Vybrant dio dye

ECFC-exosomes were labelled with Vybrant DiO dye (Molecular Probes, Carlsbad, CA, USA) according to the manufacturer's instructions. The labelled exosomes (8 μl) were incubated with HMECs at 37 °C for 2 h. HMECs were washed with PBS, fixed in 4% paraformaldehyde for 15 min, and stained with DAPI for 5 min at room temperature. After washing, the cells were analysed using a fluorescence microscope (Leica DMI6000B, Solms, Germany).

3T3, 3T3-FAP, and PDAC299 cells were grown to 80% confluency in 96-well plates and incubated with DTPA-700DX-MB in binding buffer (DMEM with 0.5% w/v BSA, BB) or with BB alone at 37 °C in a humidified atmosphere with 5% CO₂ for 2.5 h. After washing with PBS, regular culture medium was added. The cells were then exposed to 0 or 60 J/cm² 690 nm light at a fluency rate of 200 mW/cm². Cell viability was measured 24 h after tPDT using the CellTiter-Glo assay (Promega, Madison, WI, USA). Furthermore, 3T3-FAP cells were labelled with Vybrant DiO dye according to manufacturer’s protocol (Thermo Fisher Scientific, Waltham, MA, USA) and cocultured with PDAC299 tumour cells in Costar 96-well flat-bottom, clear plates in DMEM with 10% FCS. Cells were incubated with 3 nM DTPA-700DX-MB for 2 h at 37 °C, and upon washing, the plate was irradiated with 60 J/cm² 690 nm light. After 24 h, the cells were incubated with 1 µg/mL propidium iodide (PI) in PBS. After washing twice with PBS, cells were imaged with the EVOS FL cell imaging system with the suitable LED cubes (PI = RFP; DiO = GFP).