The invention features modular chambers for culturing cells in which the volume of a chamber can be adjusted without compromising the seal or 
sterility of the chamber. The invention is based on the principle that the volume of a chamber formed between two plates sandwiching a compressible 
gasket and a substantially incompressible stop can be adjusted using a 
gasket that forms a fluid-tight seal between the plates at a plurality of levels of compression. The invention enables the culture of cells between substantially parallel and rigid plates in which a relatively large volume can be used to seed the cells and the holdup volume reduced for 
perfusion without opening or otherwise disassembling the 
system to compromise its liquidtightness and 
sterility. The new closed, modular and scalable 
cell-culturing chamber can be thus perfused and used to culture cells (e.g., hepatocytes) with high levels of 
cell function in organ (e.g., liver) assist systems, for production of cells, for production of 
cell-derived products, such as proteins or viruses, or for systems to treat biological liquids to remove toxins, such as 
ammonia, add cell-synthesized products, or both.