title: Assembly of basement membrane in vitro by cooperation between alveolar epithelial cells and pulmonary fibroblasts.
abstract: To investigate basement membrane formation by cooperation between pneumocytes and pulmonary fibroblasts, we cultured type II alveolar epithelial cells obtained from rats transfected with SV40-large T antigen gene (SV40-T2 cells) on type I collagen matrices. On fibroblasts-embedded gel (T2-Fgel), SV40-T2 cells ultrastructurally formed a continuous and thin layer of lamina densa, while on collagen gel without fibroblasts (T2-gel) SV40-T2 cells produced only discontinuous and diffuse deposits. Stripping SV40-T2 cells off the tissues by H2O2 treatment revealed a continuous and plane surface of lamina densa assembled on the T2-Fgel tissue, whereas only amorphous deposits appeared on the T2-gel tissue. Immunolocalization of major basement membrane components showed that type IV collagen, laminin, perlecan and entactin (nidogen) were continuously integrated on the lamina densa in T2-Fgel. In T2-gel, all these components were discontinuously distributed beneath SV40-T2 cells. The contribution of pulmonary fibroblasts to the assembly of basement membrane through reorganization of collagen matrix and/or soluble factors was examined by the cultured of SV40-T2 cells on the freeze-thawed fibroblast-tissue and/or with the fibroblast-conditioned medium. Both SV40-T2 cells on the freeze-thawed fibroblast-tissue and SV40-T2 cells in T2-gel in the fibroblast-conditioned medium failed to produce a lamina densa. SV40-T2 cells could assemble a lamina densa only on the freeze-thawed fibroblast-tissue in the fibroblast-conditioned medium. These results show that the basement membrane components are assembled to a lamina densa by combination of the reorganization of collagen matrix and the supply of soluble factors by pulmonary fibroblasts.
authors.affiliation: Environmental Health Sciences Division, National Institute for Environmental Studies, Ibaraki, Japan. kawagoe@nies.go.jp
authors.forename: A
authors.initials: A
authors.lastname: Furuyama
authors.forename: K
authors.initials: K
authors.lastname: Kimata
authors.forename: K
authors.initials: K
authors.lastname: Mochitate
mesh_terms: D000818:Animals; D000952:Antigens, Polyomavirus Transforming / Q000235:genetics; D001485:Basement Membrane / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure; D002450:Cell Communication / Q000502:physiology*; D002478:Cells, Cultured; D003094:Collagen / Q000032:analysis; D004847:Epithelial Cells / Q000166:cytology* / Q000648:ultrastructure; D005109:Extracellular Matrix / Q000737:chemistry / Q000378:metabolism; D005347:Fibroblasts / Q000166:cytology / Q000648:ultrastructure; D005455:Fluorescent Antibody Technique; D007797:Laminin / Q000032:analysis; D008854:Microscopy, Electron; D008855:Microscopy, Electron, Scanning; D011650:Pulmonary Alveoli / Q000166:cytology*; D051381:Rats; D014162:Transfection
chemical_list: D000952:Antigens, Polyomavirus Transforming; D007797:Laminin; D003094:Collagen