The morphological development of neurons derived from EGF- and FGF-2-driven human CNS precursors depends on their site of integration in the neonatalrat brain

Neural precursor cells derived from the developing human brain were expande d in vitro under the influence of fibroblast growth factor-2 (FGF-2) and ep idermal growth hormone (EGF), and were then transplanted into different reg ions of the neonatal rat brain. Four weeks later neurons were seen to have developed from human embryonic precursors, using a human-specific antibody to tau (htau). There were morphological differences between implanted neuro ns developing in the hippocampus, striatum and neocortex, which were confir med by cell volume measurements, although no specific neurochemical phenoty pes were identified. Htau-positive fibres were seen to project extensively along fibre pathways appropriate for the site of neuronal integration. This study demonstrates that, following cell division in vitro, neurons differe ntiating from human precursor cell populations retain the ability to respon d appropriately to regional determinants present in the neonatal rat brain. This is important for the application of such cells in CNS repair strategi es, in particular neural transplantation.