A hydrogel-forming composition is formed from a protein polymer derivative having a plurality of cross-linkable units depending therefrom, and a non-protein polymer derivative having a plurality of cross-linkable units depending therefrom, said non-protein polymer derivatives having hydrolysable units disposed between the polymer backbone of said derivative and at least some of said cross-linkable units. The use of a combination of protein and non-protein polymers provides for biodegradability of the hydrogel by hydrolysis of the hydrolysable units and/or enzymatic degradation of the proteins, along with mechanical properties such as strength and elasticity.