Adipose matrix complex: a high-rigidity collagen-rich adipose-derived material for fat grafting

Due to the low percentage of collagen, the rigid support capacity of fat grafts remains unsatisfactory for some clinical applications. In this study, we evaluated a strategy in which adipose matrix complex (AMC) was collected via a mechanical process and transplanted for supportive filling of the face. Our AMC samples were collected from adipose tissue by a filter device consisting of a sleeve, three internal sieves, and a filter bag (100 mesh). AMC derived from adipose tissue had fewer cells than Coleman fat, but much higher levels of collagen and stiffness. Retention rates 90 days after transplantation in nude mice were higher for AMC than for Coleman fat (75±7.5% vs. 42±13.5%; P < 0.05). In addition, AMC maintained a higher stiffness (~6 kPa vs. ~2 kPa; P < 0.01) and stably retained a higher level of collagen. Our findings demonstrate that mechanical collection of AMC from adipose tissue is a practical method for improving fat graft retention and rigid support. This strategy has the potential to improve the quality of lipoaspirates for patients requiring rigid supportive filling.

Influence of software parameters on measurements in automatized image-based analysis of fat tissue histology

The understanding of fat tissue plays an eminent role in plastic surgery as well as in metabolic research. Histopathological analysis of tissue samples provides insight in free fat graft survival and culture experiments help to better understand fat tissue derived stem cells (ASCs). To facilitate such experiments, modern image-based histology could provide an automatized approach to a large amount of data to gain not only qualitative but also quantitative data. This study was designed to critically evaluate image-based analysis of fat tissue samples in cell culture or in tissue probes and to identify critical parameters to avoid bias in further studies. In the first part of the study, ASCs were harvested and differentiated into adipocytes in cell culture. Histology was performed with the fluorescent dye BODIPY and the obtained digital images were analyzed using Image J software. In the second part of the study, digitalized histology of a previous in vivo study was subjected to automatized fat vacuole quantification using Image J. Both approaches were critically reviewed, and different software parameter settings were tested. Results showed that automatized digital image analysis allows the quantification of fat tissue probes with enough precision giving significant results. But the testing of different software parameters revealed a significant influence of parameters themselves on calculated results. Therefore, we recommend the use of image-based analysis to quantify fat tissue probes to improve the comparability of studies. But we also emphasize to calibrate software using internal controls in every single experimental approach.

Microstructural features of lyophilized adipose - A new concept to estimate the metabolic symptoms for obese patients

The aim of this study was to investigate the distribution of different morphological features in different layers of lyophilized adipose tissue. In this work the scanning electron microscopy (SEM) was adopted for investigation of lyophilized adipose tissue taken from obese patients. The adipose tissue was taken from subcutaneous (SAT), preperitoneal (PAT) and visceral (VAT) layers of adipose tissue. The obtained results of the main microstructural features provided information about morphological features of subcutaneous, preperitoneal and visceral layers in obese people. The obtained SEM results possibly could be used for the estimation of metabolic symptoms and prediction different diseases. The SEM method was never used before to investigate morphology of SAT, PAT and VAT layers of lyophilized human adipose tissue.

Analysis of mitochondrial respiratory function in tissue biopsies and blood cells

PURPOSE OF REVIEW

The review provides an overview on latest methodological strategies to assess mitochondrial respiratory function in tissue biopsies or blood cells. In addition, it summarizes the recent literature related to this topic.

RECENT FINDINGS

Today, the study of mitochondrial function in key metabolic active tissues has been become more relevant, with increasing focus in clinical applications. In addition, assessment of mitochondrial function in blood cells by respirometry might be a sensitive biomarker of disease progression. High-Resolution Respirometry provides a modern tool to study mitochondrial respiratory physiology which allows direct measurement of cellular metabolic function during health and disease. Moreover, standard operating procedures are required regarding instrumental settings, sample collection and preparation, protocol design and respirometric data analysis of mitochondrial respiratory function in tissue biopsies (such as skeletal muscle, liver and adipose tissue), as well as isolated blood cells.

SUMMARY

Mitochondrial function is a key factor in many metabolic diseases. Although various analytical approaches are available, certain well-established protocols for isolated mitochondria are limited for the analysis of mitochondrial function in tissue biopsies or blood cells. Thus, cautious considerations in selecting appropriate protocols and analytical endpoints are crucial for the interpretation of the gained data and to draw robust conclusions.

AMP-activated protein kinase, fatty acid metabolism, and insulin sensitivity

PURPOSE OF REVIEW

Insulin resistance is an important risk factor for metabolic diseases such as type 2 diabetes, cardiovascular disease and certain cancers. A common characteristic of strategies that improve insulin sensitivity involves the activation of the energy sensing enzyme of the cell, AMP-activated protein kinase (AMPK). The purpose of this review is to explore the mechanisms associated with AMPK activation to improve insulin sensitivity with a focus on fatty acid metabolism. We will also discuss the literature surrounding direct AMPK activators to improve insulin resistance and important considerations for the design of direct AMPK activators.

RECENT FINDINGS

AMPK activation can decrease de novo lipogenesis, increase fatty acid oxidation and promote mitochondrial integrity to improve insulin sensitivity. Drugs targeted to directly activate AMPK show therapeutic promise, yet in vivo data is lacking.

SUMMARY

Designing a drug to directly activate AMPK may improve insulin resistance by reducing liver de novo lipogenesis and increasing brown and white adipose tissue mitochondrial function. However, in vivo experimental procedures to support this notion are not extensive and more research is required.

[Preparation and evaluation of extracellular matrix scaffold of human adipose tissue]

Objective To prepare extracellular matrix scaffold of human adipose tissue and evaluate the effectiveness of decellularization,component,mechanical properties and cellular compatibility so as to select an ideal biologic scaffold for adipose tissue engineering.

METHODS

25 g normal adipose tissue was cut into pieces. Then repeated freeze-thaw,enzymatic digestion,organic solvent extraction and vacuum freeze-drying were performed.Adult adipose tissue extracellular tissue matrix was obtained. The traits of extracellular matrix scaffold were observed.HE staining, Masson staining and DAPI fluorescence staining were used to test the effectiveness of the decellularization.Immunohistochemistry was used to detect the reservations of extracellular matrix (Ⅳ collagen, laminin).Scanning electron microscopy was introduced to observe the ultrastructure of extracellular matrix scaffold, and universal mechanical testing machine was used to measure the mechanical properties of the scaffolds. Enzyme digestion method was used to extract human adipose-derived stem cells (hADSCs),and then the 3rd passage hADSCs were cocultured with extracellular matrix scaffold.CCK8 was introduced to assay cell proliferation activity,and scanning electron microscopy was used to observe cellular adhesion. The cells on the scaffold were induced to adipocytes and observed by freezing section and Oil Red O staining after 14 days.

RESULTS

The extracellular matrix scaffold of adipose tissue was porous sponges architecture. The cells in tissue were relatively removed. The collagen and laminin were preserved relatively, and the mechanical properties did not decline too much. The cell proliferation, adhesion and differentiation on the scaffold was very well.

CONCLUSIONS

The extracellular matrix scaffold of adipose tissue, prepared through the methods of physical, chemical, enzymatic digestion and vacuum freeze-drying method, keeps the main ingredients of extracellular matrix and presents a well cellular compatibility, therefore it should be an ideal biologic scaffold for adipose tissue engineering.

