Applications and Approaches for Three-Dimensional Precision-Cut Lung Slices. Disease Modeling and Drug Discovery

Abstract

Chronic lung diseases (CLDs), such as chronic obstructive pulmonary disease, interstitial lung disease, and lung cancer, are among the leading causes of morbidity globally and impose major health and financial burdens on patients and society. Effective treatments are scarce, and relevant human model systems to effectively study CLD pathomechanisms and thus discover and validate potential new targets and therapies are needed. Precision-cut lung slices (PCLS) from healthy and diseased human tissue represent one promising tool that can closely recapitulate the complexity of the lung's native environment, and recently, improved methodologies and accessibility to human tissue have led to an increased use of PCLS in CLD research. Here, we discuss approaches that use human PCLS to advance our understanding of CLD development, as well as drug discovery and validation for CLDs. PCLS enable investigators to study complex interactions among different cell types and the extracellular matrix in the native three-dimensional architecture of the lung. PCLS further allow for high-resolution (live) imaging of cellular functions in several dimensions. Importantly, PCLS can be derived from diseased lung tissue upon lung surgery or transplantation, thus allowing the study of CLDs in living human tissue. Moreover, CLDs can be modeled in PCLS derived from normal lung tissue to mimic the onset and progression of CLDs, complementing studies in end-stage diseased tissue. Altogether, PCLS are emerging as a remarkable tool to further bridge the gap between target identification and translation into clinical studies, and thus open novel avenues for future precision medicine approaches.

Keywords: PCLS; drug discovery; ex vivo lung disease; translation.

Figure 1.

Development of precision-cut lung slices (PCLS) generation, leading to disease modeling and drug discovery. Ex vivo culturing of lung tissue has been performed since the early 1940s, although limited progress was made in the technique for the first two decades. Early studies were limited to short culture times and analyses of metabolites and toxicological studies. Mechanistic studies did not start until the 1970s. Precise and reproducible generation of thin lung slices began at the end of the 1980s, when agar was used to support the three-dimensional structure. The first lung slice from human lungs was generated in the early to mid 1990s. Most recently, lung slices from animal and human tissues have been used to explore in-depth mechanisms of lung diseases. COPD = chronic obstructive pulmonary disease; DOC = dynamic organ culture; IPF = idiopathic pulmonary fibrosis.

Figure 2.

Schematic outline of PCLS use for disease modeling and drug discovery. Paired analysis of slices obtained from the same lung region allows exploration of stimulus-specific effects (open circles). Furthermore, this effect can be explored in different regions of the same lung to assess patient-specific tissue heterogeneity and responses to a certain stimulus. PCLS generation from healthy explants and diseased tissue can reveal anatomic differences in the molecular interactions that occur within the microenvironment of the lung. Disease modeling of healthy tissue can be achieved ex vivo by mimicking disease characteristics. Ultimately, disease models from natively diseased tissue or models developed ex vivo can be used for therapeutic exploration. Images reproduced and modified from Servier Medical Art with permission (http://smart.servier.com/).

Figure 3.

PCLS disease modeling of COPD, IPF, and lung cancer. (A) Three-dimensional reconstruction of collagen I and E-cadherin staining on PCLS generated from healthy and COPD human explants (15). Scale bars: 100 μm. (B) Collagen I and elastin fibers in an ex vivo elastase COPD disease model in mouse PCLS (38). Scale bars: 10 μm. (C) Extracellular matrix deposition of fibronectin in PCLS treated with a fibrotic cocktail (FC) to model early fibrosis-like changes (48). Scale bar: 1 mm. (D) PCLS immunostained against phalloidin and Kras. PCLS were obtained from the mouse KRAS model (58). Scale bars: 50 μm. (E) Structural differences between tumor and tumor-free regions of PCLS generated from human explants. Scale bars: 50 μm. Reprinted by permission from References , , , and . CC = control cocktail; FN1 = fibronectin; WT = wild-type.

Figure 4.

PCLS applications and approaches: current strategies and future opportunities for disease modeling and drug discovery. PCLS may be of value for a variety of (pre)clinical applications, including identification of novel pathomechanisms and targets using novel methodologies and imaging techniques, testing of novel drug delivery options (e.g., nanoparticles and vesicles), discovery and validation of novel drugs and compounds, and assessment of individual side effects and treatment responses. PD = pharmacodynamic; PK = pharmacokinetic.