Background: Mesothelial cell monolayers cover the serous cavities and internal organs, and
provide a protective low-friction interface between apposed organs and tissues. The mesothelium
also regulates inflammation, fluid and cell exchange, and tissue repair in these compartments
and possibly tumor metastasis. In the present study, a stable pleural mesothelial
cell line (MIM) was isolated and characterized, and the expression of several lymphatic specific
markers by these cells examined.
Methods and Results: MIM were isolated from mice stably expressing a temperature-sensitive
SV40 large T antigen ('Immortomouse', strain: H-2Kb-tsA58). These cells were compared
with lymphatic endothelial cells (LEC) derived from the mesenteric adventitia of the Immortomouse.
MIM and LEC expression of lymphatic-specific markers (Flt-4, LYVE-1, and
Prox-1) was examined, and the tight junction protein (ZO-1) was studied by immunofluorescence
and immunoblotting in these cells.
Results: LYVE-1, Prox-1, and Flt-4 were detected in both MIM and LEC, with Prox-1 and
LYVE-1 more strongly expressed on LEC than MIM. Conversely, Flt-4 was more densely expressed
on MIM than on LEC. Spatially, ZO-1 was prominent at MIM junctions, but was less
well organized in LEC.
Conclusion: MIM and LEC share several characteristic markers usually associated with lymphatic
endothelium. MIM might be useful for studying the biology and pathology of mesothelial
cells in vitro and help in the development of therapies for mesothelial-related diseases,
such as mesothelioma and pleural effusion.
