The growth of liver cells in the pancreas after intra-splenic implantation: the effects of portal perfusion.

A newly developed rat model of portal diversion, in which the pancreas gland is perfused by splanchnic effluent, has been used to monitor the effects of such portal perfusion on the development of isolated hepatocytes within the pancreatic parenchyma. Two groups of animals (control and portally-perfused) received intra-splenic hepatocyte implants (2 x 10(6) cells). The development of liver cells in the pancreas was then assessed histologically 10 days-9 months later. Portal diversion did not alter the incidence of hepatocytes within the pancreas as a whole (70% of all animals). However hepatocyte-islet rosettes (the intimate association between liver cells and endocrine tissue) were found in a significantly higher percentage of portally-perfused pancreases (92%) in comparison to controls (43%) 6 and 9 months after implantation. It appears that liver cell translocation from the spleen to the pancreas is dependent largely on factors associated with the implantation procedure itself. The growth of liver cells specifically around the islets of Langerhans, however, seems to be positively influenced by portal factors. These studies provide further evidence for the theory that extrahepatic liver cells are susceptible to local and systemic growth factors in a similar way to homotopic hepatocytes in the intact liver.