Reduced xenograft rejection in rat striatum after pretransplant photodynamic therapy of murine neural xenografts

Object. The goal of this study was to develop a method of reducing neural x enograft rejection by pretreating the graft with photodynamic therapy (PDT) . Methods. Xenograft cell suspensions were prepared from fetal mouse mesencep halon, after which they were incubated for 30 minutes with various concentr ations of a photosensitizer. verteporfin for injection, and light exposure. The xenograft cell suspensions were injected into the dopamine-depleted st riata of 40 hemiparkinsonian rats assigned to different treatment groups. F our weeks after transplantation, xenograft function (determined by methamph etamine-induced rotation) and survival (determined by immunohistochemical s taining for murine neurons) were compared. Group 1 animals (xenografts pret reated with 25 ng/ml verteporfin) and Group 3 animals (no verteporfin pretr eatment, but daily administration of cyclosporin A) had significantly bette r xenograft survival and function compared with control animals (no pretrea tment with verteporfin). Group 2 animals (xenografts pretreated with 250 ng /ml verteporfin) had no significant improvement. Conclusions. This work demonstrates improved neural xenograft survival and function when using pretransplant PDT of the graft in a rodent model. The p otential benefits of this new therapy are its convenience (one pretransplan t treatment) and its compatibility with host immunosuppression.