1-Butyryl-glycerol: a novel angiogenesis factor secreted by differentiating adipocytes

Dietary monoglyceride supplementation to support intestinal integrity and host defenses in health-challenged weanling pigs

Frequent incidence of postweaning enterotoxigenic Escherichia coli (ETEC) diarrhea in the swine industry contributes to high mortality rates and associated economic losses. In this study, a combination of butyric, caprylic, and capric fatty acid monoglycerides was investigated to promote intestinal integrity and host defenses in weanling pigs infected with ETEC. A total of 160 pigs were allotted to treatment groups based on weight and sex. Throughout the 17-d study, three treatment groups were maintained: sham-inoculated pigs fed a control diet (uninfected control [UC], n = 40), ETEC-inoculated pigs fed the same control diet (infected control [IC], n = 60), and ETEC-inoculated pigs fed the control diet supplemented with monoglycerides included at 0.3% of the diet (infected supplemented [MG], n = 60). After a 7-d acclimation period, pigs were orally inoculated on each of three consecutive days with either 3 mL of a sham-control (saline) or live ETEC culture (3 × 109 colony-forming units/mL). The first day of inoculations was designated as 0 d postinoculation (DPI), and all study outcomes reference this time point. Fecal, tissue, and blood samples were collected from 48 individual pigs (UC, n = 12; IC, n = 18; MG, n = 18) on 5 and 10 DPI for analysis of dry matter (DM), bacterial enumeration, inflammatory markers, and intestinal permeability. ETEC-inoculated pigs in both the IC and MG groups exhibited clear signs of infection including lower (P < 0.05) gain:feed and fecal DM, indicative of excess water in the feces, and elevated (P < 0.05) rectal temperatures, total bacteria, total E. coli, and total F18 ETEC during the peak-infection period (5 DPI). Reduced (P < 0.05) expression of the occludin, tumor necrosis factor α, and vascular endothelial growth factor A genes was observed in both ETEC-inoculated groups at the 5 DPI time point. There were no meaningful differences between treatments for any of the outcomes measured at 10 DPI. Overall, all significant changes were the result of the ETEC infection, not monoglyceride supplementation.

Oxygen and metabolic reprogramming in the tumor microenvironment influences metastasis homing

Tumor metastasis is the leading cause of cancer mortality, often characterized by abnormal cell growth and invasion to distant organs. The cancer invasion due to epithelial to mesenchymal transition is affected by metabolic and oxygen availability in the tumor-associated micro-environment. A precise alteration in oxygen and metabolic signaling between healthy and metastatic cells is a substantial probe for understanding tumor progression and metastasis. Molecular heterogeneity in the tumor microenvironment help to sustain the metastatic cell growth during their survival shift from low to high metabolic-oxygen-rich sites and reinforces the metastatic events. This review highlighted the crucial role of oxygen and metabolites in metastatic progression and exemplified the role of metabolic rewiring and oxygen availability in cancer cell adaptation. Furthermore, we have also addressed potential applications of altered oxygen and metabolic networking with tumor type that could be a signature pattern to assess tumor growth and chemotherapeutics efficacy in managing cancer metastasis.

Buffered formic acid and a monoglyceride blend coordinately alleviate subclinical necrotic enteritis impact in broiler chickens

The objective of this study was to evaluate the effect of 2 different doses of a partially buffered formic acid product (Amasil NA; 61% formic acid, 20.5% sodium formate), and a monoglyceride blend of short- and medium-chain fatty acids (BalanGut LS P) on necrotic enteritis (NE) infected broilers in terms of performance, intestinal microbial population and short-chain fatty acids concentrations in the gastrointestinal tract. A total of 528-day-old as hatched Ross 308 broilers were allocated to 48 pens with 11 birds in each pen. Six dietary treatments applied in the study were: T1) nonsupplemented diet (Control); T2) antibiotic supplemented diets; T3) and T4) high (Starter: 0.5%; Grower and Finisher: 0.5%) and low (Starter: 0.3%; Grower and Finisher: 0.2%) dose of Amasil NA; and groups T5) and T6) high (Starter: 0.3%; Grower and Finisher: 0.2%) and low dose (Starter: 0.3%; Grower: 0.15%; Finisher: 0.075%) of (BalanGut LS P). All birds in this study were fed starter (d 0-10), grower (d 11-24) and finisher (d 25-35) diets and challenged with NE. To induce subclinical NE, oral administrations of Eimeria oocysts (d 9) followed by inoculation of Clostridium perfringens strains (d 14 and 15) were applied. Results showed that birds fed the high dose of Amasil NA, had a higher feed conversion ratio (FCR,P < 0.05) compared to the nonsupplemented group during the starter period. Antibiotic supplementation reduced FCR during the grower (P < 0.001), finisher (P < 0.05) and overall (P < 0.001) periods of the experiment. Both levels of BalanGut LS P and low levels of Amasil NA enhanced overall FCR (P < 0.05) compared to the birds in the nonsupplemented group. Compared to the nonsupplemented group, high levels of Amasil NA and low levels of BalanGut LS P improved FCR in the finisher stage (P < 0.05). On d 16, cecum digesta of birds fed with antibiotic supplemented diets showed a significantly lower number of C. perfringens (P < 0.001) compared to the nonsupplemented and high level of BalanGut LS P group. Bacillus (P < 0.01) and Ruminococcus numbers were significantly lower in the birds fed with high level of Amasil NA (P < 0.05) compared to the antibiotic supplemented diets. High doses of Amasil NA, showed the highest propionate concentration in the cecum (P < 0.001). The study suggests that supplementation of BalanGut LS P and Amasil NA at different feeding phases may achieve optimal performance improvement in broilers under NE challenge.

Adipose tissue development and lipid metabolism in the human fetus: The 2020 perspective focusing on maternal diabetes and obesity

During development, the human fetus accrues the highest proportion of fat of all mammals. Precursors of fat lobules can be found at week 14 of pregnancy. Thereafter, they expand, filling with triacylglycerols during pregnancy. The resultant mature lipid-filled adipocytes emerge from a developmental programme of embryonic stem cells, which is regulated differently than adult adipogenesis. Fetal triacylglycerol synthesis uses glycerol and fatty acids derived predominantly from glycolysis and lipogenesis in liver and adipocytes. The fatty acid composition of fetal adipose tissue at the end of pregnancy shows a preponderance of palmitic acid, and differs from the mother. Maternal diabetes mellitus does not influence this fatty acid profile. Glucose oxidation is the main source of energy for the fetus, but mitochondrial fatty acid oxidation also contributes. Indirect evidence suggests the presence of lipoprotein lipase in fetal adipose tissue. Its activity may be increased under hyperinsulinemic conditions as in maternal diabetes mellitus and obesity, thereby contributing to increased triacylglycerol deposition found in the newborns of such pregnancies. Fetal lipolysis is low. Changes in the expression of genes controlling metabolism in fetal adipose tissue appear to contribute actively to the increased neonatal fat mass found in diabetes and obesity. Many of these processes are under endocrine regulation, principally by insulin, and show sex-differences. Novel fatty acid derived signals such as oxylipins are present in cord blood with as yet undiscovered function. Despite many decades of research on fetal lipid deposition and metabolism, many key questions await answers.

