Devices and methods are described herein for engraftment of stem cells into a pancreas using an endovascular approach. Targeted intra-arterial injection of stem cells selectively in a splenic artery can achieve engraftment of insulin producing cells in the tail of the pancreas with high efficiency and without systemic circulation of these cells to other organs. In one embodiment, a catheter device includes expandable occlusion elements in the form of inflatable balloons that can be used to isolate a proximal and distal end of a pancreatic portion of the splenic artery. In another embodiment, the occlusion elements include a filter element instead of a balloon. In some embodiments, targeted delivery of stem cells to the pancreatic tail can be achieved for treatment of, for example, diabetes. In some embodiments, an arterial section of the splenic artery can be isolated for selective perfusion of therapeutic cells/drugs to the tail of the pancreas.