Magnetic-activated cell sorting (MACS) is a method for separation of various cell populations depending on their surface antigens (CD molecules) invented by Miltenyi Biotec. The method was developed with Miltenyi Biotec’s MACS system, which uses superparamagnetic nanoparticles and columns. The 100 nm superparamagnetic nanoparticles are used to tag the targeted cells in order to capture them inside the column. The column is placed between permanent magnets so that when the magnetic particle-cell complex passes through it, the tagged cells can be captured.