Adipose Tissue Lipokines: Recent Progress and Future Directions

Beyond classical metabolic functions in energy storage and energy expenditure, adipose tissue is also a dynamic endocrine organ that secretes bioactive factors into blood plasma. Historically, studies of the adipose secretome have predominantly focused on polypeptide adipokines. Recently, adipose-derived blood-borne lipids ("lipokines") have emerged as a distinct class of endocrine factors. Lipokines are intimately connected to intracellular pathways of fatty acid metabolism and therefore uniquely poised to communicate the intracellular energy status of adipocytes to other nonadipose tissues including liver, muscle, and pancreas. Here, we discuss recent progress on our understanding of adipose-secreted lipokines as endocrine regulators of glucose and lipid metabolism. We also provide our perspective on future directions for adipose-secreted lipids, including limitations of the currently available experimental data as well as potential strategies for addressing the remaining open questions.

Regulation of Obesity by Antiangiogenic Herbal Medicines

Obesity is the result of an energy imbalance caused by an increased ratio of caloric intake to energy expenditure. In conjunction with obesity, related metabolic disorders, such as dyslipidemia, atherosclerosis, and type 2 diabetes, have become global health problems. Obesity progression is thought to be associated with angiogenesis and extracellular matrix (ECM) remodeling. Angiogenesis occurs in growing adult adipose tissues, which are similar to neoplastic tissues. Adipose tissue is highly vascularized, and each adipocyte is nourished by an extensive capillary network. Adipocytes produce proangiogenic factors, such as vascular endothelial growth factor A and fibroblast growth factor 2, which promote neovascularization within the adipose tissue. Furthermore, matrix metalloproteinases (MMPs), including MMP-2 and MMP-9, play important roles in adipose tissue development and microvessel maturation by modifying the ECM. Thus, modulation of angiogenesis and MMP activity provides a promising therapeutic approach for controlling human obesity and its related disorders. Over the past decade, there has been a great increase in the use of alternative treatments, such as herbal remedies, for these diseases. This review will focus on the role of angiogenesis in adipose tissue growth and the regulation of obesity by antiangiogenic herbal medicines.

Weighing the Risk: effects of Obesity on the Mammary Gland and Breast Cancer Risk

Obesity is a preventable risk factor for breast cancer following menopause. Regardless of menopausal status, obese women who develop breast cancer have a worsened prognosis. Breast tissue is comprised of mammary epithelial cells organized into ducts and lobules and surrounded by adipose-rich connective tissue. Studies utilizing multiple in vivo models of obesity as well as human breast tissue have contributed to our understanding of how obesity alters mammary tissue. Localized changes in mammary epithelial cell populations, elevated secretion of adipokines and angiogenic mediators, inflammation within mammary adipose tissue, and remodeling of the extracellular matrix may result in an environment conducive to breast cancer growth. Despite these significant alterations caused by obesity within breast tissue, studies have suggested that some, but not all, obesity-induced changes may be mitigated with weight loss. Here, we review our current understanding regarding the impact of obesity on the breast microenvironment, how obesity-induced changes may contribute to breast tumor progression, and the impact of weight loss on the breast microenvironment.

Adipogenesis and metabolic health

Obesity is characterized by increased adipose tissue mass and has been associated with a strong predisposition towards metabolic diseases and cancer. Thus, it constitutes a public health issue of major proportion. The expansion of adipose depots can be driven either by the increase in adipocyte size (hypertrophy) or by the formation of new adipocytes from precursor differentiation in the process of adipogenesis (hyperplasia). Notably, adipocyte expansion through adipogenesis can offset the negative metabolic effects of obesity, and the mechanisms and regulators of this adaptive process are now emerging. Over the past several years, we have learned a considerable amount about how adipocyte fate is determined and how adipogenesis is regulated by signalling and systemic factors. We have also gained appreciation that the adipogenic niche can influence tissue adipogenic capability. Approaches aimed at increasing adipogenesis over adipocyte hypertrophy can now be explored as a means to treat metabolic diseases.

Tissue Engineering of the Microvasculature

The ability to generate new microvessels in desired numbers and at desired locations has been a long-sought goal in vascular medicine, engineering, and biology. Historically, the need to revascularize ischemic tissues nonsurgically (so-called therapeutic vascularization) served as the main driving force for the development of new methods of vascular growth. More recently, vascularization of engineered tissues and the generation of vascularized microphysiological systems have provided additional targets for these methods, and have required adaptation of therapeutic vascularization to biomaterial scaffolds and to microscale devices. Three complementary strategies have been investigated to engineer microvasculature: angiogenesis (the sprouting of existing vessels), vasculogenesis (the coalescence of adult or progenitor cells into vessels), and microfluidics (the vascularization of scaffolds that possess the open geometry of microvascular networks). Over the past several decades, vascularization techniques have grown tremendously in sophistication, from the crude implantation of arteries into myocardial tunnels by Vineberg in the 1940s, to the current use of micropatterning techniques to control the exact shape and placement of vessels within a scaffold. This review provides a broad historical view of methods to engineer the microvasculature, and offers a common framework for organizing and analyzing the numerous studies in this area of tissue engineering and regenerative medicine. © 2019 American Physiological Society. Compr Physiol 9:1155-1212, 2019.

