Aromatase overexpression in dysfunctional adipose tissue links obesity to postmenopausal breast cancer

The number of breast cancer cases has increased in the last a few decades and this is believed to be associated with the increased prevalence of obesity worldwide. The risk of breast cancer increases with age beyond menopause and the relationship between obesity and the risk of breast cancer in postmenopausal women is well established. The majority of postmenopausal breast cancers are estrogen receptor (ER) positive and estrogens produced in the adipose tissue promotes tumor formation. Obesity results in the secretion of inflammatory factors that stimulate the expression of the aromatase enzyme, which converts androgens into estrogens in the adipose tissue. Evidence demonstrating a link between obesity and breast cancer has led to the investigation of metabolic pathways as novel regulators of estrogen production, including pathways that can be targeted to inhibit aromatase specifically within the breast. This review aims to present some of the key findings in this regard.

Comparative analysis of biological characteristics of adult mesenchymal stem cells with different tissue origins

OBJECTIVE

To invest the differences among mesenchymal stem cells (MSCs) derived from different tissues and their impacts on clinical applications.

METHODS

In this study, MSCs were isolated from adipose tissue (AD), umbilical cord tissue (UC), and menstrual blood (Men) and compared their biological characteristics in terms of proliferation capacity, passage capacity, colony formation, and surface markers were compared.

RESULTS

The stem cells (SCs) obtained from different sources were all characterized as MSCs, but demonstrated some differences. Umbilical cord-derived MSCs (UCMSCs) were able to overcome density inhibition. The proliferation rate decreased in the order UCMSCs > MenSCs > ADSCs, while the colony-forming ability decreased in the order MenSCs > ADSCs > UCMSCs. Based on gene-expression data for MSCs from different sources within the same donor, 768 MenSC genes were found that were specifically upregulated or downregulated compared with bone marrow-derived MSCs and UCMSCs, most of which were involved in cell function-related pathways. In addition, MenSCs appeared to be superior in terms of immune inflammation, stress response, and neural differentiation potentials, but weaker in terms of osteogenic and chondrogenic differentiation capacities, compared with UCMSCs and bone marrow-derived MSCs.

CONCLUSIONS

MenSCs have higher extraction efficiency, colony-forming ability, and long time passage capacity. Although the proliferation capacity is inferior to UCMSCs.

Testosterone and obesity

Testosterone is a key hormone in the pathology of metabolic diseases such as obesity. Low testosterone levels are associated with increased fat mass (particularly central adiposity) and reduced lean mass in males. These morphological features are linked to metabolic dysfunction, and testosterone deficiency is associated with energy imbalance, impaired glucose control, reduced insulin sensitivity and dyslipidaemia. A bidirectional relationship between testosterone and obesity underpins this association indicated by the hypogonadal-obesity cycle and evidence weight loss can lead to increased testosterone levels. Androgenic effects on enzymatic pathways of fatty acid metabolism, glucose control and energy utilization are apparent and often tissue specific with differential effects noted in different regional fat depots, muscle and liver to potentially explain the mechanisms of testosterone action. Testosterone replacement therapy demonstrates beneficial effects on measures of obesity that are partially explained by both direct metabolic actions on adipose and muscle and also potentially by increasing motivation, vigour and energy allowing obese individuals to engage in more active lifestyles. The degree of these beneficial effects may be dependent on the treatment modality with longer term administration often achieving greater improvements. Testosterone replacement may therefore potentially be an effective adjunctive treatment for weight management in obese men with concomitant hypogonadism.

Evaluating the bone regeneration in calvarial defect using osteoblasts differentiated from adipose-derived mesenchymal stem cells on three different scaffolds: an animal study

The aim of this study was to investigate the effect of three different scaffolds on the viability and differentiation of adipose-derived mesenchymal stem cells (ADMSCs) to osteoblast for bone regeneration of calvarial defect in rabbit model. Adipose was harvested from the nape of 12 rabbits by direct surgery or hollow-tip cannula. Two standardized circular calvarial defects (case and control), 8 mm in diameter each, were created in all the animals. The animals were divided into 3 different groups. In group 1 (G1), the defect was filled with polyamide + ADMSC. In group 2, poly lactic-co-glycolic acid + ADMSC was used. In group 3, decellularized amniotic membrane + ADMSC was applied. In the control defect, the non-seeded scaffolds were applied for filling the defect. Decellularized pericardial scaffolds were used as a membrane on the scaffolds. The animals were euthanized 2, 4, and 8 weeks of operation and new bone formation was assessed by different analyses. Immunohistochemical (IHC) staining with osteopontin and osteocalcin antibodies was also performed. After 2 weeks of wound healing, minimal bone regeneration was detected in all groups. Almost complete defect closure was observed in all experimental groups after 8 weeks of operation, with the greatest defect closure in the animals treated with polyamide scaffolds as compared to biopsies obtained from control defects and other experimental groups. The maximal tensile load was higher in G1, 4 and 8 weeks postoperatively, suggesting the usefulness of polyamide + ADMSC for bone regeneration in calvarial defects. Results of the IHC staining demonstrated a significant difference between seeded and non-seeded scaffold in both short- and long-term follow-ups (P < 0.05). In addition, a significant difference was observed in enhancement of IHC staining of both markers in polyamide group (seeded or non-seeded) 4 and 8 weeks postoperatively in comparison with other scaffolds. It was concluded that bone regeneration in critical calvarial defect was more successful in seeded polyamide.

