title: A novel GFP nude rat model to investigate tumor-stroma interactions.
abstract: BACKGROUND
  A key strategy for the study of the tumor microenvironment is to implant human tumor cells in an immunodeficient rodent strain ubiquitously expressing a fluorescent marker. Here, a novel nude rat expressing a green fluorescent protein (GFP) transgene was established and engrafted with primary human tumor tissue in order to separate tumor from stromal cell populations for subsequent molecular analysis.
  
  
  METHODS
  SD-TG (GFP) 2BalRrrc transgenic rats were crossed with HsdHan™: rnu/rnu Rowett nude rats to develop a GFP expressing immunocompromised rat. PCR and flow cytometry were used to follow the GFP genotype and phenotype in newborns. After three to four generations, animals were implanted with 4 T1 dsRed murine breast cancer cells or primary human glioblastoma (GBM) biopsies to generate xenografts for subsequent separation by fluorescence-activated cell sorting (FACS).
  
  
  RESULTS
  Fluorecence microscopy and reverse transcription-PCR demonstrated that GFP, under the control of the human ubiquitin C promoter, was stably maintained and expressed in diverse organs over several generations. Immunophenotyping of blood samples by flow cytometry confirmed that the immunodeficient features of the parental rat strain, HsdHan™: rnu/rnu, were retained in the GFP nude rat. Both the murine cell line and human GBM biopsies engrafted, and stromal cell populations were isolated from dissociated xenografts by FACS to > 95% purity.
  
  
  CONCLUSIONS
  A GFP transgene was stably introduced into a nude rat background in which human and murine cancer cells successfully engrafted. This animal strain provides a novel in vivo system for detailed cellular and molecular characterization of tumor-stroma interactions.
authors: Department of Neurosurgery, Qilu Hospital of Shandong University, Jinan, China ; Department of Biomedicine, University of Bergen, N-5009 Bergen, Norway ; Brain Science Research Institute, Shandong University, Jinan, China.
authors: Ning
authors: N
authors: Yang
authors: Department of Neurosurgery, Qilu Hospital of Shandong University, Jinan, China ; Brain Science Research Institute, Shandong University, Jinan, China.
authors: Bin
authors: B
authors: Huang
authors: Department of Biomedicine, University of Bergen, N-5009 Bergen, Norway.
authors: Oleg
authors: O
authors: Tsinkalovsky
authors: Department of Biomedicine, University of Bergen, N-5009 Bergen, Norway.
authors: Narve
authors: N
authors: Brekkå
authors: Department of Biomedicine, University of Bergen, N-5009 Bergen, Norway.
authors: Huaiyang
authors: H
authors: Zhu
authors: Department of Biomedicine, University of Bergen, N-5009 Bergen, Norway ; Neuro Clinic, Haukeland University Hospital, Bergen, Norway.
authors: Lina
authors: L
authors: Leiss
authors: Department of Biomedicine, University of Bergen, N-5009 Bergen, Norway ; Department of Neurosurgery, Haukeland University Hospital, Bergen, Norway.
authors: Per Øyvind
authors: PØ
authors: Enger
authors: Department of Neurosurgery, Qilu Hospital of Shandong University, Jinan, China ; Brain Science Research Institute, Shandong University, Jinan, China.
authors: Xingang
authors: X
authors: Li
authors: Department of Biomedicine, University of Bergen, N-5009 Bergen, Norway ; Brain Science Research Institute, Shandong University, Jinan, China.
authors: Jian
authors: J
authors: Wang
keywords: Breast cancer; Glioblastoma; Tumor biology; Tumor-stroma interaction; Xenograft