title: Molecular imaging of expression of vascular endothelial growth factor a (VEGF a) in femoral bone grafts transplanted into living mice.
abstract: The biology of cells transplanted with bone grafts is incompletely understood. Focusing on the early angiogenic response postgrafting, we report a mouse femur graft model in which grafts were derived from mice transgenic for a firefly luciferase (FLuc) bioluminescence reporter gene driven by a promoter for the angiogenic signaling molecule vascular endothelial growth factor (VEGF). Upon transplantation into wild-type (wt) mice, in vivo bioluminescence imaging (BLI) permitted longitudinal visualization and measurements of VEGF promoter activity in the transplanted graft cells and demonstrated a lag period of 7 days posttransplantation prior to robust induction of the promoter. To determine cellular mediators of VEGF induction in graft bone, primary graft-derived osteoblastic cells (GDOsts) were characterized. In vitro BLI on GDOsts showed hypoxia-induced VEGF expression and that this induction depended on PI3K signaling and, to a lesser degree, on the MEK pathway. This transcriptional regulation correlated with VEGF protein production and was validated in GDOsts seeded on demineralized bone matrix (DBM), a bone graft substitute material. Together, combined imaging of VEGF expression in living animals and in live cells provided clues about the regulation of VEGF in cells post-bone grafting. These data are particularly significant toward the development of future smart bone graft substitutes.
authors.affiliation: Research Division, Hospital for Special Surgery, New York, NY, USA.
authors.forename: Olga
authors.initials: O
authors.lastname: Strachna
authors.forename: Daniel
authors.initials: D
authors.lastname: Torrecilla
authors.forename: Marie K
authors.initials: MK
authors.lastname: Reumann
authors.forename: Inna
authors.initials: I
authors.lastname: Serganova
authors.forename: Jihye
authors.initials: J
authors.lastname: Kim
authors.forename: Simone
authors.initials: S
authors.lastname: Gieschler
authors.forename: Adele L
authors.initials: AL
authors.lastname: Boskey
authors.forename: Ronald G
authors.initials: RG
authors.lastname: Blasberg
authors.forename: Philipp
authors.initials: P
authors.lastname: Mayer-Kuckuk
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D015687:Cell Hypoxia; D005260:Female; D005269:Femur / Q000166:cytology* / Q000378:metabolism / Q000473:pathology; D049409:Luciferases, Firefly / Q000235:genetics / Q000378:metabolism; D020930:MAP Kinase Kinase Kinases / Q000378:metabolism; D008297:Male; D051379:Mice; D057054:Molecular Imaging; D010006:Osteoblasts / Q000166:cytology* / Q000378:metabolism / Q000637:transplantation; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D011401:Promoter Regions, Genetic; D015398:Signal Transduction; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism*; D014945:Wound Healing
chemical_list: D042461:Vascular Endothelial Growth Factor A; D049409:Luciferases, Firefly; D019869:Phosphatidylinositol 3-Kinases; D020930:MAP Kinase Kinase Kinases