*2.6. Cell Culture and Proliferation*

MRC-5 cells were used to assess the cell culture and proliferation. The cells were cultured in a humidified chamber containing 5% CO2 at 37 ◦C using Dulbecco's modified eagle's medium/F-12 (DME/F-12) containing 10% fetal bovine serum. Extraction experiment was carried out according to the instruction of ISO 10993-12: 2002. Serum free cell culture medium (DME/F-12) was used to obtain the extraction media of the GZ0, GZ1 and GZ2. The extraction ratio (the ratio of sample quality to extraction medium) was 0.1 g·mL−1. GZ0, GZ1 and GZ2 soaked in the medium were incubated in a humidified atmosphere with 5% CO2 at 37 ◦C for 24 h. Cell culture medium (DME/F-12) was used as a negative control.