Implications of butyrate and its derivatives for gut health and animal production

Butyrate is produced by microbial fermentation in the large intestine of humans and animals. It serves as not only a primary nutrient that provides energy to colonocytes, but also a cellular mediator regulating multiple functions of gut cells and beyond, including gene expression, cell differentiation, gut tissue development, immune modulation, oxidative stress reduction, and diarrhea control. Although there are a large number of studies in human medicine using butyrate to treat intestinal disease, the importance of butyrate in maintaining gut health has also attracted significant research attention to its application for animal production, particularly as an alternative to in-feed antibiotics. Due to the difficulties of using butyrate in practice (i.e., offensive odor and absorption in the upper gut), different forms of butyrate, such as sodium butyrate and butyrate glycerides, have been developed and examined for their effects on gut health and growth performance across different species. Butyrate and its derivatives generally demonstrate positive effects on animal production, including enhancement of gut development, control of enteric pathogens, reduction of inflammation, improvement of growth performance (including carcass composition), and modulation of gut microbiota. These benefits are more evident in young animals, and variations in the results have been reported. The present article has critically reviewed recent findings in animal research on butyrate and its derivatives in regard to their effects and mechanisms behind and discussed the implications of these findings for improving animal gut health and production. In addition, significant findings of medical research in humans that are relevant to animal production have been cited.

Inflammasomes, the eye and anti-inflammasome therapy

Inflammasomes, key molecular regulators that play an important role in inflammation, consist of a central protein, an adaptor protein ASC (apoptosis speck-like protein) and a caspase-1 protein. Upon activation, caspase-1 induces maturation of cytokines such as interleukin-1β (IL-1β) and interleukin-18 (IL-18). The release of these cytokines can result in inflammation. Inflammasomes are activated by a variety of factors and their activation involves complex signalling leading to resolution of infection, but can also contribute to the pathology of inflammatory, autoimmune, and infectious diseases. The role of NLRP1, NLRP3, NLRC4 and AIM2 inflammasomes in the pathogenesis of ocular diseases such as glaucoma, age related macular degeneration (AMD), diabetic retinopathy, dry eye and infections of the eye has been established over the past decade. In experimental studies and models, inhibition of inflammasomes generally helps to reduce the inflammation associated with these eye diseases, but as yet the role of these inflammasomes in many human eye diseases is unknown. Therefore, a need exists to study and understand various aspects of inflammasomes and their contribution to the pathology of human eye diseases. The goal of this review is to discuss the role of inflammasomes in the pathology of eye diseases, scope for anti-inflammasome therapy, and current research gaps in inflammasome-related eye disease.

The fat and the bad: Mature adipocytes, key actors in tumor progression and resistance

Growing evidence has raised the important roles of adipocytes as an active player in the tumor microenvironment. In many tumors adipocytes are in close contact with cancer cells. They secrete various factors that can mediate local and systemic effects. The adipocyte-cancer cell crosstalk leads to phenotypical and functional changes of both cell types, which can further enhance tumor progression. Moreover, obesity, which is associated with an increase in adipose mass and an alteration of adipose tissue, has been established as a risk factor for cancer incidence and cancer-related mortality. In this review, we summarize the mechanisms of the adipocyte-cancer cell crosstalk in both obese and lean conditions as well as its impact on cancer cell growth, local invasion, metastatic spread and resistance to treatments. Better characterization of cancer-associated adipocytes and the key molecular events in the adipocyte-cancer cell crosstalk will provide insights into tumor biology and suggest efficient therapeutic opportunities.

Adipose crosstalk with other cell types in health and disease

In addition to storing and mobilizing energy, adipocytes secrete circulating factors to signal to other tissues and coordinate energy metabolism. These functions can become disrupted in the setting of obesity, contributing to the development of diabetes, cardiovascular disease, and cancer. Since the discovery of leptin and adiponectin, an increasing number of adipokines have been identified and their functions elucidated. More recent studies have highlighted other modes by which adipose tissue can participate in crosstalk with other cell types and tissues. These modes of communication, which are reviewed here, include the secretion of enzymes, lipid species, and exosomes. Advances in profiling technology suggest that a substantial number of adipose-derived factors remain to be characterized. Further advances in this growing field are likely to provide important basic insights into the molecular control of metabolism.

Adipose-derived stem cell differentiation as a basic tool for vascularized adipose tissue engineering

The development of in vitro adipose tissue constructs is highly desired to cope with the increased demand for substitutes to replace damaged soft tissue after high graded burns, deformities or tumor removal. To achieve clinically relevant dimensions, vascularization of soft tissue constructs becomes inevitable but still poses a challenge. Adipose-derived stem cells (ASCs) represent a promising cell source for the setup of vascularized fatty tissue constructs as they can be differentiated into adipocytes and endothelial cells in vitro and are thereby available in sufficiently high cell numbers. This review summarizes the currently known characteristics of ASCs and achievements in adipogenic and endothelial differentiation in vitro. Further, the interdependency of adipogenesis and angiogenesis based on the crosstalk of endothelial cells, stem cells and adipocytes is addressed at the molecular level. Finally, achievements and limitations of current co-culture conditions for the construction of vascularized adipose tissue are evaluated.

Plasticity of human dedifferentiated adipocytes toward endothelial cells

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

What we talk about when we talk about fat

There has been an upsurge of interest in the adipocyte coincident with the onset of the obesity epidemic and the realization that adipose tissue plays a major role in the regulation of metabolic function. The past few years, in particular, have seen significant changes in the way that we classify adipocytes and how we view adipose development and differentiation. We have new perspective on the roles played by adipocytes in a variety of homeostatic processes and on the mechanisms used by adipocytes to communicate with other tissues. Finally, there has been significant progress in understanding how these relationships are altered during metabolic disease and how they might be manipulated to restore metabolic health.

Inhibition of the methionine aminopeptidase 2 enzyme for the treatment of obesity

Worldwide prevalence of obesity has nearly doubled since 1980. Obesity is the result of interactions among the environmental factors, genetic predisposition, and human behavior. Even modest weight reduction in obese patients provides beneficial health outcomes. For effective weight reduction, a drug should either increase energy expenditure or decrease energy intake without causing serious adverse effects. To overcome lack of efficacy and central nervous system related side effects, exploitation of the peripheral mechanism of anti-obesity action is needed. Inhibition of pathological angiogenesis in adipose tissue is one such peripheral mechanism that has attracted the attention of researchers in this area. Although originally developed as anti-cancer agents, methionine aminopeptidase (MetAP2) inhibitors induce significant and sustained weight reduction. Here, we review preclinical and clinical pharmacology of MetAP2 inhibitors. Beloranib is a prototype MetAP2 inhibitor, and currently in advanced clinical trials for the treatment of obesity. Clinical data of beloranib indicate that MetAP2 inhibitors could be a future treatment option for weight reduction without serious adverse effects. Further clinical data from Phase III trials will add to our growing knowledge of MetAP2 inhibitor potential for anti-obesity therapy.