Autophagy Is Dispensable for Macrophage-Mediated Lipid Homeostasis in Adipose Tissue

Adipose tissue (AT) macrophages (ATMs) contribute to obesity-induced inflammation and metabolic dysfunction, but also play critical roles in maintaining tissue homeostasis. ATMs catabolize lipid in a lysosomal-dependent manner required for the maintenance of AT; deficiency in lysosomal acid lipase (Lipa), the enzyme required for lysosome lipid catabolism, leads to AT atrophy and severe hepatic steatosis, phenotypes rescued by macrophage-specific expression of Lipa Autophagy delivers cellular products, including lipid droplets, to lysosomes. Given that obesity increases autophagy in AT and contributes to lipid catabolism in other cells, it was proposed that autophagy delivers lipid to lysosomes in ATMs and is required for AT homeostasis. We found that obesity does increase autophagy in ATMs. However, genetic or pharmacological inhibition of autophagy does not alter the lipid balance of ATMs in vitro or in vivo. In contrast to the deficiency of lysosomal lipid hydrolysis, the ablation of autophagy in macrophages does not lead to AT atrophy or alter metabolic phenotypes in lean or obese animals. Although the lysosomal catabolism of lipid is necessary for normal ATM function and AT homeostasis, delivery of lipid to lysosomes is not autophagy dependent and strongly suggests the existence of another lipid delivery pathway critical to lysosome triglyceride hydrolysis in ATMs.

Subcutaneous Construction of Engineered Adipose Tissue with Fat Lobule-Like Structure Using Injectable Poly-Benzyl-L-Glutamate Microspheres Loaded with Adipose-Derived Stem Cells

Porous microcarriers were fabricated from synthesized poly(γ-benzyl-L-glutamate) (PBLG) polymer to engineer adipose tissue with lobule-like structure via the injectable approach. The adipogenic differentiation of human adipose-derived stem cells (hASCs) seeded on porous PBLG microcarriers was determined by adipogenic gene expression and glycerol-3-phosphate dehydrogenase enzyme activity. In vitro adipogenic cultivation was performed for 7 days, and induced hASC/PBLG complex (Adi-ASC/PBLG group) was subcutaneously injected into nude mice. Injections of PBLG microcarriers alone (PBLG group) and non-induced hASC/PBLG complex (ASC/PBLG group) served as controls. Newly formed tissues were harvested after 4 and 8 weeks. Generation of subcutaneous adipose tissue with typical lobule-like structure separated by fibrous septa was observed upon injection of adipogenic-induced hASC/microsphere complex. Adipogenesis significantly increased in the Adi-ASC/PBLG group compared with the control groups. The angiogenesis in the engineered adipose tissue was comparable to that in normal tissue as determined by capillary density and luminal diameter. Cell tracking assay demonstrated that labeled hASCs remained detectable in the neo-generated tissues 8 weeks post-injection using green fluorescence protein-labeled hASCs. These results indicate that adipose tissue with typical lobule-like structure could be engineered using injectable porous PBLG microspheres loaded with adipogenic-induced hASCs.

Autophagy in adipose tissue of patients with obesity and type 2 diabetes

BACKGROUND

Pathophysiology of obesity is closely associated with enhanced autophagy in adipose tissue (AT). Autophagic process can promote survival or activate cell death. Therefore, we examine the occurrence of autophagy in AT of type 2 diabetes (T2D) patients in comparison to obese and lean individuals without diabetes.

METHODOLOGY/PRINCIPAL FINDINGS

Numerous autophagosomes accumulated within adipocytes were visualized by electron transmission microscopy and by immunofluorescence staining for autophagy marker LC3 in obese and T2D patients. Increased autophagy was demonstrated by higher LC3-II/LC3-I ratio, up-regulated expression of LC3 and Atg5 mRNA, along with decreased p62 and mTOR protein levels. Increased autophagy occurred together with AT inflammation.

CONCLUSIONS

Our data suggest fat depot-related differences in autophagy regulation. In subcutaneous AT, increased autophagy is accompanied by increased markers of apoptosis in patients with obesity independently of T2D. In contrast, in visceral AT only in T2D patients increased autophagy was related to higher markers of apoptosis.

Effect of extracellular vesicles of human adipose tissue on insulin signaling in liver and muscle cells

OBJECTIVE

Insulin resistance (IR) is a key mechanism in obesity-induced cardiovascular disease. To unravel mechanisms whereby human adipose tissue (AT) contributes to systemic IR, the effect of human AT-extracellular vesicles (EVs) on insulin signaling in liver and muscle cells was determined.

METHODS

EVs released from human subcutaneous (SAT) and omental AT (OAT)-explants ex vivo were used for stimulation of hepatocytes and myotubes in vitro. Subsequently, insulin-induced Akt phosphorylation and expression of gluconeogenic genes (G6P, PEPCK) was determined. AT-EV adipokine levels were measured by multiplex immunoassay, and AT-EVs were quantified by high-resolution flow cytometry.

RESULTS

In hepatocytes, AT-EVs from the majority of patients inhibited insulin-induced Akt phosphorylation, while EVs from some patients stimulated insulin-induced Akt phosphorylation. In myotubes AT-EVs exerted an ambiguous effect on insulin signaling. Hepatic Akt phosphorylation related negatively to G6P-expression by both SAT-EVs (r = -0.60, P = 0.01) and OAT-EVs (r = -0.74, P = 0.001). MCP-1, IL-6, and MIF concentrations were higher in OAT-EVs compared to SAT-EVs and differently related to lower Akt phosphorylation in hepatocytes. Finally, the number of OAT-EVs correlated positively with liver enzymes indicative for liver dysfunction.

CONCLUSIONS

Human AT-EVs can stimulate or inhibit insulin signaling in hepatocytes- possibly depending on their adipokine content- and may thereby contribute to systemic IR.

The mechanical properties of human adipose tissues and their relationships to the structure and composition of the extracellular matrix

Adipose tissue (AT) expansion in obesity is characterized by cellular growth and continuous extracellular matrix (ECM) remodeling with increased fibrillar collagen deposition. It is hypothesized that the matrix can inhibit cellular expansion and lipid storage. Therefore, it is important to fully characterize the ECM's biomechanical properties and its interactions with cells. In this study, we characterize and compare the mechanical properties of human subcutaneous and omental tissues, which have different physiological functions. AT was obtained from 44 subjects undergoing surgery. Force/extension and stress/relaxation data were obtained. The effects of osmotic challenge were measured to investigate the cellular contribution to tissue mechanics. Tissue structure and its response to tensile strain were determined using nonlinear microscopy. AT showed nonlinear stress/strain characteristics of up to a 30% strain. Comparing paired subcutaneous and omental samples (n = 19), the moduli were lower in subcutaneous: initial 1.6 ± 0.8 (means ± SD) and 2.9 ± 1.5 kPa (P = 0.001), final 11.7 ± 6.4 and 32 ± 15.6 kPa (P < 0.001), respectively. The energy dissipation density was lower in subcutaneous AT (n = 13): 0.1 ± 0.1 and 0.3 ± 0.2 kPa, respectively (P = 0.006). Stress/relaxation followed a two-exponential time course. When the incubation medium was exchanged for deionized water in specimens held at 30% strain, force decreased by 31%, and the final modulus increased significantly. Nonlinear microscopy revealed collagen and elastin networks in close proximity to adipocytes and a larger-scale network of larger fiber bundles. There was considerable microscale heterogeneity in the response to strain in both cells and matrix fibers. These results suggest that subcutaneous AT has greater capacity for expansion and recovery from mechanical deformation than omental AT.

Immunohistochemical and ultrastructural changes in rat fat tissue related to the local hCG injection

OBJECTIVES

Recently, it has been observed that weight loss is accelerated by human chorionic gonadotropin (hCG) hormone preparation used for hypothalamic dysfunction in obesity treatment in both sexes. hCG is also used for in vitro fertilization and in treatment of hypogonadotropic hypogonadism. Our aim was to observe the ultrastructural changes caused by local injections of hCG made for purpose of weight loss and to present them to inform those receiving such therapy.

MATERIALS AND METHODS

In our study, 10 obese female, 10 male obese, 10 non-obese female and 10 non-obese male rats were used. In each group, single dose of subcutaneous hCG injection has been applied to 7 rats for 5 weeks in 5 days of the week, and placebo has been applied to the remaining 3 rats. Following the injection, the tissues were evaluated morphologically, immunohistochemically and ultrastructurally.

RESULTS

Leptin immunoreactivity was similar in all groups. When the adipose tissue samples were examined under electron microscope, they were observed to exhibit normal structure with organelles located around the nuclei and nucleoli, and no distinctive features were found among the groups.

