New synthetic absorbable polymers as BMP carriers: Plastic properties of poly-D,L-lactic acid-polyethylene glycol block copolymers
✍ Scribed by Saito, Naoto ;Okada, Takao ;Toba, Shigeyuki ;Miyamoto, Shimpei ;Takaoka, Kunio
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 389 KB
- Volume
- 47
- Category
- Article
- ISSN
- 0021-9304
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✦ Synopsis
Bone morphogenetic proteins (BMPs) are biologically active molecules capable of eliciting new bone formation. In combination with biomaterials, these proteins can be used in a clinical setting as bone-graft substitutes to promote bone repair. To find new synthetic absorbable polymers with plastic nature that can be used as BMP-carrier materials, six types of poly-D,L-lactic acid-polyethylene glycol block copolymer (PLA-PEG) with various molecular weights of PLA and PEG were synthesized. These were PLA6,500-PEG3,000 (P-1), PLA11,500-PEG3,000 (P-2), PLA17,500-PEG3,000 (P-3), PLA6,500-PEG1,000 (P-4), PLA15,000-PEG8,000 (P-5), and PLA8,500-PEG1,000 (P-6). Fifty milligrams of these polymers was mixed with 0 g (control) or 5, 10, or 20 g of recombinant human BMP-2 (rhBMP-2). These pellets were implanted into the dorsal muscle pouches of 144 mice (six pellets consisting of the same polymer and dose of rhBMP-2 for a specific group). Three weeks after surgery, the pellets were harvested and examined by radiographic and histological methods. All P-1 pellets with 10 or 20 g of rhBMP-2 showed bone formation with hematopoietic marrow and bony trabeculae, as did one third of those with 5 g of rhBMP-2. The incidence of new bone formation with P-2 pellets or that of P-5 pellets was lower than that of P-1 pellets. No bone was formed in any other type of pellet. These results indicated that the PLA6,500-PEG3,000 polymer with plastic properties was found to work well as a BMP carrier.