title: Stem cell antigen-1+ cell-based bone morphogenetic protein-4 gene transfer strategy in mice failed to promote endosteal bone formation.
abstract: BACKGROUND
  This study assessed whether a Sca-1+ cell-based ex vivo gene transfer strategy, which has been shown to promote robust endosteal bone formation with a modified fibroblast growth factor-2 (FGF2) gene, can be extended to use with bone morphogenetic protein (BMP)2/4 hybrid gene.
  
  
  METHODS
  Sublethally irradiated recipient mice were transplanted with lentiviral (LV)-BMP2/4-transduced Sca-1+ cells. Bone parameters were monitored by pQCT and microCT. Gene expression was assessed by the real-time reverse transcriptase-polymerase chain reaction.
  
  
  RESULTS
  Recipient mice of LV-BMP2/4-transduced Sca-1+ cells yielded high engraftment and increased BMP4 mRNA levels in marrow cells; but exhibited only insignificant increases in serum and bone alkaline phosphatase activity compared to control mice. pQCT and microCT analyses of femurs showed that, with the exception of small changes in trabecular bone mineral density and cortical bone mineral content in LV-BMP2/4 mice, there were no differences in measured bone parameters between mice of the LV-BMP2/4 group and controls. The lack of large endosteal bone formation effects with the BMP4 strategy could not be attributed to ineffective engraftment or expansion of BMP4-expressing Sca-1+ cells, an inability of the transduced cells to secrete active BMP4 proteins, or to use of the LV-based vector.
  
  
  CONCLUSIONS
  Sca-1+ cell-based BMP4 ex vivo strategy did not promote robust endosteal bone formation, raising the possibility of intrinsic differences between FGF2- and BMP4-based strategies in their ability to promote endosteal bone formation. It emphasizes the importance of choosing an appropriate bone growth factor gene for delivery by this Sca-1+ cell-based ex vivo systemic gene transfer strategy to promote bone formation.
authors.affiliation: Musculoskeletal Disease Center (151), Jerry L. Pettis Memorial VA Medical Center, 11201 Benton Street, Loma Linda, California 92357, USA. susan.hall1@va.gov
authors.forename: Susan L
authors.initials: SL
authors.lastname: Hall
authors.forename: Shin-Tai
authors.initials: ST
authors.lastname: Chen
authors.forename: Reinhard
authors.initials: R
authors.lastname: Gysin
authors.forename: Daila S
authors.initials: DS
authors.lastname: Gridley
authors.forename: Subburaman
authors.initials: S
authors.lastname: Mohan
authors.forename: K-H William
authors.initials: KH
authors.lastname: Lau
mesh_terms: D000818:Animals; D000950:Antigens, Ly / Q000096:biosynthesis*; D055396:Bone Morphogenetic Protein 2 / Q000096:biosynthesis / Q000235:genetics; D055415:Bone Morphogenetic Protein 4 / Q000096:biosynthesis* / Q000235:genetics; D016222:Fibroblast Growth Factor 2 / Q000096:biosynthesis / Q000235:genetics; D015870:Gene Expression; D015316:Genetic Therapy; D005822:Genetic Vectors; D018380:Hematopoietic Stem Cell Transplantation; D006412:Hematopoietic Stem Cells / Q000378:metabolism / Q000473:pathology; D006801:Humans; D008565:Membrane Proteins / Q000096:biosynthesis*; D051379:Mice; D010012:Osteogenesis / Q000235:genetics*; D010024:Osteoporosis / Q000235:genetics / Q000378:metabolism / Q000628:therapy*; D019009:Proto-Oncogene Proteins c-kit / Q000172:deficiency; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000235:genetics; D014161:Transduction, Genetic
chemical_list: D000950:Antigens, Ly; D055396:Bone Morphogenetic Protein 2; D055415:Bone Morphogenetic Protein 4; C074650:Ly6a protein, mouse; D008565:Membrane Proteins; D011993:Recombinant Fusion Proteins; D016222:Fibroblast Growth Factor 2; D019009:Proto-Oncogene Proteins c-kit