CONCLUSIONS

Administering hCG in addition to diet had no advantage on weight reduction in rats.

Inhibition of class I histone deacetylases unveils a mitochondrial signature and enhances oxidative metabolism in skeletal muscle and adipose tissue

Chromatin modifications are sensitive to environmental and nutritional stimuli. Abnormalities in epigenetic regulation are associated with metabolic disorders such as obesity and diabetes that are often linked with defects in oxidative metabolism. Here, we evaluated the potential of class-specific synthetic inhibitors of histone deacetylases (HDACs), central chromatin-remodeling enzymes, to ameliorate metabolic dysfunction. Cultured myotubes and primary brown adipocytes treated with a class I-specific HDAC inhibitor showed higher expression of Pgc-1α, increased mitochondrial biogenesis, and augmented oxygen consumption. Treatment of obese diabetic mice with a class I- but not a class II-selective HDAC inhibitor enhanced oxidative metabolism in skeletal muscle and adipose tissue and promoted energy expenditure, thus reducing body weight and glucose and insulin levels. These effects can be ascribed to increased Pgc-1α action in skeletal muscle and enhanced PPARγ/PGC-1α signaling in adipose tissue. In vivo ChIP experiments indicated that inhibition of HDAC3 may account for the beneficial effect of the class I-selective HDAC inhibitor. These results suggest that class I HDAC inhibitors may provide a pharmacologic approach to treating type 2 diabetes.

PCOS is associated with increased CD11c expression and crown-like structures in adipose tissue and increased central abdominal fat depots independent of obesity

CONTEXT

Adipose tissue macrophage (ATM) infiltration is a major pathway for obesity-induced insulin resistance but has not been studied as a mechanism for insulin resistance in PCOS.

OBJECTIVE

We tested whether polycystic ovary syndrome (PCOS) is associated with increased ATM infiltration, especially of inflammatory subtype identified by the CD11c marker.

DESIGN AND SETTING

We conducted a case-control study at an academic medical center in the United States.

PARTICIPANTS AND INTERVENTIONS

Fourteen PCOS and 14 control women of similar age and body mass index (BMI) underwent a gluteal fat biopsy. Markers of ATM, integrins, TNF-α, and adiponectin, were analyzed by quantitative RT-PCR using a standard curve method. Crown-like structures (CLS) were identified by immunohistochemistry. Abdominal magnetic resonance imaging and frequently sampled i.v. glucose tolerance test were performed to assess abdominal fat and insulin sensitivity (SI).

MAIN OUTCOME

Women with PCOS were compared with control women of similar age and BMI for ATM markers, CLS density, adipose tissue expression of inflammatory cytokines and adiponectin, SI, and abdominal fat depots.

RESULTS

Women with PCOS had an increase in CD11c expression (P = 0.03), CLS density (P = 0.001), α5 expression (P = 0.009), borderline increase in TNF-α expression (P = 0.08), and a decrease in adiponectin expression (P = 0.02) in gluteal adipose tissue. Visceral (P = 0.009) and sc abdominal fat (P = 0.005) were increased in PCOS. SI was lower in PCOS (P = 0.008).

CONCLUSIONS

PCOS is associated with an increase in CD11c expression and CLS density and a decrease in adiponectin expression in sc adipose tissue. Additionally, PCOS is associated with higher central abdominal fat depots independent of BMI. These alterations are present among mostly nonobese women and could represent mechanisms for insulin resistance.

Triglyceride-lowering Effect of Respiratory Uncoupling in White Adipose Tissue

OBJECTIVE

Hypolipidemic drugs such as bezafibrate and thiazolidinediones are known to induce the expression of mitochondrial uncoupling proteins (UCPs) in white adipose tissue. To analyze the potential triglyceride (TG)-lowering effect of respiratory uncoupling in white fat, we evaluated systemic lipid metabolism in aP2-Ucp1 transgenic mice with ectopic expression of UCP1 in adipose tissue.

RESEARCH METHODS AND PROCEDURES

Hemizygous and homozygous transgenic mice and their nontransgenic littermates were fed chow or a high-fat diet for up to 3 months. Total TGs, nonesterified fatty acids, and the composition of plasma lipoproteins were analyzed. Hepatic TG production was measured in mice injected with Triton WR1339. Uptake and the use of fatty acids were estimated by measuring adipose tissue lipoprotein lipase activity and fatty acid oxidation, respectively. Adipose tissue gene expression was assessed by quantitative reverse transcriptase-polymerase chain reaction.

RESULTS

Transgene dosage and the high-fat diet interacted to markedly reduce plasma TGs. This was reflected by decreased concentrations of very-low-density lipoprotein particles in the transgenic mice. Despite normal hepatic TG secretion, the activity of lipoprotein lipase in epididymal fat was enhanced by the high-fat diet in the transgenic mice in a setting of decreased re-esterification and increased in situ fatty acid oxidation.

DISCUSSION

Respiratory uncoupling in white fat may lower plasma lipids by enhancing their in situ clearance and catabolism.

[Adipose tissue sample preparation for scanning electron microscopy]

Conventional sample preparation technique for adipose tissue is difficult to achieve satisfactory results for scanning electron microscopy (SEM). We adopted a strategy of postfix with osmium tetroxide to stabilize the fatty acids, phospholipids protein, and hence the membrane structure. Also by extending the dehydration time to fully replace the organic solvents, we achieved satisfactory results for SEM of adipose samples.

[Morphological characteristics of human adipose-derived stem cells]

This paper is aimed to isolate and to cultivate human adipose-derived stem cells (hADSCs) from the adipose tissue by a combination of collagenase digestion, adherence to flasks and monoclonal cultural method so as to observe the morphological characteristics of the hADSCs. The immunophenotypes of hADSCs were detected by flow cytometry techniques. The general morphological characteristics of hADSCs were observed by cytochemical and immunofluorescent techniques. The ultrastructure of hADSCs was observed by transmission electron microscopy (TEM). The experimental results showed that hADSCs had unique immunophenotypes and they were positive for CD29, CD44, CD90, CD105 and CD166, but negative for CD31, CD45 and HLA-DR. Cytochemistry showed that cytoplasm of hADSCs was stained with light blue by hematoxylin-eosin, negative for Oil red O and AKP, and positive for immunofluorescence CD29 and CD166. There were abundant organella and microvilli in the ultrastructure of hADSCs. The results validate that they will offer a morphological foundation for application of the hADSCs.

Lipoatrophy induced by subcutaneous insulin infusion: ultrastructural analysis and gene expression profiling

CONTEXT AND OBJECTIVE

Subcutaneous adipose tissue (SAT) lipoatrophy (LA) is a rare complication of insulin therapy. We aimed to analyze the ultrastructural and molecular aspects of LA lesions.

SETTING AND PATIENTS

Macroscopic and microscopic morphology of SAT beneath the LA areas from patients with type 1 diabetes treated with Lispro insulin by continuous sc insulin infusion was studied using magnetic resonance imaging, immunohistochemistry, electron microscopy, and quantitative PCR for adipose tissue-specific genes.

RESULTS

SAT was present in LA lesions characterized by: 1) smaller, unilocular perilipin-positive adipocytes, with lipofuscin granules; 2) some "slimmed cells" losing lipid droplets as those we observed during starvation; and 3) numerous perivascular preadipocytes. We did not identify inflammatory cells. SAT in LA areas displayed a strong leptin down-regulation and an increase of AEBP1, a preadipocyte marker.

CONCLUSIONS

Our results clearly indicate that the remarkable reduction in fat cell lipid droplets and adipocyte size justifies the decrease of SAT without a reduction in adipocyte number because of necrosis or apoptosis. Thus, immune cells and any other toxic damaging fat cells were not involved in the generation of LA. We speculate that adipocytes chronically exposed to high local insulin concentrations could become severely insulin resistant, dramatically increasing lipolysis and giving rise to "slimmed cells." Clinical LA regression could be explained by the active recruitment of preadipocytes, even if they were unable to differentiate and regenerate adipose tissue unless the insulin injection was removed.

