Cell culture models using rat primary alveolar type I cells

There is a lack of cell culture models using primary alveolar type I (AT I) cells. The purpose of this study was to develop cell culture models using rat AT I cells and microvascular endothelial cells from the lung (MVECL). Two types of model systems were developed: single and co-culture systems; additionally a 3-dimensional model system was developed. Pure AT I cell (96.3 ± 2.7%) and MVECL (97.9 ± 1.1%) preparations were used. AT I cell morphology, mitochondrial number and distribution, actin filament arrangement and number of apoptotic cells at confluence, and telomere attrition were characterized. AT I cells maintained their morphometric characteristics through at least population doubling (PD) 35, while demonstrating telomere attrition through at least PD 100. Furthermore, AT I cells maintained the expression of their specific markers, T1α and AQ-5, through PD 42. For the co-cultures, AT I cells were grown on the top and MVECL were grown on the bottom of fibronectin-coated 24-well Transwell Fluroblok™ filter inserts. Neither cell type transmigrated the 1 μm pores. Additionally, AT I cells were grown in a thick layer of Matrigel® to create a 3-dimensional model in which primary AT I cells form ring-like structures that resemble an alveolus. The development of these model systems offers the opportunities to investigate AT I cells and their interactions with MVECL in response to pharmacological interventions and in the processes of disease, repair and regeneration.