Pulmonary Models

The Respiratory Toxicology Program utilizes state-of-the-art in vitro and ex-vivo models of pulmonary (and related) tissue. Models available offer a range of testing types, including screening and high content analysis for complex events. The choice of cell line (including reporter cells), primary cells, or 3-dimensional tissues depends on the throughput desired and level of assessment needed. Consider our oral cavity tissues to also model ingestion exposures. Let IIVS guide you to the model best for you!

Cell Lines

Pulmonary cell lines are readily available that are derived from lung tissue. Screening efforts often require rapid and cost-effective throughput to prioritize products in development. Cells lines such as Beas 2B, A549, and H292 are commonly employed as a means to make basic determinations of cytotoxicity and viability following test article exposure. Reporter cell lines (not necessarily of pulmonary origin) can answer more specific questions about effects of materials on cells, such as oxidative stress (Nrf2/ARE) and the activation on inflammatory pathways (NFκβ). These can also be multi-plexed with other endpoints to maximize return. Cell lines are most efficient and cost-effective option when screening large numbers of materials.

2D cell culture: stained with DAPI and Calcein AM (viability marker)

2D cell culture: stained with DAPI and Calcein AM (viability marker)

Primary Cells

Non-immortalized cells derived directly from primary tissue offer researchers an in vitro platform more closely resembling native cells. Normal human bronchial epithelial cells (NHBE) are often used to understand the effect of materials on pulmonary epithelium when cell function more closely resembles that found in vivo. Primary cells are typically more metabolically, and immune response competent. Other primary cells of interest may include those downstream of initial respiratory epithelium responses such as endothelial cells or circulating blood cells capable of mediating systemic responses such as inflammation.

Primary cells often represent a more physiologically relevant model than immortalized or transformed cell lines.
Reconstructed Human Airways (RHuA)

Recent technology advances has allowed the development of reconstructed airway epithelium. Primary cells obtained from donor tissue are expanded, seeded onto porous membranes, and cultured at an Air-Liquid-Interface (ALI) into a pseudostratified mucociliary tissue that recapitulate key physiologic functions. The RHuA contain multiple cell types including ciliated columnar cells, mucus-producing Goblet cells, and basal cells. IIVS has strong ties to both MatTek, Inc. and Epithelix Sarl; manufacturers of high quality tissues, EpiAirway™ and MucilAir™, respectively. Available RHuA tissues can be generated from cells of nasal, tracheal, and bronchial origin and be of healthy or diseased origin. Cultures can extend to weeks and months and allow the observation of short term (e.g. changes in ciliary beat frequency; CBF) and long term events (e.g. Goblet cell hyperplasia; GCH). Recent additions to the portfolio of RHuA cultures grown at ALI include Epithlix’s SmallAir™ and MatTek’s EpiAlveolar™ – tissues modeling the small airways and alveolar regions of the lung, respectively. The tissues generate inflammatory cytokine responses and are unique in that they are a 3D multi-cellular model with distinct sampling compartments, including the airway space that allows inhalation-like exposures.

RHuA example: A: MatTek’s EpiAirway™ (H&E) showing pseudostratification
RHuA example: B: Epithelix’s Small Air™ (IHC for CC10, a marker of Club cells)
RHuA tissues offer distinct compartments to expose and sample from. Apical rinse, Tissue, and Medium samples can be used to model what may happen in lavage fluid, airways, and blood, respectively.
Precision-Cut Lung Slices (PCLS)

Ex-vivo precision-cut lung slices are perhaps the most complex non-animal model available to assess pulmonary injury. PCLS are created from donor tissues obtained in a clinical setting and are created and maintained at IIVS using our custom PCLS culture system. The tissue offers an advantage over other models since it contains all lung cell types present in the tissue at the time of slicing. Further, it retains the native architecture of the lung – including small airways and respiratory parenchyma. PCLS have been maintained for many weeks and demonstrate changes not shown in other complex models of the lung. Acute (including robust cytokine responses, loss of viability, etc.) and chronic (increases in activated macrophage staining, collagen deposition, tissue remodeling) toxicities can be monitored following test article-exposures. PCLS have also been used to show no effect level and to identify drug concentration-specific reversibility of inflammatory marker expression – a key element in understanding whether an insult to respiratory tissue may persist or resolve after test article removal. As many diseases such as fibrosis or COPD are believed to be driven by chronic inflammatory processes, the availability of a long term pulmonary model of human origin that harbors vital immune cells and can deliver a wealth of data is a welcome addition to IIVS’ in vitro/ex vivo toolbox!

Oral Cavity Models

Many products entering the respiratory tract first pass through the oral cavity or are consumed in the mouth where adverse effects may occur. IIVS uses 3-dimensional human reconstructed buccal and gingival tissues to assess the impact of product exposure in the oral cavity. Both tissue models created by MatTek Inc. (EpiOral™ and EpiGingival™) provide researchers with high quality systems to evaluate product penetration and the potential for irritation and inflammation. IIVS routinely uses these tissues to gauge the properties of materials that may be consumed via the oral route of exposure.  EpiOral ™ and EpiGingival™ tissues are derived from normal epithelial cells of human donor origin. They are created by growing cells on specially prepared inserts using serum-free medium. Highly differentiated and organized at maturity, these multilayered models of human buccal and gingival tissues exhibit in vivo-like properties that make them attractive to researchers that wish to utilize state-of-the-art models to evaluate tissue responses. The stratification of cell types and expression of tissue-specific markers of interest also lend these models to histological evaluation of exposure effects. IIVS conducts permeation, cytotoxicity, and viability studies with many MatTek tissues and recommend the use of EpiOral™ and EpiGingival™ tisues for high-quality results when evaluating oral exposure materials.