KARL SCHUMACHER, M.D.,1 YUET-MEI KHONG, M.S.,1,2 SHI CHANG, M.D.,3 JUN NI, M.S.,1,2
WANXIN SUN, Ph.D.,1 and HANRY YU, Ph.D.1,2,3
http://www.liebertonline.com/doi/abs/10.1089/ten.2006.0046

Liver slice culture plays an important role in liver tissue engineering. Liver tissue contains hepatocytes, which are responsible for specific functions of liver such as xenobiotic metabolism and toxicity, glucose storage, fatty acid metabolism, protein synthesis and bile formation. These complicated metabolic functions make the liver culture technique challenging so that the tissue can maintain not only its structure but also its functionalities without its supporting cells. Similar to other tissues, intracellular and hormonal interactions are essential in culturing functional hepatocytes. In addition, the tissue’s extracellular matrix helps to maintain and stable the tissue. These components need to be maintained in a long-term culture to prevent the reduction in function and morphological damage of liver tissue without the blood supply.
Here, the alterations in the protein expression and ECM of both parenchymal and non-parenchymal cells of liver are investigated, using the conventional culture methods such as static and dynamic cultures, and an additional perfusion culture where the culture media is continuous exchanged. The protein-expression profiles were observed at different time points for different types of cultures. The reduced protein marker expression indicates the loss in function and changes in the phenotype of the tissue. HNF4α is a central regulator of hepatocyte functions and differentiation. A reduction in HNF4α protein expression shows the tissue’s functions decrease. After 5 hours, HNF4α was still found in the tissue. After 24 hours, there was a severe change in static culture, but HNF4α expression was able to maintain in perfusion culture. After 24 hours, only the double-sided perfusion culture expressed vimentin and collagen. However, changes in hepatocyte differentiation occurred after 24 hours due to the loss of non-perenchymal cells and ECM. The experiment shows that perfusion culture with media’s movement and continuous exchange gives a significant improvement in maintaining the tissue by balancing between the shear stress and mass transfer of media fluid.
Liver is considered one of the multi-functional tissues in human body where different biochemical and metabolic reactions occur. The paper provides a newly effective way to culture the liver tissue being outside of its supporting cells while still maintaining an efficient amount of its important proteins over a long-term period. By not only allowing a flow of media around the tissue, a constant refreshing of media is needed to improve the culture maintenance. This cell culture technique can also be used in culturing other highly functional tissues in human body.