Abstract: In some embodiments, a flow system includes a medical device mount, fluid and a conduit containing the fluid and medical device mount. The conduit is mounted on an assembly that moves the conduit along with the medical device mount to induce relative motion of the fluid relative to the medical device mount. In preferred embodiments, pulsatile fluid motion is generated. In some embodiments, the fluid includes viable cells. In alternative embodiments, a flow system includes a continuous flow pump connected to a conduit loop having multiple branch conduits downstream from the pump providing alternative paths over a section of the conduit loop. Each branch conduit has a valve controlling flow through the branch. In some embodiments, at least one branch includes a medical device mount.