title: Molecular profile of osteoprogenitor cells seeded on allograft bone.
abstract: In order to optimize and modulate bone formation it is essential to understand the expression patterns of key bone-specific growth factors, as osteoprogenitor cells undergo the processes of proliferation, differentiation and maturation. This study reports the sequential expression of bone-related growth and transcription factors when bone marrow-derived osteoprogenitor cells from C57BL mice were cultured on allograft bone discs. Mineralization and osteocalcin protein levels were used to track osteogenic differentiation and maturation. Bone-related growth factors, such as Bmp-2, Bmp-7, Ctnnb-1, Fgf-2, Igf-1, Vegf-a and Tgf-β1, and transcription factors, such as Runx-2 and osteocalcin, were examined by enzyme-linked immunosorbent assay (ELISA) and reverse transcription polymerase chain reaction (RT-PCR). Total density of mineralized bone was significantly increased 7.6 ± 0.7% in allografts cultured with cells, compared with a 0.5 ± 2.0% increase in the controls without cells (p < 0.01). Osteocalcin protein levels peaked at day 4. Protein expression showed peaks of BMP-2 and TGF-β1 on day 2, with VEGF peaking on day 8, and IGF-1 decreasing on day 2. mRNA for Pdgf-a peaked on day 2; Bmp-2 on days 4 and 16; Ctnnb-1 on days 8 and 20; Vegf-a, Fgf-2, Runx-2 and Igf-1 on day 12; Tgf-β1 on day 16; and Pdgf-b on day 20. Osteogenic growth factors correlated with Runx-2 and Ctnnb-1, whereas a predominant vascular growth factor, Vegf-a, did not follow this pattern. Specific bone-related genes and proteins were expressed in a time-dependent manner when osteoprogenitor cells were cultured on cortico-cancellous bone discs in vitro.
authors.affiliation: Department of Orthopedic Surgery, Stanford University, CA, USA.
authors.forename: Kierann E
authors.initials: KE
authors.lastname: Smith
authors.forename: Zhinong
authors.initials: Z
authors.lastname: Huang
authors.forename: Ting
authors.initials: T
authors.lastname: Ma
authors.forename: Afraaz
authors.initials: A
authors.lastname: Irani
authors.forename: R
authors.initials: R
authors.lastname: Lane Smith
authors.forename: Stuart B
authors.initials: SB
authors.lastname: Goodman
mesh_terms: D000818:Animals; D001842:Bone and Bones / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D002454:Cell Differentiation / Q000187:drug effects; D002478:Cells, Cultured; D003470:Culture Media / Q000494:pharmacology; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000187:drug effects; D008297:Male; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D010006:Osteoblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D015675:Osteocalcin / Q000378:metabolism; D010012:Osteogenesis / Q000187:drug effects / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D018709:Statistics, Nonparametric; D014184:Transplantation, Homologous
chemical_list: D003470:Culture Media; D012333:RNA, Messenger; D015675:Osteocalcin