[en] Purpose: To evaluate the interreader agreement of a three-tier craniocaudal grading system for brown fat activation and investigate the accuracy of the distinction between the three grades. Materials and methods: After IRB approval, 340 cases were retrospectively selected from patients undergoing (18)FDG-PET/CT between 2007 and 2015 at our institution, with 85 cases in each grade and 85 controls with no active brown fat. Three readers evaluated all cases independently. Furthermore standardized uptake values (SUV) measurements were performed by two readers in a subset of 53 cases. Agreement between the readers was assessed with Cohen's Kappa (k), the concordance correlation coefficient (CCC) and the intraclass correlation coefficient (ICC). Accuracy was assessed with Bland-Altman and receiver operating characteristics (ROC) analysis. A Bonferroni-corrected two-tailed p < 0.016 was considered statistically significant. Results: Agreement for BAT grade was excellent by all three metrics with k = 0.83–0.89, CCC = 0.83–0.89 and ICC = 0.91–0.94. Bland-Altman analysis revealed only slight average over- or underestimation (−0.01−0.14) with the majority of disagreements within one grade. ROC analysis yielded slightly less accurate classification between higher vs. lower grades (Area under the ROC curves 0.78–0.84 vs. 0.88–0.92) but no significant differences between readers. Agreement was also excellent for the maximum SUV and the total brown fat volume (k = 0.90 and 0.94, CCC = 0.93 and 0.99, ICC = 0.96 and 0.99), but Bland-Altman plots revealed a tendency to underestimate activity by one of the readers. Conclusion: Grading the activation of brown fat by assessment of the most caudally activated depots results in excellent interreader agreement, comparable to SUV measurements.

[en] Highlights: • HDAC6 regulates thermogenesis of brown adipose tissue. • cAMP-PKA signaling is responsible for HDAC6-dependent thermogenic regulation to control UCP1 expression. • HDAC6-dependent regulation of UCP1 affects lipid metabolism in brown adipose tissue. Mitochondrial uncoupling protein 1 (UCP1) is responsible for nonshivering thermogenesis in brown adipose tissue (BAT). UCP1 increases the conductance of the inner mitochondrial membrane (IMM) for protons to make BAT mitochondria generate heat rather than ATP. HDAC6 is a cytosolic deacetylase for non-histone substrates to regulate various cellular processes, including mitochondrial quality control and dynamics. Here, we showed that the body temperature of HDAC6 knockout mice is slightly decreased in normal hosing condition. Interestingly, UCP1 was downregulated in BAT of HDAC6 knockout mice, which extensively linked mitochondrial thermogenesis. Mechanistically, we showed that cAMP-PKA signaling plays a key role in HDAC6-dependent UCP1 expression. Notably, the size of brown adipocytes and lipid droplets in HDAC6 knockout BAT is increased. Taken together, our findings suggested that HDAC6 contributes to mitochondrial thermogenesis in BAT by increasing UCP1 expression through cAMP-PKA signaling pathway.

[en] Highlights: • Bcl2l13 expression is induced in Browning of white adipose tissues in Mice. • Knockdown of Bcl2l13 in beige adipocytes represses adipogenesis and thermogenic programing. • Bcl2l13 induces thermogenic programing by regulating mitochondrial dynamic and biogenesis. Bcl2l13 is a member of the Bcl-2 family that has been found to play a central role in regulating apoptosis. Recently Bcl2l13 has been reported to induce mitophagy as a functional mammalian homolog of Atg32. However, the role of Bcl2l13 in adipose tissue has not been investigated yet. In the present study, we found that Bcl2l13 expression was increased in white adipose tissue browning process stimulated by cold exposure or β3-adrenergic agonist CL-316,243 in vivo as well as during brown adipocytes differentiation in vitro. Moreover, Bcl2l13 disruption dramatically inhibited the browning program of preadipocytes, evidenced by reduced Prdm16, Ucp1, Dio2 and Adrb3 expression. Our findings revealed that the inhibition effect of Bcl2l13 disruption on browning program may be independent of altering autophagy activity, but through regulating mitochondrial dynamic and biogenesis, supported by decreased mitochondrial fission/fussion genes, PGC-1α and mitochondrial respiratory chain complexes expression. Taken together, our study uncovered a novel function of Bcl2l13 in adipocytes differentiation and promoting browning program.

