2.3. Cell culture
The mouse macrophage cell line, RAW 264.7 was maintained in Dulbecco’s modified Eagle’s medium (DMEM) supplemented with 10% fetal bovine serum (Hyclone Laboratories, Logan, USA),100 U/ml penicillin (Sigma) and 100 ug/ml streptomycin (Sigma) in a humidified 37◦C incubator. Cells were co-cultured with placenta extract for the indicated period of time and stimulated with 1g/ml LPS (Sigma) for 8 h for all analysis.