Analysis of patients treated with living pig tissue for evidence of infection by porcine endogenous retroviruses

The use of pigs as a source of cells and organs for transplantation has the potential to reduce the cur-rent chronic shortage of organs for the treatm ent of many end-stage diseases. The risk of transmission of infectious agen ts across the species bat-tier (zoonoses) has to be assessed. Many such age nts can be eliminated from the pig herd. However, porcine endogenous retrov iruses, which are carried within the pig genome, are not easily eliminated. They can infect primary and immortalized human cells in vitro, but to date no evidence for in vivo infection has been found in retrospective studies of humans exposed to viable porcine cells. Small-scale clinical trials usin g porcine cells for the treatment of Parkinson and Huntington's disease are currently in progress. The prospective monitoring of these patients in con junction with further research into the biology of this virus will help add ress safety issues. (C) 2001, Elsevier Science Inc.