Diffusion of fibroblast growth factor from a plaster of Paris carrier

Fibroblast growth factor (FGF) is a polypeptide that has been shown to have a stimulatory effect on osseous tissues in vitro. This study characterized the release of FGF from plaster of Paris (PLP) and measured the dissolution of PLP in various solutions with the aim of developing a reliable carrier system for the release of FGF in vivo. The study consisted of five experiments: (I) FGF diffusion from PLP pellets, (II) FGF diffusion from PLP discs, (III) PLP dissolution in saline, (IV) PLP dissolution in serum, and (V) FGF adsorption by commercially pure titanium. FGF was observed to be released at a rate directly proportional to the rate of dissolution of the PLP carrier, suggesting that either the FGF binds to the PLP; or, alternatively, the FGF may be entrapped by the PLP. Dissolution rate, and thus release rate, could be varied by varying the mass of the carrier. Greater diffusion of FGF was observed in larger, more slowly dissolving PLP carriers. Dissolution of PLP was observed to be slower in serum than in saline, apparently due to stabilization by factors in the serum but not due to a concentration gradient effect. Titanium coupons did not adsorb significant amounts of FGF. These results indicate that PLP, which has been shown in the past neither to aggravate inflammatory response nor to interfere with bone ingrowth, may serve as delivery vehicle for FGF to osseous tissues in vivo.