A membrane-free perfusion catheter comprising an exchange surface having a filament structure, a delivery unit for delivery of perfusion fluid to a lumen of the filament structure in a manner to allow for an exchange of substances between a medium surrounding the lumen and the perfusion fluid via the filament structure, and a drain unit for draining the medium surrounding the exchange surface and/or for draining the perfusion fluid delivered to the lumen of the filament structure after the exchange of substances between the medium surrounding the lumen and the perfusion fluid via the filament structure.