Transgenic ω-3 PUFA enrichment alters morphology and gene expression profile in adipose tissue of obese mice: Potential role for protectins

OBJECTIVE

Dietary administration of ω-3 polyunsaturated fatty acids (PUFA) is often associated with altered adipose tissue (AT) morphology and/or function in obese mice. Yet, it is unclear whether this is an indirect consequence of reduced weight gain or results from direct actions of ω-3 PUFA. Here we studied the AT of high fat (HF)-fed fat-1 transgenic mice that convert endogenous ω-6 to ω-3 PUFA while maintaining equivalent fat accretion as their wild-type (WT) counterparts.

MATERIALS AND METHODS

Adipocyte size profiling, Affymetrix microarray pathway analysis, qPCR and protectin identification and analysis were performed in epididymal AT from hemizygous fat-1(+/-) mice and their wild type littermates that had been fed a HF diet for 8weeks from 6weeks of age.

RESULTS

Despite equivalent fat pad mass, we found that epididymal AT from HF-fed transgenic animals possesses fewer large and very large but more mid-size adipocytes compared to WT mice. In order to better understand the underlying mechanisms contributing to the observed alteration in adipocyte size we performed an Affymetrix microarray. Pathway analysis of these data highlighted adipogenesis, cholesterol biosynthesis, insulin signaling, prostaglandin synthesis/regulation and small ligand GPCRs as points where differentially expressed genes were significantly overrepresented. Observed changes were confirmed for four candidate genes: Cnr1, Cnr2, Faah and Pparg by qPCR. Finally we demonstrated that protectin DX is present in AT and that protectin DX and protectin D1 promote comparable PPARγ transcriptional activity.

CONCLUSIONS

These data provide unprecedented evidence that ω-3 PUFA coordinately regulate AT gene expression programs in a manner that is independent of restriction of weight gain or fat accrual and highlight an important influence of ω-3 PUFA on adipogenesis. Furthermore we provide primary evidence suggesting that protectins likely contribute to these effects via their influence on PPARγ.

Adipocyte glucocorticoid receptors mediate fat-to-brain signaling

Stress-related (e.g., depression) and metabolic pathologies (e.g., obesity) are important and often co-morbid public health concerns. Here we identify a connection between peripheral glucocorticoid receptor (GR) signaling originating in fat with the brain control of both stress and metabolism. Mice with reduced adipocyte GR hypersecrete glucocorticoids following acute psychogenic stress and are resistant to diet-induced obesity. This hypersecretion gives rise to deficits in responsiveness to exogenous glucocorticoids, consistent with reduced negative feedback via adipocytes. Increased stress reactivity occurs in the context of elevated hypothalamic expression of hypothalamic-pituitary-adrenal (HPA) axis-excitatory neuropeptides and in the absence of altered adrenal sensitivity, consistent with a central cite of action. Our results identify a novel mechanism whereby activation of the adipocyte GR promotes peripheral energy storage while inhibiting the HPA axis, and provide functional evidence for a fat-to-brain regulatory feedback network that serves to regulate not just homeostatic energy balance but also responses to psychogenic stimuli.

IGF1 Promotes Adipogenesis by a Lineage Bias of Endogenous Adipose Stem/Progenitor Cells

Adipogenesis is essential for soft tissue reconstruction following trauma or tumor resection. We demonstrate that CD31(-)/34(+)/146(-) cells, a subpopulation of the stromal vascular fraction (SVF) of human adipose tissue, were robustly adipogenic. Insulin growth factor-1 (IGF1) promoted a lineage bias towards CD31(-)/34(+)/146(-) cells at the expense of CD31(-)/34(+)/146(+) cells. IGF1 was microencapsulated in poly(lactic-co-glycolic acid) scaffolds and implanted in the inguinal fat pad of C57Bl6 mice. Control-released IGF1 induced remarkable adipogenesis in vivo by recruiting endogenous cells. In comparison with the CD31(-)/34(+)/146(+) cells, CD31(-)/34(+)/146(-) cells had a weaker Wnt/β-catenin signal. IGF1 attenuated Wnt/β-catenin signaling by activating Axin2/PPARγ pathways in SVF cells, suggesting IGF1 promotes CD31(-)/34(+)/146(-) bias through tuning Wnt signal. PPARγ response element (PPRE) in Axin2 promoter was crucial for Axin2 upregulation, suggesting that PPARγ transcriptionally activates Axin2. Together, these findings illustrate an Axin2/PPARγ axis in adipogenesis that is particularly attributable to a lineage bias towards CD31(-)/34(+)/146(-) cells, with implications in adipose regeneration.

