Role of laminin in maintenance of type II pneumocyte morphology and function

Abstract

Loss of differentiated function by type II pneumocytes plated on plastic surfaces was demonstrated by decreased lamellar body content, increased cellular protein, and rapid cellular flattening, changes that were retarded modestly by plating cells on laminin-coated surfaces. Laminin surfaces also inhibited [3H]thymidine (THM) incorporation into cellular DNA by 40% compared with plastic at 40 h, but did not alter an additional mitogenic effect of rat serum over fetal calf serum. In contrast, cells plated on the laminin-rich basement membrane-like gel formed from an extract of EHS mouse sarcoma, matrix gel (MG), maintained a high content of intracellular lipids in lamellar inclusions and retained a rounded morphology for at least 3 days. MG markedly inhibited THM incorporation and morphological changes when cells were cultured on this surface or when MG was formed over cells initially plated on plastic for various intervals. The importance of the laminin component of MG was demonstrated when these surfaces were pretreated with a highly specific antilaminin serum. Type II cells commenced flattening on the treated MG surface, and THM incorporation increased with the same time course as did control cells on plastic. The data suggest that short-term culture and study of differentiated type II pneumocytes may require a laminin-rich substratum. THM incorporation into type II cell DNA provides an important early and sensitive index of cell-basement membrane interaction and subsequent maintenance of function.

Characterization of α1, β1, and γ1 laminin subunits during rabbit fetal lung development

“…Previous studies have shown that heterogeneity exists in the composition of the basement membranes beneath type I and type I1 cells and that these differences may be important in regulating alveolar epithelial differentiation (Sannes, 1991). An important role for laminin in lung development has already been demonstrated in the process of branching morphogenesis and in the phenotypic maintenance of isolated alveolar type I1 cells in culture (Rannels et al, 1987;Schuger et al, 1990). However, the correlation between alveolar epithelial differentiation and the differential expression of the laminin chains in vivo has not been evaluated.…”

“…In addition, cultured type I1 cells lose functional characteristics, such as the ability to synthesize the lipid and protein components of surfactant (Shannon et al, 1987(Shannon et al, , 1990. However, when isolated type I1 cells are cultured on Matrigel, an extract of basement membrane proteins prepared from the EHS tumor (Timpl et al, 1979; as much as 80% of Matrigel total protein is laminin-1), the type I1 cells maintain the morphological and functional characteristics of the differentiated cell type (Rannels et al, 1987). There is a loss of laminin immunoreactivity around and under cultured type I1 cells that have begun to flatten and lose their differentiated phenotype (Rannels et al, 1987).…”

“…However, when isolated type I1 cells are cultured on Matrigel, an extract of basement membrane proteins prepared from the EHS tumor (Timpl et al, 1979; as much as 80% of Matrigel total protein is laminin-1), the type I1 cells maintain the morphological and functional characteristics of the differentiated cell type (Rannels et al, 1987). There is a loss of laminin immunoreactivity around and under cultured type I1 cells that have begun to flatten and lose their differentiated phenotype (Rannels et al, 1987). Isolated alveolar type I1 cells also actively synthesize and modulate the turnover of extracellular matrix components (Rannels et al, 1992).…”

Effects of vascular endothelial growth factor on isolated fetal alveolar type II cells

“…After 48-h incorporation by cells cultured on plastic in 24-well culture plates, cells were rinsed twice with cold PBS, and DNA was precipitated with 5% TCA, dissolved in 200 l of 1 N sodium hydroxide, and neutralized by 200 l of 1 N acetic acid (28). After being scraped with the aid of a rubber policeman, 200-l aliquots were used to determine incorporated radioactivity in OptiPhase "Hisafe" scintillation cocktail (Wallac Scintillation Products, Perkin Elmer).…”

Type II Pneumocytes in Mixed Cell Culture of Human Lung: A Light and Electron Microscopic Study

“…Neither do they divide in isolated cell culture (13,14). The normal morphology of Type II cells in vitro can be prolonged by plating onto exogenous extracellular matrices (ECM), such as laminin (15), collagen gels (16) or basement membrane derived from cultured cells (15,17), and other sources (18,19). Furthermore, macrophage-or fibroblast-derived factors are thought to influence the differentiated function of Type H cells in vitro (17,20).…”