Development of a dynamic in vitro stretch model of the alveolar interface with aerosol delivery

Abstract

We describe the engineering design, computational modeling, and empirical performance of a moving air–liquid interface (MALI) bioreactor for the study of aerosol deposition on cells cultured on an elastic, porous membrane which mimics both air–liquid interface exposure conditions and mechanoelastic motion of lung tissue during breathing. The device consists of two chambers separated by a cell layer cultured on a porous, flexible membrane. The lower (basolateral) chamber is perfused with cell culture medium simulating blood circulation. The upper (apical) chamber representing the air compartment of the lung is interfaced to an aerosol generator and a pressure actuation system. By cycling the pressure in the apical chamber between 0 and 7 kPa, the membrane can mimic the periodic mechanical strain of the alveolar wall. Focusing on the engineering aspects of the system, we show that membrane strain can be monitored by measuring changes in pressure resulting from the movement of media in the basolateral chamber. Moreover, liquid aerosol deposition at a high dose delivery rate (>1 µl cm−2 min−1) is highly efficient (ca. 51.5%) and can be accurately modeled using finite element methods. Finally, we show that lung epithelial cells can be mechanically stimulated under air–liquid interface and stretch‐conditions without loss of viability. The MALI bioreactor could be used to study the effects of aerosol on alveolar cells cultured at the air–liquid interface in a biodynamic environment or for toxicological or therapeutic applications.

A Biomimetic, Copolymeric Membrane for Cell‐Stretch Experiments with Pulmonary Epithelial Cells at the Air‐Liquid Interface

“…This patented ALICE Cloud technology has become commercially available as VITROCELL Cloud MAX (VITROCELL Systems, Waldkirch, Germany). [ 61,62 ]…”

“…The cell‐deposited particle dose of 2.1 µg cm −2 was determined from the previously determined aerosol deposition efficiency of 52% of the CIVIC system. [ 61 ] For this dose, the fractional area coverage was determined to be 30% and 3% for NPs and MPs, respectively (density of PS‐NH 2 : 1.05 g cm −3 ). After the nebulization of particles, a cyclic physiologic mechanical stretch (21% ∆SA strain) was applied to the cells.…”

“…Dynamic Cell Culturing: The CIVIC system was used to apply cyclic stretch to cells grown on the BETA membrane under ALI culture conditions. The CIVIC system is a modified version of the previously described MALI system, [61,62] which has been improved for technical performance mainly related to material stability, membrane fixation, and pressure sealing. While the geometry of the bioreactor system was not changed over the previously described version, some parts were modified to improve the airtightness of the bioreactor chamber and ease of handling.…”

“…This patented ALICE Cloud technology has become commercially available as VITROCELL Cloud MAX (VITROCELL Systems, Waldkirch, Germany). [61,62] The elastic modulus of the membrane was measured using the bioreactor system during cell culturing. Two pressure sensors (MPX5050, Freescale Semiconductor, Munich, Germany) were devised in the apical compartment of the bioreactor (P 1 ) and the headspace of the reservoir chamber (P 2 ) as depicted in Figure 6A.…”

A Bioinspired in vitro Lung Model to Study Particokinetics of Nano-/Microparticles Under Cyclic Stretch and Air-Liquid Interface Conditions

“…This is supported by newly applied analytical parameters (e.g., 3D porosity and mapping of surface topology of the membrane). Moreover, we provide a detailed technical description of the recently introduced Cyclic In VItro Cellstretch (CIVIC) bioreactor for cell-stretch experiments under ALI conditions (Doryab et al, 2020) with particular attention to refinements over its earlier version (MALI, Moving Air-Liquid Interface bioreactor) (Cei et al, 2020). Subsequently, the effect of cyclic stretch on the particokinetics of aerosol-delivered nano-(100 nm) and microparticles (1,000 nm) in an alveolar tissue barrier model (A549) cultured under ALI conditions was investigated quantitatively with respect to size-dependent cellular uptake and transepithelial transport of particles.…”