Figure 1. Cartoon illustration of two key challenges facing cortical cell transplantation.

A. Multiple cortical cell types accumulate damage with age and need replacement. The co-transplantation of mixed precursor cell types, including vascular, glial, and neuronal precursors, could serve to replace cells of multiple types while enhancing the survival and function of transplant-derived neurons. B. Engineered cells that migrate prior to differentiating into neurons could be used to disperse new cells and circumvent the damage that would otherwise occur from closely arrayed injections of cells throughout the cortex.