Comparison of two methods to assess the tissue/blood partition coefficient for xenon in subcutaneous adipose tissue in man

Summary. A new method to calculate the tissue/blood partition coefficient (Λ) for xenon in studies on the subcutaneous adipose tissue blood flow was compared with a previously reported method based on local skinfold thickness (Λ_LSt). The former method included needle biopsies from the abdominal and femoral subcutaneous adipose tissue, and the mean fat cell diameter was measured (Λ_ECT)- The extracellular tissue fraction in subcutaneous tissue was then estimated from a diagram. The tissue lipid content was approximated to equal the relative intracellular volume and Ostwald's solubility coefficients for ¹³³Xe, based on the distribution of xenon in lipid, albumin and 0.9% saline were applied. Estimated Λ-values based on needle biopsies from the abdominal site were: 8.6±0.1 versus 9.9±0.4 ml g^-1 (meanæ) (P<0.05) and from the femoral site: 9.1±0.1 versus 9.6±0.2 in lean (n=10) and obese subjects (n=10), respectively. The corresponding Λ-values obtained from skinfold measurements were: 6.2±0.5 versus 11.0±0.4 (P<0.001) and 6.9±03 versus 11.4±0.4 (P<0.001) in lean and obese subjects, respectively. Pooled Λ_LsT-values correlated positively with estimated adipose tissue blood flow (ATBF) (r: 0.34, P<0.05, n=40) whereas no such correlation was found for Λ_ECT-values. In conclusion, a new method is presented which may allow an accurate determination of, and which may lead to reliable data on, subcutaneous ATBF in both lean and obese subjects. Comparative studies indicate that the widely used Λ-value of 10.0 in subcutaneous adipose tissue may be used as a rough estimate for subcutaneous blood flow studies in these patient groups.     

Comparison of infrapatellar and subcutaneous adipose tissue stromal vascular fraction and stromal/stem cells in osteoarthritic subjects

Since inflammatory mechanisms have been postulated to link obesity to osteoarthritis, the current study evaluated the ratio of immune cells to multipotent stromal cells within the infrapatellar fat pad (IPFP) and subcutaneous adipose tissue (SQ) of the knee; each depot has potential as a source of regenerative cells. The immunophenotypes of stromal vascular fraction (SVF) and adipose‐derived stem cells (ASCs) of the IPFP and SQ were determined in tissues from osteoarthritic subjects (n = 7) undergoing total knee replacement. Based on a subset of surface antigens, the immunophenotype of ASCs from SQ of OA subjects was not significantly different from that of relatively healthy and leaner subjects undergoing elective liposuction surgery. Flow‐cytometry comparison of SVF cell populations in the IPFP of OA subjects resembled those within the subject's own matched SQ, with the exception of the endothelial marker CD31⁺, which was significantly greater in cells from SQ. In the OA subjects, lower numbers of capillary‐like structures and higher numbers of stromal and alkaline phosphatase colony‐forming units in the IPFP vs SQ were consistent with this finding; however, ASCs from both depots in OA subjects exhibited comparable adipogenic and osteogenic differentiation potential. Thus, the IPFP contains an ASC and immune cell population similar to that of donor‐matched SQ, making it an alternative ASC source for tissue regeneration. Further studies will be needed to determine whether IPFP immune cell infiltrates play an aetiological role in osteoarthritis equivalent to that shown in diabetes associated with obesity. Copyright © 2012 John Wiley & Sons, Ltd.     

