Methods for producing porous freeze-dried fibrin matrices substantially devoid of external anti-fibrinolytic agents. Resilient matrices, also known as sponges, that are particularly beneficial for supporting three dimensional cell growth are obtained from plasma proteins substantially devoid of plasminogen or from partially purified plasma proteins, thus obviating the need for exogenous anti-fibrinolytic agents. Furthermore, incorporation of glycosaminoglycans and bioactive agents during the formation of the matrix results in a sponge having advantageous biological, mechanical and physical properties. The compositions made by the method of the present invention are useful clinically or as cell-bearing implants.