Filtration devices, and systems and methods for using them

A filtration device, comprising:

• a tubular outer member comprising a proximal portion, a distal portion sized for introduction into a body lumen, and a first lumen extending between the proximal portion and an outlet in the distal portion;
• an elongate inner member slidably disposed within the first lumen such that a distal end of the inner member extends from the outlet and a proximal end is disposed adjacent the proximal portion;
• a plurality of tubular porous members comprising first ends attached to the distal portion of the outer member and second ends attached to the distal end of the inner member and a plurality of segments spaced apart axially between the first and second ends such that axial movement of the inner member relative to the outer member axially compresses or extends the porous members to expand and collapse the segments;
• and
• filtration media within the segments of the porous members configured to adsorb or bind one or more agents from fluid passing through the porous members.