title: In vivo dedifferentiation of adult adipose cells.
abstract: BACKGROUND
  Adipocytes can dedifferentiate into fibroblast-like cells in vitro and thereby acquire proliferation and multipotent capacities to participate in the repair of various organs and tissues. Whether dedifferentiation occurs under physiological or pathological conditions in vivo is unknown.
  
  
  METHODS
  A tissue expander was placed under the inguinal fat pads of rats and gradually expanded by injection of water. Samples were collected at various time points, and morphological, histological, cytological, ultrastructural, and gene expression analyses were conducted. In a separate experiment, purified green fluorescent protein+ adipocytes were transplanted into C57 mice and collected at various time points. The transplanted adipocytes were assessed by bioluminescence imaging and whole-mount staining.
  
  
  RESULTS
  The expanded fat pad was obviously thinner than the untreated fat pad on the opposite side. It was also tougher in texture and with more blood vessels attached. Hematoxylin and eosin staining and transmission electron microscopy indicated there were fewer monolocular adipocytes in the expanded fat pad and the morphology of these cells was altered, most notably their lipid content was discarded. Immunohistochemistry showed that the expanded fat pad contained an increased number of proliferative cells, which may have been derived from adipocytes. Following removal of the tissue expander, many small adipocytes were observed. Bioluminescence imaging suggested that some adipocytes survived when transplanted into an ischemic-hypoxic environment. Whole-mount staining revealed that surviving adipocytes underwent a process similar to adipocyte dedifferentiation in vitro. Monolocular adipocytes became multilocular adipocytes and then fibroblast-like cells.
  
  
  CONCLUSIONS
  Mature adipocytes may be able to dedifferentiate in vivo, and this may be an adipose tissue self-repair mechanism. The capacity of adipocytes to dedifferentiate into stem cell-like cells may also have a more general role in the regeneration of many tissues, notably in fat grafting.
authors.affiliation: Department of Plastic and Cosmetic Surgery, Nanfang Hospital, Southern Medical University, Guang Zhou, Guang Dong, P.R, China.
authors.forename: Yunjun
authors.initials: Y
authors.lastname: Liao
authors.affiliation: Department of Plastic and Cosmetic Surgery, Nanfang Hospital, Southern Medical University, Guang Zhou, Guang Dong, P.R, China.
authors.forename: Zhaowei
authors.initials: Z
authors.lastname: Zeng
authors.affiliation: Department of Plastic and Cosmetic Surgery, Nanfang Hospital, Southern Medical University, Guang Zhou, Guang Dong, P.R, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Lu
authors.affiliation: Department of Plastic and Cosmetic Surgery, Nanfang Hospital, Southern Medical University, Guang Zhou, Guang Dong, P.R, China.
authors.forename: Ziqing
authors.initials: Z
authors.lastname: Dong
authors.affiliation: Department of Plastic and Cosmetic Surgery, Nanfang Hospital, Southern Medical University, Guang Zhou, Guang Dong, P.R, China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Chang
authors.affiliation: Department of Plastic and Cosmetic Surgery, Nanfang Hospital, Southern Medical University, Guang Zhou, Guang Dong, P.R, China.
authors.forename: Jianhua
authors.initials: J
authors.lastname: Gao
mesh_terms: D017667:Adipocytes / Q000166:cytology* / Q000502:physiology*; D000273:Adipose Tissue / Q000166:cytology* / Q000502:physiology*; D000818:Animals; D054337:Cell Dedifferentiation / Q000502:physiology*; D002468:Cell Physiological Phenomena / Q000502:physiology; D049109:Cell Proliferation / Q000502:physiology; D005347:Fibroblasts / Q000166:cytology / Q000502:physiology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D051381:Rats; D017207:Rats, Sprague-Dawley; D012038:Regeneration / Q000502:physiology