The morphology, integration, and functional efficacy of striatal grafts differ between cell suspensions and tissue pieces

In order to develop a surgical protocol for use in clinical trials of stria tal transplantation in Huntington's disease (HD), the issues involved in th e preparation and implantation of the embryonic striatal tissue must be add ressed. Rodent models of HD offer the best experimental paradigm with which to study various aspects of striatal transplantation. In this article we p resent the results of an investigation of the role of trypsin and the proce ss of trituration in the preparation of cell suspensions compared to the us e of solid pieces of tissue. The embryonic material was derived from the la teral ganglionic eminence (LGE) and implanted into the excitotoxically lesi oned striatum of the host rats. Twelve weeks following implantation, retrog rade tracing of projections from the graft to the globus pallidus was perfo rmed. Grafts derived from cell suspensions triturated in the presence of tr ypsin contained larger quantities of striatal tissue within the graft and m ore DARPP-32-positive medium spiny neurons than grafts implanted as fragmen ts of tissue. Afferent and efferent connectivity was also better in the try psinized suspension graft group. Modest recovery in paw reaching was observ ed contralateral to the grafted side in animals implanted with solid fragme nts of embryonic striatal tissue. No relationship was observed between func tional effect and the graft anatomy. These results suggest that local graft -host interaction may also be involved in graft-mediated functional recover y.