Extracorporeal cell-based therapeutic devices and delivery systems are disclosed which provide a method for therapeutic delivery of biologically active molecules produced by living cells in response to a dynamic physiologic environment. One embodiment includes long hollow fibers in which a layer of cells are grown within the intraluminal volume or within a double hollow-filled chamber. Another embodiment includes a wafer or a series of wafers providing a substrate onto which cells are grown. The wafer(s) are inserted into a device. A device may deliver a pre-selected molecule, for example, a hormone, into a mammal's systemic circulation and/or may deliver a member of different cell products. The device is adapted to secure viable cells which produce and secrete the pre-selected molecule into blood or fluid. The invention also provides a minimally invasive method for percutaneously introducing into a preselected blood vessel or body cavity the device of the invention.