Impact of simvastatin on adipose tissue: pleiotropic effects in vivo

Statins belong to a class of drugs well known for their ability to reduce circulating low-density lipoprotein cholesterol. In addition to cholesterol lowering, they also exhibit potential antiinflammatory and antioxidant properties, suggesting that tissues other than liver may be targeted by statins to exert their beneficial metabolic effects. Adipocytes have received very little attention as a potential target of these drugs, possibly because adipocytes are not a major source of biosynthetic cholesterol. Here, we examine the effects of simvastatin on the secretory pathway, inflammation, and cellular metabolism of adipocytes as well as on whole-body insulin sensitivity. We find that statins have a selective effect on the secretion of the insulin-sensitizing adipokine adiponectin by reducing circulating levels of the high-molecular-weight form of adiponectin specifically with a concomitant increase in intracellular adiponectin levels. However, these effects on adiponectin do not translate into changes in metabolism or whole-body insulin sensitivity, potentially due to additional antiinflammatory properties of statins. In addition, ob/ob mice treated with statins have reduced adiposity and an altered ultrastructure of the plasma membrane with respect to caveolar histology. Our data demonstrate that statins have major effects on the cellular physiology of the adipocyte on multiple levels.

EGFR tyrosine kinase inhibitor (PD153035) improves glucose tolerance and insulin action in high-fat diet-fed mice

OBJECTIVE

In obesity, an increased macrophage infiltration in adipose tissue occurs, contributing to low-grade inflammation and insulin resistance. Epidermal growth factor receptor (EGFR) mediates both chemotaxis and proliferation in monocytes and macrophages. However, the role of EGFR inhibitors in this subclinical inflammation has not yet been investigated. We investigated, herein, in vivo efficacy and associated molecular mechanisms by which PD153035, an EGFR tyrosine kinase inhibitor, improved diabetes control and insulin action.

RESEARCH DESIGN AND METHODS

The effect of PD153035 was investigated on insulin sensitivity, insulin signaling, and c-Jun NH(2)-terminal kinase (JNK) and nuclear factor (NF)-kappaB activity in tissues of high-fat diet (HFD)-fed mice and also on infiltration and the activation state of adipose tissue macrophages (ATMs) in these mice.

RESULTS

PD153035 treatment for 1 day decreased the protein expression of inducible nitric oxide synthase, tumor necrosis factor (TNF)-alpha, and interleukin (IL)-6 in the stroma vascular fraction, suggesting that this drug reduces the M1 proinflammatory state in ATMs, as an initial effect, in turn reducing the circulating levels of TNF-alpha and IL-6, and initiating an improvement in insulin signaling and sensitivity. After 14 days of drug administration, there was a marked improvement in glucose tolerance; a reduction in insulin resistance; a reduction in macrophage infiltration in adipose tissue and in TNF-alpha, IL-6, and free fatty acids; accompanied by an improvement in insulin signaling in liver, muscle, and adipose tissue; and also a decrease in insulin receptor substrate-1 Ser(307) phosphorylation in JNK and inhibitor of NF-kappaB kinase (IKKbeta) activation in these tissues.

CONCLUSIONS

Treatment with PD153035 improves glucose tolerance, insulin sensitivity, and signaling and reduces subclinical inflammation in HFD-fed mice.

The structure and possible functions of the milkfish Chanos chanos adipose eyelid

Basic histological sections (with different staining methods) and scanning electron microscopy (SEM) examinations showed that there were three distinctive layers in the adipose eyelid of milkfish Chanos chanos, which is found in the cephalie region and covers the entire eye. The outer and inner layers were epithelial tissues and the middle layer was composed of connective tissue formed by type I collagen fibrils. No adipose tissue was found in any of the three layers of the so-called adipose eyelid. Examination by transmission spectrophotometer showed that the adipose tissue could filter out ambient light with a wavelength shorter than 305 nm. A photoretinoscope was used to investigate whether the adipose eyelid influenced the mechanism of eye focusing. Eye diopter values did not differ before or after eyelid removal, which indicated that the adipose eyelid did not play a role in eye focusing. In light of these findings, it is suggested that the adipose eyelid serves to block exposure of harmful ultraviolet light into eyes and may also to offer some protection against impact to the eye in the aquatic environment.

Clinical implications of epidural fat in the spinal canal. A scanning electron microscopic study

BACKGROUND AND OBJECTIVES

This review of articles summarizes recent developments in relation to fat located in the epidural space and also in dural sleeves of spinal nerve roots in order to improve our understanding of the clinical effects of the epidural blockade.

METHOD

Medline search was carried cross-matching of the following words: "epidural fat", "epidural space", "adipose tissue" and "fat cells" from 1966 to 2008 in which articles referring to different pathologies that alter the epidural fat were also reviewed. Techniques used by different authors included the use of samples from dissections, cryomicrotome sections, as well as light and electron microscopy.

RESULTS

Fat in the epidural space has a metameric distribution along the spinal canal that can be altered in some pathological conditions. Epidural fat is not evenly distributed. At cervical level fat is absent while in the lumbar region, fat in the anterior and posterior aspects of the epidural space forms two unconnected structures. Fat cells are found also in the thickness of dural sleeves enveloping spinal nerve roots but not in the region of the dural sac. Epidural lipomatosis is characterized by an increase in epidural fat content. When a patient has a combination of kyphosis and scoliosis of the spine, the epidural fat distributes asymmetrically. Spinal stenosis is frequently accompanied by a reduction in the amount of epidural fat around the stenotic area.

CONCLUSIONS

The epidural space contains abundant epidural fat that distributes along the spinal canal in a predictable pattern. Fat cells are also abundant in the dura that forms the sleeves around spinal nerve roots but they are not embedded within the laminas that form the dura mater of the dural sac. Drugs stored in fat, inside dural sleeves, could have a greater impact on nerve roots than drugs stored in epidural fat, given that the concentration of fat is proportionally higher inside nerve root sleeves than in the epidural space, and that the distance between nerves and fat is shorter. Similarly, changes in fat content and distribution caused by different pathologies may alter the absorption and distribution of drugs injected in the epidural space.

Multiphoton microscopic imaging of adipose tissue based on second-harmonic generation and two-photon excited fluorescence

The fresh adipose tissue was investigated by the use of multiphoton microscopy (MPM) based on two-photon excited fluorescence and second-harmonic generation (SHG). Microstructure of collagen and adipose cells in the adipose tissue is clearly imaged at a subcellular level with the excitation light wavelengths of 850 and 730 nm, respectively. The emission spectrum of collagen SHG signal and NADH and FAD fluorescence signal can also be obtained, which can be used to quantify the content of collagen and adipose cells and reflect the degree of pathological changes when comparing normal tissue with abnormal adipose tissue in the same condition. The results indicate that MPM has the potential to be applied to investigate the adipose tissue and can be used in the research field of lipid and connective tissues.

Trypanosoma cruzi infection of cultured adipocytes results in an inflammatory phenotype

Infection with Trypanosoma cruzi, the etiologic agent of Chagas disease is accompanied by an intense inflammatory reaction. Our laboratory group has identified adipose tissue as one of the major sites of inflammation during disease progression. Because adipose tissue is composed of many cell types, we were interested in investigating whether the adipocyte per se was a source of inflammatory mediators in this infection. Cultured adipocytes were infected with the Tulahuen strain of T. cruzi for 48-96 h. Immunoblot and quantitative PCR (qPCR) analyses demonstrated an increase in the expression of proinflammatory cytokines and chemokines, including interleukin (IL)-1 beta, interferon-gamma, tumor necrosis factor-alpha, CCL2, CCL5, and CXCL10 as well as an increase in the expression of Toll-like receptors-2 and 9 and activation of the notch pathway. Interestingly, caveolin-1 expression was reduced while cyclin D1 and extracellular signal-regulated kinase (ERK) expression was increased. The expression of PI3kinase and the activation of AKT (phosphorylated AKT) were increased suggesting that infection may induce components of the insulin/IGF-1 receptor cascade. There was an infection-associated decrease in adiponectin and peroxisome proliferator-activated receptor-gamma (PPAR-gamma). These data provide a mechanism for the increase in the inflammatory phenotype that occurs in T. cruzi-infected adipocytes. Overall, these data implicate the adipocyte as an important target of T. cruzi, and one which contributes significantly to the inflammatory response observed in Chagas disease.

