Chronic respiratory diseases cause approximately 7% of all deaths worldwide and represent 4% of the global burden of disease. The isolation and characterisation of lung stem/progenitor cells is an important step towards the understanding of lung pathogenesis, lung repair after injury and the identification of target cells of transformation in lung carcinogenesis. This work aims to isolate human lung stem/progenitor cells and to determine their role in lung diseases.
To isolate lung epithelial subpopulations, human lung samples were dissociated into a single cell suspension. Using a combination of specific cell surface markers, four discrete epithelial populations were isolated. Electron microscopy and qPCR analysis showed that these subsets were enriched in basal cells, Clara cells/ciliated cells/goblet cells, alveolar type I cells, and alveolar type II cells. Basal cells and type II cells demonstrated colony-forming capacity in vitro with the formation of phenotypically distinct colonies when cultured in a three-dimension matrix.
Gene expression analysis of the different subpopulations was performed using Next-Gen sequencing. To evaluate the role of each population in lung pathogenesis, gene signatures of the different cellular subsets were compared to genetic profiles of lung diseases. Specifically, to identify the potential cells of origin for the different lung tumour subtypes, gene signatures of the normal cellular subsets were compared to the gene expression profiles of lung carcinomas. Results from this bioinformatical analysis are currently being validated in vivo by introducing oncogenic mutations into the different human lung progenitor cells and evaluating oncogenic transformation.
In depth characterization of human lung stem/progenitor cells will provide insights into their role in lung diseases and lung repair. This constitutes a critical step in evaluating the possible use of lung stem/progenitor cells in lung regenerative medicine.