Improved Oxygen Delivery to Hepatic Hollow Fiber Bioreactors

Oxygen provision to hepatocytes (and other types of cells) maintained within the extracapillary space of a hollow fiber (HF) bioreactor is believed to be transport limited because of the low solubility of oxygen in aqueous media and the high cellular oxygen demand. This problem limits hepatocyte functional capabilities. Alleviating this problem is of significant biomedical interest, since hepatic HF bioreactors can serve as both an in vitro model for studying liver biotransformation, detoxification, and metabolic functions, and as a device used to sustain patients suffering from acute liver failure. One means of improving the oxygen carrying capacity of a HF bioreactor media stream is via supplementation of the circulating media stream with bovine red blood cells (bRBCs). This dissertation describes the initiation and development of a project aimed at employing bRBC supplementation to improve the oxygen environment within the HF bioreactor hepatocyte space. The work presented is organized into three sections. The first presents mathematical models depicting oxygen transport within the bioreactor system. One of these models was also utilized to demonstrate the potential benefit of bRBC supplementation. The remaining sections present the results of experiments aimed at evaluating bRBC supplementation within a C3A cell containing HF bioreactor and at examining the ability to engineer bRBC properties. Briefly, it was found that a C3A cell containing HF bioreactor maintained with media bRBC supplementation exhibited signs of an improved C3A cell space oxygen environment in comparison to a control (a C3A cell containing HF bioreactor not maintained with bRBC supplementation). Additionally, from the research conducted on engineering the properties of bRBCs, the ability to improve the cell's osmotic stability and to alter its oxygen binding/dissociation properties was demonstrated. This could allow for the creation of a tunable, novel oxygen carrier well-suited for use within a HF bioreactor system. Lastly, the results obtained from this work have led to the design of a rigorous set of experiments which utilize bRBC supplementation to explore the impact (on function, etc) of oxygen provision on hepatocytes maintained within a HF bioreactor.