Affinity evaluation of gelatin for hepatocyte growth factor of different types to design the release carrier

The objective of this study was to investigate the physicochemical interaction of hepatocyte growth factor (HGF) and its variant with 5 amino-acid residues deleted (dHGF) with an acidic gelatin for the design of factors release from the gelatin hydrogel. When the interaction of HGF or dHGF with gelatin-immobilized agarose beads was evaluated by Scatchard binding assay, the dissociation constant of dHGF was higher than that of HGF, although the two proteins had a similar binding ratio. dHGF was released more rapidly from the hydrogel of acidic gelatin than HGF. In vivo release study with ¹²⁵I-labeled HGF or dHGF in mice subcutis showed that HGF was released from the gelatin hydrogel as a result of hydrogel degradation. In contrast, dHGF was rapidly released by a simple diffusion from the gelatin hydrogel. From electrophoresis experiments, mixing with the acidic gelatin enabled HGF to complex and suppressing the trypsin-digested molecular weight loss, in marked contrast to that of dHGF. In addition, the percentage of HGF recognized by the antibody was reduced by the gelatin complexation, but that of dHGF was not. We conclude that unlike dHGF, HGF has a strong affinity for the acidic gelatin, resulting in the controlled release of HGF accompanied with hydrogel degradation of the release carrier.