Proliferating bovine intramuscular preadipocyte cells synthesize leptin

Leptin is thought to be not only a satiety factor but also a stimulator of angiogenesis. We examined leptin, PPARγ2, and vascular endothelial growth factor (VEGF) expression in bovine intramuscular preadipocyte (BIP) cells during proliferation. The cells were seeded at 0.85 × 10(4) cells/cm(2) and collected every day until the fifth day after passage. Leptin mRNA was present in the cells between days 2 and 4, as indicated by RT-PCR analysis. Western blot analysis showed a band for leptin at approximately 16 kDa on all of the days during growth, and the cytoplasmic concentration of leptin was highest on day 2 and decreased gradually thereafter. A PPARγ2 band at approximately 54 kDa was also observed on all days. The concentration was highest on day 2 and decreased thereafter, which is similar to the expression pattern of leptin. In constant, the expression level of VEGF protein did not change while in culture. We have demonstrated that BIP cells can synthesize both leptin and PPARγ2, with maximal synthesis occurring during maximal proliferation. Given the role of leptin in angiogenesis, we speculate that leptin is involved in the neovascularization of adipose tissue, because new organization of adipose tissue requires the growth of new blood vessels.

Adipose tissue engineering with cells in engineered matrices

Tissue engineering has shown promise for the development of constructs to facilitate large volume soft tissue augmentation in reconstructive and cosmetic plastic surgery. This article reviews the key progress to date in the field of adipose tissue engineering. In order to effectively design a soft tissue substitute, it is critical to understand the native tissue environment and function. As such, the basic physiology of adipose tissue is described and the process of adipogenesis is discussed. In this article, we have focused on tissue engineering using a cell-seeded scaffold approach, where engineered extracellular matrix substitutes are seeded with exogenous cells that may contribute to the regenerative response. The strengths and limitations of each of the possible cell sources for adipose tissue engineering, including adipose-derived stem cells, are detailed. We briefly highlight some of the results from the major studies to date, involving a range of synthetic and naturally derived scaffolds. While these studies have shown that adipose tissue regeneration is possible, more research is required to develop optimized constructs that will facilitate safe, predictable and long-term augmentation in clinical applications.

Augmentation of tendon healing with butyric acid-impregnated sutures: biomechanical evaluation in a rabbit model

BACKGROUND

Butyric acid (BA) has been shown to be angiogenic and to enhance transcriptional activity in tissue. These properties of BA have the potential to augment biological healing of a repaired tendon.

PURPOSE

To evaluate this possibility both biomechanically and histologically in an animal tendon repair model.

STUDY DESIGN

Controlled laboratory study.

METHODS

A rabbit Achilles tendon healing model was used to evaluate the biomechanical strength and histological properties at 6 and 12 weeks after repair. Unilateral tendon defects were created in the middle bundle of the Achilles tendon of each rabbit, which were repaired equivalently with either Ultrabraid BA-impregnated sutures or control Ultrabraid sutures.

RESULTS

After 6 weeks, BA-impregnated suture repairs had a significantly increased (P < .0001) Young's modulus and ultimate tensile strength relative to the control suture repairs. At 12 weeks, no statistical difference was observed between these measures. The histological data at 6 weeks demonstrated significantly increased (P < .005) vessel density within 0.25 mm of the repair suture in the BA-impregnated group. There was also an associated 42% increase in the local number of myofibroblasts in the BA samples relative to the controls at this time. By 12 weeks, these differences were not observed.

CONCLUSION

Tendons repaired with BA-impregnated sutures demonstrated improved biomechanical properties at 6 weeks relative to control sutures, suggesting a neoangiogenic mechanism of enhanced healing through an increased myofibroblast presence.

CLINICAL RELEVANCE

These findings demonstrate that a relatively simple alteration of suture material may augment early tendon healing to create a stronger repair construct during this time.

A randomized phase II trial of Arginine Butyrate with standard local therapy in refractory sickle cell leg ulcers

Sickle cell leg ulcers are often debilitating, refractory to healing, and prone to recurrence. Healing of leg ulcers was incidentally observed during dose-ranging trials of Arginine Butyrate in beta haemoglobinopathies. Here, a controlled Phase II trial was performed in sickle cell patients who had lower extremity ulcers refractory to standard care for at least 6 months. Patients were randomized to receive standard local care alone (Control Arm) or standard care with Arginine Butyrate administered 5 d/week (Treatment Arm), for 12 weeks. Ulcers were photographed weekly, traced, and ulcer areas were calculated by computerized planimetry and compared between the two study arms. Twenty-seven study courses were evaluated. Control Arm subjects had 25 ulcers with a mean area of 25·7 cm(2) initially and 23·2 cm(2) after 12 weeks; 2/25 (8%) healed completely. Treatment Arm subjects had 37 ulcers with a mean area of 50·6 cm(2) initially and 28·3 cm(2) at 12 weeks; 11/37 of these (30%) healed completely. After 3 months, proportions of ulcers which healed were 6/25 (24%) and 29/37 (78%), in the Control and Treatment Arms respectively (P < 0·001). These findings strongly suggest that Arginine Butyrate merits further evaluation for the treatment of refractory sickle cell leg ulcers in larger trials.

Adipose angiogenesis: quantitative methods to study microvessel growth, regression and remodeling in vivo

Genetic and diet-induced rodent obesity models provide outstanding opportunities to study the role of angiogenesis and vascular remodeling in modulation of adipogenesis and obesity. In this study, we describe methods to quantitatively study adipose angiogenesis and vascular remodeling on the basis of immunohistochemical analyses. Fresh white adipose tissue or brown adipose tissue are prepared for whole mount, cryosectioned and paraffin-embedded samples, followed by staining with specific markers such as platelet endothelial cell adhesion molecule-1 (PECAM-1)/CD31, CD34, isolectin B4 or alpha-smooth muscle actin. Adipocytes are visualized by staining lipid droplets with 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene-3-dodecanoic acid (BODIPY) 558/568 C(12). This protocol may take 2-5 d to obtain results. In the view of the crucial roles of vasculature in modulation of adipogenesis and obesity, this protocol is valuable for studying the molecular mechanisms of angiogenesis in obese adipose tissues and for assessing the anti-obesity activity of angiogenesis modulators.

