An apparatus is disclosed for differentially treating a medical device. One portion of the device is treated with a first fluid and a separate portion is treated with a second fluid. The second fluid generally is substantially different from the first fluid. The first fluid can be contacted with an flow region of the medical device. The apparatus can include a conduit system, where fluid flowing through the conduit system flows through the flow region. Sheet material can be treated differentially on the opposite surfaces of the sheet. The medical device can include vascular tissue.