NO EVIDENCE OF PIG DNA OR RETROVIRAL INFECTION IN PATIENTS WITH SHORT-TERM EXTRACORPOREAL CONNECTION TO PIG KIDNEYS

Background The xenotransplantation of organs and tissues, in particula r those from pigs, is viewed as a means to alleviate the shortage of h uman donor organs and cells available for transplantation and also as a therapy for other diseases. The potential microbiological hazards of xenotransplantation have recently attracted much attention. One conce rn is over pig endogenous retroviruses (PERV). Until the possible cons equences of infection by PERV are better understood it is unlikely tha t a significant number of porcine xenotransplants will proceed. Howeve r, a small number of patients have already been treated with dr expose d to living porcine cells or tissue, and investigation of these patien ts may provide valuable information. Methods We took serial blood samp les from two renal dialysis patients whose circulation had been linked extracorporeally to pig kidneys and tested them for pig DNA and PERV DNA by nested PCR. The patients' plasma was also tested for neutralisi ng antibodies to two anthropotropic PERV strains. Findings Having esta blished that the nested PCRs could detect single molecules of target s equence, we analysed DNA isolated from patients' peripheral blood mono nuclear cells. We found no evidence of pig or PERV DNA in either patie nt, even in samples taken as early as 6 h after the perfusion. Further more, we found no evidence of seroconversion for PERV-specific antibod ies. Interpretation The absence of porcine cells in the circulation of both patients, even in the samples taken soon after the perfusion exp eriment, suggests that any porcine cells dislodged from the kidney bec ame rapidly sequestered from the circulation. Since cell-to-cell conta ct increases the efficency of infection of PERV this removal of porcin e cells may increase the risk of transmission of PERV to the xenograft recipient. We did not, however, detect indications of infection by PE RV by PCR or neutralisation assay. The genetic and serological methods described here will be useful for detection of possible PERV infectio n in other patients.