Alveolar type 2 cell growth on a pulmonary endothelial
extracellular matrix.
Adamson, Ian Y. R., and Linda Young.
Department of Pathology, University of Manitoba, Winnipeg,
Canada
APStracts 3:0024L, 1996.
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 2 cell growth and function, we now
study the effects of culturing isolated rat alveolar Type 2 cells on
an extracellular matrix (ECM) freshly produced by pulmonary vascular
endothelial cells grown 5 days in culture. Type 2 cells from the same
rats were cultured on plastic or Matrigel for comparison. A large
increase in mitotic activity was seen in Type 2 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 2 cells on endothelial ECM showed a sudden
decline in DSPC/DNA by day 4 as compared to 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 1
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 2 cells respond briefly
to growth factors in pulmonary endothelial ECM then this type of
matrix promotes cell spreading with loss of Type 2 function as cells
subsequently resemble Type 1 epithelium.
Received 1 September 1995; accepted in final form 24 January
1996.
APS Manuscript Number L270-5.
Article publication pending Am. J. Physiol. (Lung Cell. Mol.
Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 8 February 96