Adipose tissue angiogenesis as a therapeutic target for obesity and metabolic diseases

Current pharmacotherapeutic options for treating obesity and related metabolic disorders remain limited and ineffective. Emerging evidence shows that modulators of angiogenesis affect the expansion and metabolism of fat mass by regulating the growth and remodelling of the adipose tissue vasculature. Pharmacological manipulation of adipose tissue neovascularization by angiogenic stimulators and inhibitors might therefore offer a novel therapeutic option for the treatment of obesity and related metabolic disorders. This Perspective discusses recent progress in understanding the molecular mechanisms that control adipose tissue angiogenesis and in defining potential new vascular targets and approaches for the treatment of this group of diseases.

Angiogenic capacity of human adipose-derived stromal cells during adipogenic differentiation: an in vitro study

BACKGROUND

Improving vascularization of engineered adipose tissue constructs is a major challenge in the field of plastic surgery. Although human adipose-derived stromal cells (hASCs) are known to release factors that stimulate new blood vessel formation, detailed information about the effects of adipogenic differentiation on the angiogenic potential of hASCs remains largely unknown. In the present study, we studied the expression and secretion of a large panel of angiogenic factors during hASC differentiation and evaluated the effects of hASC-conditioned medium (hASC-CM) on endothelial cells.

METHODS

hASCs were cultured on adipogenic medium or basal medium. Conditioned medium was collected, and cells were harvested following 0, 3, 7, 14, and 22 days of culture. The stage of adipogenic differentiation of hASC was assessed using Oil Red O staining, fatty acid binding protein-4 gene expression, and glycerol-3-phosphate dehydrogenase activity.

RESULTS

Gene expression of vascular endothelial growth factor (VEGF), placental growth factor, angiopoietin-1 (ANGPT1), angiopoietin-2 (ANGPT2), and protein secretion of VEGF significantly increased during short-term adipogenic differentiation of hASCs. Moreover, conditioned medium from differentiated hASCs strongly enhanced endothelial cell numbers compared to conditioned medium from undifferentiated hASCs.

CONCLUSION

In vitro adipogenic differentiation of hASCs improves their ability to support endothelial viable cell numbers and suggests that hASCs differentiated for a short period potentially improve angiogenic responses for in vivo implantation.

Adipose tissue engineering in vivo with adipose-derived stem cells on naturally derived scaffolds

Placental decellular matrix (PDM) and PDM combined with cross-linked hyaluronan (XLHA) scaffolds, seeded with primary human adipose-derived stem cells (ASC), were investigated in a subcutaneous athymic mouse model. The in vivo response at 3 and 8 weeks was characterized using histological and immunohistochemical staining. Fibrous capsule formation was assessed and the relative number of adipocytes in each scaffold was quantified. Undifferentiated ASC were localized using immunostaining for human vimentin. Unilocular and multilocular adipocytes were identified by intracellular lipid accumulation. Staining for murine CD31 assessed implant vascularization. Both scaffolds macroscopically maintained their three-dimensional volume and supported mature adipocyte populations in vivo. There was evidence of implant integration and a host contribution to the adipogenic response. The results suggested that incorporating the XLHA had a positive effect in terms of angiogenesis and adipogenesis. Overall, the PDM and PDM with XLHA scaffolds showed great promise for adipose tissue regeneration.

Defining stem and progenitor cells within adipose tissue

Adipose tissue-derived stem cells (ADSC) are routinely isolated from the stromal vascular fraction (SVF) of homogenized adipose tissue. Freshly isolated ADSC display surface markers that differ from those of cultured ADSC, but both cell preparations are capable of multipotential differentiation. Recent studies have inferred that these progenitors may reside in a perivascular location where they appeared to coexpress CD34 and smooth muscle actin (alpha-SMA) but not CD31. However, these studies provided only limited histological evidence to support such assertions. In the present study, we employed immunohistochemistry and immunofluorescence to define more precisely the location of ADSC within human adipose tissue. Our results show that alpha-SMA and CD31 localized within smooth muscle and endothelial cells, respectively, in all blood vessels examined. CD34 localized to both the intima (endothelium) and adventitia neither of which expressed alpha-SMA. The niche marker Wnt5a was confined exclusively to the vascular wall within mural smooth muscle cells. Surprisingly, the widely accepted mesenchymal stem cell marker STRO-1 was expressed exclusively in the endothelium of capillaries and arterioles but not in the endothelium of arteries. The embryonic stem cell marker SSEA1 localized to a pericytic location in capillaries and in certain smooth muscle cells of arterioles. Cells expressing the embryonic stem cell markers telomerase and OCT4 were rare and observed only in capillaries. Based on these findings and evidence gathered from the existing literature, we propose that ADSC are vascular precursor (stem) cells at various stages of differentiation. In their native tissue, ADSC at early stages of differentiation can differentiate into tissue-specific cells such as adipocytes. Isolated, ADSC can be induced to differentiate into additional cell types such as osteoblasts and chondrocytes.

Cell therapy based on adipose tissue-derived stromal cells promotes physiological and pathological wound healing

OBJECTIVE

We hypothesized that adipose tissue may contain progenitors cells with cutaneous and angiogenic potential.

METHODS AND RESULTS

Adipose tissue-derived stroma cells (ADSCs) were administrated to skin punched wounds of both nonirradiated and irradiated mice (20 Gy, locally). At day 14, ADSCs promoted dermal wound healing and enhanced wound closure, viscolesticity, and collagen tissue secretion in both irradiated and nonirradiated mice. Interestingly, GFP-positive ADSCs incorporated in dermal and epidermal tissue in vivo and expressed epidermal markers K5 and K14. Cultured ADSCs in keratinocyte medium have been shown to differentiate into K5- and K14-positive cells and produced high levels of KGF. At Day 7, ADSCs also improved skin blood perfusion assessed by laser Doppler imaging, capillary density, and VEGF plasma levels in both irradiated and nonirradiated animals. GFP-positive ADSCs incorporated into capillary structures in vivo and expressed the endothelial cell marker CD31. Finally, in situ interphase fluorescence hybridization showed that a small number of ADSCs have the potential to fuse with endogenous keratinocytes.

CONCLUSIONS

ADSCs participate in dermal wound healing in physiological and pathological conditions by their ability to promote reepithelialization and angiogenesis. Hence, adipose lineage cells represent a new cell source for therapeutic dermal wound healing.

