Influence of Air Exposure Treatment on Alveolar Type II Epithelial Cells Cultured on Extracellular Matrix.

Abstract

ABSTRACT. Wecultured isolated alveolar type II epithelial cells on a collagen gel matrix. At confluence, cultured type II cells were exposed to air. Under these conditions, the cellular density of the type II cells increased and they nodularly aggregated. The cultured cells consisted mainly of flattened epithelia intermingled with cuboidal cells. In the cytoplasm and at the apical surface of cuboidal cells, a surfactant protein was detected by inimunohistochemistry and electron microscopy. Electron microscopic examination revealed that the surfactants in the cytoplasm increased when the cells were exposed to air. On the other hand, the flattened cells morphologically resembled type I cells in vivo. Air exposure treatment on the collagen gel matrix promoted the maintenance of the characteristic differentiation of alveolar epithelial cells. This culture system seemedto provide an appropriate physiological environment in which to study differentiation and disorders of pulmonary alveoli.The pulmonaryalveolar epithelium consists of two cell types. The bulk of the alveolar surface is covered by type I cells, which are characterized by their flattened profile and lack of distinctive organella and they appear to be terminally differentiated and do not proliferate either during growth or in response to lung injury. They do not proliferate in the culture system. On the other hand, type II cells are cuboidal and serve as the stem cell for the alveolar epithelium, with potential to proliferate and to assume type I phenotype (3, 16, 18,25).For this reason, investigators have used isolated type II cells to study alveolar cell biology, biochemistry, and molecular biology (2,4,12,13,21,24,25 (2,12,13). Briefly, 21-to 28-day-old male Wistar rats were anesthetized with diethyl ether, and the pulmonary circulation was per fused with a balanced salt solution, and the trachea was cannulated. To remove macrophages, the lung was lavaged through the trachea with a 1,000 protease units/ml bacterial neutral protease (Dispase I, Goudou-Shusei Co., Ltd., Tokyo, Japan) several times. Dispase I was instilled into the lung for 20 minutes at 37°C. Subsequently the lungs were removed from the tracheobronchial tree and minced with scissors in the presence of Eagle's Minimal Essential Medium (MEM,Nissui Pharmaceu-

Effects of fat cells on keratinocytes and fibroblasts in a reconstructed rat skin model using collagen gel matrix culture

“…For this reason, the proliferative activity of keratinocytes decreased on exposure to air. Exposure of laryngeal epithelial cells or alveolar epithelial cells to air also promoted their differentiation 31,32 . Recently, we reported that exposure of laryngeal squamous cell carcinoma cells on a collagen gel to air promoted invasive growth into the gel 23 .…”

“…Exposure of laryngeal epithelial cells or alveolar epithelial cells to air also promoted their differentiation. 31,32 Recently, we reported that exposure of laryngeal squamous cell carcinoma cells on a collagen gel to air promoted invasive growth into the gel. 23 The effects of fat cells on keratinocytes in this study were not modified fundamentally by air exposure.…”

Foveolar Differentiation of Mouse Gastric Mucosa in Vitro

“…In the next series of experiments, we examined the effects of an ALI on gastric surface mucous cells in the reconstructed gastric mucosa ( Figure 1D), because ALI culture conditions promote the differentiation of various epithelial cell types. [11][12][13][14][15][16][17] When the epithelial cells were treated with an ALI environment, they showed a tall columnar shape, central oval nuclei, and considerably lesser PAS-positive mucus just under the apical membrane ( Figure 2D compared to Figure 2B). Mean cell height was 13.4 Ϯ 0.2 m, mean nuclear height 6.4 Ϯ 0.1 m, and the nuclear vertical-horizontal ratio 1.98 Ϯ 0.05.…”

“…The ALI culture method is known to be useful in promoting the specific differentiation of several epithelial cell types. [11][12][13][14][15][16][17] Additionally, our recent studies have demonstrated that an ALI environment induces invasive growth of squamous cell carcinoma cells, 32 the active proliferation of fibroblasts involving a mitogen-activated protein kinase cascade, 23 and the long-term preservation of thyroid follicles with C cells in vitro. 33 Although the precise mechanisms of ALI-modified cytodifferentiation remain unclear, we believe that the ALI technique is close to the physiological environment for surface epithelial cells in that the cells are supplied with nutrients from the basal side and are not immersed in the apical media.…”

“…The air-liquid interface (ALI) culture method is known to be useful in promoting the specific differentiation of several epithelial cell types. [11][12][13][14][15][16][17] However, little is known about the application of the ALI culture technique to gastrointestinal epithelial cells. We have tried to examine the effect of ALI culture on gastric epithelial cells in primary culture.…”