? It costs half a trillion dollars to bring a drug candidate to market. This expense is causing pharmaceutical companies to focus on compounds that have the greatest earning potential, orphan the development of critically needed drugs that have low revenue projections, and transfer high research costs to the consumer. All of these industry trends significantly increase the number of patients who can not access needed medicine because it is unavailable or unaffordable. The pharmaceutical industry is attempting to address this problem by heavily investing in human pre-clinical research as a mechanism to control cost and enhance the success of drug development. The industry is anxious for new tools to support the human pre-clinical research initiative. There is a particular need for advanced in vitro model systems to evaluate the toxicity of chemicals and drugs. This project's goal is to develop such a system. ? ? Abstract: ? The current in vitro technology for testing drug candidates is based on two-dimensional (2-D) sandwich livercell culturing techniques developed four decades ago. These In vivo models are complicated by the presence of structural and functional heterogeneity of biochemical pathways at the tissue and organism levels, and do not allow for mechanisms to be clearly defined or reproducibly examined. An in vitro system that is a much better model of a human liver is needed. Over the past dozen years this research team has been developing a state-of-the-art multicoaxial bioreactor (MCB) for creating the first human bioartificial liver. Over the past four years the team has focused on identifying the optimum human liver cell population for seeding the three-dimensional (3-D) bioreactor cultures. It has been determined that an unfractionated mixture of human liver cells shown to contain hepatic stem/progenitors provides favorable bioreactor results. In addition to this work the team has developed versatile NMR-compatible bioreactors that can obtain in situ metabolomics and fluxomics data. ? ? In this project we will create the first 3-D human bioartificial entero-hepatic organ-system and establish the feasibility of using this model system to evaluate the toxicity of chemicals and drugs. The proposed technology will be based on incorporating a defined population of human liver cells in an extracellular matrix thus creating a microenvironment composed of a precise composition of insoluble factors to interact with the cells. The encapsulated hepatocytes will be placed in a bioreactor compartment adjacent to a compartment containing a human derived- intestinal cell line, CaCo-2. This will be achieved using two multiple compartment bioreactor designs; a multicoaxial bioreactor (MCB) and a NMR-compatible bioreactor. The proposed bioreactor designs contain at least 4 compartments. This will permit the two cell types to interact across a small space and be perfused by separate plasma/intestinal compartments representing the blood and the intestinal compartments. This will mimic blood flow of the human entero-hepatic system. The advantage of the MCB bioreactor is that the intestinal barrier is better replicated. The advantage of the NMR-compatible bioreactor is that a novel interleaved NMR method can obtain in situ metabolomic and fluxomic data simultaneously from the two tissues. The expected result of this project will be an artificial human liver model that will be used with computational metabolomic and fluxomic analysis to identify toxicological and pharmacological drug targets. ? ? ?