Enhanced angiogenesis in obesity and in response to PPARgamma activators through adipocyte VEGF and ANGPTL4 production

PPARgamma activators such as rosiglitazone (RSG) stimulate adipocyte differentiation and increase subcutaneous adipose tissue mass. However, in addition to preadipocyte differentiation, adipose tissue expansion requires neovascularization to support increased adipocyte numbers. Paradoxically, endothelial cell growth and differentiation is potently inhibited by RSG in vitro, raising the question of how this drug can induce an increase in adipose tissue mass while inhibiting angiogenesis. We find that adipose tissue from mice treated with RSG have increased capillary density. To determine whether adipose tissue angiogenesis was stimulated by RSG, we developed a novel assay to study angiogenic sprout formation ex vivo. Angiogenic sprout formation from equally sized adipose tissue fragments, but not from aorta rings, was greatly increased by obesity and by TZD treatment in vivo. To define the mechanism involved in RSG-stimulated angiogenesis in adipose tissue, the expression of proangiogenic factors by adipocytes was examined. Expression of VEGFA and VEGFB, as well as of the angiopoietin-like factor-4 (ANGPTL4), was stimulated by in vivo treatment with RSG. To define the potential role of these factors, we analyzed their effects on endothelial cell growth and differentiation in vitro. We found that ANGPTL4 stimulates endothelial cell growth and tubule formation, albeit more weakly than VEGF. However, ANGPTL4 mitigates the growth inhibitory actions of RSG on endothelial cells in the presence or absence of VEGF. Thus, the interplay between VEGF and ANGPTL4 could lead to a net expansion of the adipose tissue capillary network, required for adipose tissue growth, in response to PPARgamma activators.

Angiogenesis in adipose tissue

Angiogenesis is required for the growth and expansion of both healthy and pathological tissues. The plasticity of the adipose tissue is reflected by its remarkable ability to expand or to reduce in size throughout the adult lifespan. We, and others, have recently shown that expansion of fat mass is dependent on angiogenesis, and suppression of angiogenesis might provide a novel therapeutic approach for prevention and treatment of obesity. Here, we outline two technical procedures for assessment of angiogenesis in adipose tissues.

Overweight/obesity and cancer genesis: more than a biological link

The classical view according to which overweight/obesity is related to cancer considers adipose tissue as an active and metabolic "organ", acting through endocrine, autocrine and paracrine processes. Consequently, it has been hypothesized, that genesis and progression of cancer may be caused by different biological factors acting through diverse mechanisms including changes in the synthesis and bioavailability of sex hormones, insulin resistance, release of growth factors and/or proinflammatory cytokines and abnormal energetic disposal and expenditure. We have shown that overweight/obesity can be experimentally induced by benzo[a]pyrene, a universal well characterized chemical pollutant and that overweight/obesity may in fact be caused by several types of chemical pollutants. In this paper we propose that in addition to the above hypothetical biological mechanisms, adipose tissue acts as a reservoir for lipophilic, liposoluble environmental carcinogens, so that chemical pollution may in fact generate both overweight/obesity and cancer. More precisely, we propose that many carcinogens, be they mutagens or promotors can be stored in the adipose tissue, be released at convenient dose in the blood circulation and therefore target peripheral tissues to induce carcinogenesis. Such carcinogens mainly include organochlorine pesticides and PCBs. Their association with an increased risk of cancer seems to be demonstrated for breast and prostate carcinoma, as well as for lymphoma, not only in obese patients, but also in normal weight or even leaner patients suggesting that the adipose tissue may act as a reservoir for environmental carcinogens in obese as well as in non-obese patients.

Angiogenesis modulates adipogenesis and obesity

Substantial evidence shows that neoplastic and nonneoplastic tissue growth is dependent on angiogenesis. Neovascularization and adipogenesis are temporally and spatially coupled processes during prenatal life and they continue to reciprocally interact via paracrine signaling systems throughout adult life. Activated adipocytes produce multiple angiogenic factors including leptin, angiopoietins, HGF, GM-CSF, VEGF, FGF-2, and TGF-beta, which either alone or collectively stimulate neovascularization during fat mass expansion. Thus antiangiogenic agents provide a novel therapeutic option for prevention and treatment of human obesity and its related disorders.

Adipose tissue-derived cells: from physiology to regenerative medicine

During the last past years, the importance and the role of adipose tissues have been greatly expanded. After finding that adipose tissues are metabolically very active, the discovery of leptin moved the status of adipose tissue towards an endocrine tissue able to interact with all major organs via secretion of adipokines. Some years ago, the presence of adipocyte precursors, termed preadipocytes, has been described in all adipose tissue depots from various species of different age. More recently, the discovery that different phenotypes can be obtained from stroma cells of adipose tissue has largely emphazised the concept of adipose tissue plasticity. Therefore, raising great hope in regenerative medicine as adipose tissue can be easily harvested in adults it could represent an abundant source of therapeutic cells. Thus, adipose tissue plays the dual role of Mr Obese Hyde as a main actor of obesity and of Dr Regenerative Jekyll as a source of therapeutic cells. Adipose tissue has not yet revealed all its mysteries although one facet could not be well understood without the other one.

CpG methylation profiles of endothelial cell-specific gene promoter regions in adipose tissue stem cells suggest limited differentiation potential toward the endothelial cell lineage

In vivo endothelial commitment of adipose stem cells (ASCs) has scarcely been reported, and controversy remains on the contribution of ASCs to vascularization. We address the epigenetic commitment of ASCs to the endothelial lineage. We report a bisulfite sequencing analysis of CpG methylation in the promoters of two endothelial-cell-specific genes, CD31 and CD144, in freshly isolated and in cultures of ASCs before and after induction of endothelial differentiation. In contrast to adipose tissue-derived endothelial (CD31(+)) cells, freshly isolated ASCs display a heavily methylated CD31 promoter and a mosaically methylated CD144 promoter despite basal transcription of both genes. Methylation state of both promoters remains globally stable upon culture. Endothelial stimulation of ASCs in methylcellulose elicits phenotypic changes, marginal upregulation of CD31, and CD144 expression and restrictive induction of a CD31(+)CD144(+) immunophenotype. These events are accompanied by discrete changes in CpG methylation in CD31 and CD144 promoters; however, no global demethylation that marks CD31(+) cells and human umbilical vein endothelial cells occurs. Immunoselection of CD31(+) cells after endothelial stimulation reveals consistent demethylation of one CpG immediately 3' of the transcription start site of the CD31 promoter. Adipogenic or osteogenic differentiation maintains CD31 and CD144 methylation patterns of undifferentiated cells. Methylation profiles of CD31 and CD144 promoters suggest a limited commitment of ASCs to the endothelial lineage. This contrasts with the reported hypomethylation of adipogenic promoters, which reflects a propensity of ASCs toward adipogenic differentiation. Analysis of CpG methylation at lineage-specific promoters provides a robust assessment of epigenetic commitment of stem cells to a specific lineage.

