Liver cell transplantation: the road to clinical application

Isolation of human hepatocytes from livers rejected for liver transplantation on a national basis: results of a 2-year experience

The offer of liver transplantation to many patients affected by liver failure is limited by organ shortage. Clinical application of human-based liver cell therapies, such as bioartificial liver and hepatocyte transplantation, might support liver transplantation, allowing more patients to be treated and decreasing mortality in the waiting list. The development of a standardized method of hepatocyte isolation is a mainstay for large-scale application of liver cell therapy. The aim of this study is to analyze retrospectively a 2-year experience of human hepatocyte isolation from livers rejected from transplantation at organ harvesting, performed on a national basis in Italy. All the livers judged unsuitable for transplantation were considered for hepatocyte isolation. Macrosteatosis greater than 60% was the most common reason of refusal, followed by nonviral cirrhosis. Fifty-four organs were used. Human hepatocyte isolation resulted in more that 7 million liver cells/g of tissue digested with 73% +/- 14% viability. Steatotic organs gave better results in terms of cell yield than cirrhotic livers. Isolated hepatocytes were able to perform specific liver functions, and evidence of factor IX and albumin messenger RNA (mRNA) production was reported when cells were plated in culture. Modifications of the traditional method of hepatocyte isolation, aimed at reducing ischemia-reperfusion damage and improving post-isolation cell conditions, showed improvements in post-isolation viability. In conclusion, we show that it is possible to use the vast majority of livers not suitable for transplantation on a national basis for human hepatocyte isolation, obtaining a large amount of viable functioning human hepatocytes that might be used for cell transplantation and therapy.

Intraportal infusion of 99mtechnetium-macro-aggregrated albumin particles and hepatocytes in rabbits: assessment of shunting and portal hemodynamic changes

BACKGROUND

Partial correction of metabolic liver disease by hepatocyte transplantation requires infusion of a large number of cells into the portal vein. Uncontrolled infusion of cells leads to extrahepatic shunting. Obstruction of the sinusoidal space may result in hemodynamic changes and impairment of liver function.

METHODS

Catheters connected to a port were placed into the caudal mesenteric vein of rabbits. After injection of 99mtechnetium-macroaggregated albumin (99mTc-MAA) surrogates or 99mTc-MAA/hepatocyte (Hc) mixtures (1:125), shunting into the lung was scintigraphically monitored. Volume flow (mL/min) and maximum velocity of the portal vein were recorded by color-coded Doppler ultrasound during intraportal application of 2.5 x 10(7) MAA particles, 2.5 x 10(7) isolated hepatocytes, and saline solution without particles or cells.

RESULTS

99mTc-MAA particles (2.5 x 10(7)) or equivalent MAA/Hc mixtures were completely retained in the liver. With additional application of 2.5 x 10(7) particles, shunting into the lung was observed in two animals of the MAA group. All animals in the hepatocyte group have received 5 x 10(7) MAA/Hc mixtures, and three of these received 10(8) mixtures without shunting. Maximum velocity and volume flow increased with saline infusion. Hepatocyte suspended in the same volume blunted the increase observed in the control group, but parameters remained normal. Liver enzymes increased after hepatocyte application but returned to normal values within 5 days.

CONCLUSIONS

Sinusoidal uptake capacity for hepatocyte or MAA particles varies at a wide range in normal rabbits. Scintigraphic monitoring of transplanted cells allows efficient monitoring of cell translocation into the lungs. No significant impairments of portal hemodynamics and liver function were detected.

Emerging therapies for hepatocellular carcinoma: opportunities for radiologists

Emerging molecular therapies offer an exciting new challenge to interventional radiologists, who are expected to play an essential role in the targeted delivery of many of these novel drug- and cell-based therapies. Specifically for the treatment of liver tumors, not only are several novel therapies being developed that will require direct intratumoral delivery, but drugs are also being produced to further enhance local delivery by increasing tumor permeability. Some therapies are being developed to inhibit efflux of drugs out of tumors and others to recruit immune cells into or around tumors. In this review, the authors describe the basic science behind these emerging technologies to provide interventional radiologists with a comprehensive background into the types of therapies they will be delivering.