Clinical translation of cell transplantation in the brain.

PURPOSE OF REVIEW: We identify the major recent advances in sourcing, preparation and delivery of primary and stem cell transplants into the brain, the preclinical studies in animal models and preliminary results on feasibility, safety and efficacy in an increasing range of human neurodegenerative diseases.

RECENT FINDINGS: After a decade of debate concerning the reliability and safety of foetal cell transplantation in Parkinson's and Huntington's diseases, the conditions for eliminating side-effects and achieving more consistent efficacy are being implemented in renewed trials. In parallel, rapid advances are being made in identifying alternative sources of stem cells for transplantation, establishing the protocols for their reliable differentiation into specific neuronal phenotypes and translating these novel sources to cell therapy for patients in new clinical trials. Objective assessment of efficacy in patients does not always reveal outcomes that are as impressive as claimed - either in the preclinical animal models or by many commercial stem cell clinics - and even when stem cell therapies do appear to have been validated, the mechanisms are not always clear.

SUMMARY: In spite of rapid progress, the conditions for reliable, well tolerated and effective cell therapies in brain disease are not yet fully established.