Biaxial distension of precision-cut lung slices

Abstract

The mechanical forces acting on lung parenchyma during (mechanical) ventilation and its (patho)physiological consequences are currently under intense scrutiny. Several in vivo and cell culture models have been developed to study the pulmonary responses to mechanical stretch. While providing extremely useful information, these models do also suffer from limitations in being either too complex for detailed mechanical or mechanistic studies, or in being devoid of the full complexity present in vivo (e.g., different cell types and interstitial matrix). Therefore in the present study it was our aim to develop a new model, based on the biaxial stretching of precision-cut lung slices (PCLS). Single PCLS were mounted on a thin and flexible carrier membrane of polydimethylsiloxane (PDMS) in a bioreactor, and the membrane was stretched by applying varying pressures under static conditions. Distension of the membrane-PCLS construct was modeled via finite element simulation. According to this analysis, lung tissue was stretched by up to 38% in the latitudinal and by up to 44% in the longitudinal direction, resulting in alveolar distension similar to what has been described in intact lungs. Stretch for 5 min led to increased cellular calcium levels. Lung slices were stretched dynamically with a frequency of 15/min for 4 h without causing cell injury {3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) test; live/dead straining}. These findings suggest that stretching of PCLS on PDMS-membranes may represent a useful model to investigate lung stretch in intact lung tissue in vitro for several hours.

Static and dynamic imaging of alveoli using optical coherence tomography needle probes

“…Similar measurements have been performed with ex vivo tissue samples using light microscopy and multiphoton microscopy (10,15), and these small-scale measurements have been correlated against whole lung measurements of elastance (5). OCT is capable of performing highly localized measurements of the viscoelastic properties of tissue, a technique referred to as optical coherence elastography (21,22,49).…”

Dilatation of the Constricted Human Airway by Tidal Expansion of Lung Parenchyma

“…We therefore developed a new experimental system in which human airways within thin lung slices can be studied under conditions of dynamic load that simulate breathing, while precisely monitoring airway size and its tidal fluctuation (Figure 1). Our approach builds on prior work by Wohlsen and others (40,41,(53)(54)(55)(56)(57), who assessed airway contraction in the absence of simulated breathing, and on that of Dassow and colleagues (58) and Sanderson (59), who have also developed systems to stretch lung slices.…”

Airway Contractility in the Precision-Cut Lung Slice after Cryopreservation

“…An attractive new preparation for studying reactivity of the small airway is the precision-cut lung slice (PCLS) (15)(16)(17)(18)(19)(20)(21)(22)(23)(24).…”

“…Additional practical advantages of the PCLS include ease of preparation, widespread applicability to nearly every animal species including human (22,25), and suitability for high-resolution imaging (19,21). In the PCLS, even responses to neural stimulation (20,23) and stretch (18,22,24) have been evaluated. The use of the PCLS for assessment of airway responsiveness is limited by tissue viability in culture, which lasts 3 to 6 days from the time of tissue harvest (19).…”