Decellularized placental matrices for adipose tissue engineering

A tissue-engineered adipose substitute would be invaluable to plastic surgeons for reconstructive, corrective, and cosmetic procedures. This work involves the design of a scaffold for soft tissue augmentation incorporating the decellularized extracellular matrix (ECM) of human placenta. We have developed a protocol to decellularize an intact, large segment (8 cm by 8 cm) of the human placenta. To facilitate the complete decellularization of the dense matrix, a system was designed to perfuse the required chemicals into the placenta via the existing vasculature. Following processing, the original architecture of the placental ECM was preserved, including an intact vascular network. Histological, immunohistochemical, and scanning electron microscopic analyses confirmed the removal of the cells and cellular debris and characterized the composition and structure of the matrix. In vitro cell culture experimentation showed that the placental decellular matrix (PDM) could facilitate the adhesion of primary human adipose precursor cells at early time points. The PDM has great potential for use as a scaffold for adipose tissue engineering, as the placenta is a rich source of human ECM components that can be readily harvested without harm to the donor.

Human adipose tissue-derived mesenchymal stem cells improve postnatal neovascularization in a mouse model of hindlimb ischemia

BACKGROUND/AIM

It has been reported that adipose tissue contain progenitor cells with angiogenic potential and that therapy based on adipose tissue-derived progenitor cells administration may constitute a promising cell therapy in patients with ischemic disease. In this study we evaluated the effect of culture-expanded mesenchymal stem cells (MSC) derived from adipose tissue on neovascularization and blood flow in an animal model of limb ischemia in immunodeficient mice.

METHODS

MSC were cultured from human adipose tissue by collagenase digestion. Hindlimb ischemia was created by ligating the proximal femoral artery of male nude mice. Human adipose tissue stromal cells (hADSC) were transplanted one day or 7 days after ligation.

RESULTS

During culture expansion of hADSC CD34 expression was downregulated. The laser Doppler perfusion index was significantly higher in the CD34(-), Flk-1(-), CD31(-) ADSC-transplanted group than in the control group, even when cells were transplanted 7 days after hindlimb ischemia. Histological examination showed that hADSC transplantation recovered muscle injury and increased vascular density, compared with the control group. The effect of hADSC was correlated with the number of transplanted cells, but not with the ratio of CD34 expression. In vitro, hADSC can form vessel-like structure and express von Willibrand Factor. Conditioned media from hADSC increased proliferation and inhibited apoptotic cell death in of human aortic endothelial cells.

CONCLUSION

This study showed that hADSC can be an ideal source for therapeutic angiogenesis in ischemic disease.

Characterizing medullary and human mesenchymal stem cell-derived adipocytes

Throughout postnatal years, medullary adipocytes (MAs) increase in both number and size; however, knowledge of these cells pales in comparison to that of other adipocyte depots. It is widely hypothesized that MAs derive from multipotent progenitor cells of the bone marrow, such as human mesenchymal stem cells (hMSCs). Nevertheless, there is a paucity of comparative, molecular-level studies in support of this hypothesis. In the present article, RTPCR was used to examine similarities and differences in gene expression among MAs, hMSC-derived adipocytes, and subcutaneous adipocytes. While little or no message for lineage-specific markers was detected in undifferentiated hMSCs, the data demonstrate that hMSC-derived adipocytes, MAs, and subcutaneous adipocytes commonly express mRNA encoding for adipogenic transcription factors (PPARgamma2, C/EBPalpha, and SREBP1), adipokines (adipsin, leptin, APM1, and angiotensinogen), and lipid-metabolizing agents (aP2 and LPL), among other genes. None of the cell populations examined expressed a detectable level of the brown fat marker UCP1. This suggests highly similar gene expression between human subcutaneous and MAs, not previously substantiated to this degree. Coupled with the hMSC-derived adipocyte analysis, these data provide a framework ultimately for characterizing MAs and identifying their origin and function.

Hepatocyte growth factor secreted by cultured adipocytes promotes tube formation of vascular endothelial cells in vitro

OBJECTIVE

Adipose tissue is closely associated with angiogenesis, but the mechanisms are not fully understood. Some of the adipocyte-derived cytokines are hypothesized to play an important role in angiogenesis. We evaluated tube formation of human umbilical vascular endothelial cells (HUVECs) cultured in type I collagen gel when overlaid with the supernatant of 3T3-L1 cell culture, and expression of tube-forming factor(s) in 3T3-L1 cells with or without pioglitazone. We also studied plasma growth factor levels in patients with type 2 diabetes mellitus treated with pioglitazone.

RESULTS AND METHODS

The supernatant of 3T3-L1 cells increased tube formation of HUVECs by 9.03-fold of control. Reverse transcription-polymerase chain reaction showed that hepatocyte growth factor (HGF) and vascular endothelial growth factor (VEGF) mRNA were expressed in 3T3-L1 cells. Western blot analysis also demonstrated HGF and VEGF protein expression. When 3T3-L1 cells were treated with 100 nM small interfering RNAs (siRNAs) for HGF, the HGF mRNA and protein were suppressed. The VEGF mRNA and protein in the cells were also suppressed by siRNA for VEGF. The supernatant of 3T3-L1 cells treated with HGF siRNA suppressed tube formation of HUVECs by 61% compared with the supernatant of cells treated with control siRNA. Addition of VEGF siRNA resulted in no significant changes. The supernatant conditioned with pioglitazone further promoted the tube formation. Pioglitazone enhanced HGF mRNA expression in 3T3-L1 cells. After 12 weeks of pioglitazone treatment, the changes of plasma HGF levels in patients treated with pioglitazone were significantly higher than those in control.

CONCLUSION

These results suggest that HGF secreted from 3T3-L1 cells may be the major factor regulating the tube formation, and agents that enhance the differentiation of adipocytes may promote tube formation of HUVECs mediated by HGF secreted by adipocytes.

