Abstract
In vitro−differentiated embryonic stem (ES) cells comprise a useful source for cell replacement therapy, but the efficiency and safety of a translational approach are highly dependent on optimized protocols for directed differentiation of ES cells into the desired cell types in vitro. Furthermore, the transplantation of three‐dimensional ES cell−derived structures instead of a single‐cell suspension may improve graft survival and function by providing a beneficial microenvironment for implanted cells. To this end, we have developed a new method to efficiently differentiate mouse ES cells into neural aggregates that consist predominantly (>90%) of postmitotic neurons, neural progenitor cells, and radial glia−like cells. When transplanted into the excitotoxically lesioned striatum of adult mice, these substrate‐adherent embryonic stem cell−derived neural aggregates (SENAs) showed significant advantages over transplanted single‐cell suspensions of ES cell−derived neural cells, including improved survival of GABAergic neurons, increased cell migration, and significantly decreased risk of teratoma formation. Furthermore, SENAs mediated functional improvement after transplantation into animal models of Parkinson's disease and spinal cord injury. This unit describes in detail how SENAs are efficiently derived from mouse ES cells in vitro and how SENAs are isolated for transplantation. Furthermore, methods are presented for successful implantation of SENAs into animal models of Huntington's disease, Parkinson's disease, and spinal cord injury to study the effects of stem cell−derived neural aggregates in a disease context in vivo. Curr. Protoc. Stem Cell Biol. 21:2D.11.1‐2D.11.19. © 2012 by John Wiley & Sons, Inc.