Autologous transplantation of photoactivated subcutaneous adipose tissue improves glucose homeostasis in high‐fat diet‐induced obese mice

Increasing evidence indicates that normal adipose tissue transplantation improves whole‐body energy metabolism and glucose homeostasis in a high‐fat diet (HFD)‐induced obese mouse model. Adipose tissue macrophages are associated with glucose homeostasis and insulin resistance in type 2 diabetes and obesity in humans, offering a potential target for therapeutics. However, whether transplantation of autologous adipose tissue that changes the macrophage phenotype directly contributes to systemic glucose intolerance has not been determined. We specifically developed our device, with more refined wavelengths of light to activate the macrophage phenotype in isolated subcutaneous white adipose tissue (sWAT) from host HFD mice. Autologous transplantation of photoactivated sWAT into HFD mice significantly reverses the M1 macrophage phenotype into M2, reduces the infiltration of macrophages in adipose tissues of HFD mice, and decreases the levels of proinflammatory cytokines. Strikingly, this transplantation reduced blood glucose levels and caused significant improvement in glucose tolerance, which was not shown in sham‐operated or nonphotoactivated sWAT‐transplanted HFD mice. Moreover, positron emission/computed tomography scans indicated higher glucose uptake in the heart but not in the liver, hindlimb muscles, or abdominal sWAT. These data suggested that the ability of photoactivation to shift Adipose tissue macrophage polarization in HFD mice caused a significant improvement in glucose homeostasis and that autologous transplantation might be a promising therapeutic option for the treatment of diabetes.     

Non-invasive cooling wear as an effective means of reducing subcutaneous adipose tissue mass: an in-vivo study

ObjectiveThe increasing prevalence of obesity is a major health problem worldwide. Several non-surgical treatments are now available that reduce body and subcutaneous fat mass. We aimed to determine the efficacy of mild cold for body mass reduction.MethodsNovel cooling wear, which induces mild cooling via evaporation, was worn by 29 women with overweight for 4 weeks. Specifically, the participants wore a cooling waist belt and chaps for 1 hour per day. Non-invasive lipometry was used to determine their subcutaneous adipose tissue thicknesses, and the total weight loss, abdominal circumference, and body mass index (BMI) of the participants were measured.ResultsThe participants achieved a significant total weight loss of 0.7 kg (0.9%), and significant reductions in BMI (0.2 kg/m²) and abdominal circumference (1.9 cm, 1.7%). Furthermore, there was a trend towards a reduction in abdominal subcutaneous fat thickness and a significant reduction in thickness of the anterior thigh was noted. A questionnaire-based evaluation indicated high usability and comfort of the cooling wear.ConclusionThere is a high and growing demand for non-invasive treatment strategies for obesity. Cooling wear represents a novel and promising approach that may be of particular use for individuals who do not require bariatric surgery.     

Practical approach for estimation of subcutaneous and visceral adipose tissue

OBJECTIVES: The first objective was to investigate the correlations between anthropometrical measurements and visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) in two cohorts differing in age using magnetic resonance imaging (MRI) as reference. A second objective was to investigate the potential usage of abdominal diameters in practical estimation of adipose tissue compartments using these cohorts. METHODS: Measurements of body mass index, waist circumference, sagittal abdominal diameter (sagittal AD) and transverse abdominal diameter (transverse AD) were obtained from 336 volunteers of age 14-70 years. Manual measurements of VAT and SAT from single slice MRI at the L4-L5 level were used as reference. The abdominal diameters were measured from the MR images. Linear correlations between the anthropometrical measurements and the reference were studied. RESULTS: Sagittal AD showed the strongest correlation to VAT (r >or= 0 x 780, P<0 x 0001) and transverse AD was found to give information about the amount of SAT (r >or= 0 x 866, P<0 x 0001). The ellipse spanned by the sagittal AD and the transverse AD was strongly correlated to the total amount of adipose tissue (r >or= 0 x 962, P<0 x 0001). CONCLUSION: Strong correlations were found between sagittal and transverse abdominal diameters, assessed using MRI, and VAT and SAT, respectively. These results suggest the use of abdominal diameters in practical estimations of VAT and SAT depots.     

