A fibrin/fibrinogen binding conjugate for forming a depot for the sustained release of a pharmaceutically active substance from a fibrin clot. The conjugate comprises a fibrin/fibrinogen binding moiety bound to a pharmaceutically active substance either directly or via an intervening substance capturing moiety such as an antibody. The conjugate can also be a recombinant fusion protein comprising a fibrin/fibrinogen binding moiety such as VEGF.sub.165 C-terminal domain fused to a wound-healing substance such as leptin.