Syngeneic Rat Liver Research Articles

Regional administration of natural killer cells in a rat hepatic metastasis model results in better tumor infiltration and anti-tumor response than systemic administration.

A syngeneic rat liver metastasis model, the CC531 colon carcinoma cell line in Wag rats, was used to study the homing properties and anti-tumor effects of adoptively transferred, interleukin-2 (IL-2)-activated, cultured natural killer (A-NK) cells. To identify the route of administration that gives the highest tumor infiltration, 1.5 x 10(8) A-NK cells were dyed with fluorescent rhodamine and injected via 4 different routes into rats, bearing subcapsularly induced (day 10) liver metastases. The routes chosen were: jugular vein, portal vein, hepatic artery and directly into the peritoneal cavity (i.p). The rats were sacrificed 20 hr after administration of A-NK cells. The highest (p < 0.05) infiltration of tumors by A-NK cells was found both at the tumor border and in the tumor center after injection via the hepatic artery: 65 +/- 7 A-NK cells/mm2 at the tumor border and 26 +/- 14 A-NK cells/mm2 in the center of the tumor (jugular vein infusion: 32 +/- 10 and 9 +/- 5 A-NK cells/mm2, respectively; portal vein infusion: 36 +/- 13 and 7 +/- 4 A-NK cells/mm2, respectively). No A-NK cells were detected in the liver after i.p. injection. Rats bearing day 5 tumors were injected with 1.5 x 10(8) A-NK cells via the hepatic artery or via the jugular vein (n = 5 and n = 6 respectively). Regional administration of A-NK cells via the hepatic artery resulted in a significant (p < 0.05) lower weight (35 +/- 23 mg) of tumors than did systemic administration (70 +/- 10 mg). Our results suggest that both the level of tumor infiltration by adoptively transferred A-NK cells and the therapeutic outcome depend on the route of administration.

In vivo targeting of surface-modified liposomes to metastatically growing colon carcinoma cells and sinusoidal endothelial cells in the rat liver

We prepared immunoliposomes by covalent coupling of a randomly thiolated monoclonal antibody against the rat colon adenocarcinoma cell line CC531 to MPB-PE on the outer surface of conventional as well as PEGylated liposomes of about 100-nm diameter. We attempted to target these immunoliposomes in vivo to CC531 cells growing metastatically in the liver of syngeneic rats. Only when the immunoliposomes contained PEG-DSPE, did we observe, both with fluorescent and radioactive labels, accumulation of label in many, but not all, metastatic nodules. The fluorescent label concentrated in scattered areas within the nodules. By means of transmission electronmicroscopy, using colloidal gold particles as an encapsulated morphological marker, we established that the large majority of the tumor-associated gold particles located in areas not containing tumor cells. Most of the gold was detected in cells with a macrophage morphology. We tentatively ascribe this to either tumor morphology or to the coupling procedure we applied for the preparation of the immunoliposomes, or both. The random thiolation step of the antibody molecule conceivably allows for the exposure of the Fc portion of (part of) the antibody molecules so as to permit interaction with Fc receptors on the macrophages. Experiments with immunoliposomes prepared either by coupling of the antibody specifically via its Fc portion or by using F(ab')2 fragments are in progress. The crucial condition of liposomal longevity as in the above experiments, where PEG-ylation of the immunoliposomes was necessary in order to achieve accumulation in the tumor area, by no means represents a general requirement for successful liposome targeting. We have shown that for efficient liposome targeting to a cell population which is readily accessible from the circulation, and has a high affinity for the liposomes, i.e. the hepatic sinusoidal endothelial cells, the presence of PEG chains may even be counter-productive.

Glutamine metabolism and neuropathologic disorders in experimental hepatic encephalopathy: Effect of transplanted hepatocytes

Physiopathology of hepatic encephalopathy remains unclear. Recent studies have suggested that ammonia would not act by itself but through an increase in glutamine in the brain. We have previously demonstrated that transplantation of syngeneic hepatocytes into the spleen was able to correct both behavioral deficits and plasma amino acid changes observed in portacaval shunted rats. The aim of the present work was to show a correlation between the correction of chronic hepatic encephalopathy by means of intrasplenic hepatocyte transplantation and two parameters, brain glutamine concentration and ultrastructural aspects of astrocytes. Inbred male Wistar Furth rats were divided into three groups: sham-operated rats (n = 10), rats subjected to portacaval shunt (n = 10), and rats subjected to portacaval shunt and intrasplenic hepatocellular transplantation of 10(7) hepatocytes isolated from livers of syngeneic rats (n = 10). Chronic hepatic encephalopathy was quantified 30 and 60 days after operation by means of nose-poke exploration and spontaneous activity. Pathologic examination and measurement of glutamine concentrations in the corpus striatus and in the cerebral cortex were performed 60 days after operation. Portacaval shunt rats showed reduced spontaneous activity and nose-poke exploration scores. After portacaval shunt a significant glutamine increase occurred in the corpus striatus and in the cerebral cortex when compared with sham rats (p < 0.05). Ultrastructural examination showed modification of astrocytes named Alzheimer type II after portacaval shunt. Correction of behavioral abnormalities by means of intrasplenic hepatocyte transplantation was associated with partial correction of striatal glutamine increase and with decrease in astrocyte alterations. Cortex glutamine concentration in portacaval shunt-intrasplenic hepatocyte transplantation group and in portacaval shunt rats did not differ significantly. These data show that intrasplenic hepatocyte transplantation not only prevents neurologic disorders of hepatic encephalopathy but can also decrease glutamine and ultrastructural alterations in the corpus striatus in an experimental model of chronic liver failure. These data are in favor of the involvement of glutamine in chronic hepatic encephalopathy. These results suggest that intrasplenic hepatocyte transplantation might be of therapeutic interest in chronic liver failure.

Intrasplenic hepatocellular transplantation corrects hepatic encephalopathy in portacaval-shunted rats

The aim of this work was to evaluate the effect of intrasplenic hepatocellular transplantation on hepatic encephalopathy in an experimental model of chronic liver failure induced by end-to-side portacaval shunt in the rat. Inbred male Wistar Furth rats were divided into three groups: rats subjected to portacaval shunt (n = 10), rats subjected to portacaval shunt and intrasplenic hepatocellular transplantation of 10(7) hepatocytes isolated from livers of syngeneic rats (n = 10) and sham-operated rats (n = 10). Behavior tests were performed in a blind fashion at 3 wk, at 2 mo and at 3 mo after surgery. Spontaneous activity and nose-poke exploration by individual rats were studied in automated open field boxes equipped with infrared cells. Each cell beam interruption was automatically recorded on a microcomputer and transformed into a score index (counts/hour). Plasma levels of amino acids, ammonia and total biliary acids were measured. Portacaval shunt rats showed reduced spontaneous activity and nose-poke exploration scores. Intrasplenic hepatocellular transplantation significantly increased spontaneous activity after 2 mo and improved nose-poke exploration after 3 wk. At 3 mo, spontaneous activity and nose-poke exploration in portacaval shunt/intrasplenic hepatocellular transplantation rats were not significantly different from those of sham rats. Increases in plasma ammonia levels after portacaval shunt were not corrected. Amino acid imbalance and bile acid concentration in plasma were partially corrected by intrasplenic hepatocellular transplantation. These data show that intrasplenic hepatocellular transplantation can correct the neurological symptoms of hepatic encephalopathy in an experimental model of chronic liver failure and suggest that intrasplenic hepatocellular transplantation might be of therapeutic interest in chronic liver failure.