title: Cell-based delivery of cytokines allows for the differentiation of a doxycycline inducible oligodendrocyte precursor cell line in vitro.
abstract: BACKGROUND
  Stem cells, having the property of self renewal, offer the promise of lifelong repair of damaged tissue. However, somatic tissue-committed primary stem cells are rare and difficult to expand in vitro. Genetically modified stem-like cells with the ability to expand conditionally provide a valuable tool with which to study stem cell biology, especially the cellular events of proliferation and differentiation. In addition, stem cells may be appropriate candidates for therapeutic applications.
  
  
  METHODS
  Double transgenic mice possesing SV40 T antigen (Tag) under the control of the reverse tetracycline-transactivator (rtTA) were used to establish cell lines. One brain cell line was partially characterized by DNA sequencing, morphology, antigen expression using flow cytometry, confocal microscopy, and electrophysiology using the patch clamp technique. Cell cycle analysis was performed using propidium iodide staining; cell viability and H3-thymidine incorporation assays. The ability of this cell line to differentiate was assessed by confocal microscopy following co-culture with stem cells secreting cytokines.
  
  
  RESULTS
  We report here the establishment and partial characterization of a cell line derived from the brain tissue of rtTA-SV40 Tag transgenic mice. Analysis of the morphology and antigen markers has shown that this cell line mimics some aspects of primary glial precursors. The results of electrophysiology are consistent with this and suggest that the cell line is derived from O2A glial precursor cells. Cell cycle progression of this cell line is doxycycline-dependent. In the absence of doxycycline, cells become apoptotic. Differentiation into mature type 2 astrocytes and (precursor) oligodendrocytes can be induced upon withdrawal of doxycycline and addition of epithelial stem cells secreting cytokine, such as hIL3 (human Interleukine 3) or hIL6 to the culture. In contrast, co-culturing with hCNTF (human Ciliary NeuroTrophic Factor)-secreting epithelial stem cells did not induce them to mature into progeny cell types.
  
  
  CONCLUSIONS
  The differentiation of this O2A glial precursor line does not occur automatically in culture. Additional external help is required from the cell-based delivery of appropriate transgenic cytokines. Withdrawal of doxycycline from the culture medium removes the proliferation signals and induces a fatal outcome.
authors.affiliation: Institute of Medical Microbiology, Stem Cell Therapy Division, Clinic of the Justus-Liebig-University of Giessen, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Muth
authors.forename: C
authors.initials: C
authors.lastname: Elmshauser
authors.forename: S
authors.initials: S
authors.lastname: Broad
authors.forename: C
authors.initials: C
authors.lastname: Schipke
authors.forename: H
authors.initials: H
authors.lastname: Kettenmann
authors.forename: E
authors.initials: E
authors.lastname: Beck
authors.forename: M
authors.initials: M
authors.lastname: Kann
authors.forename: I
authors.initials: I
authors.lastname: Motta
authors.forename: U
authors.initials: U
authors.lastname: Chen
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D000952:Antigens, Polyomavirus Transforming / Q000235:genetics; D015415:Biomarkers / Q000032:analysis; D002454:Cell Differentiation; D002455:Cell Division; D002460:Cell Line; D002461:Cell Line, Transformed; D002470:Cell Survival; D002478:Cells, Cultured; D018920:Coculture Techniques / Q000379:methods*; D016207:Cytokines / Q000378:metabolism*; D004318:Doxycycline / Q000494:pharmacology*; D004594:Electrophysiology; D051379:Mice; D018345:Mice, Knockout; D008822:Mice, Transgenic; D018613:Microscopy, Confocal; D009836:Oligodendroglia / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D013234:Stem Cells / Q000166:cytology / Q000502:physiology; D015533:Transcriptional Activation
chemical_list: D000900:Anti-Bacterial Agents; D000952:Antigens, Polyomavirus Transforming; D015415:Biomarkers; D016207:Cytokines; D004318:Doxycycline