title: Sequestration and homing of bone marrow-derived lineage negative progenitor cells in the lung during pneumococcal pneumonia.
abstract: BACKGROUND
  Bone marrow (BM)-derived progenitor cells have been shown to have the potential to differentiate into a diversity of cell types involved in tissue repair. The characteristics of these progenitor cells in pneumonia lung is unknown. We have previously shown that Streptococcus pneumoniae induces a strong stimulus for the release of leukocytes from the BM and these leukocytes preferentially sequester in the lung capillaries. Here we report the behavior of BM-derived lineage negative progenitor cells (Lin- PCs) during pneumococcal pneumonia using quantum dots (QDs), nanocrystal fluorescent probes as a cell-tracking technique.
  
  
  METHODS
  Whole BM cells or purified Lin- PCs, harvested from C57/BL6 mice, were labeled with QDs and intravenously transfused into pneumonia mice infected by intratracheal instillation of Streptococcus pneumoniae. Saline was instilled for control. The recipients were sacrificed 2 and 24 hours following infusion and QD-positive cells retained in the circulation, BM and lungs were quantified.
  
  
  RESULTS
  Pneumonia prolonged the clearance of Lin- PCs from the circulation compared with control (21.7 +/- 2.7% vs. 7.7 +/- 0.9%, at 2 hours, P < 0.01), caused preferential sequestration of Lin- PCs in the lung microvessels (43.3 +/- 8.6% vs. 11.2 +/- 3.9%, at 2 hours, P < 0.05), and homing of these cells to both the lung (15.1 +/- 3.6% vs. 2.4 +/- 1.2%, at 24 hours, P < 0.05) and BM as compared to control (18.5 +/- 0.8% vs. 9.5 +/- 0.4%, at 24 hours, P < 0.01). Very few Lin- PCs migrated into air spaces.
  
  
  CONCLUSIONS
  In this study, we demonstrated that BM-derived progenitor cells are preferentially sequestered and retained in pneumonic mouse lungs. These cells potentially contribute to the repair of damaged lung tissue.
authors.affiliation: The James Hogg iCAPTURE Centre for Cardiovascular and Pulmonary Research, St, Paul's Hospital, University of British Columbia, Room 166, 1081 Burrard Street, Vancouver, British Columbia, V6Z 1Y6, Canada. hsuzuki-jpn@umin.ac.jp
authors.forename: Hisashi
authors.initials: H
authors.lastname: Suzuki
authors.forename: James C
authors.initials: JC
authors.lastname: Hogg
authors.forename: Stephan F
authors.initials: SF
authors.lastname: van Eeden
mesh_terms: D000818:Animals; D001773:Blood Cells / Q000473:pathology; D001854:Bone Marrow Cells / Q000473:pathology*; D002454:Cell Differentiation; D019070:Cell Lineage; D002465:Cell Movement; D005456:Fluorescent Dyes; D008168:Lung / Q000473:pathology / Q000503:physiopathology*; D051379:Mice; D008810:Mice, Inbred C57BL; D053758:Nanoparticles; D011018:Pneumonia, Pneumococcal / Q000473:pathology* / Q000503:physiopathology*; D011652:Pulmonary Circulation; D013234:Stem Cells / Q000473:pathology*
chemical_list: D005456:Fluorescent Dyes