[Micromorphological studies in Dupuytren's disease]

Based on histological and scan electron microscopic investigations the morphology of Dupuytren's disease was studied. For comparison normal samples from the palm of the hand were used. Because scan electron microscopy permits a three dimensional observation of surfaces, cut as well as break preparations of cases in stages II, III and IV as well as from relapse cases were furnished and examined. The findings were as follows: 1) The border between cutis and underlying tissue was not distinct any more. 2) The subcutaneous fat tissue has been thrust aside and replaced by newly formed collagen. 3) Starting from the aponeurosis thickened net-like collagen fibers stretch across into the cutis causing skin retractions 4) Within the aponeurosis palmaris collagen bundles exhibit considerable deviation in diameter and structure. 5) A classification of different stages of the disease according to morphological findings proves to be impossible.

Apoptosis in orbital fibroadipose tissue and its association with clinical features in Graves' ophthalmopathy

PURPOSE

To evaluate the rate of apoptosis in orbital fibroadipose tissue in Graves' ophthalmopathy (GO) patients and investigate its associations with disease characteristics.

METHODS

Orbital tissue samples were obtained during decompression surgery from 25 GO patients. Disease activity was evaluated using the Clinical Activity Score, while the clinical features of GO were evaluated using the Total Eye Score (TES). Tissue samples of 12 patients without any thyroid or autoimmune disease were studied as controls. The rate of apoptosis was evaluated with a terminal deoxyribonucleotidyl transferase-mediated dUTP-digoxigenin nick-end labeling (TUNEL) assay, and ultrastructural features of apoptosis were evaluated with electron microscopy.

RESULTS

The rate of apoptosis in orbital fibroadipose tissue was significantly higher in GO cases than in the control group (p < 0.001) and significantly correlated with TES (r: 0.545; p = 0.005). The rate of apoptosis was 7.9% +/- 6.5%, and 22.0% +/- 7.8% in type 1 and type 2 cases, respectively (p = 0.001). The rate of apoptosis was 21.6% +/- 7.5% in eyes showing dysthyroid optic neuropathy (DON) and 6.7% +/- 5.4% in eyes without DON (p = 0.005).

CONCLUSIONS

The rate of apoptosis was high in the orbital fibroadipose tissue of GO cases and was related to the clinical features of the disease.

Loss-of-function mutation in Toll-like receptor 4 prevents diet-induced obesity and insulin resistance

Obesity is associated with insulin resistance and a state of abnormal inflammatory response. The Toll-like receptor (TLR)4 has an important role in inflammation and immunity, and its expression has been reported in most tissues of the body, including the insulin-sensitive ones. Because it is activated by lipopolysaccharide and saturated fatty acids, which are inducers of insulin resistance, TLR4 may be a candidate for participation in the cross-talk between inflammatory and metabolic signals. Here, we show that C3H/HeJ mice, which have a loss-of-function mutation in TLR4, are protected against the development of diet-induced obesity. In addition, these mice demonstrate decreased adiposity, increased oxygen consumption, a decreased respiratory exchange ratio, improved insulin sensitivity, and enhanced insulin-signaling capacity in adipose tissue, muscle, and liver compared with control mice during high-fat feeding. Moreover, in these tissues, control mice fed a high-fat diet show an increase in IkappaB kinase complex and c-Jun NH(2)-terminal kinase activity, which is prevented in C3H/HeJ mice. In isolated muscles from C3H/HeJ mice, protection from saturated fatty acid-induced insulin resistance is observed. Thus, TLR4 appears to be an important mediator of obesity and insulin resistance and a potential target for the therapy of these highly prevalent medical conditions.

New scanning electron microscopic method for determination of adipocyte size in humans and mice

OBJECTIVE

To evaluate a new scanning electronic microscopic (EM) method for assessing fat cell sizes and compare fat cell size distribution in human adipose tissue from different fat depots before and after weight loss.

RESEARCH METHODS AND PROCEDURES

Identical human fat tissue biopsies were separated into two fractions: one used to prepare a fat cell suspension by collagenase digestion followed by photomicrography (collagenase method) and the other fixed in formalin for EM analysis. The EM method was evaluated further by determining fat cell sizes from lean and ob/ob mice. Finally, the EM method was used to assess fat cell sizes in biopsies of different human depots from before and after weight loss.

RESULTS

Fat cell size distributions measured by the two methods were not identical, but differences were generally small. The EM method reproduced the well-documented fat cell size difference between lean and ob/ob mice. Large variation was detected in fat cell distributions among three depots in humans. Weight loss reduced fat cell sizes in subjects with large baseline fat cells but had no effect in subjects with small baseline fat cell sizes.

DISCUSSION

Our results suggest that the EM method may be a useful alternative for fat cell size analysis of clinical samples.

Production of a new tissue-engineered adipose substitute from human adipose-derived stromal cells

Adipose tissue is an accessible and abundant source of mesenchymal stem cells for soft-tissue reconstruction. In an attempt to create a novel, entirely autologous tissue-engineered adipose substitute, we extracted human stromal cells from either lipoaspirated or resected fat, and assessed their capacity to produce a three-dimensional adipose tissue using an adapted "self-assembly" culture methodology. This strategy involved a concomitant induction of adipogenic differentiation whilst ascorbic acid supplementation stimulated the stromal cells to produce and organize their own "biomaterial" in the form of extracellular matrix, forming manipulatable sheets that are then assembled into thicker reconstructed adipose tissues. When compared to resected fat, lipoaspiration-derived cells featured an increased adipogenic potential and the enhanced ability to recreate an adipose substitute in vitro. When viewed by scanning electron microscopy, the appearance of these reconstructed adipose tissues was strikingly similar to subcutaneous fat. Furthermore, these substitutes secreted adipokines and mediated beta-adrenergic receptor-stimulated lipolysis, hence reproducing known major biological functions of white adipose tissue. Therefore, our cell-based tissue engineering strategy led to the production of a functional and entirely natural reconstructed adipose tissue, which offers the potential to be used for specific in vitro applications as well as for autologous soft-tissue reconstruction.

Imaging of Lipids in Human Adipose Tissue by Cluster Ion TOF-SIMS

Biopsies of human subcutaneous adipose tissue were taken from healthy donors. Samples were high-pressure frozen, freeze-fractured, and freeze dried. Imaging mass spectrometry of samples was performed in a TOF-SIMS mass spectrometer equipped with a bismuth cluster ion source. Blood vessels, the connective tissue, and adipocytes can be seen in TOF-SIMS images. Blood vessels were found labeled by a high content of sodium ions and potassium ions in their lumen and phosphocholine signal in smooth muscle cells of the vessel wall. The connective tissue showed high signal levels of CN(-) fragments, derived from proteins and nucleic acids. Adipocytes showed high signal levels of phosphocholine and cholesterol ubiquitously in their membranes and diacylglycerols in some membrane sites. The central part of adipocytes showed high levels of triacylglycerols and fatty acids. These results are in accordance to those of biochemical studies; however, a precise spatial localization of lipids in adipocytes is demonstrated with MS imaging.

