Stem Cell–derived Respiratory Epithelial Cell Cultures as Human Disease Models

Abstract

Advances in stem cell biology and the understanding of factors that determine lung stem cell self-renewal have enabled long-term in vitro culture of human lung cells derived from airway basal and alveolar type II cells. Improved capability to expand and study primary cells long-term, including in clonal cultures that are recently derived from a single cell, will allow experiments that address fundamental questions about lung homeostasis and repair, as well as translational questions in asthma, chronic obstructive pulmonary disease (COPD), pulmonary fibrosis, and lung cancer research. Here, we provide a brief history of post-natal lung epithelial cell culture and describe recent methodological advances, including some culture systems that now permit clonal cell culture. We further discuss the applications of primary cultures in defining 'normal' epithelium, modelling lung disease and in future cell therapies.

Cell-intrinsic differences between human airway epithelial cells from children and adults

“…Upon culture, substantial transcriptomic changes were induced in airway basal cells, demonstrating one of the limitations of airway cell culture models. 29 However, our finding that culture conditions may affect basal cells from children differently to those from adults raises questions about whether cells from children are better able to buffer the effects of the artificial environment than those from adults. As an example, inflammatory response pathways were upregulated in adult basal cells compared to pediatric basal cells, although it has previously been shown that pediatric basal cells in these culture conditions can mount an inflammatory response upon stimulation with poly I:C. 30 These age-specific changes induced by culture should be a consideration in disease modeling using primary cells, particularly as donor age also affected the production of the mucin MUC5AC in the 3D tracheosphere model.…”

Cell-intrinsic differences between human airway epithelial cells from children and adults

“…Upon culture, substantial transcriptomic changes were induced in airway basal cells, demonstrating one of the limitations of airway cell culture models (Orr and Hynds, 2021). However, our finding that culture conditions may affect basal cells from children differently to those from adults raises questions about whether cells from children are better able to buffer the effects of the artificial environment than those from adults.…”

Human models for COVID‐19 research

“…Some immortalised airway epithelial cell lines, such as 16HBE14, and spontaneous cancer cells (i.e. Calu-3 and H441) (see table in review article: (Orr & Hynds, 2021)) that are cultured on semipermeable membranes, can form tight junctions, secrete mucins, and show differential distribution of plasma membrane transport proteins between the apical membrane and the basolateral membrane epithelium (Castellani et al, 2018), but do not produce ciliated and other important specialised cell types. Calu-3 cells, are a popular epithelial cell line for infection studies as they are known to generate higher transepithelialresistance, produce mucus, and express a diverse set of immune and inflammatory modulators (Grainger et al, 2006;Braakhuis et al, 2020).…”

“…In traditional airway epithelial cell culture systems, primary cells do not survive for more than a few passages and their characteristics can deteriorate rapidly with age. One solution of many (see review article: Orr & Hynds, 2021) to increase proliferative capacity of the progenitor cells has been to expand the progenitor cells in co-culture with irradiated/mitotically inactivated fibroblasts prior to conversion to ALI for differentiation (Butler et al 2016). Another solution has been to introduce anti-senescent mechanisms such as viral oncogenes or the human polycomb protein BMI-1 (Fulcher et al 2009;Munye et al 2016;Gianotti et al 2018).…”

“…Some immortalised airway epithelial cell lines, such as 16HBE14, and spontaneous cancer cells (i.e. Calu‐3 and H441) (see table in review article: Orr & Hynds, 2021) that are cultured on semipermeable membranes can form tight junctions, secrete mucins, and show differential distribution of plasma membrane transport proteins between the apical membrane and the basolateral membrane epithelium (Castellani et al . 2018), but do not produce ciliated and other important specialised cell types.…”