Glucocorticoid hormone binding to human adipose tissue

Binding of triamcinolone was examined in cytosolic preparations of human adipose tissue obtained during surgery. A saturable specific binding was found. Non-specific binding comprised on an average 28% of total binding. The affinity and concentration of binding sites were in the same order as previously described for glucocorticoid hormone binding in other tissues and in rat adipose tissue. There was a large difference in these variables between different individuals. The binding was inhibited competitively by non-labelled triamcinolone, promegestone, dexamethasone and 17-beta-estradiol, in that order of potency. The promegestone inhibition was effective requiring only about 25% higher concentration than triamcinolone to obtain inhibition of half the triamcinolone binding. There was more binding of triamcinolone in omental than in subcutaneous abdominal adipose tissue when expressed per unit of protein and per unit cell surface area but not when expressed per adipocyte.     

The Glucose Uptake of Human Adipose Tissue in Obesity

Abstract. Radioactivity in adipose tissue triglycerides was followed after giving an intravenous injection of 25 g of glucose with 50 μCi of U-¹⁴C-glucose to 12 obese and 7 control patients. Seventy-five minutes after injection the radioactivity could be measured with sufficient precision. Recirculation of label was probably small during this period. Total adipose tissue glucose uptake could therefore be estimated knowing the variation of adipose tissue triglyceride radioactivity in different selected regions, and total body fat, and was found to be only a few per cent of all assimilated glucose in the body. Triglyceride radio-activity per gram of adipose tissue was similar in obese subjects and controls. Consequently total adipose tissue label was higher in the obese. Triglyceride radioactivity per fat cell correlated positively with fat cell size which in turn correlated positively with plasma insulin concentration. During the two first weeks after injection adipose tissue triglyceride radioactivity increased after which it began to fall in some patients.     

Promotion of skeletal muscle repair in a rat skeletal muscle injury model by local injection of human adipose tissue‐derived regenerative cells

Human adipose tissue‐derived regenerative cells (ADRCs) can be isolated easily and aseptically from unwanted subcutaneous fat without culturing. ADRCs have been used in clinical cosmetic therapy. In addition, they are expected to be an attractive and feasible source of cell‐based therapies in regenerative medicine. Therefore, this paper investigates whether transplantation of human adult ADRCs into skeletal muscle injury models promotes the repair of muscle tissues. This was done by locally injecting human ADRCs into an injured site after laceration of the nude‐rat tibialis anterior muscle. Phosphate‐buffered saline (PBS) and bone marrow mononuclear cells (MNCs) were injected as negative and positive controls, respectively. After injury, recovery of muscle strength was accelerated by transplantation of ADRCs compared to administration of PBS and MNCs. Moreover, transplantation of ADRCs also enhanced angiogenesis and myogenesis, but the number of vascular and muscular cells labeled with the human cell‐specific maker was limited at the injury site. Results showed that transplantation of ADRCs into a skeletal muscle injury model promoted repair of muscle tissues in a paracrine manner rather than differentiation of itself into blood vessels and myofibres. Thus, it is believed that ADRCs are a useful and feasible cell source not only for cosmetic therapy but also for regenerative therapy. Copyright © 2012 John Wiley & Sons, Ltd.     

In vivo tissue engineering of an adipose tissue flap using fat grafts and Adipogel

For decades, plastic surgeons have spent considerable effort exploring anatomical regions for free flap design. More recently, tissue‐engineering approaches have been utilised in an attempt to grow transplantable tissue flaps in vivo. The aim of this study was to engineer a fat flap with a vascular pedicle by combining autologous fat grafts and a novel acellular hydrogel (Adipogel) in an established tissue‐engineering model comprising a chamber and blood vessel loop. An arteriovenous loop was created in the rat groin from the femoral vessels and positioned inside a perforated polycarbonate chamber. In Group 1, the chamber contained minced, centrifuged autologous fat; in Group 2, Adipogel was added to the graft; and in Group 3, Adipogel alone was used. Constructs were histologically examined at 6 and 12 weeks. In all groups, new tissue was generated. Adipocytes, although appearing viable in the graft at the time of insertion, were predominantly nonviable at 6 weeks. However, by 12 weeks, new fat had formed in all groups and was significantly greater in the combined fat/Adipogel group. No significant difference was seen in final construct total volume or construct neovascularisation between the groups. This study demonstrated that a pedicled adipose flap can be generated in rats by combining a blood vessel loop, an adipogenic hydrogel, and a lipoaspirate equivalent. Success appears to be based on adipogenesis rather than on adipocyte survival, and consistent with our previous work, this adipogenesis occurred subsequent to graft death and remodelling. The regenerative process was significantly enhanced in the presence of Adipogel.     