Comparative study of autologous stromal vascular fraction and adipose-derived stem cells for erectile function recovery in a rat model of cavernous nerve injury

The abilities of intracavernous injection of autologous stromal vascular fraction (SVF) and adipose-derived stem cells (ADSCs) to facilitate recovery of erectile function in a rat model of cavernous nerve (CN) injury were compared. Forty male Sprague-Dawley rats were randomly divided into four groups: sham and control groups (intracavernous injection of phosphate-buffered saline), SVF group (intracavernous injection of SVF), and ADSC group (intracavernous injection of ADSCs). Rats in the latter three groups underwent bilateral CN injury prior to injection. The evaluation of erectile function and histomorphometric studies were performed 4 weeks after injection. The ratio of maximal intracavernous pressure to mean arterial pressure was significantly lower in the control group than in the sham group (0.18 vs. 0.56, p < .001). Intracavernous injection of SVF (0.36, p = .035) significantly improved erectile function compared with that in the control group, whereas the ADSC group (0.35, p = .052) showed marginally significant improvement. The smooth muscle/collagen ratio, smooth muscle content, number of neuronal nitric-oxide synthase-positive nerve fibers, and expression of von Willebrand factor were significantly higher in the SVF and ADSC groups than in the control group. Expression of endothelial nitric-oxide synthase was significantly increased in the SVF group. The increases in the smooth muscle/collagen ratio and von Willebrand factor expression were larger in the SVF group than in the ADSC group. Intracavernous injection of SVF or ADSCs was equally effective in recovering penile erection in a rat model of CN injury.

Adipose stromal cells repair pressure ulcers in both young and elderly mice: potential role of adipogenesis in skin repair

More than 2.5 million patients in the U.S. require treatment for pressure ulcers annually, and the elderly are at particularly high risk for pressure ulcer development. Current therapy for pressure ulcers consists of conservative medical management for shallow lesions and aggressive debridement and surgery for deeper lesions. The current study uses a murine model to address the hypothesis that adipose-derived stromal/stem cell (ASC) treatment would accelerate and enhance pressure ulcer repair. The dorsal skin of both young (2 months old [mo]) and old (20 mo) C57BL/6J female mice was sandwiched between external magnets for 12 hours over 2 consecutive days to initiate a pressure ulcer. One day following the induction, mice were injected with ASCs isolated from congenic mice transgenic for the green fluorescent protein under a ubiquitous promoter. Relative to phosphate-buffered saline-treated controls, ASC-treated mice displayed a cell concentration-dependent acceleration of wound closure, improved epidermal/dermal architecture, increased adipogenesis, and reduced inflammatory cell infiltration. The ASC-induced improvements occurred in both young and elderly recipients, although the expression profile of angiogenic, immunomodulatory, and reparative mRNAs differed as a function of age. The results are consistent with clinical reports that fat grafting improved skin architecture in thermal injuries; the authors of this published study have invoked ASC-based mechanisms to account for their clinical outcomes. Thus, the current proof-of-principle study sets the stage for clinical translation of autologous and/or allogeneic ASC treatment of pressure ulcers.

SIGNIFICANCE

Adipose-derived stromal/stem cells (ASCs) promote the healing of pressure ulcer wounds in both young and old mice. ASCs enhance wound healing rates through adipogenic differentiation and regeneration of the underlying architecture of the skin.

Adipose stem cells: biology, safety, regulation, and regenerative potential

This article discusses adipose-derived stem cell (ASC) biology, describes the current knowledge in the literature for the safety and regulation of ASCs, and provides a brief overview of the regenerative potential of ASCs. It is not an exhaustive listing of all available clinical studies or every study applying ASCs in tissue engineering and regenerative medicine, but is an objective commentary of these topics.

