The rationale for transplantation Unlike other tissues in the body, the adult brain has a limited ability to generate new cells to replace dead ones. In Parkinson s disease, the idea is to replace the dopamine-producing neurones that have died with younger neurones that can restore function and promote repair. Successful tissue transplantation provides an advantage over drug therapy as it replenishes brain dopamine by replacing the dead cells with new ones. Donor tissue sources Sources of donor tissue for transplantation present ethical dilemmas that must be addressed. Potentially there are a number of tissue sources that can be used.
Experiments show that transplanted neurones spontaneously release dopamine to near-normal levels.
Tissue transplantation from a donor and a host of the same species is known as allotransplantation. However, ethical and practical problems are posed by human allotransplantation which requires as many as eight human foetal donors for a successful transplantation. This limits the use of human tissue and has led to finding alternative donor sources. Tissue transplantation from one species to another is called xenotransplantation. Since donor tissue needs to be compatible with the host tissue, it is limited to large mammals with similar brain structure such as pigs and the great apes.