ARID1A PDX Growth in Dental Sponges

The ARID1A mutant Patient-Derived Xenograft AB555B was grown in dental sponges as previously described ^{47 (link),48 (link)}. Spongostan gelatine dental sponges were pre-soaked in explant culture media with or without inhibitors (250 nM JQ1 and 1 µM IBET762) and warmed in a 37°C incubator. One sponge per well was placed in a sterile 24-well tissue culture plate, along with 500 µl explant culture media RPMI 1640 (phenol red-free, L-glutamine-free) (Gibco, 32404-014) with 10% heat inactivated fetal bovine serum (Gibco A3840401), 2mM L-glutamine (Sigma G7513), 10 µg/ml Sigma hydrocortisone (Sigma H0888), 10 µg/ml human recombinant insulin (Sigma I9278)), 100 U penicillin, 100 µg streptomycin, 250 ng amphotericin B /ml (from 1x Sigma anti-biotic, anti-mycotic solution; #A5955). PDX material was cut into 9-12 smaller pieces and each piece was analysed as a replicate. Samples on the sponges were incubated with media with inhibitors for 2 days at 37°C with 5% CO₂. These were collected from sponges and fixed in 10% neutral buffered formalin overnight at room temperature. Tissues were processed and embedded in paraffin for histological assessment. Slides were scanned on an Aperio AT2 (Leica) at 20X magnification (resolution 0.5um per pixel) and analysed using HALO software (Indica labs), with the multiplex IHC v2.1.1 module.