Stem cell-derived neurons grafted in the striatum are expelled out of the brain after chronic cortical stroke.

BACKGROUND AND PURPOSE: In humans and rodents, cortical stroke can lead to cortex atrophy in long-term survivors. In the rodent, fetal brain neural precursors or stem cell-derived neurons grafted in the stroke-lesioned brain integrate successfully and reduce infarct in the short term. We have examined the fate, in the long term, of mouse embryonic stem cell-derived neural precursors grafted after permanent middle cerebral artery occlusion in mice. METHODS: Green fluorescent protein-labeled neural precursors were grafted in the striatum of control and lesioned mice and their fate examined 9 months later. RESULTS: In control mice, the neuronal progeny of mouse embryonic stem cells innervated distant brain structures, in a way remarkably similar between animals, displayed a laterality preference and remained polysialated neural cell adhesion molecule-immunoreactive. In lesioned mice, grafted cells were expelled out of the brain. CONCLUSIONS: Stroke-related brain atrophy and reshaping were not prevented by cell grafting and, eventually, led to the expulsion of the graft.