title: Transduction of CD34(+) and CD34(-)/lin(-) hemopoietic progenitors by lentivirus vectors.
abstract: BACKGROUND
  While hemopoietic stem cells have been thought to reside predominantly in the CD34(+) population, recent data suggests that repopulating cells may, in fact, also reside in the lin(-)/CD34(-) population. Transduction of both these populations by murine retroviral vectors is limited by quiescence of hemopoietic stem cells.
  
  
  METHODS
  We therefore sought to transduce these populations using a VSV-G pseudotyped, HIV-based, human lentiviral vector, encoding eGFP. CD34(+) cells and lin(-)/CD34(-) cells were selected from the same BM samples by immunomagnetic beads (StemSep) to deplete lineage-positive cells and by CD34 selection columns (Miltenyi) to separate CD34(+) and CD34(-) populations. We transduced target cells, with or without prestimulation with cytokines, using conventional suspension culture, or fibronectin plates, or flow-through transduction. Transduction efficiency was analyzed by flow cytometry and clonogenic assay.
  
  
  RESULTS
  We found that transduction on fibronectin plates was more efficient than flow-through transduction, or suspension cultures, for both cell populations. Mean transduction rates on fibronectin plates, analyzed by flow cytometry, were 14% and 5% for CD34(+) cells and lin(-)/CD34(-) cells respectively, without prestimulation, and 31% and 20% with prestimulation. By contrast, a murine retroviral vector transduces CD34(+) cells with lower efficiency (mean 16.1% with prestimulation) and does not induce any significant transduction of the CD34(-)/lin(-) population (mean < 2%). When lentiviral transduction was assayed in short- and long-term clonogenic assays there was minimal transduction of CD34 cells without prestimulation, increasing to 20% with prestimulation.
  
  
  CONCLUSIONS
  Lentiviral eGFP vectors can transduce hematopoietic progenitors effectively and efficiency is improved by cytokine prestimulation and the use of fibronectin. Moreover, the human viral vectors can transduce a candidate stem-cell population that is resistant to murine retroviral transduction.
authors.affiliation: Center for Cell and Gene Therapy, Baylor College of Medicine, Houston, Texas, USA.
authors.forename: K
authors.initials: K
authors.lastname: Moriwaki
authors.forename: R E
authors.initials: RE
authors.lastname: Sutton
authors.forename: M
authors.initials: M
authors.lastname: Perez
authors.forename: M K
authors.initials: MK
authors.lastname: Brenner
authors.forename: H E
authors.initials: HE
authors.lastname: Heslop
mesh_terms: D018952:Antigens, CD34 / Q000096:biosynthesis*; D005353:Fibronectins / Q000737:chemistry / Q000378:metabolism; D005434:Flow Cytometry / Q000379:methods; D005822:Genetic Vectors; D049452:Green Fluorescent Proteins / Q000737:chemistry; D006678:HIV / Q000235:genetics; D006412:Hematopoietic Stem Cells / Q000166:cytology*; D006801:Humans; D018189:Immunomagnetic Separation / Q000379:methods; D016086:Lentivirus / Q000235:genetics*; D008562:Membrane Glycoproteins / Q000378:metabolism; D012190:Retroviridae / Q000235:genetics; D013234:Stem Cells / Q000166:cytology; D014759:Viral Envelope Proteins / Q000378:metabolism
chemical_list: D018952:Antigens, CD34; D005353:Fibronectins; C028391:G protein, vesicular stomatitis virus; D008562:Membrane Glycoproteins; D014759:Viral Envelope Proteins; D049452:Green Fluorescent Proteins