Cytosolic lipid droplets: from mechanisms of fat storage to disease

The lipid droplet (LD) is a phylogenetically conserved organelle. In eukaryotes, it is born from the endoplasmic reticulum, but unlike its parent organelle, LDs are the only known cytosolic organelles that are micellar in structure. LDs are implicated in numerous physiological and pathophysiological functions. Many aspects of the LD has captured the attention of diverse scientists alike and has recently led to an explosion in information on the LD biogenesis, expansion and fusion, identification of LD proteomes and diseases associated with LD biology. This review will provide a brief history of this fascinating organelle and provide some contemporary views of unanswered questions in LD biogenesis.

Pre-exposure of human adipose mesenchymal stem cells to soluble factors enhances their homing to brain cancer

Recent research advances have established mesenchymal stem cells (MSCs) as a promising vehicle for therapeutic delivery. Their intrinsic tropism for brain injury and brain tumors, their lack of immunogenicity, and their ability to breach the blood-brain barrier make these cells an attractive potential treatment of brain disorders, including brain cancer. Despite these advantages, the efficiency of MSC homing to the brain has been limited in commonly used protocols, hindering the feasibility of such therapies. In the present study, we report a reproducible, comprehensive, cell culture-based approach to enhance human adipose-derived MSC (hAMSC) engraftment to brain tumors. We used micro- and nanotechnological tools to systematically model several steps in the putative homing process. By pre-exposing hAMSCs to glioma-conditioned media and the extracellular matrix proteins fibronectin and laminin, we achieved significant enhancements of the individual homing steps in vitro. This homing was confirmed in an in vivo rodent model of brain cancer. This comprehensive, cell-conditioning approach provides a novel method to enhance stem cell homing to gliomas and, potentially, other neurological disorders.

Equine adipose-derived mesenchymal stem cells: phenotype and growth characteristics, gene expression profile and differentiation potentials

OBJECTIVE

Because of the therapeutic application of stem cells (SCs), isolation and characterization of different types of SCs, especially mesenchymal stem cells (MSCs), have gained considerable attention in recent studies. Adipose tissue is an abundant and accessible source of MSCs which can be used for tissue engineering and in particular for treatment of musculoskeletal disorders. This study was aimed to isolate and culture equine adipose-derived MSCs (AT-MSCs) from little amounts of fat tissue samples and determine some of their biological characteristics.

MATERIALS AND METHODS

In this descriptive study, only 3-5 grams of fat tissue were collected from three crossbred mares. Immediately, cells were isolated by mechanical means and enzymatic digestion and were cultured in optimized conditions until passage 3 (P3). The cells at P3 were evaluated for proliferative capacities, expression of specific markers, and osteogenic, chondrogenic and adipogenic differentiation potentials.

RESULTS

Results showed that the isolated cells were plastic adherent with a fibroblast-like phenotype. AT-MSCs exhibited expression of mesenchymal cluster of differentiation (CD) markers (CD29, CD44 and CD90) and not major histocompatibility complex II (MHC-II) and CD34 (hematopoietic marker). Cellular differentiation assays demonstrated the chondrogenic, adipogenic and osteogenic potential of the isolated cells.

CONCLUSION

Taken together, our findings reveal that equine MSCs can be obtained easily from little amounts of fat tissue which can be used in the future for regenerative purposes in veterinary medicine.

Impact of source tissue and ex vivo expansion on the characterization of goat mesenchymal stem cells

BACKGROUND

There is considerable interest in using goats as models for genetically engineering dairy animals and also for using stem cells as therapeutics for bone and cartilage repair. Mesenchymal stem cells (MSCs) have been isolated and characterized from various species, but are poorly characterized in goats.

RESULTS

Goat MSCs isolated from bone marrow (BM-MSCs) and adipose tissue (ASCs) have the ability to undergo osteogenic, adipogenic and chondrogenic differentiation. Cytochemical staining and gene expression analysis show that ASCs have a greater capacity for adipogenic differentiation compared to BM-MSCs and fibroblasts. Different methods of inducing adipogenesis also affect the extent and profile of adipogenic differentiation in MSCs. Goat fibroblasts were not capable of osteogenesis, hence distinguishing them from the MSCs. Goat MSCs and fibroblasts express CD90, CD105, CD73 but not CD45, and exhibit cytoplasmic localization of OCT4 protein. Goat MSCs can be stably transfected by Nucleofection, but, as evidenced by colony-forming efficiency (CFE), yield significantly different levels of progenitor cells that are robust enough to proliferate into colonies of integrants following G418 selection. BM-MSCs expanded over increasing passages in vitro maintained karyotypic stability up to 20 passages in culture, exhibited an increase in adipogenic differentiation and CFE, but showed altered morphology and amenability to genetic modification by selection.

CONCLUSIONS

Our findings provide characterization information on goat MSCs, and show that there can be significant differences between MSCs isolated from different tissues and from within the same tissue. Fibroblasts do not exhibit trilineage differentiation potential at the same capacity as MSCs, making it a more reliable method for distinguishing MSCs from fibroblasts, compared to cell surface marker expression.

