title: Impaired response of mature adipocytes of diabetic mice to hypoxia.
abstract: Adipose tissue contains various cells such as infiltrated monocytes/macrophages, endothelial cells, preadipocytes, and adipocytes. Adipocytes have an endocrine function by secreting adipokines such as interleukin (IL)-6, tumor necrosis factor (TNF)-α, leptin, and adiponectin. Dysregulation of adipokines in adipose tissues leads to a chronic low-grade inflammation which could result in atherosclerosis, hypertension, and type 2 diabetes. A sustained inflammatory state, which is characterized by prolonged persistence of macrophages and neutrophils, is found in diabetic wounds. In addition, subcutaneous adipocytes are enormously increased in amount clinically in type 2 diabetes. However, the function of subcutaneous adipocytes, which play an important role in injured tissue subjected to hypoxia, has not been well characterized in vitro due to the difficulty of maintaining mature adipocytes in culture using conventional methods because of their buoyancy. In this study, we established a novel in vitro culture method of mature adipocytes by enclosing them in a hyaluronan (HA) based hydrogel to study their role in response to stress such as hypoxia. BrdU labeling and Ki67 immunostaining experiments showed that hydrogel enclosed mature adipocytes proliferate in vitro. Both mRNA and protein expression analyses for hypoxia regulated genes, such as vascular endothelial growth factor (VEGF) and heme oxygenase 1 (HO1), showed that mature adipocytes of wild type mice respond to hypoxia. In contrast, mature adipocytes of diabetic db/db and TallyHo mice did not efficiently respond to hypoxia. Our studies suggest that mature adipocytes are functionally active cells, and their abnormal function to hypoxia can be one of underlining mechanisms in type 2 diabetes.
authors.affiliation: Laboratory for Wound Repair and Regenerative Medicine, Department of Surgery, Division of Plastic and Reconstructive Surgery, Feinberg School of Medicine, Northwestern University, USA. seok-hong@northwestern.edu
authors.forename: Seok Jong
authors.initials: SJ
authors.lastname: Hong
authors.forename: Da P
authors.initials: DP
authors.lastname: Jin
authors.forename: Donald W
authors.initials: DW
authors.lastname: Buck
authors.forename: Robert D
authors.initials: RD
authors.lastname: Galiano
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Mustoe
mesh_terms: D052438:Adipocytes, White / Q000166:cytology / Q000378:metabolism*; D054392:Adipokines / Q000235:genetics; D000818:Animals; D018929:Cell Culture Techniques; D015687:Cell Hypoxia / Q000502:physiology*; D049109:Cell Proliferation; D048429:Cell Size; D002470:Cell Survival; D002478:Cells, Cultured; D003432:Cross-Linking Reagents / Q000737:chemistry; D003924:Diabetes Mellitus, Type 2 / Q000378:metabolism* / Q000503:physiopathology; D004195:Disease Models, Animal; D005780:Gelatin / Q000737:chemistry; D015870:Gene Expression / Q000235:genetics; D051547:Heme Oxygenase-1 / Q000235:genetics; D006820:Hyaluronic Acid / Q000737:chemistry; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000138:chemical synthesis / Q000737:chemistry; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism; D019394:Ki-67 Antigen / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D054411:Receptors, Leptin / Q000235:genetics; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism
chemical_list: D054392:Adipokines; D003432:Cross-Linking Reagents; C497443:Hif1a protein, mouse; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D019394:Ki-67 Antigen; D054411:Receptors, Leptin; D042461:Vascular Endothelial Growth Factor A; C515447:leptin receptor, mouse; C467480:vascular endothelial growth factor A, mouse; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D005780:Gelatin; D006820:Hyaluronic Acid; D051547:Heme Oxygenase-1