Cryopreserved Fetal Liver Cell Transplants Support the Chronic Failing Liver in Rats with CCl4-Induced Cirrhosis

Hepatocyte transplantation is a promising method for supporting hepatic function in a broad spectrum of liver diseases. The aim of this work was to test the efficacy of human fetal liver cells to support the chronic failing liver in an experimental model of carbon tetrachloride (CCl4)-induced cirrhosis in rats. Liver cirrhosis was induced by intraperitoneal administration of CCl4 at a dose of 0.2 ml (50% v/v solution)/100 g body weight, twice a week for 3 months in rats. Ten days after stopping CCl4 administration (experimental day 0), rats received intrasplenic injection of cryopreserved fetal liver cells (FLC, 1 × 107 cells in 0.3 ml medium). As a cirrhotic control group, CCl4-induced cirrhotic rats were used with intrasplenic injection of an equal volume of medium alone. Animals were sacrificed on experimental day 15. Human fetal liver cell transplantation almost completely prevented the death of cirrhotic animals during the 2 weeks after treatment, while high ongoing mortality was seen in the cirrhotic control group. Cell transplantation into the spleen normalized total bilirubin and TBARSs levels and increased albumin levels in blood serum, as well as restoring mitochondrial function and liver detoxification function (assessed by cytochrome P450 contents and activity) compared with the activities seen in the cirrhosis control group. In parallel with this restoration of biochemical and functional liver indices, morphological patterns of liver recovery or regeneration after liver cell transplantation were demonstrated in day 15 samples by light microscopy. These were absent in the group that had received only medium alone.

Functional hepatic recovery after xenotransplantation of cryopreserved fetal liver cells or soluble cell-factor administration in a cirrhotic rat model: are viable cells necessary?

BACKGROUND AND AIM

Chronic liver failure results in the decrease of the number of functioning hepatocytes. It dictates the necessity of using exogenous viable cells or/and agents that can stimulate hepatic regenerative processes. Fetal liver contains both hepatic and hematopoietic stem cells with high proliferative potential, which may replace damaged cells. Also, immature cells produce fetal-specific factors which may support the injured liver. Our aim was to test the ability of human fetal liver cells and cell-free fetal-specific factors of non-hepatic origin to stimulate recovery processes in an experimental model of carbon tetrachloride-induced cirrhosis in rats.

METHODS

Cirrhotic rats were intrasplenically injected with fetal liver cells (1 x 10(7) cells/0.3 mL medium) or cell-free fetal-specific factors (0.3 mL/1 mg protein). Control groups received medium alone. Serum indexes, hepatic functions, and morphology were evaluated for 15 days.

RESULT

Human fetal liver cell transplantation was shown to abrogate the mortality of cirrhotic animals, to improve serum markers, and to restore liver mitochondrial function and detoxification. Morphological patterns of liver recovery were observed by histology. In comparison, an injection of fetal-specific factors produced similar functional recovery, whilst a more limited liver regeneration was observed by histology.

CONCLUSIONS

The positive effects of fetal liver cell and cell-free fetal-specific factors in experimental cirrhosis may result from the presence of stage-specific factors activating hepatocellular repair.

[Effect of starvation on the metabolism of the xenobiotic p-nitroanisole in isolated hepatocytes of rats of both sexes]

Hepatocytes isolated from fed female rats are characterized by the lower contents of cytochrome P-450 and more slowly metabolize the xenobiotic p-nitroanisole (p-NA) than hepatocytes from males. The starvation does not change the cytochrome P-450 contents, but depresses the p-NA biotransformation. The inhibition of p-NA O-demethylation capacity is a result of insufficiently reduced equivalent supply, because the addition of exogenous NADPH to the cells with digitonin-permeabilized plasma membrane increases p-nitrophenol (p-NPh) formation. In the presence of exogenous NADPH hepatocytes from fasting male and female rats produce more p-NPh, than those from fed ones. That suggests the induction of xenobiotic biotransformation system during starvation. Sex differences in response of xenobiotic biotransformation system to starvation manifest themselves in different ratio in contents of free and conjugated p-NPh.

Sex differences in biotransformation of the xenobiotic p-nitroanisole in isolated rat hepatocyte under the influence of phenobarbital

Different sensitivity of the xenobiotic biotransformation system to phenobarbital treatment in female and male rat hepatocytes is shown. Hepatocytes isolated from females had less cytochrome P-450 content and metabolized the xenobiotic p-nitroanisole (p-NA) more slowly than hepatocytes from males. Phenobarbital treatment increased the cytochrome P-450 amount and the p-nitrophenol (p-NPh) formation rate in hepatocytes from female and male rats to the same extent. However, in control and female induced cells the main form of p-NPh was so conjugates, while induction of male rats reactions of conjugation were depressed and free p-NPh accumulated. The sex differences in the response of xenobiotic biotransformation system to an inducing treatment should be taken into account into transplantation and prescription of drug treatment courses.

Separation of intact and damaged hepatocytes in sucrose following non-enzymatic liver perfusion

This study deals with isolation of rat hepatocytes by a non-enzymatic method and the separation of intact and damaged cells in sucrose medium. Low speed centrifugation in isotonic sucrose medium of a hepatocyte suspension obtained by mechanical desaggregation of liver pre-perfused with EDTA solution results in the formation of a cell pellet which contains two different layers. A darker layer contains hepatocytes with intact plasma membranes. Their respiratory activity and xenobiotic metabolism are close to those of the cells isolated by collagenase perfusion. The study of distribution of lipophilic cation tetraphenylphosphonium (TPP(+)) indicates a predominantly mitochondrial localization of TPP(+) in the intact cells following non-enzymatic and collagenase isolation. Hepatocytes in the upper layer have damaged plasma membranes. As a result they lose the potential to accumulate TPP(+), and have low rates of endogenous respiration and biotransformation activity. Addition of exogenous NADPH restores the capability to metabolize xenobiotics. Washing and incubation of these hepaticytes in an intracellular type medium results in restoration of uncoupler-stimulated oxygen consumption and generation of membrane potential in the presence of a succinate substrate. These properties are close to those of hepatocytes permeabilized by digitonin treatment. Thus, the procedure allows the simultaneous isolation of both intact and permeabilized hepatocytes with functionally active intracellular structures without the use of relatively expensive chemicals such as collagenase and Percoll.

Inhibition of biotransformation of xenobiotic p-nitroanisole after cryopreservation of isolated rat hepatocytes

Cryopreservation of isolated rat hepatocytes with dimethyl sulfoxide (Me2SO) using a rapid two-step freezing protocol allows significant preservation of cell recovery and xenobiotic p-nitroanisole (p-NA) metabolism. A decrease in the rate of O-demethylation of p-NA after cryopreservation correlates with a change in cellular viability. A freeze-thaw procedure in the absence of a cryoprotectant results in a sharp inhibition and subsequent washing causes a complete loss of the ability of cells to metabolize the xenobiotic. In the presence of exogenous NADPH the rate of p-NA biotransformation is restored. The content of cytochrome P-450 does not change during a hepatocyte freeze-thaw procedure in the presence or absence of Me2SO. Separation of cells after cryopreservation using a Percoll solution permits the isolation of a suspension, the viability of which does not differ from that of the freshly isolated control, but which metabolizes p-NA at a slower rate. During incubation, viability of cryopreserved cells was reduced. The data indicate that inhibition of monooxygenative activity after hepatocyte cryopreservation results from the loss of endogenous reduced pyridine nucleotides. The loss of pyridine nucleotides results from damage of plasma membrane during both cryopreservation and subsequent incubation in the presence of xenobiotic.