胰岛素抵抗人群皮下脂肪组织中脂肪甘油三酯脂酶和激素敏感性脂肪酶表达减低

目的 通过检测胰岛素抵抗人群皮下脂肪组织中脂肪甘油三酯脂酶(ATGL)和激素敏感性脂肪酶(HSL)的表达,探讨脂肪动员异常与胰岛素抵抗的关系及在胰岛素抵抗中的作用.方法 选则本院择期行腹腔镜胆囊切除术的住院患者55例,根据胰岛素抵抗指数,将患者分为胰岛素敏感组27例和胰岛素抵抗组28例.在手术过程中取皮下脂肪组织.采用半定量逆转录聚合酶链反应测定脂肪组织中ATGL、HSLmRNA的表达,采用Westernblot法测定脂肪组织中ATGL、HSL蛋白的表达.结果 胰岛素抵抗组的体质量指数、腰臀比、血清甘油三酯、血清空腹胰岛素及游离脂肪酸水平均明显高于胰岛素敏感组,体质量指数25.31±1.54 vs 23.11±1.03,腰臀比0.98±0.24 vs 0.75±0.15,甘油三酯(1.98±0.56)mmol/L VS(1.04±0.24)mmol/L,空腹胰岛素(25.87±14.21)mU/LVS(11.15±4.67)mU/L.游离脂肪酸(1.35±0.46)mmol/L vs (0.66±0.23)mmol/ L(P<0.01).胰岛素抵抗组皮下脂肪组织中ATGL mRNA和蛋白表达均明显低于胰岛素敏感组,0.92±0.13 vs 2.03±0.21、1.03±0.08 vs 1.98±0.11(P<0.01);HSL mRNA和蛋白表达也均明显低于胰岛素敏感组,1.35±0.21 vs 1.64±0.12、1.25±0.09 VS 1.42±0.15(P<0.01).ATGL的蛋白表达与空腹胰岛素、胰岛素抵抗指数及游离脂肪酸呈负相关(r=-0.235、-0.356和-0.214,P<0.01或<0.05);HSL 的蛋白表达与空腹胰岛素、游离脂肪酸和腰臀比呈负相关(r=-0.185、-0.246和-0.145,P<0.01或<0.05).结论 胰岛素抵抗状态时皮下脂肪组织中ATGL和HsL的表达减低.     

A novel method for the isolation of subpopulations of rat adipose stem cells with different proliferation and osteogenic differentiation potentials

Bone marrow has been the elected cell source of studies published so far concerning bone and cartilage tissue-engineering approaches. Recent studies indicate that adipose tissue presents significant advantages over bone marrow as a cell source for tissue engineering. Most of these studies report the use of adipose stem cells (ASCs) isolated by a method based on the enzymatic digestion of the adipose tissue and on the ability of stem cells to adhere to a cell culture plastic surface. Using this method, a heterogeneous population was obtained containing different cell types that have been shown to compromise the proliferation and differentiation potential of the stem cells. This paper reports the development and optimization of a new isolation method that enables purified cell populations to be obtained that exhibit higher osteogenic differentiation and/or proliferation potential. This method is based on the use of immunomagnetic beads coated with specific antibodies and it is compared with other methods described in the literature for the selection of stem cell populations, e.g. methods based on a gradient solution and enzymatic digestion. The results showed that the isolation method based on immunomagnetic beads allows distinct subpopulations of rat ASCs to be isolated, showing different stem cells marker expressions and different osteogenic differentiation potentials. Therefore, this method can be used to study niches in ASC populations and/or also allow adipose tissue to be used as a stem cell source in a more efficient manner, increasing the potential of this cell source in future clinical applications.     

