Transmission electron microscopic study of hepatocytes in bioartificial liver

Establishment of an animal model for human keloid scars using tissue engineering method

The aim of this study is to establish an animal model for human keloid scarring using tissue engineering method and to improve the research for keloid scarring in clinical and laboratory settings. After primary and passage culture, human keloid fibroblasts (KFBs) were transferred to poly(lactic-co-glycolic acid) (PLGA) copolymer and cultured in a rotatory cell culture system for 1 week. The complex of KFBs and PLGA (experimental group), and PLGA only (control group) were then transplanted to subcutaneous pouches in athymic mice. The implants were collected on days 30, 60, 120, and 180 for histological observation. All mice survived after surgery. The size of implants in the experimental group kept increasing from days 30 to 180, whereas the implants in control group became smaller. Using different histological stainings, KFB and collagen were observed at all time points in the implants under light microscopy. Large amounts of KFBs and collagen were found in the implants of day 180, which exhibited similar histological features to human keloid. Also, the fibroblasts in the implants had abundant rough endoplasmic reticulum in the cytoplasm under transmission electron microscopy. These findings indicate that the fibroblasts retain cellular characteristics in the implant. The combination of KFBs and PLGA can form keloid-like tissue in athymic mice. Establishment of this promising animal model for keloid is worthwhile, and this model might help our understanding of the pathological process and our ability to evaluate drug efficacy to human keloid scars in clinical trials.

A novel bioartificial liver with culture of porcine hepatocyte aggregates under simulated microgravity

An extracorporeal bioartificial liver device could provide vital support to patients suffering from acute liver failure. We designed a novel, customized bioreactor for use as a bioartificial liver (patent pending). The Innsbruck Bioartificial Liver (IBAL) contains aggregates of porcine hepatocytes grown under simulated microgravity. The culture vessel rotates around its longitudinal axis and is perfused by two independent circuits. The circuit responsible for exchange of plasma components with the patient consists of a dialysis tube winding spirally around the internal wall of the culture vessel. IBAL was evaluated in vitro. Viability tests showed sufficient viability of hepatocytes for up to 10 days. Cytologic examination of samples from the bioreactor showed liver cell aggregates. These were also examined by electron microscopy. A number of biochemical parameters were analyzed. In conclusion, cell culture is possible for at least 10 days in the IBAL system, organoid hepatocyte aggregates are formed and synthetic activity of the hepatocytes was demonstrated.

Hepatocyte organoid culture in elliptic hollow fibers to develop a hybrid artificial liver

A novel organoid culture was developed in which hepatocytes maintain high liver functions for more than several weeks in vitro. The main disadvantage of tissue-engineered organoids is the lack of a blood vessel structure between the aggregated cells. Because of depletion of oxygen, the thickness from the surface of an organoid at which hepatocytes can survive is limited. This study showed that a rat hepatocyte organoid that forms by using centrifugal force in a hollow fiber (HF) had a survival limit thickness of about 80 - 100 microm from the surface of the organoid. Based on the value, we designed an elliptic HF having less than 150 microm minor diameter by using a simple annealing method. All hepatocytes were supplied with oxygen and formed an organoid without a dead cell layer in this HF A hepatocyte organoid in an elliptic HF maintained ammonia removal activity twice as high as in the original HF for at least one month during culture. Albumin secretion activity of an organoid in an elliptic HF was also maintained for at least one month and was the same level as that of liver in a living body. In conclusion, organoid culture by using an elliptic HF seems to be a promising technique to develop a hybrid artificial liver.