No abstract

Fatty liver disease is the most common pathological condition in the liver. Here, we generated high-fat diet-(HFD-) induced nonalcoholic fatty liver disease (NAFLD) in mice and tested the effects of docosahexaenoic acid (DHA) and lysine during a four-week regular chow (RC)feeding. Our results showed that 1% lysine and the combination of 1% lysine + 1% DHA reduced body weight. Moreover, serum triglyceride levels were reduced by 1% DHA and 1% lysine, whereas serum alanine transaminase activity was reduced by 1% DHA and 1% DHA + 0.5% lysine. Switching to RC reduced hepatic lipid droplet accumulation, which was further reduced by the addition of DHA or lysine. Furthermore, the mRNA expressions of hepatic proinflammatory cytokines were suppressed by DHA and combinations of DHA + lysine, whereas the mRNA for the lipogenic gene, acetyl-CoA carboxylase 1 (ACC1), was suppressed by DHA. In the gonadal adipose tissues, combinations of DHA and lysine inhibited mRNA expression of lipid metabolism-associated genes, including ACC1, fatty acid synthase, lipoprotein lipase, and perilipin. In conclusion, the present study demonstrated that, in conjunction with RC-induced benefits, supplementation with DHA or lysine further ameliorated the high-fat diet-induced NAFLD and provided an alternative strategy to treat, and potentially prevent, NAFLD.

The unique advantage of easy access and abundance make the adipose-derived stem cells (ADSCs) a promising system of multipotent cells for transplantation and regenerative medicine. Among the available sources, porcine ADSCs (pADSCs) deserve especial attention due to the close resemblance of human and porcine physiology, as well as for the upcoming availability of humanized porcine models. Here, we report on the isolation and conversion of pADSCs into glucose-responsive insulin-secreting cells. We used the stromal-vascular fraction of the dorsal subcutaneous adipose from 9-day-old male piglets to isolate pADSCs, and subjected the cells to an induction scheme for differentiation on chitosan-coated plates. This one-step procedure promoted differentiation of pADSCs into pancreatic islet-like clusters (PILC) that are characterized by the expression of a repertoire of pancreatic proteins, including pancreatic and duodenal homeobox (Pdx-1), insulin gene enhancer protein (ISL-1) and insulin. Upon glucose challenge, these PILC secreted high amounts of insulin in a dose-dependent manner. Our data also suggest that chitosan plays roles not only to enhance the differentiation potential of pADSCs, but also to increase the glucose responsiveness of PILCs. Our novel approach is, therefore, of great potential for transplantation-based amelioration of type 1 diabetes.

Adiponectin and its receptors have been demonstrated to play important roles in regulating glucose and lipid metabolism in mice. Obesity, type II diabetes and cardiovascular disease are highly correlated with down-regulated adiponectin signaling. In this study, we generated mice overexpressing the porcine Adipor1 transgene (pAdipor1) to study its beneficial effects in metabolic syndromes as expressed in diet-induced obesity, hepatosteatosis and insulin resistance. Wild-type (WT) and pAdipor1 transgenic mice were fed ad libitum with a standard chow diet (Chow) or a high-fat/sucrose diet (HFSD) for 24 weeks, beginning at 6 to 7 weeks of age. There were 12 mice per genetic/diet/sex group. When challenged with HFSD to induce obesity, the pAdipor1 transgenic mice resisted development of weight gain, hepatosteatosis and insulin resistance. These mice had lowered plasma adiponectin, triglyceride and glycerol concentrations compared to WT mice. Moreover, we found that (indicated by mRNA levels) fatty acid oxidation was enhanced in skeletal muscle and adipose tissue, and liver lipogenesis was inhibited. The pAdipor1 transgene also restored HFSD-reduced phosphoenolpyruvate carboxykinase 1 (Pck1) and glucose transporter 4 mRNA in the adipose tissues, implying that the increased Pck1 may promote glyceroneogenesis to reduce glucose intolerance and thus activate the flux of glyceride-glycerol to resist diet-induced weight gain in the adipose tissues. Taken together, we demonstrated that pAdipor1 can prevent diet-induced weight gain and insulin resistance. Our findings may provide potential therapeutic strategies for treating metabolic syndromes and obesity, such as treatment with an ADIPOR1 agonist or activation of Adipor1 downstream targets.

A new class of adipose tissue, termed beige adipose tissue (BeAT) has recently been identified to possess distinct origin, properties and function from the other two, white and brown adipose tissues, and implicated in regulating energy homeostasis that may affect metabolic syndrome. In an effort to study nutrient effects on the regulation of adipogenesis and amelioration of metabolic syndrome in humans, we identified BeAT‐like adipocytes differentiated from the human adipose‐derived stem cells (ADSC) isolated from the breast subcutaneous fats of breast cancer patients undergoing mastectomy. The procedure was approved by the Ethics Committee of National Taiwan University Hospital. The stromal‐vascular cells were isolated and maintained according to general procedures. After reaching to confluence and cultured in standard differentiation medium containing rosiglitazone for 15 days, the cells started to accumulated lipid droplets as stained by Oil‐Red‐O under light microscope and the expressions of brown adipose tissue‐or BeAT‐associated genes, such as UCP‐1, PRDM‐16, Tmem26, and CD137, were identified by quantitative real‐time PCR. Our current study, therefore, not only demonstrates that the human breast subcutaneous fat harbors the potential to differentiate into BeAT under adipogenic differentiation procedures, but also creates a novel model system for the study of BeAT and sheds new lights on future design of therapeutic approaches for metabolic diseases and regenerative medicine..

While its ease of isolation, abundant source and multipotency have made the adipose‐derived stem cell (ADSC) a promising system for cell therapy and regenerative medicine, the approach on utilizing porcine ADSC to generate insulin‐secreting cells has not been explored. In our current study, subcutaneous adipose tissue on the back were dissected from 9‐day‐old male piglets (Y × L) purchased from a local pig farm and processed as previously described to isolate the stromal‐vascular fraction (SVF). Cells were then cultured in differentiation medium based on serum‐free DMEM/F12 as modified from Timper et al.. Our results showed that under light microscope, the morphology of pancreatic islet‐like clusters were observed at day 3 of culture, the function of insulin production identified by immunocytochemical analysis with confocal microscope and the expression of pancreatic β‐cell differentiation‐associated genes, including Pdx1, Pax4, Islet1, glucokinase, glucagon and Glut2, by RT‐PCR. Moreover, upon glucose challenge, the clusters secreted significantly higher amount of insulin as measured by ELISA on day 9 in a dose‐dependent manner compared to the basal level (5.5 mM glucose). Our present study, therefore, demonstrates the success of isolating and differentiating porcine ADSC into glucose responsive insulin‐secreting clusters. Their potentials in ameliorating type I diabetes in mouse and pig models are currently under investigation.