Cellular differentiation in three-dimensional lung cell cultures

Introduction: Aspects of human biology that are not sufficiently addressed by current cell culture models are cellular differentiation and three-dimensional (3-D) structural organization. A model that more closely associates the presence and biology of organelles to molecular expressions relevant to these organelles may provide evidence of cellular differentiation and the beginning steps in the construction of a 3-D architecture. The development of a new model - 3-D cell cultures - may ultimately provide a better understanding of lung biology and pathobiology. Purpose: The purpose of this study was to develop both traditional monolayer and 3-D cell cultures of a known and well documented normal lung cell line and then to determine similarities and differences between these cultures in terms of differentiation and molecular marker expression. Results: Electron microscopy identified presence of lipid inclusion, microvilli, extra cellular matrix, and tight junctions in the 3-D cultures; differentiation not seen in ML cultures. The degree of differentiation determined by immunohistochemistry when the cell line was grown as ML or 3-D cultures shows that ultra-structure and marker expressions were more representative of control tissue than when cells were grown in 3-D than as MLs. Methods: An immortalized cell line was grown as a traditional monolayer (ML) in culture flasks and as 3-D cultures in rotating walled vessels and incubated under identical conditions. Comparison for presence of differentiation and marker expression between these cultures and control tissue collected from surgical patient specimens was studied. Electron microscopy for identification of ultra structures, and immunohistochemistry (ZO-1, EMA, ICAM-1, villin, tubulin, CK 18, VWF, Collagen IV and human mucin) for phenotypic comparisons between cells in ML and 3-D cell cultures was conducted. Summary: The development of 3-D cell cultures will provide for a new and more powerful tool in the study of lung biology and pathobiology.