Activation of primary porcine endothelial cells induces release of porcine endogenous retroviruses.
BACKGROUND
Endothelial cells form the interface between the porcine graft and the recipient and frequently become activated after xenotransplantation. To evaluate the safety of xenotransplantation further, we assessed the effect of cellular activation on the expression and release of porcine endogenous retroviruses from primary endothelial cells isolated from transgenic and nontransgenic pigs.


METHODS
Primary porcine endothelial cells, cultured from pigs transgenic for human decay accelerating factor, were treated with human tumor necrosis factor-alpha, porcine interferon-gamma, or lipopolysaccharide. The release of porcine endogenous retroviruses into the supernatant was monitored at 24-hr intervals (up to 72 hr) by polymerase chain reaction-based reverse transcriptase (PBRT) assay. Activated and unactivated endothelial cells were co-cultured with human cells to investigate the capacity of any virus released from the porcine cells to infect human cells.


RESULTS
Virus was not detected in supernatants from quiescent cells by PBRT analysis. The number of viral particles released from endothelial cells was 10 to 5 x 10 viral particles/mL after cellular activation with tumor necrosis factor-alpha, interferon-gamma, or lipopolysaccharide, as shown by PBRT analysis. In contrast, in vitro infection of human cells was observed with unactivated endothelial cells only and was not observed in co-cultures with the activated porcine cells.


CONCLUSIONS
Cytokine treatment of primary porcine endothelial cells results in an increase in the release of virus into the supernatant, but the observed increase in viral titer was not mirrored by an increase in infectivity toward human cells.
Cunningham
Deirdre A
DA
Department of Parasitology, National Institute for Medical Research, Mill Hill, London, United Kingdom. deirdrecunningham@cunning48.freeserve.co.uk
Dos Santos Cruz
Gabriella J
GJ
Fernández-Suárez
Xosé M
XM
Whittam
Alison J
AJ
Herring
Christopher
C
Copeman
Laura
L
Richards
Andrew
A
Langford
Gillian A
GA
D000818:Animals; D018958:CD55 Antigens / Q000502:physiology*; D002478:Cells, Cultured; D020077:Endogenous Retroviruses / Q000302:isolation & purification*; D042783:Endothelial Cells / Q000821:virology*; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000494:pharmacology; D016133:Polymerase Chain Reaction; D013552:Swine / Q000821:virology*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D018958:CD55 Antigens; D008070:Lipopolysaccharides; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma