Methods Administered dose of PERC to NHEK were determined according to neutral red uptake(NRU)assay with free serum culture in vitro.

• [方法]用0.；25%25的胰蛋白酶经冷温两步消化皮肤；分离得到NHEK；进行体外无血清培养; 用中性红吸附试验(NRU)测定PERC对NHEK的中性红吸附减少50%25的浓度(NR50值)；并据此确定PERC细胞毒性试验的染毒剂量;