Characterization of rhBMP-2 pharmacokinetics implanted with biomaterial carriers in the rat ectopic model

Recombinant human bone morphogenetic protein‐2 (rhBMP‐2) is a member of the bone morphogenetic protein family involved in de novo bone induction. Successful use of rhBMP‐2 requires implantation with a biomaterial which can act as a scaffold for cell invasion for osteoinduction and retains rhBMP‐2 at a site of implantation. This study was carried out to characterize rhBMP‐2 pharmacokinetics from a variety of biomaterial carriers in a rat ectopic model. Retention of rhBMP‐2 within carriers after 3 h was variable among the carriers (range, 75–10%), with collagenous sponges retaining the highest fraction of implanted dose. A gradual loss of rhBMP‐2 was subsequently observed, the kinetics of which was strongly dependent on the implanted carrier. Collagenous carriers were observed to lose rhBMP‐2 gradually from the implant site, whereas some of the mineral‐based carriers retained a fraction of implanted rhBMP‐2 within the implants. These differences in protein pharmacokinetics among carriers, in addition to their physicochemical nature, are expected to affect the biological activity of implanted rhBMP‐2. © 1999 John Wiley & Sons, Inc. J Biomed Mater, 46, 193–202, 1999.