Scientists have been able to create artificial organs with varying degrees of success. The mechanical heart (in its various forms, e.g. ventricular assist) is able to sustain life for some period of time.
Efforts to grow whole organs in the lab will probably ultimately lead to a more pragmatic solution. What aspects of the renal physiology are standing in the way of an implantable mechanical kidney (fashioned more so from tubules and membranes than simply being a shrunken down dialysis machine)?