNK protein exacted a significant reduction in visfatin expression (**p<0.01), whilst NF-κB blockade increased visfatin (*p<0.05), thus identifying JNK as the more influential factor in visfatin regulation. Additional in vitro analysis on adipokines regulating visfatin showed that only Abd Sc adipocytes treated with recombinant human (rh)IL-6 increased visfatin protein (*p<0.05), whilst rh visfatin treatment, itself, had no influence on TNF-α, IL-6 or resistin secretion from Sc adipocytes. These data highlight visfatin's regulation by insulin and RSG, potentially acting through NF-κB and JNK mechanisms, with only rh IL-6 modestly affecting visfatin regulation. Taken together, these findings suggest that visfatin may represent a pro-inflammatory cytokine that is influenced by insulin/insulin sensitivity via the NF-κB and JNK pathways.

Age-associated adaptations in murine adipose tissues

Ageing is associated with an increase in visceral obesity in men and women. Although wild-type mice with a C57Bl/6 genetic background are extensively used in studies on obesity and metabolism, little information is available on age-associated changes in their adipose tissues. We have evaluated development and composition of subcutaneous (SC) and gonadal (GON) adipose tissue in male C57Bl/6 mice at the ages of 10 weeks, 12 months or 24 months, while kept on normal chow. Total body weight as well as SC and GON fat mass significantly increased between 10 weeks and 12 months, but markedly decreased again up to 24 months of age. Adipocyte size in both fat depots and blood vessel size in GON fat followed this trend. Plasma leptin levels correlated positively with body weight and SC or GON fat mass. Both 12 and 24 months old mice displayed better insulin sensitivity as compared to 10 weeks old counterparts, reflected by significantly decreased plasma levels of insulin and/or glucose. Thus, ageing of C57Bl/6 male mice is associated with a biphasic pattern (increase up to 12 months followed by a decrease up to 24 months) of body weight, SC and GON fat mass, adipocyte and blood vessel size.

IKKbeta and the anti-adipogenic effect of platelet-derived growth factor in human abdominal subcutaneous preadipocytes

To clarify how anti-adipogenic factors act on preadipocytes to inhibit their differentiation, we compared preadipocyte signaling responses generated by platelet-derived growth factor (PDGF; anti-adipogenic) versus insulin (pro-adipogenic). PDGF, but not insulin, stimulated the phosphorylation of inhibitor of kappaB kinase beta (IKKbeta) in a time-dependent manner. This PDGF-dependent phosphorylation event was inhibited by 60% (P<0.05) when the cells were pretreated with wortmannin, indicating a requirement for the phosphatidylinositol (PI) 3-kinase/AKT pathway. IKKbeta phosphorylation by PDGF was neither accompanied by IkappaBalpha degradation nor NF-kappaB activation. PDGF inhibited human adipocyte differentiation, assessed by triacylglycerol accumulation (75% reduction; P<0.01) and by fatty acid synthase protein expression (60% reduction; P<0.05); these responses were no longer apparent in the presence of sc-514, a selective inhibitor of IKKbeta. Our data describe a novel PDGF response in human preadipocytes that involves the pro-inflammatory kinase IKKbeta and demonstrate that it is required for the inhibition of adipogenesis.

Differences in stem and progenitor cell yield in different subcutaneous adipose tissue depots

BACKGROUND

Human adipose tissue has been shown to contain multipotent cells with properties similar to mesenchymal stromal cells. While there have been many studies of the biology of these cells, no study has yet evaluated issues associated with tissue harvest.

METHODS

Adipose tissue was obtained from the subcutaneous space of the abdomen and hips of 10 donors using both syringe and pump-assisted liposuction. Tissue was digested with collagenase and then assayed for the presence of different stem and progenitor cell types using clonogenic culture assays, including fibroblast colony-forming unit (CFU-F) and alkaline phosphatase-positive colony-forming unit (CFU-AP). Paired analysis of samples obtained from the same individual was used to compare harvest method and site.

RESULTS

Syringe suction provided significantly greater recovery of adipocytes and a non-significant trend towards improved recovery of cells in the adipocyte-depleted fraction. There was considerable donor-to-donor variation in stem cell recovery. However, paired analysis of tissue obtained from different subcutaneous sites in the same donor showed that tissue harvested from the hip yielded 2.3-fold more CFU-F/unit volume and a 7-fold higher frequency of CFU-AP than that obtained from the abdomen. These differences were statistically significant.

DISCUSSION

Harvest site influences the stem and progenitor cell content of subcutaneous adipose tissue.