Therapeutic Potential of Adipose-Derived SSEA-3-Positive Muse Cells for Treating Diabetic Skin Ulcers

Stage-specific embryonic antigen-3 (SSEA-3)-positive multipotent mesenchymal cells (multilineage differentiating stress-enduring [Muse] cells) were isolated from cultured human adipose tissue-derived stem/stromal cells (hASCs) and characterized, and their therapeutic potential for treating diabetic skin ulcers was evaluated. Cultured hASCs were separated using magnetic-activated cell sorting into positive and negative fractions, a SSEA-3+ cell-enriched fraction (Muse-rich) and the remaining fraction (Muse-poor). Muse-rich hASCs showed upregulated and downregulated pluripotency and cell proliferation genes, respectively, compared with Muse-poor hASCs. These cells also released higher amounts of certain growth factors, particularly under hypoxic conditions, compared with Muse-poor cells. Skin ulcers were generated in severe combined immunodeficiency (SCID) mice with type 1 diabetes, which showed delayed wound healing compared with nondiabetic SCID mice. Treatment with Muse-rich cells significantly accelerated wound healing compared with treatment with Muse-poor cells. Transplanted cells were integrated into the regenerated dermis as vascular endothelial cells and other cells. However, they were not detected in the surrounding intact regions. Thus, the selected population of ASCs has greater therapeutic effects to accelerate impaired wound healing associated with type 1 diabetes. These cells can be achieved in large amounts with minimal morbidity and could be a practical tool for a variety of stem cell-depleted or ischemic conditions of various organs and tissues.

Generation of Islet-like Cell Aggregates from Human Adipose Tissue-derived Stem Cells by Lentiviral Overexpression of PDX-1

BACKGROUND

Pancreatic duodenal homeobox1 (PDX-1) is a transcription factor that is important in regulating pancreas development and maintaining β-cell function. β-cell replacement is an effective approach for the treatment of type 1 diabetes. Human adipose-mesenchymal stem cells (hAMSCs) are the ideal population cells for differentiating into insulin-producing cells.

OBJECTIVE

To determine if islet-like cell aggregates production could be generated from hAMSCs by lentiviral overexpression of PDX-1.

METHODS

After isolation of hAMSCs, characteristics of these cells were identified by flow-cytometic analysis and multilineage differentiation studies. PDX-1 gene delivered into hAMSCs through lentiviral vector for differentiating hAMSCs into insulin-producing cells (IPCs) at the utilized protocol for 14 days. Characteristics of IPCs were evaluated by immunocytofluorescence, dithizone staining, and quantitative reverse transcription PCR. In response to high glucose medium, insulin release was detected by chemiluminescence enzyme immunoassay.

RESULTS

The islet-like cell aggregates appeared about 10 days after introduction of PDX-1 into hAMSCs. PDX-1 induced its own expression (auto-induction), a number of islet-related genes such as Ngn3, Nkx2-2, and insulin. The insulin-positive cells were detected in the PDX-1 transduced cells. In response to glucose challenge test, secretion of insulin hormone in the medium with high glucose concentration significantly increased in the PDX-1-transduced cells related to medium with low glucose concentration.

CONCLUSION

Introduction of lentiviral PDX-1 significantly induces hAMSCs to differentiate into islet-like cell aggregates, which may provide a source of adipose stem cells-derived insulin-producing cells for cell replacement therapy in type 1 diabetes.

Bladder muscular wall regeneration with autologous adipose mesenchymal stem cells on three-dimensional collagen-based tissue-engineered prepuce and biocompatible nanofibrillar scaffold

OBJECTIVE

Tissue-engineered prepuce scaffold (TEPS) is a collagen-rich matrix with marvelous mechanical properties, promoting in vivo and in vitro tissue regeneration. In this study, adipose-derived mesenchymal stem cells (ADMSCs) were used to seed TEPS for bladder wall regeneration. Its potential in comparison with other materials such as polyglycolic acid (PGA) and nanofibrous scaffolds were evaluated.

MATERIALS AND METHODS

Rat ADMSCs were cultured and seeded into prepared TEPS. A synthetic matrix of electrospun nanofibrous polyamide was also prepared. Sprague Dawley rats (n=32) underwent bladder wall regeneration using (a) TEPS, (b) TEPS+PGA, (c) TEPS+nanofibrous scaffold, and (d) ADMSC-seeded TEPS, between bladder mucosa and seromuscular layer. Animals were followed for 30 and 90 days post implantation for evaluation of bladder wall regeneration by determining CD31/34 and SMC α-actin. Cystometric evaluation was also performed in all groups and in four separate rats as sham controls 3 months postoperatively.

