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Xenotransplantation promising in Parkinson's disease A team of US researchers report this month on the safety and clinical effects of implantation of pig embryonic cells into the brains of patients with Parkinson's disease. In the study --the first, say the authors, to look at xenotransplantation of neural tissue into people--clinical benefits varied between patients but there were no serious adverse events. Author Samuel Ellias (Boston Medical Center, Boston, MA, USA), says he is "encouraged by this first step in the clinical testing of this new potential therapy for Parkinson's disease". After 10 years of treatment, most patients with Parkinson's disease have disabilities that cannot be satisfactorily controlled by drugs such as levodopa. This problem has spurred on the search for alternative treatments that might improve long-term outcome. Transplantation of human embryonic mesencephalic tissue has been one of the most promising approaches. However, this tissue is available only in limited amounts and there are ethical concerns associated with its use. Thus, researchers have turned to the pig as an alternative donor: porcine and human dopaminergic neurons are similar physiologically and porcine xenografts have corrected motor deficits in animal models of Parkinson's disease. In the new study, central mesencephalic-cell suspensions prepared from embryonic porcine fetuses were implanted in 12 patients with advanced idiopathic Parkinson's disease. The transplantation was done under local anaesthesia. 12 million cells were deposited unilaterally in the striatum. Six patients received immunosuppression with cyclosporin; in the other six patients, the embryonic pig cells were pretreated with the F(ab9)2 fragment of a monoclonal antibody against MHC class I. Cloned pigs bring xenotransplantation nearer On March 14, PPL Therapeutics announced that five cloned piglets were born on March 5 at its US facility. The birth, says the company, "opens the door to making modified pigs whose organs and cells can be successfully transplanted into humans". The piglets were made by nuclear transplant, as was Dolly the sheep, but new techniques had to be developed to accommodate the pig's unique reproductive biology. Jane Bradbury 1 year after transplantation, the total score in a unified Parkinson's disease rating scale had improved by an average of 19% in the medication-off state of ten evaluable patients. The improvement was similar in patients given cyclosporin and in those given porcine cells pretreated to mask the MHC complex. Improved scores in the "off" state related mainly to gait and activities of daily living. However, fluorodopa uptake was not increased within the striatum sites where cells had been implanted. Importantly, porcine endogenous retrovirus DNA sequences in peripheral blood mononuclear cells were not detected in any patient at any time after surgery (Neurology 2000; 54: 1042-50 [PubMed]). Robert Hauser (University of South Florida, Tampa, FL, USA) comments that "this initial study offers hope that the replacement of lost dopaminergic cells through [xeno]transplantation may become a viable treatment". Ellias adds that "a double-blind, controlled trial with a larger number of porcine cells implanted into both sides of the brain is in progress to further assess the safety and efficacy of xenotransplantation in Parkinson's disease". by Xavier Bosch Journal: The Lancet ISSN : 0140-6736 Volume : 355 Issue : 9208 Date : 18-Mar-2000 http://www.thelancet.com/ janet paterson 53 now / 41 dx / 37 onset a new voice: http://www.geocities.com/janet313/ 613 256 8340 PO Box 171 Almonte Ontario Canada K0A 1A0