Adamson I Y, Young L
Department of Pathology, University of Manitoba, Winnipeg, Canada.
Am J Physiol. 1996 Jun;270(6 Pt 1):L1017-22. doi: 10.1152/ajplung.1996.270.6.L1017.
Most of the alveolar epithelium overlies a fused basement membrane produced by epithelial and endothelial cells. To determine how this type of matrix influences type II cell growth and function, we studied the effects of culturing isolated rat alveolar type II cells on an extracellular matrix (ECM) freshly produced by pulmonary vascular endothelial cells grown 5 days in culture. Type II cells from the same rats were cultured on plastic or Matrigel for comparison. A large increase in mitotic activity was seen in type II cells grown on the endothelial ECM at 2 days only; thereafter cells spread rapidly to confluence and lost their lamellar bodies. Cells grown on Matrigel remained cuboidal with lamellar bodies but grew more slowly, as judged by [3H]thymidine uptake and cell numbers. Incorporation of labeled choline into disaturated phosphatidylcholine (DSPC) was used as a marker of surfactant synthesis. After the rapid, brief burst of proliferation, type II cells on endothelial ECM showed a sudden decline in DSPC-DNA by day 4 compared with cells grown on matrigel. Binding of the lectin Bauhinia purpurea (BPA) indicated that after a phase of division, cells on endothelial ECM developed as type I epithelium by 4 days of culture, when > 70% of cells stained positively for BPA binding, whereas few cuboidal cells on Matrigel were stained. The results indicate that type II cells respond briefly to growth factors in pulmonary endothelial ECM; then this type of matrix promotes cell spreading with loss of type II function as cells subsequently resemble type I epithelium.
大多数肺泡上皮覆盖着由上皮细胞和内皮细胞产生的融合基膜。为了确定这种类型的基质如何影响II型细胞的生长和功能，我们研究了将分离的大鼠肺泡II型细胞培养在由培养5天的肺血管内皮细胞新鲜产生的细胞外基质（ECM）上的效果。将来自相同大鼠的II型细胞培养在塑料或基质胶上作为对照。仅在第2天，在内皮ECM上生长的II型细胞中观察到有丝分裂活性大幅增加；此后细胞迅速铺展至汇合，失去其板层小体。通过[3H]胸苷摄取和细胞数量判断，在基质胶上生长的细胞保持立方体形并带有板层小体，但生长较慢。将标记的胆碱掺入二饱和磷脂酰胆碱（DSPC）中用作表面活性剂合成的标志物。在快速短暂的增殖爆发后，与在基质胶上生长的细胞相比，内皮ECM上的II型细胞在第4天时DSPC-DNA突然下降。紫羊蹄甲凝集素（BPA）的结合表明，在一个分裂阶段后，内皮ECM上的细胞在培养4天时发育为I型上皮，此时>70%的细胞BPA结合染色呈阳性，而基质胶上很少有立方体细胞被染色。结果表明，II型细胞对肺内皮ECM中的生长因子有短暂反应；然后这种类型的基质促进细胞铺展，随着细胞随后类似于I型上皮而丧失II型功能。
