This video demonstrates an in vitro assay evaluating the cytotoxic effects of CAR T cells on 3D tumor spheroids expressing fluorescent proteins. This assessment utilizes the Annexin V red fluorescent probe, which binds to exposed phosphatidylserine residues on the outer leaflet of apoptotic cancer cells after interactions with CAR T cells. The red fluorescence emitted by the probe aids in distinguishing these cells from healthy ones emitting green fluorescence.
Protocol
1. 3D Tumor Spheroid Killing Assay After 6 days or once spheroids reach the desired size, remove the plate from the incubator. Using a multichannel pipette, gently remove 100 µL/well of complete RMPI 1640 medium from the spheroid plates. For this step, angle the tips towards the inside wall of the 96-well plate, avoiding contact with the bottom of the well in order to minimize disturbance of the spheroids. The remaining volume should be around 100 …