Prediction of Metabolic Functions of Primary Human Liver Cells Maintained in Perfused 3D Multi-Compartment Bioreactors for Extracorporeal Liver Support

Abstract

Aims: The development of a bioreactor providing a three-dimensional network of interwoven capillary membranes with integrated oxygenation and decentralized mass exchange enables the culture of primary liver cells under conditions closely reflecting the natural environment of the cells in vivo (1,2). In order to allow an early estimation of the quality of bioreactor cultures intended for clinical application, the determination of predictive parameters allowing the prognosis of the long-term culture performance is of interest. Methods: Human liver cells were obtained from 18 human livers discarded from the liver transplantation program and cultured over 7 to 34 days in bioreactors (n=18). To determine cell vitality and cell function during culture maintenance, LDH and transaminase release, electrolyte concentrations, glucose metabolism, ammonia detoxification, urea and albumin secretion as well as galactose and sorbitol uptake were measured daily in the culture perfusate. Data were analyzed with respect to the parametersrsquor; kinetics over time by data mining methods. The approach applied was based on fuzzy clustering of the individual parametersrsquor; kinetics and subsequent rule extraction. This way, multivariate relations between the parameters based on their clusters were investigated and the prognostic values of the individual parameters assessed. Results: The data mining results obtained showed that galactose uptake is the most relevant parameter of those measured to predict the long-term performance of primary human liver cells during bioreactor culture. On the basis of galactose uptake at day three of the culture, the sub-sequent culture quality (high, medium or low) could be predicted in all 18 cases (100%). Galactose measurement on the first or second culture day (24h or 48h after cell inoculation) allowed the prediction of the later bioreactor performance in 16 of 18 cases (89%). On the basis of urea secretion, prediction of the long-term culture performance was possible on day six in 16 of 18 (89%), on day two and day three in 15 of 18 (83%) and on day one in 13 of 18 cases (72%). The other parameters had no relevant prognostic values. Conclusion: The data mining approach applied revealed that galactose uptake allows a highly reliable prognosis of the long- term performance of bioreactor cultures of primary human liver cells after three days of culture and, with less accuracy, already after the first 24h of culture.