Microfabricated silicon nitride membranes for hepatocyte sandwich culture

We have developed a hepatocyte sandwich culture with improved mass transport properties based on ultra-thin microfabricated porous silicon nitride (Si3N4) membranes. The dimensions and uniformity of the membrane pores can be configurable, which confers more control over the mass transport. Instead of collagen gels used in conventional sandwich culture, we utilized galactose ligands immobilized on the Si3N4 membranes to support hepatocyte attachment and function in the sandwich culture. Diffusion studies using FITC-dextrans confirmed that mass transport of the microfabricated Si3N4 membrane based sandwich was significantly better than conventional collagen gel sandwich and can be configured by varying the porosity of the Si3N4 membrane. Hepatocytes cultured in the microfabricated Si3N4 membrane based sandwich culture exhibited earlier apical repolarization and biliary excretion, improved differentiated functions and enhanced drug sensitivity compared to hepatocytes cultured in a collagen gel sandwich. The Si3N4 membrane based sandwich culture allows for a systematic optimization of the mass transport properties of hepatocyte culture by changing the pore size and inter-pore distance. This will enable more effective drug testing applications where optimal mass transport is required for hepatocyte function maintenance and drug accessibility.