Alpha minimum essential medium α mem

Human embryonic kidney (HEK) 293T cells, mouse melanoma B16-F10 cells, and mouse embryonic fibroblast BALB/3T3 cells were obtained from the Bioresource Collection and Research Center (BCRC, Hsinchu City, Taiwan, ROC). These cells were cultured in Dulbecco’s modified Eagle’s medium (DMEM; Invitrogen, Gaithersburg, MD, USA) supplemented with inactivated 10% foetal bovine serum (FBS; Invitrogen) and 1% penicillin–streptomycin amphotericin B (PSA; Biological industries, New York, NY, USA). Human natural killer NK-92 MI cells were grown in alpha minimum essential medium (αMEM; Sigma-Aldrich, St. Louis, MO, USA) supplemented with 0.2 mM inositol (Sigma-Aldrich), 0.2 mM 2-mercaptoethanol (Sigma-Aldrich), 0.02 mM folic acid (Sigma-Aldrich), 12.5% horse serum (Gibco BRL, Gaithersburg, MD, USA) and 12.5% FBS. All cells were incubated at 37 °C in an atmosphere of 5% CO₂.
Male C57BL/6 mice (6–8 weeks old) were purchased from the National Laboratory Animal Center (NLAC, Taipei City, Taiwan, ROC).
1,2-Dioleoyl-sn-glycero-3-phosphocholine (DOPC) (Avanti Polar Lipids, Inc., Alabaster, AL, USA), 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC) (Avanti Polar Lipids, Inc.) and polyethylene glycol (PEG, MW 1.500) (Shimo-Meguro, Meguro-Ku, Tokyo, Japan), PEG (MW 8.000, Sigma-Aldrich) and polyethylenimine (PEI, branched, MW 25.000, Sigma-Aldrich) were purchased to prepare LPPC.