Coronary vessel-wall and lumen imaging using radial k-space acquisition with MRI at 3 Tesla

This study investigates the feasibility of imaging the coronary lumen and vessel-wall, using MRI with a radial k-space trajectory at 3 T. Such radial trajectories offer the advantage of greater vessel sharpness than traditional Cartesian trajectories. This field strength offers an increased signal-to-noise ratio (SNR) compared with 1.5 T, which compensates for the slight SNR reduction due to the radial sequence. Images of the coronary lumen were acquired for seven healthy volunteers. In ten volunteers the vessel wall was scanned, with blood suppression using oblique-slab adiabatic re-inversion. Scans were performed during free breathing, using prospective respiratory navigator-gating. Coronary lumen scans had SNR of 16.0+/-1.9 and contrast-to-noise ratio (CNR) of 10.3+/-2.1, showing acceptable image quality. Vessel wall images showed good image quality, with mean SNR of 16.6+/-2.0/5.8+/-2.8/10.1+/-2.2 for vessel wall/lumen/epicardial fat. The wall-blood CNR was 10.7+/-2.7, and wall-fat CNR was 6.5+/-2.5. It is concluded that radial gradient-echo imaging at 3 T is a promising method for coronary vessel-wall imaging, and is also feasible for imaging the coronary lumen.

Adipose atrophy in cancer cachexia: morphologic and molecular analysis of adipose tissue in tumour-bearing mice

Extensive loss of adipose tissue is a hallmark of cancer cachexia but the cellular and molecular basis remains unclear. This study has examined morphologic and molecular characteristics of white adipose tissue in mice bearing a cachexia-inducing tumour, MAC16. Adipose tissue from tumour-bearing mice contained shrunken adipocytes that were heterogeneous in size. Increased fibrosis was evident by strong collagen-fibril staining in the tissue matrix. Ultrastructure of 'slimmed' adipocytes revealed severe delipidation and modifications in cell membrane conformation. There were major reductions in mRNA levels of adipogenic transcription factors including CCAAT/enhancer binding protein alpha (C/EBPalpha), CCAAT/enhancer binding protein beta, peroxisome proliferator-activated receptor gamma, and sterol regulatory element binding protein-1c (SREBP-1c) in adipose tissue, which was accompanied by reduced protein content of C/EBPalpha and SREBP-1. mRNA levels of SREBP-1c targets, fatty acid synthase, acetyl CoA carboxylase, stearoyl CoA desaturase 1 and glycerol-3-phosphate acyl transferase, also fell as did glucose transporter-4 and leptin. In contrast, mRNA levels of peroxisome proliferators-activated receptor gamma coactivator-1alpha and uncoupling protein-2 were increased in white fat of tumour-bearing mice. These results suggest that the tumour-induced impairment in the formation and lipid storing capacity of adipose tissue occurs in mice with cancer cachexia.

Characterization of Osteogenically Induced Adipose Tissue-Derived Precursor Cells in 2-Dimensional and 3-Dimensional Environments

Earlier reports on a putative precursor cell population in adipose tissue showed differentiation along several mesodermal lineages, leading some to think that adipose tissue can be a source of cells applicable in regenerative medicine. However, characterizations of these adipose-derived precursor cells (ADPC) in the 3-dimensional (3-D) environment, especially within the area of bone-specific composite scaffolds, have been lacking. In this study, ADPC plated on culture flasks or seeded on medical grade polycaprolactone-tricalcium phosphate scaffolds (mPCL-CaP) were able to differentiate along the osteogenic lineages in both 2-D and 3-D environments as assessed with immunohistochemistry of osteo-related proteins, reverse transcriptase-polymerase chain reactions and alkaline phosphatase assay. The mPCL-CaP scaffolds provided adipose-derived cells (ADC) with a suitable environment as determined by DNA and metabolic assays, light, confocal and scanning electron microscopy. Flow cytometry revealed ADC to be CD29+, CD44+, CD73+, CD90+ and CD14-, CD31-, CD34-, CD45-, CD71-, and therefore showed the absence of hematopoietic stem cells but possibly the presence of pericytes and mescenchymal stem cells with osteogenic potential. The results of this study demonstrated the potential of using ADPC in combination with mPCL-CaP scaffolds for bone regenerative medicine.

One in vitro model for visceral adipose-derived fibroblasts in chronic inflammation

One pathogenesis of the obesity-associated complications is that consistent with increased body fat mass, the elevation of adipose tissue-derived cytokines inflicts a low-grade chronic inflammation, which ultimately leads to metabolic disorders. Adipocytes and macrophages in visceral adipose (VA) have been confirmed to contribute to the chronic inflammation; however, the role of the resident fibroblasts is still unknown. We established one VA fibroblast cell line, termed VAFC. Morphological analysis indicated that there were large numbers of pits at the cell plasma membrane. In vitro VAFC cells promoted bone marrow cells to differentiate into macrophages and protected them from apoptosis in the serum-free conditions. Additionally, they also interfered in lymphocytes proliferation. On the basis of these results, this cell line might be an in vitro model for understanding the role of adipose-derived fibroblasts in obesity-associated chronic inflammation.

Giant fat containing breast masses: report of six cases

Six patients with giant fat containing breast masses encountered over a 20 year period are presented including a brief review of the literature. These benign tumours especially the giant varieties are rare but are likely to be increasingly diagnosed because of the widespread use of mammography.

Adiponectin expression in human epicardial adipose tissue in vivo is lower in patients with coronary artery disease

BACKGROUND

Intra-peritoneal adipose tissue is recognized as a predictor of metabolic syndrome and may contribute to the risk for cardiovascular disease by the production of adipocytokines, including adiponectin. Nevertheless, there is no knowledge on whether other visceral depots of adipose tissue, including the epicardial fat, have any metabolically active role, including production of adiponectin.

AIM OF THE STUDY

We sought to evaluate adiponectin protein expression in epicardial adipose tissue in vivo both in patients with severe coronary artery disease (CAD) and in subjects without CAD.

METHODS

Twenty-two patients were enrolled for the study. We selected 16 patients who underwent elective coronary artery bypass graft surgery for critical CAD, 5 who underwent surgery for valve replacement and 1 for correction of an interatrial defect. Epicardial adipose tissue biopsy samples were obtained before the initiation of cardiopulmonary bypass. Adiponectin protein level in epicardial adipose tissue was evaluated by Western blotting.

RESULTS

Adiponectin protein value, expressed as adiponectin/actin ratio, in epicardial adipose tissue was significantly lower in patients with severe CAD than in those without CAD (1.42 +/- 0.77 vs 2.36 +/- 0.84 p = 0.02, 95% CI 0.64-1.74).

CONCLUSIONS

This study showed for the first time that human epicardial adipose tissue expresses adiponectin. Adiponectin expression is significantly lower in epicardial fat isolated from patients with CAD.

Histological investigation of liposuctioned fat for injection laryngoplasty

PURPOSE

There are a few injectable biomaterials used in vocal-fold-augmentation surgery. In this study, liposuctioned autologous fat, used as the injection material, was investigated histologically.

MATERIALS AND METHODS

Liposuctioned fat, which was harvested from 13 patients during injection laryngoplasty, was examined by light and electron microscopy.

RESULTS

The cell membranes of most of the liposuctioned fat had not been damaged during harvesting and microinjection by our method. The harvested liposuctioned fat was a group of unilocular fat cells. Each cell was surrounded by a meshwork of fine reticular fibers. The cells were spherical and about 30 to 130 microm in diameter. The cells size and density were different from individual to individual. The diameters of liposuctioned fat cells were correlated with the body mass index. Dense and small fat cells were able to maintain graft volume. Sparse and large fat cells tended to not be able to maintain graft volume. There was little proliferation of unilocular fat cells, which were not able to maintain graft volume.

CONCLUSION

The structure consisting of a unilocular cell, containing a single droplet of lipid, surrounded by a meshwork of delicate reticular fiber is one of the reasons why autologous fat has viscous properties similar to those of human lamina propria. Autologous fat was not damaged by our harvesting and microinjection method. The size, density and proliferation of fat cells, and ground substance around them may be related to resorption and a decrease in surviving graft volume.

