Apoptosis induction and reduced proliferation in human osteoblasts by rhBMP-2, -4 and -7.
BACKGROUND
The role of bone morphogenetic proteins (BMPs) in bone healing has been demonstrated in numerous in vivo animal models. BMP-2, -4 and -7 have also been shown to stimulate the differentiation of human and animal stem cells into osteoblasts in vitro. There are, however, contradictory reports of BMPs causing apoptosis and inhibition of proliferation of osteoblastic cells. Therefore, a more complete understanding of the effects of BMP-2, -4 and -7 on human osteoblasts is required.


METHODS
Cells of the immortalised human fetal osteoblastic line hFOB 1.19 were exposed to recombinant human (rh) BMP-2, -4 and -7. In addition, primary human osteoblasts were exposed to rhBMP-7. Cell proliferation was measured using a colorimetric assay. Apoptotic cells were detected using the TUNEL assay.


RESULTS
The hFOB cells exposed in a dose-dependent manner to rhBMP-2, -4 and -7 had significantly lower rates of proliferation than non-treated cells, (p<0.01 for rhBMP-2, -4 and -7). The proliferation results for rhBMP-7 were replicated using primary human osteoblasts. Additionally, rhBMP-2, -4 and -7 induced a significantly higher rate of apoptosis in the hFOB cells, with a temporal and dose-dependent pattern (p<0.05), irrespective of the presence of serum growth factors.


CONCLUSIONS
Despite interest in the potential clinical application of BMPs to improve bone healing, further studies are necessary to determine their full biological function before they can be used confidently in humans.
Gautschi
O P
OP
Department of Orthopaedic and Trauma Surgery, Royal Perth Hospital, Perth, Western Australia, Australia. ogautschi@datacomm.ch
Cadosch
D
D
Zellweger
R
R
Joesbury
K A
KA
Filgueira
L
L
D017209:Apoptosis / Q000187:drug effects*; D055396:Bone Morphogenetic Protein 2 / Q000008:administration & dosage / Q000494:pharmacology*; D055415:Bone Morphogenetic Protein 4 / Q000008:administration & dosage / Q000494:pharmacology*; D055419:Bone Morphogenetic Protein 7 / Q000008:administration & dosage / Q000494:pharmacology*; D002461:Cell Line, Transformed; D049109:Cell Proliferation / Q000187:drug effects*; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D006801:Humans; D020287:In Situ Nick-End Labeling; D010006:Osteoblasts / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D011994:Recombinant Proteins / Q000494:pharmacology; D013997:Time Factors
D055396:Bone Morphogenetic Protein 2; D055415:Bone Morphogenetic Protein 4; D055419:Bone Morphogenetic Protein 7; D011994:Recombinant Proteins