Abstract
The fate of grafted neuroepithelial stem cells in the mature brain environment was assessed to confirm their feasibility in the functional repair of damaged neural circuitry. The neuroepithelial stem cells were harvested from the mesencephalic neural plate of enhanced-GFP-carrying rat embryos, and implanted into the striatum of normal adult rat or Parkinson's disease model rat. The differentiation pattern of donor-derived cells was monitored immunohistochemically. The functional abilities of the donor-derived cells and communication between them and the host were investigated using host-rat brain slices incorporating the graft with whole-cell patch-clamp recording. Vigorous differentiation of the neuroepithelial stem cells into mostly neurons was noted in the short-term with positive staining for tyrosine hydroxylase, suggesting that the donor-derived cells were following their genetically programmed fate. In the long-term, the large number of donor-derived neurons was sustained, but the staining pattern showed appearance of medium spiny or cholinergic neurons, suggesting that some neurons were following environmental cues. Some donor-derived astrocytes were also seen in the graft. Firing pattern and membrane properties suggest the presence of both dopaminergic and non-dopaminergic neurons in the donor-derived neurons. Glutamatergic and GABAergic post-synaptic currents could be evoked by electrical stimulation applied in the host region. Neuroepithelial stem cells are therefore an attractive candidate as a source of donor material for intracerebral grafting in functional repair. [J Physiol Sci. 2006;56 Suppl:S38]
