Survival and functional recovery of transplanted human dopaminergic neurons into hemiparkinsonian rats depend on the cannula size of the implantation instrument

Promising therapeutic strategies for neurodegenerative diseases such as Parkinson's disease include replacement of lost striatal dopaminergic neurons by grafting of embryonic mesencephalic cells. However, the poor survival of the transplanted tissue still limits transplantation of these cells into the human brain in a larger number of patients. We addressed the question, if the diameter of the transplantation cannulas has an effect on the number of surviving transplanted human embryonic mesencephalic cells into the striatum of 6-OHDA lesioned rats. We report a significantly higher number of surviving human cells using an ultrathin micropipette compared to cannulas with wider diameters. Importantly, higher numbers of surviving cells also correlated with a behavioral recovery of the hemiparkinsonian rats.