The effect of portal perfusion on intrasplenic hepatocytes

A newly developed rat model of portal diversion, in which the subcutaneously transposed spleen is perfused by splanchnic effluent as a result of portal vein ligation, has been used to monitor the effect of such portal perfusion on intrasplenic hepatocyte implants. Three groups of animals (controls, n = 42; transposed only, n = 70; and portally diverted, n = 58) received 2 million syngeneic liver cells. The number of hepatocytes in each spleen was assessed 5 days to 9 months later by direct counting of splenic sections. The transposed spleen was capable of supporting hepatocyte grafts even over long periods, although the number of cells was reduced in comparison with controls. Diversion of portal flow across the transposed spleen significantly increased hepatocyte numbers in the first 6 weeks (median number of cells (with inner quartile range), 1380 (70-1300) versus 600 (347-4050); n = 75), but no differences were detected thereafter. It appears that the initial lag phase of hepatocyte grafts can be partially abrogated by portal perfusion, but the subsequent 'proliferative' phase is unaffected. These effects correlate well with established theories on the importance of portal flow to the intact liver.