Other sources of cells for transplantation

In the preceding chapters we have considered the development of neural transplantation for application in a variety of human neurological diseases. The most obvious and advanced applications are to Parkinson’s disease, but it is clear that important applications are already under consideration and development for a variety of other human neurodegenerative conditions. The strategy has been to identify the cells which are lost and to assess the efficacy of their replacement in animal models of the human disease. For the most part, the most effective techniques have been to seek replacement by primary neurones taken from embryos: i.e. replacement is with the same population of neurones that are lost, but harvested from a donor at an early stage in development when the cells are dividing and growing processes to their appropriate targets in the adult host brain. This strategy has proved remarkably successful when assessed experimentally in the laboratory and gives every appearance of also having the potential for efficacy in the clinic. However, there is an obvious problem with this approach. The use of primary human foetal donors required by this strategy for clinical application raises a range of both practical and ethical problems. As a consequence there is an extremely limited availability of cells, which has proved to be the main restriction on a more rapid and widespread development of neural transplantation technologies into the clinic.