运动对高脂饲养大鼠白色脂肪组织血管内皮生成相关因子的影响

目的:观察8周中等强度有氧运动干预以及高脂饮食对雄性大鼠血管内皮生成相关因子的影响.方法:40只3周龄SPF级雄性SD大鼠适应性喂养3天后,随机分为标准安静组(CS)、标准运动组(CE)、高脂安静组(HS)、高脂运动组(HE).标准组大鼠喂饲普通饲料(D12450B),高脂组大鼠喂饲高脂饲料(D12451),所有大鼠均...     

Vascularization of prevascularized and non-prevascularized fibrin-based human adipose tissue constructs after implantation in nude mice

Adipose regeneration strategies have been hampered by the inability to supply an adequate vascular supply following implantation. Vascularization in vitro, also called prevascularization, is a promising method that could promote the vascularization of engineered adipose tissue constructs upon implantation. In this study we compared the ability of prevascularized-to-non-prevascularized fibrin-based human adipose tissue to promote vascularization. Human adipose tissue-derived stromal cells (ASCs) and different mixtures (1:1, 1:2 and 1:5) of ASCs with human umbilical vein endothelial cells (HUVECs) were cultured in fibrin at two different densities (1.0 × 10(6) and 10 × 10(6) cells/ml) for 7 days. Histological analysis revealed that prevascular structures formed in 1:5 ASC/HUVEC fibrin-based constructs seeded with a total of 10 × 10(6) cells/ml. These constructs and ASC-only constructs were implanted subcutaneously in athymic mice for 7 days and generated lipid-containing grafts. The numbers and densities of blood vessels within the ASC/HUVEC constructs were similar to those of ASC-only constructs. Furthermore, immunostaining studies demonstrated human-derived vasculature within a few of the ASC/HUVEC and ASC-only constructs. A subset of this human-derived vasculature contained erythrocytes, indicating integration with the host vasculature. In conclusion, our study indicated no difference in the rate of vascularization of prevascularized ASC/HUVEC and non-prevascularized ASC-only fibrin-based constructs, suggesting that prevascularization of these fibrin-based constructs does not promote vascularization. Our results further indicated that not only endothelial cells, but also ASCs may contribute to the formation of vascular lumina upon implantation. This finding is interesting, since it demonstrates the possibility of vascularized adipose tissue engineering from a single cell source.     

Effects of different sera on adipose tissue-derived mesenchymal stromal cells

Current cell therapy protocols require considerable numbers of mesenchymal stromal cells (MSCs), which can be obtained only by in vitro expansion. The most important issue is a choice of optimal growth supplements for cell culture. Ideally, these should be of known composition, free of animal components and allow production of large homogenic populations of MSCs in a considerably short period of time. Since this standard has not been achieved to date, we aimed to assess the molecular responses of MSCs to different growth supplements commonly in use. MSCs were isolated from breast or abdominal adipose tissue and plated into DMEM supplemented with one of four different sera: fetal calf serum (FCS), pretested fetal calf serum (FCS-Sp), human allogeneic serum (HS) or artificial serum substitute (AS). MSCs cultivated with different serum supplements demonstrated distinct morphologies, high adipogenic and osteogenic differentiation potential and expressed characteristic antigens. Using real-time PCR, we found a large increase in PPARγ and Msx2 gene expression in both lines of proliferating MSCs cultivated with AS. We found that MSCs cultivated in the presence of different sera had similar global proteomic expression patterns, but comparisons of identified proteins revealed most differences in the MSCs cultivated with AS. Our results indicate that MSCs cultivated in the presence of FCS and HS display similar growth, differentiation, immunophenotypic and proteomic properties, while AS induces more profound changes in the physiology of MSCs, suggesting that further fundamental studies should be done before its introduction into clinical practice.     

