The isolated perfused rat spleen. An original method for studying the function of hepatocytes transplanted into the...

The aim of this study was to assess directly the function of isolated hepatocytes 1 year after transplantation into the spleen, using an original model of isolated rat-spleen perfusion. Three specific liver functions, albumin synthesis, indocyanine-green clearance, and antipyrine oxidation, were studied. Five x 10(6) isolated hepatocytes were injected into the spleen of syngenic Wistar-Furth rats. One year later, splenectomy was performed, and the splenic pedicle was carefully isolated in order to allow a selective ex vivo perfusion for 3 hr. De novo albumin synthesis was studied by qualitatively using immunoelectrophoresis and autoradiography, and quantitatively using (35S)-methionine incorporation in albumin. De novo albumin synthesis was observed in spleens containing transplanted hepatocytes but not in controls (P less than 0.001); (35S)-methionine incorporation was significantly higher in spleens containing transplanted hepatocytes than in controls (132 +/- 67 cpm/spleen/hr vs. 14 +/- 6 cpm/spleen/hr, P less than 0.001). Antipyrine clearance was significantly higher in spleens with transplanted hepatocytes than in controls (67.4 +/- 4.9 microliters/min/g vs. 0.2 +/- 0.4 microliters/min/g, P less than 0.01). No statistically significant difference was observed with indocyanine-green clearance (4.2 +/- 6.0 microliters/min/g, vs. 5.2 +/- 5.1 microliters/min/g, P greater than 0.05); this was probably due to the absence of compartmentation between the sinusoid and biliary sectors in this model. In conclusion, using this original isolated rat-spleen perfusion model, it was directly observed that 1 year after transplantation, intrasplenic hepatocytes can perform two liver-specific functions, i.e., de novo albumin synthesis and antipyrine clearance.