Abstract
In contrast to the whole liver, primary hepatocytes are highly immunogenic. Thus, alternative strategies of immunomodulation after hepatocyte transplantation are of special interest. Silencing of HLA class I expression is expected to reduce the strength of allogeneic immune responses and to improve graft survival. In this study, primary human hepatocytes (PHH) were isolated using a two-step-collagenase perfusion-technique and co-cultured with allogeneic lymphocytes in terms of a mixed lymphocyte hepatocyte culture. Expression of HLA class I on PHH was silenced using lentiviral vectors encoding for β2-microglobulin-specific short hairpin RNA (shβ2m) or non-specific shRNA (shNS) as control. The delivery of shβ2m into PHH caused a decrease by up to 96% in β2m transcript levels and a down-regulation of HLA class I cell surface expression on PHH by up to 57%. Proliferative T cell alloresponses against HLA-silenced PHH were significantly lower than those observed form fully HLA-expressing PHH. In addition, significantly lower secretion of pro-inflammatory cytokines was observed. Levels of albumin, urea and aspartate-aminotransferase did not differ in supernatants of cultured PHH. In conclusion, silencing HLA class I expression on PHH might represent a promising approach for immunomodulation in the transplant setting without compromising metabolic function of silenced hepatocytes.