Designing a Microenvironment Niche for Liver-Specific Differentiation of Progenitor Cells

Deriving new sources of hepatocytes is critical for further advancement of liver-directed cell therapies, bioartificial liver-assist devices and toxicology studies.  The need for new sources of hepatocytes is driven by the overall shortage of human hepatocytes, suboptimal condition of human cells available for experiments and potential hazards associated with employing xenogenic (murine or porcine) liver cells.  An ideal source of hepatocytes should be capable of population expansion; therefore, emphasis is being placed on investigating progenitor cells or human embryonic stem cells (hESC), cells that could first be expanded and then induced to express liver-specific function.  Traditional cell culture approaches employed in stem cell differentiation studies vary biological inducers one-at-a-time, requiring large numbers of cells and considerable time investment for thorough analysis.  In addition, these culture techniques are not well-suited for engineering the precise composition of the microenvironment (e.g. intercellular contacts and cell-surface interactions) required to induce the hepatic phenotype in stem cells.  Our laboratory is interested in designing a microenvironment niche conducive to in vitro differentiation of stem cells or progenitor cells toward the liver phenotype.  In order to converge on the composition of liver-specific microenvironment niche, we are developing microfabricated cell culture surfaces where the interactions of hESC with extracellular matrix (ECM) proteins, growth factors and other cells (e.g. adult hepatocytes or nonparenchymal liver cells) can be precisely defined and tested in both rational and "combinatorial" fashion.
(Researchers involved on this project: Ji Youn Lee, Caroline Jones, Sunny Shah, Nazgul Tuleuova)

Constructing micropatterned triple cell cultures. (A) Registration of collagen micropatterns (green) with PEG hydrogel microstructures (interconnected circles) results complex biointerface with cell adhesive (collagen), non-adhesive (PEG gel) and moderately adhesive (silanized glass) regions.  (B) Selective attachment of hepatocytes to collagen domains. (C) Creating a co-culture of hepatocytes (green) and fibroblasts (red) with PEG gel-protected central regions.  These regions become available for seeding another cell type upon removal of the PEG gel.