title: Injected Implant of Uncultured Stromal Vascular Fraction Loaded Onto a Collagen Gel: In Vivo Study of Adipogenesis and Long-term Outcomes.
abstract: BACKGROUND
  Stromal vascular fraction (SVF) cells were used to increase the efficacy of a newly formed adipose tissue in a collagen gel in vitro. However, the outcome of the seeded cells in the collagen gel in vivo remains unknown. We traced the SVF cells in the host tissue and evaluated the efficacy of SVF for fat tissue engineering.
  
  
  METHODS
  The aggregates implanted in the experimental and control groups were prepared by mixing SVF with the collagen gel and Dulbecco's modified Eagle medium with the collagen gel, respectively. The aggregates were implanted using a subcutaneous injection into the backs of immunodeficient mice. The aggregates were harvested 1, 2, 4, and 6 months after implantation; and 9 mice were euthanized each time. Macroscopic changes in the volume and wet weight of the aggregates were assessed. The formation of adipose tissue was studied using hematoxylin and eosin and Nile red staining. The origin and survival of adipocytes in the aggregates were examined through the immunostaining of leptin antibodies, DNA assay, and tracing of SVF cells by 1,1'-dioctadecyl-3,3,3',3'- tetramethylindocarbocyanine perchlorate labeling.
  
  
  RESULTS
  The formation of adipose tissue was observed in all of the aggregates. Implanted human SVF cells remained in the experimental aggregates harvested after 1, 2, and 4 months but not after 6 months. At 6 months, viable adipocytes in both groups were of murine origin. Furthermore, at 6 months, the mean volume of the aggregate (P < 0.001) and the mean percentage of adipocytes (P < 0.001) were significantly higher in the experimental group than in the control group.
  
  
  CONCLUSIONS
  Implanted SVF cells could not be traced in the aggregates harvested at 6 months but promoted the recruitment of host adipocytes to generate more adipose tissue in the experimental group than in the control group.
authors.affiliation: From the *Division of Plastic Surgery, Department of Surgery, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan, †Center for Stem Cell Research, Kaohsiung Medical University, Kaohsiung, Taiwan, ‡Department of Anesthesiology, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan, §Department of Biomedical Science and Environmental Biology, Cancer Center, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan, ∥Department of Pathology, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan; and ¶Sunmax Biotechnology Co. Ltd, Tainan Science Industrial Park, Tainan County, Taiwan, ROC.
authors.forename: Sin-Daw
authors.initials: SD
authors.lastname: Lin
authors.forename: Shu-Hung
authors.initials: SH
authors.lastname: Huang
authors.forename: Yun-Nan
authors.initials: YN
authors.lastname: Lin
authors.forename: Sheng-Hua
authors.initials: SH
authors.lastname: Wu
authors.forename: Hsueh-Wei
authors.initials: HW
authors.lastname: Chang
authors.forename: Tsai-Ming
authors.initials: TM
authors.lastname: Lin
authors.forename: Chee-Yin
authors.initials: CY
authors.lastname: Chai
authors.forename: Dar-Jen
authors.initials: DJ
authors.lastname: Hsieh
authors.forename: Kao-Ping
authors.initials: KP
authors.lastname: Chang
mesh_terms: D050156:Adipogenesis; D000818:Animals; D017209:Apoptosis; D002470:Cell Survival; D003094:Collagen; D005260:Female; D005782:Gels; D006801:Humans; D045164:Mesenchymal Stem Cell Transplantation / Q000379:methods*; D051379:Mice; D008807:Mice, Inbred BALB C; D017154:Stromal Cells; D050507:Subcutaneous Fat, Abdominal / Q000166:cytology* / Q000502:physiology; D023822:Tissue Engineering / Q000379:methods*; D054457:Tissue Scaffolds
chemical_list: D005782:Gels; D003094:Collagen