title: Discrimination between lung homeostatic and injury-induced epithelial progenitor subsets by cell-density properties.
abstract: Stem/progenitor cells and their lineage derivatives are often identified by patterns and intensity of cell clusters of differentiation presentation. However, the cell biochemical façade can prove to be elusive, transient, and subject to interlaboratory disparities. To enhance current methods of lung stem cell isolation and identification and to investigate biophysical changes, which occur during homeostasis and in response to acute lung injury, we separated cells on a discontinuous density gradient, of 1.025-1.074 g/cm(3), and characterized the eluted lineages. At homeostasis, surfactant protein-C (SFTPC)-expressing cells of the alveolar type (AT)-2 lineage possessed average densities ≥1.039 g/cm(3) and aquaporin-5 producing AT1 cells equilibrated at densities <1.039 g/cm(3). While 0.74%±0.32% of lung cells were determined proliferating or postmitotic by BrdU nucleotide uptake, 73% of CD49f-, 72% of c-KIT-, and 61% of SCA-1-positive cells (putative alveolar progenitor lineage markers) showed densities ≤1.039 g/cm(3). CD49f/EpCAM(hi) progenitors, as well as c-KIT(pos)/CD45(neg) cells, could be enriched at the 1.039 g/cm(3) interface. Following acute bleomycin-induced injury, the frequency of BrdU-incorporating cells rose to 0.92%±0.36% and density could largely explain cell-lineage distribution. Specifically, a decline in the density of mitotic/postmitotic SFTPC-positive cells to ≤1.029 g/cm(3), in conjunction with an increase in CD45-positive, and proliferating CD45 and c-KIT cells in the heaviest fraction (≥1.074 g/cm(3)) were observed. These data attest to the generation of AT2 cells from low-density precursors and emphasize a relationship between cell density and molecular expression following injury, expanding on our current understanding of lung and progenitor cell dynamics.
authors: Department of Biology, Yeshiva University, New York, NY 10033, USA.
authors: Namita
authors: N
authors: Sen
authors: Samuel
authors: S
authors: Weprin
authors: Yakov
authors: Y
authors: Peter
mesh_terms: D055371:Acute Lung Injury / Q000139:chemically induced / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D000818:Animals; D051402:Aquaporin 5 / Q000235:genetics / Q000378:metabolism; D015415:Biomarkers / Q000378:metabolism; D001761:Bleomycin / Q000009:adverse effects; D002454:Cell Differentiation; D019070:Cell Lineage; D049109:Cell Proliferation; D002499:Centrifugation, Density Gradient; D004847:Epithelial Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D005260:Female; D015870:Gene Expression; D006706:Homeostasis; D039503:Integrin alpha6 / Q000235:genetics / Q000378:metabolism; D008168:Lung / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D019009:Proto-Oncogene Proteins c-kit / Q000235:genetics / Q000378:metabolism; D037721:Pulmonary Surfactant-Associated Protein C / Q000235:genetics / Q000378:metabolism; D020545:Respiratory Mucosa / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D013234:Stem Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism
chemical_list: C496036:AQP5 protein, human; D051402:Aquaporin 5; D015415:Biomarkers; D039503:Integrin alpha6; D037721:Pulmonary Surfactant-Associated Protein C; C489679:SFTPC protein, human; D001761:Bleomycin; D019009:Proto-Oncogene Proteins c-kit