Ectopic bone formation using osteogenic protein-1 carried by a solution precipitated hydroxyapatite.
Solution precipitation of calcium and phosphate is a technique to generate hydroxyapatite [Peri-Apatitetrade mark (PA), Stryker Orthopaedics, Mahwah, NJ] on metal substrate. This study was carried out to determine the capacity of PA to adsorb osteogenic protein-1 (OP-1) and the time course of release, and to determine the osteoinductive activity of OP-1. The adsorption and release studies were conducted with (125)I-labeled OP-1- and PA-coated titanium alloy disks. The results indicate that the adsorption of OP-1 on the PA-coated disks is linear with the concentration of OP-1 up to 5 mg/mL. There is an initial release of 75% to 80% of adsorbed OP-1 within the first hour, and 92% of OP-1 is released in 3 days. The osteoinductive activity of OP-1 was determined in the rat intramuscular ectopic bone formation assay. A total of 24 titanium alloy disks were evenly divided into 3 groups with different treatments for implantation, plain disks (group A), disks coated with PA (group B), and disks coated with PA plus 40 microg OP-1 (group C). Osteogenic protein-1, 40 microg in solution, was injected into the muscle pouch in animals of group D (n = 8). The rats were sacrificed 3 weeks postoperatively and the implants were retrieved. Ectopic bone formation was evaluated with radiography and histology. Results demonstrated that OP-1 induced ectopic bone in all the animals of group C and group D. The titanium alloy disks were surrounded by trabecular bone and marrow tissue. None of the animals of group A or group B showed any evidence of osteoinduction. Our findings indicate that PA can deliver OP-1 directly to titanium alloy implants and maintain the osteoinductive activity of OP-1.
Stryker Orthopaedics, 325 Corporate Drive, Mahwah, New Jersey 07430, USA. renwen.zhang@stryker.com
Renwen
R
Zhang
Dazhong
D
Xu
Tracy
T
Landeryou
Carol
C
Toth
Nena
N
Dimaano
Jenny
J
Berry
Julie
J
Evans
Monica
M
Hawkins
D000042:Absorption; D000818:Animals; D055419:Bone Morphogenetic Protein 7; D019485:Bone Morphogenetic Proteins / Q000008:administration & dosage* / Q000737:chemistry / Q000494:pharmacology*; D001842:Bone and Bones / Q000166:cytology / Q000187:drug effects; D006882:Hydroxyapatites / Q000737:chemistry*; D008297:Male; D010012:Osteogenesis / Q000187:drug effects*; D051381:Rats; D020318:Rats, Long-Evans; D012996:Solutions / Q000737:chemistry; D013997:Time Factors; D014025:Titanium / Q000737:chemistry; D016212:Transforming Growth Factor beta / Q000008:administration & dosage* / Q000737:chemistry / Q000494:pharmacology*
C525821:Bmp7 protein, rat; D055419:Bone Morphogenetic Protein 7; D019485:Bone Morphogenetic Proteins; D006882:Hydroxyapatites; D012996:Solutions; D016212:Transforming Growth Factor beta; D014025:Titanium