Regional differences in oxidative capacity of rat white adipose tissue are linked to the mitochondrial content of mature adipocytes

Two metabolic pathways of the white adipocytes (i.e. de novo lipogenesis and lipolysis) require mitochondria functionality. In this report, the oxidative capacity of two white adipose tissues of rat and their respective isolated adipocytes were evaluated. Two major white fat pads, namely inguinal and epididymal tissues, were chosen as subcutaneous and visceral adipose tissues, respectively. The mitochondrial content of these tissues was estimated using cytological and biochemical analysis. Electron microscopy analysis showed higher mitochondrial density in epididymal than in inguinal adipocytes. The mitochondrial DNA content and mitochondrial enzymatic equipment were also higher in the former than in the latter tissue. A positive correlation between two mitochondrial enzymatic activities, namely cytochrome c oxidase and citrate synthase, and the mtDNA content of adipose tissue was reported. Moreover, NRF1 protein, which belongs to the transcriptional activator family and is thought to be involved in mitochondrial biogenesis regulation, was present in higher proportions in nuclei isolated from epididymal cells than in those from inguinal cells. Finally, greater abundance of mitochondria in epididymal tissue is in agreement with higher cytochrome c oxidase activity as well as increased respiration (i.e. basal and noradrenaline-stimulated) of adipocytes isolated from epididymal tissue as compared to adipocytes isolated from inguinal tissue. Therefore, white adipose tissue appears as a heterogeneous organ with marked variation in mitochondrial content depending on its anatomical location.

A minipig model of high-fat/high-sucrose diet-induced diabetes and atherosclerosis

Summary Type 2 diabetes is a major risk factor of the development of atherosclerosis in humans. However, studies examining mechanisms underlying diabetes-accelerated atherosclerosis have been limited by the lack of suitable humanoid animal models. Pigs have a cardiovascular system that is very similar to that of humans and is useful as a model for human physiology and pathophysiology. In this study, we established a new miniature pig model for studying dyslipidaemia and atherosclerosis in diabetes. Chinese Guizhou minipigs were fed a normal control diet or a high-fat/high-sucrose diet (HFSD) for 6 months. Plasma total cholesterol (TC), high-density lipoprotein cholesterol, triglyceride (TG), insulin and glucose were quantified at monthly intervals. The induction of insulin resistance and dysfunction of the pancreatic beta-cell were assessed by oral glucose tolerance test and insulin sensitivity test. The aortic fatty streak lesions were quantified following lipid staining with Sudan IV. During the feeding period, mild high plasma TC and TG were induced. At the end of 6 months, in HFSD-fed animals, the adipocytes were hypertrophic, fat deposit in the liver was observed, loss of pancreatic beta-cells was observed, and the aortic fatty streak lesions were clearly present in the animals' aortas. Our study established that miniature pigs that were fed a HFSD without adding dietary cholesterol developed insulin resistance, mild diabetes and atherosclerotic lesions. HFSD-fed miniature pigs may be good animal models for research on the treatment of diabetic dyslipidaemia complicated with atherosclerosis.

A comparative study of the structure of human and murine greater omentum

In humans, the greater omentum is a fatty peritoneal fold that extends from the greater curvature of the stomach to cover most abdominal organs. It performs many functions, which include acting as a reservoir of resident peritoneal inflammatory cells, a storage site for lipid, and a regulator of fluid exchange in and out of the peritoneal cavity. Most importantly, the omentum readily adheres to areas of inflammation and peritoneal damage, often leading to adhesion formation. Despite its clinical importance, the omentum remains an understudied organ, and discrepancies exist as to its exact morphology. This study uses a combination of phase contrast microscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) to elucidate the structure of the greater omentum of both human and mouse and determine whether it possesses a typical surface mesothelial cell lining similar to other serosa. Results indicated that both human and murine omenta were of similar structure and composed of two distinct types of tissue, one adipose-rich and the other translucent and membranous. The adipose-rich regions were well-vascularised and covered by a continuous mesothelial cell layer except at the sites of milky spots. In contrast, translucent areas were poorly vascularised and contained numerous fenestrations of varying size. The possible function and developmental origin of these gaps is unclear; however, their role in promoting omental adhesion formation and in the successful use of omental graft material is discussed.

Human adipose-derived adult stem cells produce osteoid in vivo

Adult subcutaneous fat tissue is an abundant source of multipotent cells. Previous studies from our laboratory have shown that, in vitro, adipose-derived adult stem (ADAS) cells express bone marker proteins including alkaline phosphatase, type I collagen, osteopontin, and osteocalcin and produce a mineralized matrix as shown by alizarin red staining. In the current study, the ADAS cell ability to form osteoid in vivo was determined. ADAS cells were isolated from liposuction waste of three individual donors and expanded in vitro before implantation. Equal numbers of cells (3 x 10(6)) were loaded onto either hydroxyapatite/tricalcium phosphate (HA-TCP) cubes or the collagen/HA-TCP composite matrix, Collagraft, and then implanted subcutaneously into SCID mice. After 6 weeks, implants were removed, fixed, and demineralized and sectioned for hematoxylin and eosin staining. Osteoid formation was observed in 80% of HA-TCP implants loaded with ADAS cells. Only 20% of Collagraft implants were positive for the presence of osteoid matrix. Whereas 100% of HA-TCP implants loaded with hFOB 1.19 cells formed osteoid, Collagraft loaded with hFOB 1.19 cells displayed a high degree of adipose tissue within the matrix. Immunostaining of serial sections for human nuclear antigen demonstrated that the osteoid contained human cells. Osteoid formation was not observed in control HA-TCP or Collagraft matrices implanted without cells. In summary, the data demonstrate the ability of ADAS cells to form osteoid matrix in vivo. Because of their abundance and accessibility, ADAS cells may prove to be a novel cell therapeutic for bone repair and regeneration.

Mechanisms of enhanced carbohydrate and lipid metabolism in adipose tissue in uremia

OBJECTIVE

Hyperlipidemia is a permanent finding in advanced renal failure. It is supposed to be responsible for the accelerated arteriosclerosis and cardiovascular complications observed in patients with that disease. The background is partially determined, however, our knowledge in this matter is not yet satisfactory.

METHODS

This study is based on the experimental rat model of chronic renal failure (CRF). Considering white adipose tissue (WAT) lipogenesis upregulation in CRF, along with the determination of acetyl coenzyme A carboxylase (ACC) and fatty acid synthase (FAS) genes expression, we have measured WAT gene expression for sterol regulatory binding protein 1 (SREBP-1) at the level of protein mass and mRNA abundance. Furthermore, we have determined glucose uptake, glucose-to-CO 2 conversion rate, and glucose translocator (GLUT-4) gene expression in WAT.

RESULTS

Upregulation of both FAS and ACC gene expression was found in WAT of CRF rats. It was accompanied by WAT SREBP-1 gene overexpression. Moreover, we have observed the increased glucose uptake, glucose to CO 2 conversion rate, and GLUT-4 gene expression in WAT of CRF rats in comparison with controls.

CONCLUSION

SREBP-1 gene overexpression may contribute to enhanced lipogenesis upregulation in WAT of CRF rats. It is not excluded that the increased WAT glucose metabolism activity is also induced by this mechanism, although there is no evidence currently to that end. We hypothesize that the increased WAT lipogenesis capacity could be a part of mechanism(s) leading to CRF-induced hyperlipidemia.

Histologic evaluation of the pulsed Nd:YAG laser for laser lipolysis

BACKGROUND AND OBJECTIVES

Laser lipoplasty with pulsed Nd:YAG laser, widely used in Europe and Latin America, has recently been introduced in Japan and the USA. We report histologic analyses of the effects of the laser on human fat tissue.

STUDY DESIGN/MATERIALS AND METHODS

Freshly excised human skin and subcutaneous fat were irradiated with the pulsed Nd:YAG laser (SmartLipo, DEKA, Italy). A 1,064 nm laser at 40 Hz and 150 mJ and 100 microseconds-long pulses were used. Methods of exposure were the same as in the clinical application. In the control group, the specimens were cannulated by the handpiece without irradiation. The tissue was studied by scanning electron microscopy and hematoxylin eosin staining.

