Vascularised liver cell module: A possible 3D test system for the evaluation of substance toxicity in vitro?

Background: Liver test systems are required for investigation of biotransformation processes and substance analysis. We developed a matrix, which enables a physiological co-culture of hepatocytes (HC) and endothelial cells (EC) in long-term culture. Basis is a vascularised scaffold which admits extra cellular matrix contact to the HC and provides a blood vessel network for EC co-culture and mass transport. Methods: The matrix consists of an acellularized jejunal segment with an obtained vascular system. The vascular system is reseeded with porcine progenitor cells from bone marrow aspirate. After 7-14 days of culture HC in a collagengel suspension are seeded on the matrix lumen. During the cultivation period the matrix is perfused with medium in a bioreactor. The flow rate is controlled via PC to simulate in vivo blood flow. Results: Progenitor cells were successfully seeded in the vascular bed of the matrix. After 4 weeks they are vital and express EC specific markers. Vital HC could be efficiently populated on the surface of the lumen and partially migrate in the matrix. The culture of HC shows good results for vitality, expression of liver specific markers, conservation of liver specific functions, phase I and phase II metabolism and formation of cell-cell contacts. Perspective: Our aim is the development of a vascularised liver module with physiological functions. EC shall be co-cultivated with the HC to form a filtration barrier. For the first time a testing system should enable the arterial application of substances and identification of their metabolites in the venous system.