RESULTS

Histopathological analysis showed well-organized muscular wall generation in ADMSC-seeded TEPS and TEPS+three-dimensional (3D) nanofibrous scaffold without significant fibrosis after 90 days, while mild to severe fibrosis was detected in groups receiving TEPS and TEPS+PGA. Immunohistochemistry staining revealed the maintenance of CD34+, CD31+, and α-SMA in ADMSC-seeded TEPS and TEPS+3D nanofibrous scaffold with significantly higher density of CD34+ and CD31+ progenitor cells in ADMSC-seeded TEPS and TEPS+3D nanofibrous scaffold, respectively.

CONCLUSIONS

This work has crucial functional and clinical implications, as it demonstrates the feasibility of ADMSC-seeded TEPS in enhancing the properties of TEPS in terms of bladder wall regeneration.

Combined influence of basal media and fibroblast growth factor on the expansion and differentiation capabilities of adipose-derived stem cells

BACKGROUND

Interest in adipose-derived stem cells (ASCs) has increased in recent years due to their multi-linage differentiation capabilities. While much work has been done to optimize the differentiation media, few studies have focused on examining the influence of different expansion media on cell behavior. In this study, three basal media (low glucose Dulbecco's modified Eagle's medium (DMEM), high glucose DMEM and DMEM-F12) supplemented with or without fibroblast growth factor 2 (FGF) were examined to assess their suitability for expanding ASCs.

FINDINGS

Flow cytometry, colony-forming unit assays (CFU-Fs) and differentiation assays were utilized to study cell behavior. High glucose media CFU-Fs produced fewest colonies while the addition of FGF increased colony size. By passage 2, the majority of cells were positive for CD44, 45, 73, 90 and 105 and negative for CD14, 31 and 45, indicating a mesenchymal phenotype. A sub-population of CD34 positive cells was present among passage 2 cells; however, by passage 4 the cells were negative for CD34. FGF has a negative effective on passage 4 ASC adipogenesis and high glucose media plus FGF-enhanced osteogenic capacity of passage 4 ASCs. FGF supplemented basal media were most suitable for chondrogenesis. High glucose media plus FGF appeared to be the most beneficial for priming ASCs to induce a keratocyte phenotype.

CONCLUSIONS

These findings demonstrate the reciprocal effect FGF and basal media have on ASCs. This research has implications for those interested regenerating bone, cartilage, cornea or adipose tissues.

Pathophysiological mechanisms linking obesity and esophageal adenocarcinoma

In recent decades there has been a dramatic rise in the incidence of esophageal adenocarcinoma (EAC) in the developed world. Over approximately the same period there has also been an increase in the prevalence of obesity. Obesity, especially visceral obesity, is an important independent risk factor for the development of gastro-esophageal reflux disease, Barrett’s esophagus and EAC. Although the simplest explanation is that this mediated by the mechanical effects of abdominal obesity promoting gastro-esophageal reflux, the epidemiological data suggest that the EAC-promoting effects are independent of reflux. Several, not mutually exclusive, mechanisms have been implicated, which may have different effects at various points along the reflux-Barrett’s-cancer pathway. These mechanisms include a reduction in the prevalence of Helicobacter pylori infection enhancing gastric acidity and possibly appetite by increasing gastric ghrelin secretion, induction of both low-grade systemic inflammation by factors secreted by adipose tissue and the metabolic syndrome with insulin-resistance. Obesity is associated with enhanced secretion of leptin and decreased secretion of adiponectin from adipose tissue and both increased leptin and decreased adiponectin have been shown to be independent risk factors for progression to EAC. Leptin and adiponectin have a set of mutually antagonistic actions on Barrett’s cells which appear to influence the progression of malignant behaviour. At present no drugs are of proven benefit to prevent obesity associated EAC. Roux-en-Y reconstruction is the preferred bariatric surgical option for weight loss in patients with reflux. Statins and aspirin may have chemopreventative effects and are indicated for their circulatory benefits.

