Professor Jaesung Park (Department of Mechanical Engineering) and Korea- America co-research team including medical school of Harvard University have succeeded in observing the mutual interaction between the layers of primary hepatocyte (liver) cells and non-parenchymal (functional) cells created by the stencil created by the microfabrication techniques.

To treat damaged or diseased liver tissue, hepatic tissue engineering has been studied as a new therapeutic approach. The reconstruction of functional hepatic tissue mainly depends on the ability to control factors that influence the cell environment, including cell-matrix interactions, soluble stimuli, and cell-cell interactions. Among those, cell-cell interactions play a critical role, but it has known to be hard to culture the primary hepatocyte which functions properly.

By the conventional methods, the researches tried to observe the interactions between the hepatic tissue cells cultured on the plain culture dish in controlled environment. However, this method has a critical limitation that hepatic functions change when the cell’s location changes. The team of Park created a stencil plate by the feeder layers using microfabricated polydimethylsiloxane (PDMS). Increasing the heterotypic interface using the layered cell patterning technique in micropatterned hepatic co-cultures significantly enhances the liverspecific functions of hepatocytes, including intracellular albumin staining, urea synthesis, albumin secretion, E-cadherin expression, and glycogen storage.

To assess the hepatocelluar characteristics of micropatterned hepatocytes, they evaluated morphologic, phenotypic, and functional characteristics of hepatocytes patterned in single culture and when co-cultured on fibroblast feeder layers. The sequence of micrographs in Figure 1 illustrate step-by-step how the two different micropattern configurations were generated using the PDMS stencil with hepatobyte cells (in pink) and non-parenchymal (in green) cultured at the same time.

The results of the study showed that multidimensional interactions between cells are happening, and they found that more active interactions than of the previous method. They also succeeded to demonstrate uniform intracellular albumin staining and E-cadherin expression, increased liver-specific functions, and active glycogen synthesis in the hepatocytes when the heterotypic interface between hepatocytes and fibroblasts was increased by the layered patterning technique.

“This patterning technique can be a useful experimental tool for applications in basic science, drug screening, and tissue engineering, as well as in the design of bioartificial liver devices,” Professor Park commented.

The results are published on the issue of January 2010, Bio Techniques.