The set-up for the tangential flow filtration included a Cole Parmer MasterFlex L/S Economy Drive 7554-90 pump, Cytiva (formerly Pall Lab) Minimate; TFF system reservoir kit, TFF system fittings kit and a pressure gauge (4 bar, 60psi) connected to a 300K Minimate™ tangential flow filtration capsules with omega membrane (Cytiva formerly Pall Lab). The water and DPBS used for TFF were autoclaved and sterile filtered through a 0.22 µm vacuum filter before use. The 300 kDa cut off membrane was first washed with water to remove storage buffer and salt particles. Then the buffer was exchanged to DPBS before the isolated supernatant from IM-HCEpiC was run through the membrane in the TFF. First, the sample was concentrated down to between 100-200 mL. Then the sample was run through at a high speed but with low pressure (the waste tubing flow was limited to ~1-1.5 drop/s and the speed of the pump was 60-100 mL/min and pressure was kept at ~0.5-1.5 bar). To achieve a good purity (99.9%), seven times the amount of DPBS relative to the concentrated sample was run through. The sample was then concentrated down to <50mL and collected. The volume was noted down and the sample was filtered through a 0.22 µm filter. A sample (1000 µL) for NTA was collected and stored in the fridge.