Lipid mobilization from human abdominal, subcutaneous adipose tissue is independent of sex during steady-state exercise

The aim of the study was to elucidate whether there are sex differences of significant biological importance in the human abdominal, subcutaneous adipose tissue lipid metabolism when studied by Fick's Principle during rest and exercise in steady-state conditions. The net mobilization of fatty acids and glycerol from the abdominal, subcutaneous adipose tissue was measured by arterio-venous catheterizations and simultaneous measurements of adipose tissue blood flow with the local Xe-clearance technique in 16 healthy, young normal weight men and women during rest, during 1 h of exercise at moderate intensity, and for another 60 min during post-exercise recovery. The results show that there are not significant sex differences with respect to the steady-state fatty acid and glycerol mobilizations neither during resting condition nor during exercise.     

Effects of weight reduction on squalene, methyl sterols and cholesterol and on their synthesis in human adipose tissue

Abstract. Quantitation of cholesterol and its precursors from human adipose tissue biopsies revealed very high squalene and moderately high methyl sterol concentrations. The squalene and cholesterol values were correlated with each other. Weight reduction in obese subjects following a jejuno-ileal bypass resulted in a significant but transient increase in adipose tissue cholesterol. The squalene concentration was also increased post-operatively, the maximum being reached about 6 months later than that of cholesterol as if the mobilization of squalene from shrunken adipocytes had been slow. Weight reduction with a 2–14 day total fast significantly reduced the adipocyte size but had no consistent effect on adipose tissue squalene, methyl sterol and cholesterol concentrations or on their adipocyte contents. Incubation of adipose tissue with labelled acetate and mevalonate revealed that the bulk of the labels in non-saponifiable lipids stayed in the large intermediate pools of methyl sterols and squalene in particular, fairly little being found in the cholesterol fraction itself. The total fast inhibited the incorporation of both ¹⁴C-acetate and ³H-mevalonate to squalene, methyl sterols and cholesterol, suggesting that cholesterol synthesis was inhibited before and after the mevalonate step.     

Adipokine dysregulation and adipose tissue inflammation in human obesity

Obesity, a worldwide epidemic, confers increased risk for multiple serious conditions, including type 2 diabetes, cardiovascular diseases, nonalcoholic fatty liver disease and cancer. Adipose tissue is considered one of the largest endocrine organs in the body as well as an active tissue for cellular reactions and metabolic homeostasis rather than an inert tissue for energy storage. The functional pleiotropism of adipose tissue relies on its ability to synthesize and release a large number of hormones, cytokines, extracellular matrix proteins and growth and vasoactive factors, collectively termed adipokines that influence a variety of physiological and pathophysiological processes. In the obese state, excessive visceral fat accumulation causes adipose tissue dysfunctionality that strongly contributes to the onset of obesity‐related comorbidities. The mechanisms underlying adipose tissue dysfunction include adipocyte hypertrophy and hyperplasia, increased inflammation, impaired extracellular matrix remodelling and fibrosis together with an altered secretion of adipokines. This review describes how adipose tissue becomes inflamed in obesity and summarizes key players and molecular mechanisms involved in adipose inflammation.     

Transferring the exudate in the tissue engineering chamber as a trigger to incubate large amount adipose tissue in remote area

Tissue engineering chamber (TEC) is a technique that could incubate up to 16 folds volume increase of a fat flap. But the mechanism in the silicone chamber was still unknown. The function of exudate in the chamber was noticed recently. We developed a special model called fluid drainage model (FDM) that consisted of a traditional TEC on the back and paired fat flaps without a chamber in the groins. Then we used a silicon tube to dynamically transfer the exudate from dorsal TEC to one of the paired inguinal fat flap and the other inguinal fat flap with a sham tube was set as control. At Week 4, the volume of drainage group reached 8.7 ± 2.3 ml, 576 ± 152% to its original volume whereas the growth ratio of control group was only 130 ± 39%. Similar volume change and histological change were observed within fat flap from TEC model and drainage group. The exudate in the TEC is a heterogeneous cocktail contains cytokines as well as cells. Intriguingly, transferred exudate in the TEC model sustain the ability to incubate large amount of adipose tissue remotely.