A HIGHLY POROUS 3-DIMENSIONAL POLYPHOSPHAZENE POLYMER MATRIX FOR SKELETAL TISSUE REGENERATION

Current methods for the replacement of skeletal tissue in general invo lve the use of autografts or allografts. There are considerable drawba cks in the use of either of these tissues. In an effort to provide an alternative to traditional graft materials, a degradable 3-dimensional (3-D) osteoblast cell-polymer matrix was designed as a construct for skeletal tissue regeneration. A degradable amino acid containing polym er, poly[(methylphenoxy)(ethyl glycinato) phosphazene], was synthesize d and a 3-D matrix system was prepared using a salt leaching technique . This 3-D polyphosphazene polymer matrix system, 3-D-PHOS, was then s eeded with osteoblast cells for the creation of a cell-polymer matrix material. The 3-D-PHOS matrix possessed an average pore diameter of 16 5 mu m. Environmental scanning electron microscopy revealed a reconnec ting porous network throughout the polymer with an even distribution o f pores over the surface of the matrix. Osteoblast cells were found at tached and grew on the 3-D-PHOS at a steady rate throughout the 21-day period studied in vitro, in contrast to osteoblast growth kinetics on similar, but 2-D polyphosphazene matrices, that showed a decline in c ell growth after 7 days. Characterization of 3-D-PHOS osteoblast-polym er matrices by light microscopy revealed cells growing within the pore s as well as on surface of the polymer as early as day 1. This novel p orous 3-D-PHOS matrix may be suitable for use as a bioerodible scaffol d for regeneration of skeletal tissue. (C) 1996 John Wiley & Sons, Inc .