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AAPS PharmSciTech. 2001 September; 2(3): 66–72.
Published online 2001 October 7. doi:  10.1208/pt020317
PMCID: PMC2750582

Porous bone morphogenetic protein-2 microspheres: Polymer binding and in vitro release

Abstract

This research compared the binding and release of recombinant human bone morphogenetic protein 2 (rhBMP-2) with a series of hydrophobic and hydrophilic poly-lactide-co-glycolide (PLGA) copolymers. Porous microspheres were produced via a double emulsion process. Binding and incorporation of protein were achieved by soaking microspheres in buffered protein solutions, filtering, and comparing protein concentration remaining to nonmicrosphere-containing samples. Protein release was determined by soaking bound microspheres in a physiological buffer and measuring protein concentration (by reversed-phase high-performance liquid chromatography) in solution over time. Normalized for specific surface area and paired by polymer molecular weight. microspheres made from hydrophilic 50[ratio]50 or 75[ratio]25 PLGA bound significantly more protein than microspheres made from the corresponding hydrophobic PLGA. Increased binding capacity correlated with higher polymer acid values. With certain polymers, rhBMP-2 adsorption was decreased or inhibited at high protein concentration, but protein loading could be enhanced by increasing the protein solution:PLGA (volume:mass) ratio or by repetitive soaking. Microspheres of various PLGAs released unbound protein in 3 days, whereas the subsequent bound protein release corresponded to mass loss. RhBMP-2 binding to PLGA was controlled by the acid value, protein concentration, and adsorption technique. The protein released in 2 phases: the first occurred over 3 days regardless of PLGA used and emanated from unbound, incorporated protein, while the second was controlled by mass loss and therefore was dependent on the polymer molecular weight. Overall, control of rhBMP-2 delivery is achievable by selection of PLGA microsphere carriers.

Keyword: bone morphogenetic protein-2
PLGA microspheres: controlled delivery, protein delivery, in vitro

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.
1. Kenley RA, Yim K, Abrams J, et al. Biotechnology and bone graft substitutes. Pharm Res. 1993;10:1393–1401. doi: 10.1023/A:1018902720816. [PubMed] [Cross Ref]
2. Brekke JH, Toth JM. Principles of tissue engineering applied to programmable osteogenesis. J Biomed Mater Res. 1998;43:380–398. doi: 10.1002/(SICI)1097-4636(199824)43:4<380::AID-JBM6>3.0.CO;2-D. [PubMed] [Cross Ref]
3. Hollinger J. Strategies for regenerating bone of the craniofacial complex. Bone. 1993;14:575–580. doi: 10.1016/8756-3282(93)90196-H. [PubMed] [Cross Ref]
4. Linde A, Hedner E. Recombinant bone morphogenetic protein-2 enhances bone healing, guided by osteopromotive e-PTFE membranes: an experimental study in rats. Calcif Tissue Int. 1995;56:549–553. doi: 10.1007/BF00298588. [PubMed] [Cross Ref]
5. Hollinger JO, Brekke J, Gruskin E, Lee D. Role of bone substitutes [published erratum appears in Clin Orthop. 1997;334–387]. Clin Orthop. 1996,55–65.
6. Vukicevic S, Stavljenic A, Pecina M. Discovery and clinical applications of bone morphogenetic proteins. Eur J Clin Chem Clin Biochem. 1995;33:661–671. [PubMed]
7. Howell TH, Fiorellini J, Jones A, et al. A feasibility study evaluating rhBMP-2 absorbable collagen sponge device for local alveolar ridge preservation or augmentation. Int J Periodontics Restorative Dent. 1997;17:124–139. [PubMed]
8. Boyne PJ, Marx RE, Nevins M, et al. A feasibility study evaluating rhBMP-2 absorbable collagen sponge for maxillary sinus floor augmentation. Int J Periodontics Restorative Dent. 1997;17:10–25. [PubMed]
9. Urist MR, O'Connor BT, Burwell RG. Bone grafts, derivatives, and substitutes. Oxford, UK: Butterworth-Heinemann; 1994.
10. Lucas PA, Syftestad GT, Goldberg VM, Caplan AI. Ectopic induction of eartilage and bone by water-soluble proteins from bovine bone using a collagenous delivery vehicle. J Biomed Mater Res. 1989;23:23–39. doi: 10.1002/jbm.820231306. [PubMed] [Cross Ref]
11. Pavanetto F, Conti B, Genta Y, Giunchedi P. Solvent evaporation, solvent extraction and spray drying for polylactide microsphere preparation. Int J Pharmaceutics. 1992;84:151–159. doi: 10.1016/0378-5173(92)90055-7. [Cross Ref]
12. Guo J. Preparation methods of biodegradable microspheres on bovine serum albumin loading efficiency and release profiles. Drug Dev Ind Pharm. 1994;20:2535–2545. doi: 10.3109/03639049409042657. [Cross Ref]
13. Uchida T, Yoshida K, Goto S. Preparation and characterization of polylactic acid microspheres containing water-soluble dyes using a novel w/ow emulsion solvent evaporation method. J Microencapsul. 1996;3:219–228. doi: 10.3109/02652049609052909. [PubMed] [Cross Ref]
14. Jeyanthi R, Mehta RC, Thanoo BC, DeLuca PP. Effect of processing parameters on the properties of peptide-containing PLGA microspheres. J Microencapsul. 1997;14:163–174. doi: 10.3109/02652049709015330. [PubMed] [Cross Ref]
15. Schrier JA, Kenley RA, Williams R, et al. Degradation pathways for recombinant human macrophage colony-stimulating factor in aqueous solution. Pharm Res. 1993;10:933–944. doi: 10.1023/A:1018990001310. [PubMed] [Cross Ref]
16. Pretzer D, Schulteis BS, Smith CD, Vander Velde DG, Mitchell JW, Manning MC. Stability of the thrombolytic protein fibrolase: effect of temperature and pH on activity and conformation. Pharm Res. 1991;8:1103–1112. doi: 10.1023/A:1015842032164. [PubMed] [Cross Ref]
17. Kenley RA, Wame NW. Acid-catalyzed peptide bond hydrolysis of recombinant human interleukin II. Pharm Res. 1994;11:72–76. doi: 10.1023/A:1018945727640. [PubMed] [Cross Ref]
18. Schrier JA, DeLuca PP. Recombinant human bone morphogenetic protein-2 binding and incorporation in PLGA microsphere delivery systems. Pharm Dev Technol. 1999;4:611–621. doi: 10.1081/PDT-100101400. [PubMed] [Cross Ref]
19. Duggirala SS, Mehta RC, DeLuca PP. Interaction of recombinant human bone morphogenetic protein-2 with poly(d,l lactide-co-glycolide) microspheres. Pharm Dev Technol. 1996;1:11–19. doi: 10.3109/10837459609031413. [PubMed] [Cross Ref]
20. Duggirala SS, Rodgers JB, DeLuca PP. The evaluation of lyophilized polymer matrices for administering recombinant human bone morphogenetic protein-2. Pharm Dev Technol. 1996;1:165–174. doi: 10.3109/10837459609029891. [PubMed] [Cross Ref]

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