Bone induction by AdBMP-2/collagen implants.
BACKGROUND
Demineralized bone matrix and recombinant human bone morphogenetic protein-2 or 7 (BMP-2 or BMP-7)-containing collagenous matrix have been shown to induce new bone formation in orthotopic and heterotopic sites. We examined the ability of subcutaneous implants of collagen combined with adenoviral vector containing the BMP-2 gene (AdBMP-2) to induce bone formation in rats. We also evaluated whether targeting the AdBMP-2 vector through an alternative receptor pathway, fibroblast growth factor (FGF), would increase the vector's potency.


METHODS
In a time-course study, rat subcutaneous sites were implanted with (1) AdBMP-2 in rat-bone-derived collagen or (2) rat-bone-derived collagen alone. Samples were collected three, seven, fourteen, or thirty-five days after treatment. In a dose-response study, bone induction by AdBMP-2 in collagen (AdBMP-2/collagen) or by AdBMP-2 and FGF2 Fab' anti-adenovirus knob protein antibody in collagen (FGF2-AdBMP-2/collagen) was tested at fourteen days. Viral vector doses of 1 x 10(9) PN (viral particle number), 3 x 10(9) PN, 1 x10(10) PN, 3 x 10(10) PN, or 1 x 10(11) PN per implant were used. Equal amounts of collagen (25 mg) were used to formulate all implants. Explanted tissues were evaluated histologically to determine bone formation, specific activity of alkaline phosphatase, and calcium content.


RESULTS
AdBMP-2/collagen implants induced robust bone formation. New bone was formed by the fourteenth day after implantation. In contrast, little or no bone was induced by the implant containing collagen alone. FGF2-AdBMP-2/collagen implants stimulated significantly more bone formation (p < 0.05) than did AdBMP-2/collagen implants, regardless of the dose of viral particles.


CONCLUSIONS
Local delivery of AdBMP-2 in a collagen matrix rapidly induces bone formation, and targeting the virus through FGF receptors enhances the osteogenic potential of AdBMP-2.
Schreiber
R E
RE
Selective Genetics, San Diego, California 92121, USA. rschreiber@macropore.com
Blease
K
K
Ambrosio
A
A
Amburn
E
E
Sosnowski
B
B
Sampath
T K
TK
D000256:Adenoviridae / Q000235:genetics; D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D001857:Bone Matrix; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins / Q000008:administration & dosage*; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D016222:Fibroblast Growth Factor 2 / Q000502:physiology; D005822:Genetic Vectors; D020007:Implants, Experimental; D010012:Osteogenesis / Q000187:drug effects*; D051381:Rats; D020318:Rats, Long-Evans; D011994:Recombinant Proteins / Q000008:administration & dosage*; D016212:Transforming Growth Factor beta / Q000008:administration & dosage*
C525718:BMP2 protein, human; C525720:Bmp2 protein, rat; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins; D011994:Recombinant Proteins; D016212:Transforming Growth Factor beta; D016222:Fibroblast Growth Factor 2; D000469:Alkaline Phosphatase