Permeability studies across epithelial barriers are of primary importance in drug delivery as well as in toxicology. However, traditional in-vitro models do not adequately mimic the dynamic environment of physiological barriers.
The Membrane Bioreactor (MB) is new double flow bioreactor for mimicking physiological barriers, which combines a transwell (TW)-like system with medium flow and multi-compartmental models. The system includes a holder for commercial porous membranes, which divides the bioreactor into two independent chambers for dynamic in-vitro studies of drug diffusion through liquid–liquid or air-liquid physiological barriers (Fig. 1.A-B).
The fluid dynamic environment of the bioreactor was characterized using computational fluid dynamic models and measurements of pressure gradients (Fig. 1.C). The model predicts a maximum shear stress of 6 × 10–4 Pa in the central region of the membrane, within the range of physiological values for the small intestine (0.2 – 8 ) × 10–3 Pa
Application: In-vitro model of small intestine
Caco-2 cells were seeded on the porous membrane, comparing the effect of media flow applied in the bioreactor with traditional static transwell. Cell growth, membrane integrity, and tight junction formation were evaluated by measuring TEER values and ZO-1 expression (Fig. 1.D). The flow increases barrier integrity and tight junction expression of Caco-2 cells with respect to the static controls. Transport studies were performed in flow conditions by placing 0.1 M fluorescein in the apical side, sampling medium at regular intervals (Fig. 1.E). Fluorescein permeability increased threefold in the dynamic system, indicating that the stimulus induced by flow increases transport across the barrier, closely mimicking the in-vivo situation.
S. Giusti, T. Sbrana, M. La Marca, V. Di Patria, V. Martinucci, A. Tirella, C. Domenici, A. Ahluwalia “A novel dual-flow bioreactor simulates increased fluorescein permeability in epithelial tissue barriers”, Biotech J, Sep 9(9), pp.1175-84, 2014, doi: 10.1002/biot.201400004
S. Giusti, T. Sbrana, D. Giacopelli, V. Di Patria, A. Ahluwalia. “Multi-organ-on-plate system for in-vitro studies of intestinal drug absorption and hepatotoxicity“, presented at European Society of Toxicology In Vitro 2014 International Conference (ESTIV 2014), Egmond aan Zee, The Netherlands, 2014 (poster presentation).
T. Sbrana, S. Giusti, M. La Marca, V. Martinucci, G. Gori, C. Domenici, A. Ahluwalia. “Bioreactor for dynamic biological barriers”, presented at TERMIS-EU Congress "Tissue Engineering and Regenerative Medicine", Istanbul, Turkey, 2013 (poster presentation).