Bioinspired hollow fiber membrane bioreactor using human liver microtissue spheroids

Abstract

Event Abstract Back to Event Bioinspired hollow fiber membrane bioreactor using human liver microtissue spheroids Loredana De Bartolo1, Haysam M. Ahmed1, 2, Simona Salerno1, Shervin Khakpour1, 2, Sabrina Morelli1 and Lidietta Giorno1 1 National Research Council of Italy - CNR, Institute on Membrane Technology, Italy 2 University of Calabria, Department of Environmental and Chemical Engineering, Italy Introduction: The development of bioartificial devices that are able to favour the liver reconstruction and to modulate cell behaviour is an important challenge in liver tissue engineering. As strategy we realized liver microtissue spheroids in a crossed hollow fiber membrane bioreactor, which was developed for the in vitro long-term perfusion. The bioreactor consists of two bundles of hollow fiber (HF) polyethersulfone (PES) membranes cross-assembled in alternating manner. One bundle of HF membranes provides cells nutrients and metabolites whereas the other HF bundle removes catabolites from cell compartment mimicking in this way the in vivo arterious and venous blood vessels. The combination of these two fiber set creates three compartments: two intraluminal compartments of PES HF in which the medium flows and one extraluminal compartment represented by extracapillary network formed by the fibers in which spheroids are cultured. Materials and Methods: The bioreactor consists of two bundles of PES HF membranes cross-assembled in alternating manner and potted with polyurethane adhesive within glass housing. The membranes were previously characterised in order to establish the physico-chemical, structural and transport properties[1]. The oxygenated medium enters to the membrane bioreactor with a flow rate Qf of 1.5 mL/min that was set on the basis of average retention time. Its fluid dynamics were characterized in terms of cumulative residence time distribution (RTD). Spheroids of primary human hepatocytes were realized in agarose mold and then cultured in the extralumen compartment of the bioreactor. The oxygen uptake, urea synthesis and albumin production rates as well as biotransformation functions were evaluated with time by using specific assays[2]. Numerical analysis of the mass transfer model for oxygen, urea and albumin concentration was performed using COMSOL Multiphysics. Results and Discussion: The geometry of the bioreactor ensured optimal perfusion conditions, which plaid a crucial role together with the surface and transport properties of the HF membranes in guiding the self-assembling of liver microtissue spheroids. Indeed, adjacent spheroids fused in the extracapillary space forming liver microtissues (Fig. 1). The liver microtissue spheroids expressed liver specific functions in terms of urea synthesis, albumin production and diazepam biotransformation at high levels up to 2 weeks. The liver specific functions of the bioreactor were significantly higher with respect to those of the batch system. Furthermore, the bioreactor provided an adequate oxygenation of the liver microtissue spheroids maintaining oxygen concentration levels well above the in vivo liver periportal zone concentration. Conclusion: The bioreactor thanks to its fluid dynamics and mass transfer properties of the fibers allowed to promote the formation liver microtissue spheroids with high specific functionality.