Higher circulating leukocytes in women with PCOS is reversed by aerobic exercise

Polycystic ovary syndrome (PCOS) is characterized by insulin resistance, elevated circulating leukocytes, and hypothesized to have higher adipose tissue inflammation. Aerobic exercise reduces circulating leukocytes and improves insulin sensitivity in obese individuals, but the effect of exercise on inflammation in PCOS is not known. We investigated circulating leukocytes, insulin sensitivity by euglycemic-hyperinsulinemic clamp, serum pro- and anti-inflammatory markers (hsCRP, TNF-α, total and high molecular weight adiponectin), and abdominal subcutaneous adipose tissue (SAT) gene expression of proinflammatory markers in 8 PCOS women and 8 obese control females matched for BMI. Additionally, in a prospective study, the 8 women with PCOS underwent a 16-week aerobic exercise regimen with the same measures performed post-intervention. Compared to controls, white blood cell counts (WBC) were 30% higher (p = 0.04) and circulating total adiponectin levels were 150% lower (p = 0.03) in women with PCOS at baseline/pre-exercise conditions. SAT gene expression of macrophage migration inhibitory factor (MIF, p < 0.01) and interleukin-6 (IL-6, p < 0.05) were also lower in women with PCOS. In response to 16 weeks of aerobic exercise, insulin sensitivity improved (p < 0.01) and WBC counts decreased (p = 0.02). The exercise-induced change in WBC and circulating neutrophils correlated inversely with changes in glucose disposal rate (r = -0.73, p = 0.03; and r = -0.82, p = 0.01, respectively). Aerobic exercise reduced serum leptin (p < 0.05) after 4 weeks, trended to reduce the ratio of leptin-to-high molecular weight adiponectin (p < 0.1) by the 8th week, and significantly increased serum dehydroepiandrosterone sulfate (DHEA-S, p < 0.001) after 16 weeks. In conclusion, women with PCOS have higher circulating leukocytes compared to controls, which can be reversed by aerobic exercise and is associated with improvements in insulin sensitivity.

Cholesterol-induced inflammation and macrophage accumulation in adipose tissue is reduced by a low carbohydrate diet in guinea pigs

BACKGROUND/OBJECTIVES

The main objective of this study was to evaluate the effects of a high cholesterol (HC) dietary challenge on cholesterol tissue accumulation, inflammation, adipocyte differentiation, and macrophage infiltration in guinea pigs. A second objective was to assess whether macronutrient manipulation would reverse these metabolic alterations.

MATERIALS/METHODS

Male Hartley guinea pigs (10/group) were assigned to either low cholesterol (LC) (0.04g/100g) or high cholesterol (HC) (0.25g/100g) diets for six weeks. For the second experiment, 20 guinea pigs were fed the HC diet for six weeks and then assigned to either a low carbohydrate (CHO) diet (L-CHO) (10% energy from CHO) or a high CHO diet (H-CHO) (54% CHO) for an additional six weeks.

RESULTS

Higher concentrations of total (P < 0.005) and free (P < 0.05) cholesterol were observed in both adipose tissue and aortas of guinea pigs fed the HC compared to those in the LC group. In addition, higher concentrations of pro-inflammatory cytokines in the adipose tissue (P < 0.005) and lower concentrations of anti-inflammatory interleukin (IL)-10 were observed in the HC group (P < 0.05) compared to the LC group. Of particular interest, adipocytes in the HC group were smaller in size (P < 0.05) and showed increased macrophage infiltration compared to the LC group. When compared to the H-CHO group, lower concentrations of cholesterol in both adipose and aortas as well as lower concentrations of inflammatory cytokines in adipose tissue were observed in the L-CHO group (P < 0.05). In addition, guinea pigs fed the L-CHO exhibited larger adipose cells and lower macrophage infiltration compared to the H-CHO group.

CONCLUSIONS

The results of this study strongly suggest that HC induces metabolic dysregulation associated with inflammation in adipose tissue and that L-CHO is more effective than H-CHO in attenuating these detrimental effects.

Characterization and assessment of hyperelastic and elastic properties of decellularized human adipose tissues

Decellularized adipose tissue (DAT) has shown potential as a regenerative scaffold for plastic and reconstructive surgery to augment or replace damaged or missing adipose tissue (e.g. following lumpectomy or mastectomy). The mechanical properties of soft tissue substitutes are of paramount importance in restoring the natural shape and appearance of the affected tissues, and mechanical mismatching can lead to unpredictable scar tissue formation and poor implant integration. The goal of this work was to assess the linear elastic and hyperelastic properties of decellularized human adipose tissue and compare them to those of normal breast adipose tissue. To assess the influence of the adipose depot source on the mechanical properties of the resultant decellularized scaffolds, we performed indentation tests on DAT samples sourced from adipose tissue isolated from the breast, subcutaneous abdominal region, omentum, pericardial depot and thymic remnant, and their corresponding force-displacement data were acquired. Elastic and hyperelastic parameters were estimated using inverse finite element algorithms. Subsequently, a simulation was conducted in which the estimated hyperelastic parameters were tested in a real human breast model under gravity loading in order to assess the suitability of the scaffolds for implantation. Results of these tests showed that in the human breast, the DAT would show similar deformability to that of native normal tissue. Using the measured hyperelastic parameters, we were able to assess whether DAT derived from different depots exhibited different intrinsic nonlinearities. Results showed that DAT sourced from varying regions of the body exhibited little intrinsic nonlinearity, with no statistically significant differences between the groups.

