Mesenchyme-derived cells in the airway wall including airway smooth muscle cells, fibroblasts and myofibroblasts are known to play important roles in airway remodeling. The lack of specific phenotypic markers makes it difficult to define these cell populations in primary cultures. Most relevant studies to date have utilized animal airway tissues, vascular tissues or transformed cell lines with only limited studies attempting to phenotypically characterize human airway mesenchymal cells. The objectives of this study were to evaluate reported markers and to identify novel markers to define these cell types. We could not identify any specific marker to define these cell populations in vitro that permitted unequivocal identification using immunocytochemistry. However, characteristic filamentous a-smooth muscle actin distribution was observed in a significant (~25%) proportion of human airway smooth muscle cells whereas this was not observed in airway fibroblasts. A significantly higher proportion of airway fibroblasts expressed α1 and α2 integrin receptors compared with human airway smooth muscle cells as assessed by Fluorescence Activated Cell Sorting. Global gene expression profiling identified AKR1C3 and cathepsin K as being novel markers to define airway smooth muscle cells whereas ITGA8 and TBXAS1 were identified as novel airway fibroblast-specific markers and these findings were validated by RT-PCR. Ex vivo studies in human airway tissue sections identified h-caldesmon and α-smooth muscle alpha actin as being expressed in smooth muscle bundles whereas ITGA8 and TBXAS1 were absent from these.
- airway smooth muscle cells
- airway myofibroblasts
- airway fibroblasts
- Copyright © 2009, American Journal of Physiology - Lung Cellular and Molecular Physiology