[en] Highlights: • Microfibrous scaffolds were electrospun from a blend of collagen, hyaluronic acid and poly(l-lactide-co-ε-caprolactone) • The PLC/COL/HA scaffolds had smaller pore size and higher water uptake capacity than PLC scaffolds • The PLC/COL/HA scaffolds had a Young’s Modulus similar to that of many soft tissues • The PLC/COL/HA scaffolds better supported cell adhesion when compared with PLC scaffolds • The PLC/COL/HA scaffolds induced formation of interconnected capillaries -- Abstract: Success of 3D tissue substitutes in clinical applications depends on the presence of vascular networks in their structure. Accordingly, research in tissue engineering is focused on the stimulation of angiogenesis or generation of a vascular network in the scaffolds prior to implantation. A novel, xeno-free, collagen/hyaluronic acid-based poly(l-lactide-co-ε-caprolactone) (PLC/COL/HA) (20/9.5/0.5 w/w/w) microfibrous scaffold was produced by electrospinning. Collagen types I and III, and hyaluronic acid were isolated from human umbilical cords and blended with the GMP grade PLC. When compared with PLC scaffolds the PLC/COL/HA had higher water uptake capacity (103% vs 66%) which may have contributed to the decrease in its Young's Modulus (from 1.31 to 0.89 MPa). The PLC/COL/HA better supported adipose tissue-derived mesenchymal stem cell (AT MSC) adhesion; within 24 h the cell number on the PLC/COL/HA scaffolds was 3 fold higher. Co-culture of human umbilical vein endothelial cells and AT MSCs induced capillary formation on both scaffold types, but the PLC/COL/HA led to formation of interconnected vessels whose total length was 1.6 fold of the total vessel length on PLC. Clinical use of this scaffold would eliminate the immune response triggered by xenogeneic collagen and transmission of animal-borne diseases while promoting a better vascular network formation.

[en] Solitary fibrous tumour (SFT) is a rare soft tissue tumour of uncertain histogenesis and unpredictable biological behaviour, which was first described in the pleura and subsequently in many extra-pleural locations. Fat-forming SFT is a sub-type of SFT and only a handful of cases have been reported in the literature. We present the clinical, radiological and histological features of a case of intraspinal fat-forming SFT, along with a literature review. This is the first known report of a fat-forming SFT in the spine. (orig.)

[en] Highlights: • Aging impaired beige adipocyte differentiation of AT-MSC by induction of senescence. • The induced senescence in elderly AT-MSC caused by reduction of Sirt1 and Sirt3. • Sirt1 activated beige adipocyte differentiation of elderly AT-MSC via p53/p21 pathway. In the body, different types of adipose tissue perform different functions, with brown and beige adipose tissues playing unique roles in dissipating energy. Throughout life, adipocytes are regenerated from progenitors, and this process is impaired by aging. One of the progenitors of adipocytes are mesenchymal stem cells (MSCs), which have recently become a promising tool for stem cell therapy. However, whether or not aging impairs the brown/beige adipocyte differentiation of adipose tissue-derived MSCs (AT-MSCs) remains unclear. In the present study, we isolated AT-MSCs from two different age groups of donors (infants and elderly subjects) and examined the effects of aging on the AT-MSC brown/beige adipocyte differentiation ability. We found that none of the AT-MSCs expressed Myf5, which indicated the beige (not brown) differentiation ability of cells. Of note, an inverse correlation was noted between the beige adipocyte differentiation ability and age, with AT-MSCs derived from elderly donors showed the most severely reduced function due to induced cellular senescence. The impaired expression of Sirtuin 1 (Sirt1) and Sirt3 proved to be responsible for the induction of senescence in elderly AT-MSCs; however, only Sirt1 was directly involved in the regulation of beige adipocyte differentiation. The overexpression of Sirt1 impaired the p53/p21 pathway, thereby preventing elderly AT-MSCs from entering senescence and restoring the beige differentiation ability. Thus, our study represents the important role of Sirt1 and senescence in the regulation of beige adipocyte differentiation during aging.

[en] Cigarette smoking is one of the most important risk factors of atherosclerosis, which can induce endothelial injury. Meanwhile, adipocytes are the main cell type of perivascular adipose tissue (PVAT), the largest endocrine and paracrine organ and direct anatomical connection to adventitia, which may play a key role in the injury of endothelial cells. We used nicotine to induce dysfunctional HUVECs and adipocytes. In addition, we used a novel model to co-culture HUVECs and adipocytes in vitro by the transwell co-culture system to determine the effect of adipocytes on endothelial injury. Cell apoptosis was detected by Annexin V-FITC. Genes and proteins involved in the nuclear factor kappa B (NF-κB) signaling pathway were detected by qRT-PCR and western blot analysis, respectively. We also investigated the nuclear translocation of NF-κB p65 using immunofluorescence staining. Our results showed that nicotine dose-dependently induces the apoptosis of HUVECs and adipocytes and is associated with increased IKKβ and NF-κB p65 expression and with IkBα degradation. Meanwhile through the co-culture system, adipocytes promoted the expression of IKKβ and NF-κB p65, as well as the translocation of NF-κB p65, and they accelerated the degradation of IkBα, resulting in increased apoptosis of HUVECs compared with that of the single cultured system. In conclusion, adipocytes could promote endothelial injury via the NF-κB pathway. Moreover, the NF-κB pathway plays pivotal roles in nicotine-induced vascular injury. - Highlights: • Nicotine induces endothelial injury by activating NF-κB pathway. • Nicotine induces adipocytes injury by activating NF-κB pathway. • Adipocytes promote nicotine-induced endothelial injury via NF-κB pathway.

