Samples were obtained with informed consent. A detailed protocol learn more for gastric culture is provided in the Supplementary materials. Briefly, glands were extracted from 1 cm2 of human tissue using EDTA in cold chelation buffer,17 seeded in Matrigel (BD Biosciences), and overlaid with medium containing advanced Dulbecco’s modified Eagle medium (DMEM)/F12 supplemented with penicillin/streptomycin, 10 mmol/L HEPES, GlutaMAX, 1 × B27 (all
from Invitrogen), and 1 mmol/L N-acetylcysteine (Sigma-Aldrich). Growth factors were added to the basal medium as indicated in the Figures. The final human stomach culture medium contained the following essential components: 50 ng/mL epidermal growth factor (EGF) (Invitrogen), 10% noggin-conditioned medium, 10% R-spondin1–conditioned medium, 50% Wnt-conditioned medium, 200 ng/mL fibroblast growth factor (FGF)10
(Peprotech), 1 nmol/L gastrin (Tocris), and 2 μmol/L transforming growth factor (TGF)βi (A-83-01; Tocris). The facultative component was 10 mmol/L nicotinamide (Sigma-Aldrich). After seeding, 10 μmol/L RHOKi (Y-27632; Sigma-Aldrich) was added. Additional tested components were as follows: 100 ng/mL insulin-like growth factor (IGF) (Peprotech), 10 μmol/L p38 inhibitor (SB202190; Sigma-Aldrich), 3 μmol/L GSK3β inhibitor (CHIR99021; Axon Medchem), and 500 nmol/L prostaglandin E (PGE)2 (Tocris). Approximately 1 cm2 of cancer tissue was cut into small fragments and washed in cold chelation buffer until the supernatant was clear. Fragments were subjected to enzymatic Ergoloid digestion by 1.5 mg/mL collagenase (Gibco) and VX-809 nmr 20 μg/mL hyaluronidase (Sigma) in 10 mL advanced
DMEM/F12 (Gibco), supplemented with antibiotics (Primocin; Invivogen), for 1 hour at 37°C with shaking. Cells were washed twice in advanced DMEM/F12, seeded into Matrigel, and overlayed with medium containing HEPES, GlutaMAX, penicillin, streptomycin, B27, n-acetylcysteine, EGF, R-spondin1, noggin, Wnt, FGF10, gastrin, TGFβ inhibitor, and RHOK inhibitor as described earlier. Bacterial strains and culture conditions are specified in the Supplementary materials. For infection studies, organoids were seeded in 50 μL Matrigel in 4-well multidishes (Thermo Scientific). Antibiotic-free medium was refreshed every 2–3 days, with a minimum of 3 medium changes before infection to allow removal of antibiotics from the culture. Organoids were microinjected on day 10 after seeding with an approximate multiplicity of infection (MOI) of 50 unless otherwise stated. For calculation of MOI, organoids were disrupted into single cells by EDTA and cells were counted (approximately 4000 cells/organoid). To achieve a final MOI of 50, bacteria were suspended in advanced DMEM/F12 at a density of 1 × 109/mL and organoids were injected with approximately 0.2 μL bacterial suspension using a micromanipulator and microinjector (M-152 and IM-5B; Narishige) under a stereomicroscope (MZ75; Leica) inside a sterile bench (CleanAir).