Decellularization methods for tissue are provided. The method can include: exposing a tissue to a water-saturated, supercritical CO2. The method can further comprise, prior to exposing the tissue to the water-saturated, supercritical CO2, saturating a stream of supercritical CO2. The tissue can be exposed to the water-saturated, supercritical CO2 at a treatment temperature of about 35° C. to about 40° C. (e.g., about 37° C.). In one embodiment, the water-saturated, supercritical CO2 is completely saturated with water at the treatment temperature. The tissue can be exposed to the water-saturated, supercritical CO2 at a constant flow rate, such as less than 3 mL/min (e.g., about 0.5 mL/min to about 2.5 mL/min).