Efficient transduction of equine adipose-derived mesenchymal stem cells by VSV-G pseudotyped lentiviral vectors

Equine adipose-derived mesenchymal stem cells (EADMSC) provide a unique cell-based approach for treatment of a variety of equine musculoskeletal injuries, via regeneration of diseased or damaged tissue, or the secretion of immunomodulatory molecules. These capabilities can be further enhanced by genetic modification using lentiviral vectors, which provide a safe and efficient method of gene delivery. We investigated the suitability of lentiviral vector technology for gene delivery into EADMSC, using GFP expressing lentiviral vectors pseudotyped with the G glycoprotein from the vesicular stomatitis virus (V-GFP) or, for the first time, the baculovirus gp64 envelope protein (G-GFP). In this study, we produced similarly high titre V-GFP and G-GFP lentiviral vectors. Flow cytometric analysis showed efficient transduction using V-GFP; however G-GFP exhibited a poor ability to transduce EADMSC. Transduction resulted in sustained GFP expression over four passages, with minimal effects on cell viability and doubling time, and an unaltered chondrogenic differentiation potential.

Poor maternal nutrition during gestation in sheep reduces circulating concentrations of insulin-like growth factor-I and insulin-like growth factor binding protein-3 in offspring

To determine if poor maternal nutrition alters growth, body composition, circulating growth factors, and expression of genes involved in the development of muscle and adipose of offspring, 24 Dorset and Shropshire ewes were fed either 100% (control fed), 60% (restricted fed), or 126% (over fed) of National Research Council requirements. Diets began at day 116 ± 6 of gestation until parturition. At parturition, 1 lamb from each control fed (CON), restricted fed (RES), and over fed (OVER) ewe was necropsied within 24 h of birth (1 d; n = 3/treatment) or reared on a control diet for 3 mo (CON = 5, RES = 5, and OVER = 3/treatment) and then euthanized. Body weights and blood samples were collected from lambs from 1 d to 3 mo. Organ weights, back fat thickness, loin eye area, and tissue samples (quadriceps, adipose, and liver) were collected at 1 d and 3 mo of age. The RES lambs weighed 16% less than CON (P = 0.01) between 1 d and 3 mo of age. In RES, there was a tendency for reduced heart girth at 1 d and 3 mo (P < 0.07) and back fat was reduced 36% at 3 mo (P = 0.03). Heart weight was 30% greater in OVER at 1 d when compared with RES lambs (P = 0.02). Serum IGF-I and IGFBP-3 were reduced in RES and OVER lambs (P < 0.05). Leptin tended to be greater in OVER lambs compared with CON at 1 d and 3 mo (P ≤ 0.08). Triiodothyronine was reduced in RES at 1 d (P = 0.05) and triglycerides tended to be greater in OVER at 3 mo (P = 0.07). In liver, there was a tendency for increased expression of IGF-I in OVER (P = 0.06) and decreased IGFBP-3 in RES (P = 0.09) compared with CON lambs at 1 d. In adipose tissue, adiponectin expression was decreased in RES (P = 0.05) at 3 mo. At 1 d of age, muscle expression of IGF-I tended to increase in RES (P = 0.06). In conclusion, poor maternal nutrition during gestation reduced growth rate in offspring which may be because of reduced circulating IGF-I and IGFBP-3 and decreased expression of IGFBP-3 in the liver.

Imaging of adipose tissue

Adipose tissue is an endocrine organ that specializes in lipid metabolism and is distributed throughout the body in distinct white adipose tissue (WAT) and brown adipose tissue (BAT) depots. These tissues have opposing roles in lipid metabolism with WAT storing excessive caloric intake in the form of lipid, and BAT burning lipid through nonshivering thermogenesis. As accumulation of lipid in mature adipocytes of WAT leads to obesity and increased risk of comorbidity (Pi-Sunyer et al., 1998), detailed understanding of the mechanisms of BAT activation and WAT accumulation could produce therapeutic strategies for combatting metabolic pathologies. As morphological changes accompany alterations in adipose function, imaging of adipose tissue is one of the most important tools for understanding how adipose tissue mass fluctuates in response to various physiological contexts. Therefore, this chapter details several methods of processing and imaging adipose tissue, including bright-field colorimetric imaging of paraffin-sectioned adipose tissue with a detailed protocol for automated adipocyte size analysis; fluorescent imaging of paraffin and frozen-sectioned adipose tissue; and confocal fluorescent microscopy of whole mounted adipose tissue. We have also provided many example images showing results produced using each protocol, as well as commentary on the strengths and limitations of each approach.