The present invention relates to polymers, especially polymers useful as hydrogels, and to use of hydrogels for repair or restoration of tissue. In particular, the polymers and hydrogels of the present invention can be used for the repair or restoration of cartilage, especially articular cartilage. The polymers comprise at least a monomer for binding water, a monomer for imparting mechanical properties and a monomer for binding to an extracellular protein. The hydrogels comprise a polymer comprising at least a monomer for binding water and a monomer for binding to an extracellular protein. Crosslinking polymers by binding of said extra-cellular matrix protein forms hydrogels.