Régénération du foie humain transplanté : expression génique au moment de l'implantation du greffon

: The liver tissue mRNA expression of protooncogenes c-fos, c-myc, c-Ha-ras, c-met and c-erb B1, and TGF alpha and TGF beta genes is sequentially and temporarily increased in the early stages after partial hepatectomy, ischaemia or other mitogenic stimuli. These gene expressions were studied in 38 samples of liver tissue from 24 patients who underwent orthotopic liver transplantation, at different evolution stages. Eleven samples were obtained from surgical liver biopsies before graft implantation at day 0 (Group A), 14 samples from percutaneous liver biopsies during the post-operative period from day 9 to day 48 (Group B) and 13 samples in the long-term follow-up period from day 102 to day 1,382 (Group C). Gene expression was studied using 32P-labeled cDNA and oligonucleotidic probe hybridization in slot blots. A GAPD gene was used as a control gene. All expression values of protooncogenes were related to those of the GAPD gene. After cold ischaema, the relative gene expression (quantity of specific mRNA/quantity of GAPD mRNA ratio) tended to diminish in most cases. The relative expressions of c-fos, c-myc, c-Ha-ras, c-met and TGF alpha gene were correlated at day 0. During and after the liver transplantation, an overexpression of c-fos, c-myc, c-Ha-ras, c-met and TGF alpha was observed in different pathological conditions such as cold ischaemia and conservation injury, acute rejection, and cytomegalovirus infection. In three cases the relative expression values of c-fos, c-myc and c-Ha-ras increased over long-term follow-up without any associated acute pathology. These results suggest the necessity of an intercellular mediation--by means of graft reperfusion--in induction of hepatocyte proliferation and regeneration of the transplanted liver.