The simulated microgravity environment maintains key metabolic functions and promotes aggregation of primary porcine hepatocytes

The high aspect ratio vessel allows the culture of primary porcine hepatocy tes in an environment of low shear stress and simulated microgravity. Prima ry porcine hepatocytes have been difficult to maintain in culture long term while preserving their metabolic functions. This study was carried out in order to characterise key metabolic functions of cell aggregates formed by primary porcine hepatocytes cultured in a high aspect ratio vessel for a pr edetermined period of 21 days. 10(8) porcine hepatocytes were loaded into t he high aspect ratio vessel and continuously rotated during the experiments . 0.7 ml of the culture medium was sampled on days 1, 2, 4, 7, 10, 14 and 2 1. H-1 nuclear magnetic resonance spectroscopy of the culture medium, using the presaturation technique, assessed the following: glucose metabolism, g lutamine synthesis and ketogenesis. There was glucose breakdown anaerobical ly during the first 10 days as manifested by lactate production and pyruvat e and threonine consumption, After day 10 there was significantly smaller l actate production (day 1 vs day 10 P < 0.01). and significantly smaller pyr uvate (day 1 vs day 14 P < 0.03) and threonine consumption (day 1 vs day 10 P < 0.002), indicative of an aerobic metabolic pattern. Significantly more glutamate was produced after day 10 (day 1 vs day 10 P < 0.031). and more glutamine was consumed after day 14. There was a steadily diminishing produ ction of acetate which reached a minimum on day 14 (day 2 vs day 14 P < 0.0 0014). After an initial 10 day period of acclimatisation cell aggregates fo rmed in the high aspect ratio vessel switched from the anaerobic pattern of metabolism to the more efficient aerobic pattern, which was exhibited unti l the experiments were terminated. The high aspect ratio vessel is suitable for long-term culture of porcine hepatocytes and it is worthwhile carrying out scale-up feasibility studies. (C) 2001 Elsevier Science B.V. All right s reserved.