Bone morphogenetic protein excipients: Comparative observations on poloxamer

Clinicians await the availability of synthetic bioimplants that will replac e the need for autogeneic bone grafts in bone reconstructive surgery. For m ore than a decade, researchers have evaluated delivery vehicles for the tis sue morphogen bone morphogenetic protein. The object of this investigation was to measure induced bone development when bone morphogenetic protein was delivered by human tendon collagen, human demineralized bone matrix, hydro xyapatite, a composite of human tendon collagen and human demineralized bon e matrix (tendon collagen + demineralized bone matrix), Poloxamer 407, and a composite of human demineralized bone matrix and Poloxamer 407. Sixty-thr ee adult male Swiss Webster mice (Harlan Sprague-Dawley, Indianapolis, Ind. ) received 126 implants. The animals were divided into seven groups of nine animals, depending on carrier (six carriers plus the positive control grou p) used. Each animal received a bone morphogenetic protein-enhanced carrier in one hindquarter muscle mass, with the contralateral leg being implanted with the carrier alone. Implants were evaluated by quantitative radiomorph ometry validated by histologic methods. Radiographically, no significant di fferences were identified among any of the implants evaluated (p > 0.05). H istomorphometric analysis demonstrated that Poloxamer 407 was significantly (p < 0.05) better at delivering bone morphogenetic protein than the other carriers involved in this investigation. The net bone developed in a tubula r or spherical shape. Interaction of endogenous and exogenous delivery syst ems seems to be essential for optimal transmission of bone morphogenetic pr otein. The importance of the excipient to deliver bone morphogenetic protei n and develop a bone morphogenetic protein concentration gradient has been emphasized by other investigators and confirmed by our research on poloxame r. With further research on the physicochemical mechanisms of localization and transmission of bone morphogenetic protein, it may be possible to avoid hazardous operations with autogeneic bone.