The use of cell transplantation in the brain shows great promise for the treatment of human neurological diseases, such as Parkinson's disease or stroke. Indeed, pre-clinical studies in animal models have shown significantly improved neurological function following cell grafting. However, in human trials the results have been considerably more variable. This has, in part, been attributed to concerns with poor cell distribution within the target area. A further issue that has arisen with the challenge of scaling up from animal models to humans is the increase in the number of transcortical penetrations required to deliver therapeutic agents. For surgical cell transplantation approaches, cell sedimentation and impaired graft viability are also concerns that need to be addressed to optimize the use of this therapeutic avenue.