The sequential expression profiles of growth factors from osteoprogenitors [correction of osteroprogenitors] to osteoblasts in vitro.
In this study, we delineate the sequential expression of selected growth factors associated with bone formation in vitro. Mineralization, osteocalcin, and alkaline phosphatase (ALP-2) were measured to monitor the differentiation and maturation of osteoprogenitor cells collected from C57BL mice. Bone-related growth factors, including transforming growth factor beta (TGF-beta), fibroblast growth factor 2 (FGF-2), platelet-derived growth factor (PDGF), insulinlike growth factor (IGF)-1, vascular endothelial growth factor (VEGF), bone morphogenetic protein (BMP)-2, and BMP-7, were selected. Enzyme-linked immunosorbent assay (ELISA) and reverse transcriptase polymerase chain reaction (RT-PCR) were used to measure growth factors at the protein and messenger ribonucleic acid (mRNA) level, respectively. The results found that ALP-2 expression increased progressively over time, whereas mineralization and osteocalcin did not become evident until culture day 14. VEGF and IGF-1 were upregulated early during proliferation. PDGF and TGF-beta mRNA expression was bimodal. FGF-2 and BMP-2 mRNAs were expressed only later in differentiation. FGF-2 mRNA signal levels were highest at day 14 and remained prominent through day 28 of culture. BMP-2 showed a similar profile as FGF-2. BMP-7 was not detectable using RT-PCR or ELISA. Strong correlations existed for the expression patterns between several early-response growth factors (VEGF, TGF-beta, and IGF-1) and were also evident for several late-response growth factors (BMP-2, PDGF, and FGF-2). Differential expression for grouped sets of growth factors occurs during the temporal acquisition of bone-specific markers as osteoprogenitor cell maturation proceeds in vitro.
Huang
Zhinong
Z
Department of Orthopedic Surgery, Stanford University Medical Center, Stanford, California 94305, USA.
Nelson
Ehren Robert
ER
Smith
R Lane
RL
Goodman
Stuart B
SB
D000818:Animals; D002454:Cell Differentiation / Q000502:physiology; D020869:Gene Expression Profiling; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000096:biosynthesis* / Q000235:genetics*; D008297:Male; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D010006:Osteoblasts / Q000166:cytology / Q000378:metabolism*; D051381:Rats; D013997:Time Factors
D036341:Intercellular Signaling Peptides and Proteins