No evidence for infection of human cells with porcine endogenous retrovirus (PERV) after exposure to porcine fetal neuronal cells

Background. Recent demonstration of human cell infection in vitro with porc ine endogenous retrovirus (PERV) has raised safety concerns for new therapi es that involve transplantation of pig cells or organs to humans. To assess better the specific risk that may be associated with the transplantation o f fetal pig neuronal cells to the central nervous system of patients suffer ing from intractable neurologic disorders (Parkinson's disease, Huntington' s disease, and epilepsy), we have performed studies to determine whether th ere is evidence for in vivo or in vitro transmission of PERV from fetal pig neuronal cells to human cells. Methods. Ventral mesencephalon (VM) and lateral ganglionic eminence cells w ere isolated from fetal pigs and transplanted into patients with neurologic al conditions as part of clinical studies. Blood samples taken from patient s at various time points posttransplant were tested for evidence of PERV. I n vitro studies to test for PERV infection of human cells after cocultivati on with either fetal porcine ventral mesencephalon or porcine fetal lateral ganglionic eminence cells were also performed. Results. We found no evidence of PERV provirus integration in the DNA from PBMC of 24 neuronal transplant recipients. In addition, no PERV was release d from cultured fetal porcine neuronal cultures, and there was no transfer of PERV from fetal pig neuronal cells to human cells in vitro, Conclusions. Our results demonstrate by both examination of transplant pati ent blood samples and in vitro studies that there is no evidence for transm ission of PERV from porcine fetal neural cells to human cells.