[en] Highlights: • Prolonged time course for cold exposure was utilized to elucidate dynamic changes in BAT and in WAT browning in mice. • Loss of classic iBAT enhanced WAT browning due to compensatorily increased sympathetic WAT input in mice. • Significantly reduced adiposity in the iBAT removal group compared with the control group in mice. The strong effects of classic brown adipose tissue (BAT) and recruited beige adipocytes in treatment of obesity and metabolic syndrome have been attracting increasing research interest. Cold treatment is an effective, convenient approach to stimulate BAT activity and induce white adipose tissue (WAT) browning. Here, we utilized prolonged cold exposure (from 2 h to 2 weeks in a 4° cold chamber) to elucidate dynamic changes in BAT and in WAT browning during acute and chronic cold exposure in mice. BAT mass decreased quickly, with reduced lipid droplet sizes within 8 h of cold exposure owing to the utilization of BAT pre-storage triglycerides, and subsequently increased during prolonged cold exposure. These dynamic morphological changes in BAT were confirmed by gene expression changes in ADRB3 and PGC1α, while UCP1 and ELOVL3 expression was continuously up-regulated throughout the entire cold exposure period. Additionally, cold treatment increased BAT secretion of FGF21, which has been reported to activate beige adipocyte formation. Thus, to illustrate potential crosstalk between secreted BAT proteins (so-called BATokines) and beige adipogenesis during cold stress, we performed an interscapular BAT (iBAT) removal experiment in mice. Surprisingly, loss of classic iBAT enhanced WAT browning due to compensatorily increased sympathetic WAT input. Unexpectedly, we observed significantly reduced adiposity in the iBAT removal group compared with the control group. These results further suggest that WAT browning plays an important role in whole-body energy metabolism during cold acclimation, even without iBAT. Furthermore, our data imply that enhanced WAT browning may be an efficient therapeutic tool to combat obesity and related syndromes.

[en] Studies have demonstrated that differentiation of stem cells into cardiomyocytes is a complex phenomenon that requires sufficient inducing factors at various time points. Cardiac extracellular matrix (cECM) could provide tissue specific microenvironment and act as an inductive template for efficient cell differentiation. The aim of this study was to investigate the effect of cECM on differentiation of human adipose tissue-derived stem cells (hADSCs) into cardiomyocytes using cECM hydrogel in combination with a cardiac inductive cocktail. hADSCs were cultured on ECM-coated plates with and without inductive cocktail for 3weeks. qRT-PCR and western blot analysis were used to evaluate the expression pattern of special cardiac genes and proteins. When hADSCs were cultured in the presence of cECM cardiac genes including GATA4, HAND1, HAND2, NKX2.5, Troponin I, βMHC, Connexin43 were highly expressed in differentiated cells. Also Connexin43, cTnI and βMHC proteins were expressed as well. We could show that cECM by itself could affect viability, proliferation and differentiation of hADSCs. However, combination of cECM with a cardiac inducing cocktail could improve the results.

[en] Intramuscular adipose tissue (IMAT) formation is observed in some pathological conditions such as Duchenne muscular dystrophy (DMD) and sarcopenia. Several studies have suggested that IMAT formation is not only negatively correlated with skeletal muscle mass but also causes decreased muscle contraction in sarcopenia. In the present study, we examined w hether adipocytes affect myogenesis. For this purpose, skeletal muscle progenitor cells were transfected with siRNA of PPARγ (siPPARγ) in an attempt to inhibit adipogenesis. Myosin heavy chain (MHC)-positive myotube formation was promoted in cells transfected with siPPARγ compared to that of cells transfected with control siRNA. To determine whether direct cell-to-cell contact between adipocytes and myoblasts is a prerequisite for adipocytes to affect myogenesis, skeletal muscle progenitor cells were cocultured with pre- or mature adipocytes in a Transwell coculture system. MHC-positive myotube formation was inhibited when skeletal muscle progenitor cells were cocultured with mature adipocytes, but was promoted when they were cocultured with preadipocytes. Similar effects were observed when pre- or mature adipocyte-conditioned medium was used. These results indicate that preadipocytes play an important role in maintaining skeletal muscle mass by promoting myogenesis; once differentiated, the resulting mature adipocytes negatively affect myogenesis, leading to the muscle deterioration observed in skeletal muscle pathologies. - Highlights: • We examined the effects of pre- and mature adipocytes on myogenesis in vitro. • Preadipocytes and mature adipocytes affect myoblast fusion. • Preadipocytes play an important role in maintaining skeletal muscle mass. • Mature adipocytes lead to muscle deterioration observed in skeletal muscle pathologies