title: Phenotypic variability among density-fractionated human lung fibroblasts.
abstract: To determine if there is phenotypic variability within apparently homogeneous human lung fibroblast lines, growth-arrested lung fibroblasts were separated according to cell density. Three fibroblast fractions of specific gravity 1.023 to 1.035, 1.036 to 1.049, and 1.052 to 1.059 were obtained. These fractions differed in their cell volume and proliferative response to serum, but not in their response to growth-inhibiting soluble factors from lung mononuclear cells. The differences in proliferative capacity were not maintained during in vitro culture, and were not the result of the fractionation procedure selecting for cells at a particular point in the cell cycle. However, the fractionation procedure did separate cells based in part on their propensity to traverse the cell cycle. The least dense fraction was enriched for larger cells that were noncycling or slowly cycling, whereas the densest fibroblast fraction was enriched for small, rapidly cycling cells. Thus, there is morphologic and functional variability within adult human lung fibroblast lines. This phenotypic variability may be an important factor controlling the pulmonary fibrotic response.
mesh_terms: D002453:Cell Cycle / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002458:Cell Fractionation / Q000379:methods; D002460:Cell Line; D002478:Cells, Cultured; D002499:Centrifugation, Density Gradient; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects; D014644:Genetic Variation; D006131:Growth Inhibitors / Q000494:pharmacology; D006801:Humans; D008168:Lung / Q000166:cytology* / Q000187:drug effects; D009000:Monocytes; D015846:Monokines; D010641:Phenotype; D011506:Proteins / Q000494:pharmacology; D013046:Specific Gravity
chemical_list: D006131:Growth Inhibitors; D015846:Monokines; D011506:Proteins