Multipotent Capacity of Immortalized Human Bronchial Epithelial Cells

Abstract

While the adult murine lung utilizes multiple compartmentally restricted progenitor cells during homeostasis and repair, much less is known about the progenitor cells from the human lung. Translating the murine stem cell model to humans is hindered by anatomical differences between species. Here we show that human bronchial epithelial cells (HBECs) display characteristics of multipotent stem cells of the lung. These HBECs express markers indicative of several epithelial types of the adult lung when experimentally tested in cell culture. When cultured in three different three-dimensional (3D) systems, subtle changes in the microenvironment result in unique responses including the ability of HBECs to differentiate into multiple central and peripheral lung cell types. These new findings indicate that the adult human lung contains a multipotent progenitor cell whose differentiation potential is primarily dictated by the microenvironment. The HBEC system is not only important in understanding mechanisms for specific cell lineage differentiation, but also for examining changes that correlate with human lung diseases including lung cancer.

Organoids as a model system for studying human lung development and disease

“…The air-liquid interface (ALI) culture system is favoured when culturing primary human bronchial epithelial cell (HBECs) lines [36][37][38][39], due to retention of polarized apical-basal organization, as well as functional differentiation properties like cilliogenesis [37,40]. The ALI system utilizes an insert with a permeable culture membrane that can be submerged in media, and can be combined with a 3D extracellular matrix layer (or a "3D ALI") to create an environment that supports 3D growth, polarization and differentiation [13,41,42]. Supplementing cultures with supporting stromal cell types, including fibroblasts, endothelial cells or smooth muscle cells, can also assist in organoid formation by secreting factors that are important for determining cell fate [43].…”

“…Interestingly, the positioning of organoids-forming cells in the 3D growth environment impacts the structures derived: HBECs embedded within Matrigel organize into spheroids containing cuboidal epithelial cells, while HBECs plated on top of the Matrigel layer selforganize into tubular structures that undergo branching and budding [42].…”

“…HBECs have multipotent potential, and their microenvironment influences the organoid type they produce [42].…”

Target cell types with stem/progenitor function to isolate for in vitro reconstruction of human bronchiolar epithelia

“…In addition, the choice of medium (components) also appears to have a great deal of influence on the reconstruction process of airway epithelia. A third possibility may be to resort to immortalizing stem/progenitor cells or those possessing a comparable status (Vaughan et al, 2006;Delgado et al, 2011;Walters et al, 2013), whereas this technology is at a stage of development where many improvements are still required.…”

“…In the case of immortalized cloned stem/progenitor cell lines (Ramirez et al, 2004;Fulcher et al, 2009;Delgado et al, 2011;Walters et al, 2013), NECs or NEBs may be mixed in stem/progenitor cell suspension before being plated in inserts, or the variant club cells plated in inserts may be co-cultured with the parabronchial smooth muscle cells. It is also possible that the club cells and their subclasses of cells and variant club cells can autonomously regulate their proliferation and differentiation without the presence of NECs or NEBs when they are cultured under ALI conditions on an adequate medium (Song et al, 2012).…”