RESULTS

Scanning electron microscopy after irradiation showed greater destruction of human adipocytes than in the control. Degenerated cell membrane, vaporization, liquefaction, carbonization, and heat-coagulated collagen fibers were observed.

CONCLUSIONS

Our study showed that the SmartLipo appeared to be histologically effective for destruction of human fat tissue.

Generation of mature fat pads in vitro and in vivo utilizing 3-D long-term culture of 3T3-L1 preadipocytes

Tissue-inherent factors such as cell-cell and cell-extracellular matrix interactions are regarded to exert a potentially large impact on adipogenesis as well as on secretory functions of adipose tissue. However, an appropriate 3-D adipogenesis model useful for addressing such interactions is still lacking. In this study, using tissue-engineering techniques, we demonstrate for the first time the development of coherent fat pads consisting of unilocular signet-ring cells in vitro. The constructs were generated by differentiating 3T3-L1 preadipocytes on 3-D polymeric scaffolds for either 9, 21, or 35 days in vitro. Only long-term culture yielded uniform tissues histologically comparable to native fat. Light and scanning electron microscopy provided direct evidence of 3-D tissue coherence and cell-cell contact in a tissue context, which was in strong contrast to conventional 2-D monolayer culture. Further differences between the two culture systems included enhanced secretion of leptin in 3-D tissue culture and differences in laminin expression (mRNA and protein level). Increase of triglyceride content over culture time and mRNA expression of other adipocyte genes, such as PPARgamma and Glut-4, were found to be similar. Implantation of long-term differentiated tissue constructs in nude mice resulted in further development and maintenance of fat pads. The presented model system is suggested to contribute to a better understanding of adipose tissue development and function facilitating studies on tissue-inherent interactions in vitro and in vivo.

Morphology of ferret subcutaneous adipose tissue after 6-month daily supplementation with oral beta-carotene

Adipose tissue is an important retinoid depot and retinoids are known to influence white and brown adipocyte metabolism. Identifying nutrients that can affect the biological activity of the adipose organ would be of great medical interest in the light of the current obesity epidemic and related disorders in developed countries. The vast majority of mammal studies of chronic administration of oral beta-carotene have used murine models, while few have employed mammals exhibiting uptake and processing of intestinal beta-carotene similar to those of humans. While rodents transform practically all ingested beta-carotene into retinol, in ferrets, as in humans, part of the beta-carotene is absorbed and released into the circulation intact. We studied the effects of 6-month daily administration of two doses of oral beta-carotene (0.8 or 3.2 mg/kg/day) on ferret body weight, size of body fat depots, and, using morphological and morphometric methods, on subcutaneous (inguinal) white adipose tissue (WAT). Because of the oral mode of administration, liver, stomach, and small and large intestine were also studied. Control animals received the vehicle. Data show that at the end of treatment the higher dose induced significantly higher body weight compared with controls and significantly higher inguinal fat depot compared with animals treated with the lower dose. In addition, chronic treatment with beta-carotene induced a dose-dependent hypertrophy of white adipocytes and increased neoangiogenesis in subcutaneous WAT in all treated ferrets. Vasculogenesis was independent of adipocyte hypertrophy. We also found focally evident liver steatosis in the ferrets treated with the higher dose of beta-carotene. The other gastrointestinal tract organs studied were not significantly different from those of control animals.

Effects of obesity on the relationship of leptin mRNA expression and adipocyte size in anatomically distinct fat depots in mice

In support of leptin's physiological role as humoral signal of fat mass, we have shown that adipocyte volume is a predominant determinant of leptin mRNA levels in anatomically distinct fat depots in lean young mice in the postabsorptive state. In this report, we investigated how obesity may affect the relationship between leptin mRNA levels and adipocyte volume in anatomically distinct fat depots in mice with genetic ( Lepob/ Lepoband Ay/+), diet-induced, and aging-related obesity. In all of the obese mice examined, tissue leptin mRNA levels relative to the average adipocyte volume were lower in the perigonadal and/or retroperitoneal than in the inguinal fat depots and were lower than those of the lean young mice in the perigonadal fat depot. A close, positive correlation between leptin mRNA level and adipocyte volume was present from small to hypertrophic adipocytes within each perigonadal and inguinal fat pad in the obese mice, but the slopes of the regression lines relating leptin mRNA level to adipocyte volume were significantly lower in the perigonadal than in the inguinal fat pads of the same mice. These results suggest that obesity per se is associated with a decreased leptin gene expression per unit of fat mass in mice and that the positive correlation between leptin mRNA level and adipocyte volume is an intrinsic property of adipocytes that is not disrupted by adipocyte hypertrophy in obese mice.

Overexpression of Lipoprotein Lipase in Transgenic Watanabe Heritable Hyperlipidemic Rabbits Improves Hyperlipidemia and Obesity

Lipoprotein lipase (LPL) is the rate-limiting enzyme for the hydrolysis of the triglyceride-rich lipoproteins and plays a critical role in lipoprotein and free fatty acid metabolism. Genetic manipulation of LPL may be beneficial in the treatment of hypertriglyceridemias, but it is unknown whether increased LPL activity may be effective in lowering plasma cholesterol and improving insulin resistance in familial hypercholesterolemic patients. To test the hypothesis that stimulation of LPL expression may be used as an adjunctive therapy for treatment of homozygous familial hypercholesterolemia, we have generated transgenic (Tg) Watanabe heritable hyperlipidemic (WHHL) rabbits that overexpress the human LPL transgene and compared their plasma lipid levels, glucose metabolism, and body fat accumulation with those of non-Tg WHHL rabbits. Overexpression of LPL dramatically ameliorated hypertriglyceridemia in Tg WHHL rabbits. Furthermore, increased LPL activity in male Tg WHHL rabbits also corrected hypercholesterolemia (544 +/- 52 in non-Tg versus 227 +/- 29 mg/dl in Tg, p < 0.01) and reduced body fat accumulation by 61% (323 +/- 27 in non-Tg versus 125 +/- 21ginTg, p < 0.01), suggesting that LPL plays an important role in mediating plasma cholesterol homeostasis and adipose accumulation. In addition, overexpression of LPL significantly suppressed high fat diet-induced obesity and insulin resistance in Tg WHHL rabbits. These results imply that systemic elevation of LPL expression may be potentially useful for the treatment of hyperlipidemias, obesity, and insulin resistance.

Seasonal variation in body mass and locomotor kinetics of the fat-tailed dwarf lemur (Cheirogaleus medius)

The fat-tailed dwarf lemur (Cheirogaleus medius) is unusual among primates in storing large amounts of fat subcutaneously prior to hibernating during the winter months. In doing so, it increases its body mass by more than 50%, with a substantial weight gain in the tail. This seasonal increase in mass provides a unique natural experiment to examine how changes in body mass affect substrate reaction forces during locomotion. As body mass increases, it is expected that the limbs of the fat-tailed dwarf lemur will be subjected to greater peak vertical substrate reaction forces during quadrupedal walking. However, whether or not these peak substrate reaction forces will increase proportionally across forelimbs and hindlimbs as body mass increases is unknown. Substrate reaction forces were collected on four adult C. medius walking quadrupedally on a 28-mm pole attached to a force platform. Peak vertical substrate reaction forces (Vpk) (N) were analyzed and compared for a cross-sectional sample of different body masses (180-300 g). Forelimb and hindlimb Vpk were positively correlated with body mass, with hindlimb Vpk always higher than forelimb Vpk. However, the rate at which Vpk increased relative to body mass was higher for the hindlimb than the forelimb. This disproportion in weight distribution between the forelimbs and hindlimbs as body mass increases appears to be linked to the accumulation of fat in the tail. It is likely that storing fat in the tail region may shift the center of mass more caudally, from a more cranial position when the tail is thinner. Such a caudal shift of the center of mass-either morphological or dynamic-is believed to have played an important role in the functional differentiation of the limbs and the evolution of locomotor modes of several tetrapod groups, including dinosaurs and primates.