Secretion of neuropeptide Y in human adipose tissue and its role in maintenance of adipose tissue mass

NPY is an important central orexigenic hormone, but little is known about its peripheral actions in human adipose tissue (AT) or its potential paracrine effects. Our objective was to examine NPY's role in AT, specifically addressing NPY protein expression, the effect of NPY on adipokine secretion, and the influence of insulin and rosiglitazone (RSG) on adipocyte-derived NPY in vitro. Ex vivo human AT was obtained from women undergoing elective surgery [age: 42.7 +/- 1.5 yr (mean +/- SE), BMI: 26.2 +/- 0.7 kg/m(2); n = 38]. Western blot analysis was used to determine NPY protein expression in AT depots. Abdominal subcutaneous (AbSc) adipocytes were isolated and treated with recombinant (rh) NPY, insulin, and RSG. NPY and adipokine levels were measured by ELISA. Our results were that NPY was localized in human AT and adipocytes and confirmed by immunohistochemistry. Depot-specific NPY expression was noted as highest in AbSc AT (1.87 +/- 0.23 ODU) compared with omental (Om; 1.03 +/- 0.15 ODU, P = 0.029) or thigh AT (Th; 1.0 +/- 0.29 ODU, P = 0.035). Insulin increased NPY secretion (control: 0.22 +/- 0.024 ng/ml; 1 nM insulin: 0.26 +/- 0.05 ng/ml; 100 nM insulin: 0.29 +/- 0.04 ng/ml; 1,000 nM insulin: 0.3 +/- 0.04 ng/ml; P < 0.05, n = 13), but cotreatment of RSG (10 nM) with insulin (100 nM) had no effect on NPY secretion. Furthermore, adipocyte treatment with rh-NPY downregulated leptin secretion (control: 6.99 +/- 0.89 ng/ml; 1 nmol/l rh-NPY: 4.4 +/- 0.64 ng/ml; 10 nmol/l rh-NPY: 4.3 +/- 0.61 ng/ml, 100 nmol/l rh-NPY: 4.2 +/- 0.67 ng/ml; P < 0.05, n = 10) but had no effect on adiponectin or TNF-alpha secretion. We conclude that NPY is expressed and secreted by human adipocytes. NPY secretion is stimulated by insulin, but this increment was limited by cotreatment with RSG. NPY's antilipolytic action may promote an increase in adipocyte size in hyperinsulinemic conditions. Adipose-derived NPY mediates reduction of leptin secretion and may have implications for central feedback of adiposity signals.

Insulin differentially modulates the peripheral endocannabinoid system in human subcutaneous abdominal adipose tissue from lean and obese individuals

Human obesity has been associated with a dysregulation of the peripheral and adipose tissue (AT) endocannabinoid system (ES). The aim of this study was to elucidate the acute in vivo effects of insulin on gene expression of the cannabinoid type 1 (CB-1) and type 2 (CB-2) receptors, as well as of the fatty acid amide hydrolase (FAAH) in the sc abdominal adipose tissue (SCAAT). Nine lean (L) and 9 obese (OB), but otherwise healthy males were studied in the fasting state and during a euglycemic hyperinsulinemic clamp (40 mU/m2 * min(-1)). SCAAT biopsies were obtained at baseline and after 270 min of i.v. maintained hyperinsulinemia. The basal SCAAT gene expression pattern revealed an upregulation of the FAAH in the OB (p=0.03 vs L), whereas similar CB-1 and CB-2 mRNA levels were seen. Following hyperinsulinemia, the FAAH mRNA levels significantly increased approximately 2-fold in the L (p=0.01 vs baseline) but not in the OB. In contrast, insulin failed to significantly change both the adipose CB-1 and CB-2 gene expression. Finally, the FAAH gene expression positively correlated with the fasting serum insulin concentration (r 0.66; p=0.01), whereas an inverse association with the whole-body glucose disposal (r -0.58; p<0.05) was seen. Taken together, these first time observations demonstrate that the ES-related genes in the SCAAT differentially respond to hyperinsulinemia in lean/insulin-sensitive and in obese/insulin-resistant individuals. We suggest that insulin may play a key role in the obesity-linked dysregulation of the adipose ES at the gene level.

Macrophage infiltration into omental versus subcutaneous fat across different populations: effect of regional adiposity and the comorbidities of obesity

CONTEXT

Macrophage infiltration into adipose tissue has been demonstrated to accompany obesity, with a potential preferential infiltration into intraabdominal vs. sc fat.

OBJECTIVE

Our objective was to determine whether this occurs across different populations with a range of body mass indexes and to assess the relationship with regional adiposity and comorbidity of obesity.

SETTING AND PATIENTS

In two independent cohorts, we used paired omental (OM) and sc fat biopsies from lean controls or predominantly sc or intraabdominally obese persons with minimal comorbidity (n = 60, cohort 1), or from severely obese women with a significant rate of comorbidity (n = 29, cohort 2).

