| Preface | 5 |
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| Contents | 7 |
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| Contributors | 8 |
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| 1 Stem and Progenitor Cells of the Airway Epithelium | 10 |
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| 1 Introduction | 10 |
| 1.1 Tissue-Specific Stem Cells | 10 |
| 1.2 Lung-Epithelial-Tissue-Specific Stem Cells | 10 |
| 1.3 Facultative Progenitor Cell | 11 |
| 1.4 Lung Facultative Progenitor Cells | 11 |
| 1.5 Questions Relevant to Lung Stem Cells | 11 |
| 2 Conducting Airway Structure and Function | 12 |
| 2.1 Functional Domains | 12 |
| 2.2 Tracheobronchial Domain | 12 |
| 2.3 Bronchiolar and Terminal Bronchiolar Domain | 12 |
| 2.4 Origin of Airway Domains | 13 |
| 2.5 Birth Date of Airway Epithelial Cells | 13 |
| 3 Conducting Airway Progenitor Cell Types | 14 |
| 3.1 Tracheobronchial Epithelium | 14 |
| 3.2 Basal Cells | 14 |
| 3.2.1 Basal Cells -- Surface Epithelium | 14 |
| 3.2.2 Basal Cells -- Submucosal Glands | 14 |
| 3.2.3 Basal Cells -- Plural Membrane | 15 |
| 3.3 Secretory Cells | 15 |
| 3.3.1 Clara-Like and Clara Cells | 15 |
| 3.3.2 Secretory Cell Molecular Markers | 16 |
| 3.3.3 Secretory Cells -- Cellular Specialization | 16 |
| 3.3.4 Secretory Cells -- Submucosal Gland | 16 |
| 3.4 Bronchiolar Epithelium | 17 |
| 3.4.1 Clara Cells | 17 |
| 3.4.2 Pulmonary Neuroendocrine Cells | 17 |
| 4 Facultative Progenitor Cell Pools | 18 |
| 4.1 Basal Cells | 18 |
| 4.1.1 Steady-State and Reparative Basal Cells | 18 |
| 4.2 Clara-Like and Clara Cells | 18 |
| 4.2.1 Phenotypic Plasticity Is a Hallmark of Clara-Like and Clara Cells | 19 |
| 5 Evidence in Support of Lung Stem Cells | 19 |
| 5.1 Classic Stem Cell Methods | 19 |
| 5.2 Injury and Lung Stem Cell Analysis | 20 |
| 5.3 Injury as a Confounding Variable | 21 |
| 5.4 Tracheobronchial Stem Cells | 21 |
| 5.4.1 Evidence in Favor of a Tracheobronchial Stem Cell | 21 |
| 5.4.2 Distinctions Between the Human and Mouse Data Sets | 21 |
| 5.4.3 Predictions of the Classic Stem Cell Model | 23 |
| 5.4.4 Revision of the Classic Hierarchical Organization | 23 |
| 5.4.5 A Temporally Regulated Tissue-Specific Stem Cell Hierarchy | 24 |
| 5.5 Bronchiolar Stem Cells | 26 |
| 5.5.1 Evidence in Favor of a Bronchiolar Stem Cell | 26 |
| 5.5.2 Caveats to the ''Stemness'' Claim | 26 |
| 5.5.3 Compartmental Boundaries | 26 |
| 5.5.4 Phenotypic Plasticity | 26 |
| 5.5.5 Fulfilling Koch's Postulates | 27 |
| 6 Summary | 27 |
| 7 Future Directions | 28 |
| References | 28 |
| 2 Mesenchymal Stem Cells for Lung Repair and Regeneration | 34 |
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| 1 Introduction | 34 |
| 2 Identification, Characterization, and Culture of MSCs | 35 |
| 3 MSCs of Different Tissue Origins: Similarities and Differences | 36 |
| 4 Acquisition of an Airway or Alveolar Epithelial Phenotype by MSCs | 37 |
| 5 Immunomodulation of Lung Injuries by MSCs | 38 |
| 6 Clinical Use of MSCs in Lung Disease | 41 |
| 7 MSCs and Malignancies: Pros and Cons and Other Cautions for Use | 41 |
| 8 Summary | 42 |
| References | 43 |
| 3 The Role of Progenitor Cells in Lung Disease Prognosis | 52 |
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| 1 Introduction and Background | 52 |
| 2 Asthma | 55 |
| 3 Pulmonary Arterial Hypertension | 57 |
| 4 Pulmonary Fibrosis | 59 |
| 5 Chronic Obstructive Pulmonary Disease and Emphysema | 60 |
| 6 Acute Lung Injury/Acute Respiratory Distress Syndrome | 61 |
| 6.1 Sepsis | 64 |
| 7 Lung Cancer | 65 |
| 8 Additional Considerations | 66 |
| Acknowledgments | 67 |
| References | 67 |
| 4 The Role of Fibrocytes in Lung Repair and Fibrosis | 72 |
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| 1 Introduction | 72 |
| 2 The Fibrocyte | 73 |
| 2.1 Characteristics Suggesting a Bone Marrow Origin | 73 |
| 2.2 Diverse Functions That Promote Tissue Repair and Fibrosis | 75 |
| 2.3 Homing of Fibrocytes and the CXCR4--CXCL12 Axis | 76 |
| 2.4 Role of Fibrocytes in Human Idiopathic Pulmonary Fibrosis | 79 |
| 2.5 Effect of Hypoxia on the Circulating Fibrocyte | 80 |
| 2.6 Role of Fibrocytes in Human Asthma | 81 |
| 3 Conclusion | 82 |
| References | 82 |
| 5 Stem Cells and CellMatrix Interactions in Lung | 86 |
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| 1 Introduction | 86 |
| 2 Extracellular Matrix in Lung | 87 |
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