Volume and differentiation of striatal grafts in rats: relationship to the number of cells implanted.

A growing body of evidence suggests that graft-mediated functional recovery in animal models of Huntington's disease is influenced by the morphology of the striatal grafts. Various parameters, including embryonic dissection, tissue preparation, and surgical delivery into the brain, have been investigated with the aim of increasing the proportion of the grafts comprising striatum-like tissue. While growing evidence suggests that implants derived from the selective dissection of the lateral ganglionic eminence (LGE) contain more striatal tissue, the relationship between the quantity of LGE tissue implanted and the striatum-like proportion of the resultant grafts has not been formally investigated. In this study the volume of striatum-like tissue within the grafts did not increase in a linear manner with increasing numbers of cells implanted. The proportion of the grafts that comprised the striatum-like patch compartment or P-zone remained constant after an initial rapid increase as the number of LGE cells implanted was increased. These results have important practical implications in determining the optimum number of LGE cells to implant and hence in the design of any surgical protocol for the clinical application of this technique.