LATE BREAKING I

R. Aron badin¹, A. Padoan², M. Vadori³, M. Boldrin⁴, L. Cavicchioli⁵, G.M. De benedictis⁶, F. Fante⁴, M. Seveso⁴, D. Sgarabotto⁷, C. Jan¹, V. Daguin⁸, P. Naveilhan⁸, I. Neveu⁸, J. Soulillou⁸, B. Vanhove⁸, M. Plat⁹, F. Bottè⁹, V. Eric⁹, L. Denaro², R. Manara², P. Zampieri², D. D'avella², D. Rubello¹⁰, E. Ancona¹¹, P. Hantraye¹, E. Cozzi^12
1Mircen (molecular Imaging Research Center/cea), URA CEA-CNRS 2210, Fontenay-aux-Roses/FRANCE, ²Department Of Neurosciences, University of Padua, Padua/ITALY, ³, CORIT, Legnaro, Padova/ITALY, ⁴, CORIT(Consortium for Research in Organ Transplantation), Legnaro, Padova/ITALY, ⁵Veterinarypathology And Hygiene Institute, University of Padua, Padua/ITALY, ⁶Veterinary Clinical Sciences, University of Padua, Padua/ITALY, ⁷Department Of Infectious And Tropical Diseases, University of Padua, Padua/ITALY, ⁸, INSERM U643, Nantes/FRANCE, ⁹Physio Repro Reproduction Femelle Cr De Tours, Université de TOURS-Haras Nationaux, Nouzilly/FRANCE, ¹⁰Nuclear Medicine Service, S. Maria della Misericordia'' Hospital Rovigo, Rovigo/ITALY, ¹¹Clinica Chirurgica Iii, University Hospital of Padua, Padua/ITALY, ¹²Direzione Sanitaria, University Hospital of Padua, Padua/ITALY

Body: Background Neural transplantation, both allografting and xenografting, has been attempted as a therapeutic approach in Huntington (HD) and Parkinson (PD) patients with variable outcomes. Current data indicate that, due to the large number of cells needed and for ethical considerations, it is unlikely that neural precursors of human origin will represent a realistic source of cells for the treatment of the many patients in need. In this light, we studied what would be a suitable immunosuppressive strategy for long term cell survival, maturation and functional recovery using a challenging model of xenogeneic (pig) intrastriatal implantation of mesencephalic dopaminergic-enriched grafts in PD primates. Methods PD was induced in 12 non-human primates (macaca fascicularis) by repeated exposure to MPTP (0.25mg/kg). Once stable lesions were obtained, PD monkeys were unilaterally injected into 2 sites of the left putamen with cells from a dissection of the ventral mesencephalon of 9-10 CTLA4-Ig⁺ pig embryos (E27). Following transplantation, all primates were immunosuppressed using a clinically applicable immunosuppressive regimen based on the use of cyclosporin A, mycophenolate sodium (Myfortic^®, kindly donated by Novartis, Basel, CH) and steroids. All primates were closely monitored for clinical parameters. Evidence of xenograft survival and function was determined by daily clinical neurological assessment, videotaping and analysis of locomotor function (Ethovision software), brain imaging (positron emission tomography (PET) scan with ¹⁸F-L-DOPA), and histological studies at the end of each experiment. Results Xenografted animals have been monitored for up to 460 days post transplantation (with the longest surviving recipient still ongoing). Behavioral studies showed a very significant recovery of spontaneous locomotion in all grafted animals that is still observed after more than 15 months. Such recovery is associated with a partial restoration of dopaminergic activity detected by PET scans in at least 6 primates. Histological analysis of the brain from clinically improved animals revealed the existence of large porcine grafts composed of dopaminergic, serotoninergic and GABAergic differentiated neurons and various glial components. As PTLDs occurred in several longterm recipients, immunosuppressive drugs were reduced and 3 ongoing animals are being treated with subtherapeutic levels of the drugs. Conclusion These preliminary studies demonstrate that transplantation of CTLA4-Ig porcine embryonic grafts in the striatum of immunosuppressed parkinsonian primates may enable longterm xenograft survival and differentiation, associated with significant improvement of locomotor activity.

Disclosure: All authors have declared no conflicts of interest.