Differential effect of green tea catechins on three endothelial cell clones isolated from rat adipose tissue and on human umbilical vein endothelial cells

By single colony isolation from the cells in stromal vascular fraction (SVF) dispersed from rat adipose tissues, we isolated three independent clones with different proliferation potential. All clones showed cobblestone-like morphology at the confluence and incorporated fluorescent Dil acetylated low density lipoprotein. When plated on Matrigel, they formed a capillary network-like structure. These rat adipose tissue endothelial cell (RATEC) clones showed higher expression of wnt2, wnt4, wnt5a, wnt5b, fzd1 and fzd5 whereas lower expression of cell cycle controlling genes such as CIP1, KIP1, KIP2, CDKN2A, CDKN2B, CDKN2C and CDKN2D compared to human umbilical vein endothelial cell (HUVEC). As reported for HUVEC, the growth of RATEC was inhibited by green tea catechins such as epigallocatechin, epicatechin gallate, epicatechin and epigallocatechin gallate but with higher sensitivity than HUVEC. The sensitivity of RATEC to catechins was higher for the cultures with low plating density and for the clone with higher proliferation potential.

Plasticity of human adipose lineage cells toward endothelial cells: physiological and therapeutic perspectives

BACKGROUND

Adipose tissue development and remodeling are closely associated with the growth of vascular network. We hypothesized that adipose tissue may contain progenitor cells with angiogenic potential and that therapy based on adipose tissue-derived progenitor cells administration may constitute a promising cell therapy in patients with ischemic disease.

METHODS AND RESULTS

In mice, cultured stromal-vascular fraction (SVF) cells from adipose tissue have a great proangiogenic potential, comparable to that of bone marrow mononuclear cells in the mouse ischemic hindlimb model. Similarly, cultured human SVF cells differentiate into endothelial cells, incorporate into vessels, and promote both postischemic neovascularization in nude mice and vessel-like structure formation in Matrigel plug. In vitro, these cells represent a homogeneous population of CD34- and CD13-positive cells, which can spontaneously express the endothelial cell markers CD31 and von Willebrand factor when cultured in semisolid medium. Interestingly, dedifferentiated mature human adipocytes have the potential to rapidly acquire the endothelial phenotype in vitro and to promote neovascularization in ischemic tissue and vessel-like structure formation in Matrigel plug, suggesting that cells of endothelial and adipocyte phenotypes may have a common precursor.

CONCLUSIONS

This study demonstrates, for the first time, that adipocytes and endothelial cells have a common progenitor. Such adipose lineage cells participate in vascular-like structure formation in Matrigel plug and enhance the neovascularization reaction in ischemic tissue. These results also highlight the concept that adipose lineage cells represent a suitable new cell source for therapeutic angiogenesis in ischemic disease.

Adipocyte-secreted factors synergistically promote mammary tumorigenesis through induction of anti-apoptotic transcriptional programs and proto-oncogene stabilization

Mammary epithelial cells are embedded in a unique extracellular environment to which adipocytes and other stromal cells contribute. Mammary epithelial cells are critically dependent on this milieu for survival. However, it remains unknown which adipocyte-secreted factors are required for the survival of the mammary epithelia and what role these adipokines play in the process of ductal carcinoma tumorigenesis. Here, we take a systematic molecular approach to investigate the multiple ways adipocytes and adipokines can uniquely influence the characteristics and phenotypic behavior of malignant breast ductal epithelial cells. Microarray analysis and luciferase reporter assays indicate that adipokines specifically induce several transcriptional programs involved in promoting tumorigenesis, including increased cell proliferation (IGF2, FOS, JUN, cyclin D1), invasive potential (MMP1, ATF3), survival (A20, NFkappaB), and angiogenesis. One of the key changes in the transformed ductal epithelial cells associated with the cell cycle involves the induction of NFkappaB (five-fold) and cyclin D1 (three-fold). We show that by regulating the transcription of these molecules, the synergistic activity of adipocyte-derived factors can potentiate MCF-7 cell proliferation. Furthermore, compared to other stromal cell-secreted factors, the full complement of adipokines shows an unparalleled ability to promote increased cell motility, migration, and the capacity for angiogenesis. Adipocyte-secreted factors can affect tumorigenesis by increasing the stabilization of pro-oncogenic factors such as beta-catenin and CDK6 as a result of a reduction in the gene expression of their inhibitors (i.e. p18). An in vivo coinjection system using 3T3-L1 adipocytes and SUM159PT cells effectively recapitulates the host-tumor interactions in primary tumors. Type VI collagen, a soluble extracellular matrix protein abundantly expressed in adipocytes, is further upregulated in adipocytes during tumorigenesis. It promotes GSK3beta phosphorylation, beta-catenin stabilization, and increased beta-catenin activity in breast cancer cells and may critically contribute towards tumorigenesis when not counterbalanced by other factors.

Minireview: The adipocyte--at the crossroads of energy homeostasis, inflammation, and atherosclerosis

Adipose tissue evolved to efficiently store energy for times of caloric restriction. The large caloric excess common in many Western diets has negated the need for this thrifty function, leaving adipose tissue ill-equipped to handle this increased load. An excess of adipose tissue increases risk for a number of conditions including coronary artery disease, hypertension, dyslipidemias, type 2 diabetes, and even cancer. Indeed, the ability of the adipocyte to function properly when engorged with lipid can lead to lipid accumulation in other tissues, reducing their ability to function and respond normally. The role of adipose tissue as an endocrine organ capable of secreting a number of adipose tissue-specific or enriched hormones, known as adipokines, is gaining appreciation. The normal balance of these adipose tissue secretory proteins is perturbed in obesity. Paradoxically, the lack of normal adipose tissue, as seen in cases of lipodystrophy and lipoatrophy, is also associated with pathologic sequelae similar to what is seen with obesity. The pathologic findings associated with lack of adipose tissue, largely due to inability to properly store lipids, may also be due to a lack of adipokines. In this review, we highlight the role of adipose tissue as an endocrine organ focusing on some of the recent advances in the identification and pharmacological characterization of adipokines as well as their regulation in the context of obesity and insulin-resistant states.

Adipose graft: an original option in myringoplasty

OBJECTIVE

To describe the fat graft as a reconstructive material in myringoplasty.

METHOD

In a review of 45 patients conducted between 1993 and 1999, the authors analyzed their patients' outcomes after having myringoplasties with fat graft. Median follow-up was 2.5 years (range, 6 mo-6 yr).

RESULTS

We achieved a success rate of 91.1%. Different features of the patient and the tympanic perforation were studied to demonstrate their role in the quality of the surgical closing. A review of the literature was done to compare our results with the results of other series using this type of graft as well as with studies of the temporalis fascia as a graft material.

CONCLUSION

The high reliability of the fat graft and the technical simplicity of this procedure in anterior perforations, especially with the use of intraoperative endoscopy, make it an attractive technique.