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Congratulations Jim Finn on your appearance in CBS "60 Minutes" tonight. Your part was small but very impressive. For those who want to dig deeper, here are some extracts with library references from past issues of Current Science Reviews, that mention pig cell implants: (news item): Science News, 7 Oct 1995;148:230: Fetal tissue for grafting in PD surgery is not only controversial but scarce: There is only a narrow window of gestation age where the transplant is viable, spontaneous or ectopic sources don't work,and 5 or more fetuses are required for each transplant. A PET scan after 5 months confirmed the first successful graft using pig embryo cells, and 2 of 3 patients showed symptomatic improvement. Researchers will continue trials to establish safety and to see if immunosuppression can be avoided. Science, 24 Jan 1997:473 (news item): In a possible setback for PD surgery, a British panel cautiously approved "research" on transplantation of pig organs to humans, but not "clinical trials", and the government set up a new bureau to oversee any work in the field. BMJ, 1 Mar 1997:625 (news item): Although fetal pig cell transplants are finding success in PD trials, the British government has been cautious about any interspecies transplant, partly because of the fear that a retrovirus may gain a foothold in the human population. (A retrovirus is one that, like the HIV viruses, reproduces by subverting the host's DNA.) One such porcine retrovirus was found capable of infecting other mammalian species, with greater risk if host immunity is suppressed. Schumacher J et al; Nature Medicine 1997;3:474-475: Frosty but intense debate over risk that xenografts (e.g., porcine fetal tissue for Parkinson's Disease) might introduce new viral disease into the human population. Deacon T et al; Nat Med 1997;3:350-353: Histological study following unrelated death of a PD patient 7 months after transplant of fetal pig neural cells showed that they had thrived. Lancet, 20 Sep 1997;868 (news item): Debate continues over grafting animal tissue or organs into humans. Breeding of genetically altered pigs has resolved the hyperacute rejection problem, but the porcine endogenous retrovirus still might produce new pathogens transmissible by humans. Sanberg P et al; Nat Med 1997;3:1129-1132: Ethical and logistic problems of fetal tissue inspire a search for other sources of dopaminergic cells. A promising candidate is the Sertoli cells of the testis, readily obtainable from adult cadavers or pigs rather than aborted human fetuses, and which have improved parkinson symptoms in rat experiments. Le Tissier P et al; Nature, 16 Oct 97:681-682 and: Lancet, 18 Oct 97:1148 (news item): A retrovirus survives by invading and corrupting its host DNA, thus ensuring its transmission from one generation to the next. Some RVs cause illness in the host; others are harmless to the host but may cause illness in humans or other species. Two such dangerous RVs were found in pigs, and it looks unlikely that they can be bred out; so the future of pig cell transplants in PD for now seems bleak. Isacson O, Breakfield X; Nature Medicine 1997 Sep;3(9):964-969: Comprehensive review of benefits/risks in animal-tissue CNS grafts. Detailed analysis of 2 examples: replacement of dopamin- ergic neurons lost in PD, and apoptosis-gene transfer for suppression of brain tumors. Fetal transplants for PD, either human or animal, risk transmitting infection. An impediment to use of human tissue is the need to pre-screen the prospective mother's blood. Pig fetal cells may carry retroviruses (agents that subvert host nucleic DNA) dangerous to humans. The safest prospect is cells cultured and well-screened in the laboratory. Bach F et al; Nat Med 1998;4:141-144: After recent success with pig cells for PD, government agencies such as the National Research Council and the FDA are concerned about ethical aspects of xenotransplantation; specifically, the unknown risk of retroviral infection that might spread to the entire human species. Authors propose a moratorium until some unspecified but general public review takes place. Lancet; 31 Jan 1998;343 (news item): The US Public Health Service plans to regulate xenotransplantation by means of a standing advisory committee, registry of trials and recipients, specimen repository, possible post-trial monitoring. Cheers, Joe J. R. Bruman (818) 789-3694 3527 Cody Road Sherman Oaks, CA 91403-5013