Endovascular approach

Most trials have targeted the MCA or distal internal carotid artery as the principal site of injection. The types of catheters and microcatheters used in these studies are not always reported. We believe that microcatheters should be studied for compatibility with the cell product. There had been initial concern that too small an inner diameter could lead to cell damage during the delivery process. Every clinical trial should complete validation runs to test for biocompatibility as part of regulatory requirements. Various catheters have been tested for their impact on cell viability [12, 27, 28]. However, the functional effects of catheter passage using different types of media and solutions are not very well defined. Our preliminary findings suggest that the media, catheter passage, and exposure to heparin/contrast can play a role in activating certain cytokines released from the cells, and these changes might lead to different functionality of the cells [28]. With regard to needles, based on published reports, it appears that one can use even a 26-gauge needle without damaging the cells [27].