RESULTS

Elevated macrophage infiltration into OM vs. sc fat was observable in lean subjects and exaggerated by obesity, particularly if predominantly intraabdominal. This was paralleled by increased monocyte chemoattractant protein-1 (MCP1) and colony-stimulating factor-1 (CSF1) mRNA levels. Level of CSF1 and MCP1 mRNA correlated with the number of OM macrophages (r = 0.521, P < 0.0001 and r = 0.258, P < 0.051, respectively). In severely obese women (mean body mass index = 43.0 +/- 1.1 kg/m(2)), higher protein expression of both MCP1 and CSF1 was detected in OM vs. sc fat. Number of OM macrophages, but not of sc macrophages, correlated with waist circumference (r = 0.636, P = 0.001 vs. r = 0.170, P = 0.427) and with the number of metabolic syndrome parameters (r = 0.385, P = 0.065 vs. r = -0.158, P = 0.472, respectively). Preferential macrophage infiltration into OM fat was mainly observed in a subgroup in whom obesity was associated with impaired glucose homeostasis.

CONCLUSIONS

Preferential macrophage infiltration into OM fat is a general phenomenon exaggerated by central obesity, potentially linking central adiposity with increased risk of diabetes and coronary heart disease.

An Experimental Model for Improving Fat Graft Viability and Purity

BACKGROUND

Autologous fat is an excellent soft-tissue filler, given its abundance, ease of harvest, and natural appearance. However, graft longevity is unpredictable and is reported in the literature to be between 3 months and 8 years.

METHODS

A genetically identical, age- and sex-matched mouse experiment was used to develop a model. Inguinal fat pads were subjected to different harvest and preparatory techniques. Primary endpoints-viability and purity-were assessed with the trypan blue viability assay and component counting with a hemocytometer.

RESULTS

Viability and purity were highest after excisional harvest versus blunt or needle harvest, presumably secondary to differences in cellular trauma. Saline wash or centrifugation after harvest produced modest but statistically significant improvements in viability and purity. However, if grafts harvested in any fashion were treated with an initial collagenase digestion followed by an idealized centrifugation regimen and a single wash step, viability and purity were consistently 96 percent and 93 percent, respectively.

CONCLUSIONS

Using an in vitro murine model, the authors have systematically developed a clinically practical model for creating a pure single-cell suspension of viable adipocytes that is reproducible, regardless of tissue harvest method.

11beta-hydroxysteroid dehydrogenase type 1 in adipose tissue and prospective changes in body weight and insulin resistance

OBJECTIVE

Increased mRNA and activity levels of 11beta-hydroxysteroid dehydrogenase type 1 (11betaHSD1) in human adipose tissue (AT) are associated with obesity and insulin resistance. The aim of our study was to investigate whether 11betaHSD1 expression or activity in abdominal subcutaneous AT of non-diabetic subjects are associated with subsequent changes in body weight and insulin resistance [homeostasis model assessment of insulin resistance (HOMA-IR)].

RESEARCH METHODS AND PROCEDURES

Prospective analyses were performed in 20 subjects (two whites and 18 Pima Indians) who had baseline measurements of 11betaHSD1 mRNA and activity in whole AT (follow-up, 0.3 to 4.9 years) and in 47 Pima Indians who had baseline assessments of 11betaHSD1 mRNA in isolated adipocytes (follow-up, 0.8 to 5.3 years).

RESULTS

In whole AT, although 11betaHSD1 mRNA levels showed positive associations with changes in weight and HOMA-IR, 11betaHSD1 activity was associated with changes in HOMA-IR but not in body weight. 11betaHSD1 mRNA levels in isolated adipocytes were not associated with follow-up changes in any of the anthropometric or metabolic variables.

DISCUSSION

Our results indicate that increased expression of 11betaHSD1 in subcutaneous abdominal AT may contribute to risk of worsening obesity and insulin resistance. This prospective relationship does not seem to be mediated by increased 11betaHSD1 expression in adipocytes.

Autologous Human Fat Grafting: Effect of Harvesting and Preparation Techniques on Adipocyte Graft Survival

BACKGROUND

Autogenous fat transfer with lipoinjection for soft-tissue augmentation is a commonly used technique without a universally accepted approach. The high percentage and variable amount of fat resorption reduce the clinical efficacy of this procedure and often result in the need for further grafting. The purposes of this study were to evaluate the effect of different harvesting and preparation techniques on human fat tissue viability and to determine fat tissue viability rates among the different fat preparations transplanted into a severe combined immune deficiency mouse model at 3 months.

METHODS

Using standard liposuction and syringe aspiration, fat was removed from patients (n = 3) undergoing elective body contouring. Tissue was prepared by six different combinations of centrifugation and/or washing the cells with lactated Ringer's solution or normal saline. Metabolic activities of fat cell viability were monitored to assess overall cell viability. To analyze viability over 3 months, freshly harvested tissue specimens (minimum n = 5) were prepared by a combination of various procedures (wash, centrifugation, and different solutions) and subsequently injected under the dorsal flank skin of severe combined immune deficiency mice in two experiments. Mice were monitored for 12 weeks and the fat xenografts were removed for mass and histological evaluations.

