title: Serial bone marrow transplantation reveals in vivo expression of the pCLPG retroviral vector.
abstract: BACKGROUND
  Gene therapy in the hematopoietic system remains promising, though certain aspects of vector design, such as transcriptional control elements, continue to be studied. Our group has developed a retroviral vector where transgene expression is controlled by p53 with the intention of harnessing the dynamic and inducible nature of this tumor suppressor and transcription factor. We present here a test of in vivo expression provided by the p53-responsive vector, pCLPG. For this, we used a model of serial transplantation of transduced bone marrow cells.
  
  
  RESULTS
  We observed, by flow cytometry, that the eGFP transgene was expressed at higher levels when the pCLPG vector was used as compared to the parental pCL retrovirus, where expression is directed by the native MoMLV LTR. Expression from the pCLPG vector was longer lasting, but did decay along with each sequential transplant. The detection of eGFP-positive cells containing either vector was successful only in the bone marrow compartment and was not observed in peripheral blood, spleen or thymus.
  
  
  CONCLUSIONS
  These findings indicate that the p53-responsive pCLPG retrovirus did offer expression in vivo and at a level that surpassed the non-modified, parental pCL vector. Our results indicate that the pCLPG platform may provide some advantages when applied in the hematopoietic system.
authors.affiliation: Setor de Vetores Virais, Laboratório de Genética e Cardiologia Molecular/LIM 13, Instituto do Coração, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, CEP 05403-900, Brasil.
authors.forename: Paula
authors.initials: P
authors.lastname: Fratini
authors.forename: Bryan E
authors.initials: BE
authors.lastname: Strauss
mesh_terms: D000818:Animals; D016026:Bone Marrow Transplantation; D015870:Gene Expression; D017930:Genes, Reporter; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors; D049452:Green Fluorescent Proteins / Q000096:biosynthesis / Q000235:genetics; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D012190:Retroviridae / Q000235:genetics*; D014161:Transduction, Genetic; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
chemical_list: D016159:Tumor Suppressor Protein p53; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins