Measuring oxygen transport in a cartridge of hydrogel filled membranes

ROMINA HIDALGO; MARIANO GRASSELLI

Montevideo, Uruguay

Congreso; 6th International Congress of Biological Physics ? 5th Southern Cone Biophysics Congress; 2007

IUPAB

Novel therapies are required for the treatment of acute liver failure. Bioartificial liver (BAL) systems are under development to offer better clinical performance than ordinary therapies, because they should be able to replicate in part the critical functions of the natural organ. our design consists in a cartridge composed of a parallel bundle of hollow fibers housed within an external casing which incorporates hepatic spheroids (cells assembled together with great physiological activity). The hollow fibers are those usually used for microfiltration, but in our case we synthesized pore-filled ones with polyAcrilamide hydrogel. Blood o r plasma normally flows through the fiber lumens, and spheroids are in the extracapillary space. One of the main considerations in the design of a BAL must be the appropriate supply of oxygen to a huge amount of cells. In comparison to many other cell types, hepatocytes have elevated levels of carbohydrate, protein, and xenobiotic metabolism and are underpinned by a very high, specific oxygen consumption rate (OCR). In the core of living tissues where there are no blood vessels, oxygen transport occurs solely by diffusion. In cellular tissue artificially cultivated, this situation imposes severe restrictions on the system; necrosis due to oxygen deficiency will occur in regions where the partial oxygen pressure is lower than a certain critical value. The volumetric liquid mass transfer coefficient (kLa) is a useful parameter to characterize bioreactors capacity for aeration. This is a critical factor in this reactor design. From different available methods to determine kLa, we choose the sulfite oxidation method because it has a kinetic in the range of our system, thus is able to be adapted to dynamic conditions, simulating a continuous culture system.