RESULTS

Metabolic analyses showed improved cell viability in tissue specimens undergoing minimal manipulation. No significant differences in fat cell viability, as assessed by graft weight maintenance or histologic evaluations, were observed with regard to harvesting or preparation techniques.

CONCLUSIONS

Improved viability of freshly harvested but untreated fat specimens may be expected as compared with grafts that have undergone additional manipulations. No unique combination of preparation or harvesting techniques appeared to be more advantageous on transplanted fat grafts at 3 months. This study also demonstrated a reliable animal model for future investigation into examining novel applications for augmenting fat graft survival.

Adipose Aspirates as a Source for Human Processed Lipoaspirate Cells after Optimal Cryopreservation

BACKGROUND

The purpose of this study was to test the authors' hypothesis that previously cryopreserved adipose aspirates collected from conventional liposuction could still be a reliable source of human processed lipoaspirate cells.

METHODS

Adipose aspirates were collected from 12 adult female patients after conventional liposuction of the abdomen and were then preserved by an optimal cryopreservation method with added cryoprotective agents (0.5 M dimethyl sulfoxide and 0.2 M trehalose). Cryopreservation of the adipose tissues was subsequently conducted with controlled slow cooling and then stored in liquid nitrogen (-196 degrees C). One gram of fresh or cryopreserved (after fast rewarming) adipose aspirates was processed in vitro and the resulting cell pellet, consisting of processed lipoaspirate cells, was cultured separately. The length of time until processed lipoaspirate cells became adherent to the culture plate was recorded and the number of processed lipoaspirate cells after a 2-week culture was counted.

RESULTS

Flat, spindle-shape processed lipoaspirate cells from the cryopreserved group became adherent to the plate within 48 to 72 hours after initial culture compared with the fresh group, where the cells became adherent by 24 hours. After a 2-week culture, the cryopreserved aspirates yielded an average of 3.7 +/- 1.4 x 10(5) processed lipoaspirate cells per milliliter, equal to 90 percent of the yielded number of cells obtained from the fresh aspirates (4.1 +/- 1.4 x 10(5) cells/ml).

CONCLUSIONS

The authors' results indicate that although there is a latency of cell growth after an optimal cryopreservation, cryopreserved adipose aspirates can yield a significant number of processed lipoaspirate cells compared with fresh aspirates and may be a reliable source of human processed lipoaspirate cells because they can still be processed later after long-term preservation.

Addition of aerobic exercise to dietary weight loss preferentially reduces abdominal adipocyte size

OBJECTIVE

To determine if hypocaloric diet, diet plus low-intensity exercise, and diet plus high-intensity exercise differentially influence subcutaneous abdominal and gluteal adipocyte size in obese individuals.

DESIGN

Longitudinal intervention study of hypocaloric diet, diet plus low-intensity exercise, and diet plus high-intensity exercise (calorie deficit = 2800 kcal/week, 20 weeks).

SUBJECTS

Forty-five obese, middle-aged women (BMI = 33.0+/-0.6 kg/m2, age = 58+/-1 years).

MEASUREMENTS

Body composition testing and adipose tissue biopsies were conducted before and after the interventions. Subcutaneous abdominal and gluteal adipocyte size was determined.

RESULTS

All three interventions reduced body weight, fat mass, percent fat, and waist and hip girths to a similar degree. Diet only did not change subcutaneous abdominal adipocyte size, whereas both diet plus exercise groups significantly reduced abdominal adipocyte size. Changes in abdominal adipocyte size in the diet plus exercise groups were significantly different from that of the diet group. Gluteal adipocyte size decreased similarly in all three groups.

CONCLUSION

Addition of exercise training to dietary weight loss preferentially reduces subcutaneous abdominal adipocyte size in obese women. This may be of importance for the treatment of health complications associated with subcutaneous abdominal adiposity.

[Comparative analysis of cell populations with a phenotype similar to that of mesenchymal stem cells derived from subcutaneous fat]

Two cell populations with a phenotype similar to that of mesenchymal stem cells (MSC) with different characteristics for expression of surface antigene CD34 were derived from subcutaneous fat. CD34-positive cells were derived from subcutaneous fat of the inferior eyelid obtained during transconjuctival blepharoplasty. CD34-negative cells were derived from adipose tissue obtained during lipoaspiration from the same patients. These cells displayed common characteristics for morphology and expression of basic markers characterizing them as mesenchymal stem cells. On being induced for differentiation, these two cell populations were able to differentiate to cells of adipose (adipocytes), bone (osteoblastes, osteocytes), cartilage (chondroblasts, chondrocytes), and nervous (neurons, astrocytes and oligodendrocytes) tissues.