Bone Morphogenetic Protein-2 Binds As Multilayers To A Collagen Delivery Matrix: An Equilibrium Thermodynamic Analysis

Recombinant human bone morphogenetic protein-2 (rhBMP-2) promotes bone growth but must be retained at the delivery site for optimal efficacy in vivo. rhBMP-2 release from a collagen-based matrix has shown favorable pharmacokinetics. The present study assessed binding affinity and binding saturation of rhBMP-2 to a collagen matrix as a function of solution and rhBMP-2 isoform variables. Results indicate that rhBMP-2 binds to the collagen matrix with affinities on the order of 10(3) to 10(4) M(-1). Maximum binding, nu, was primarily a function of pH for heterogeneous rhBMP-2 and the extended (T(266)/T(266)) isoform. However, binding saturation of the