Table 1 Evidence for, and against, circulating progenitor cell generation of non-hematopoietic lung cell types.
Study Type | Disease or Model | Tissue of Origin | Lung Cell Type Formed / Frequency | Method of Detection | Ref. |
|---|---|---|---|---|---|
Animal, in-vivo | BMT | MSC | Undefined mesenchymal cells / occasional | PCR for collagen gene marker | [30] |
Animal, in-vivo | Bleomycin fibrosis | MSC | Type I pneumocytes / rare | β galactosidase protein | [23] |
Animal, in-vivo | BMT | HSC enrichment | Type II pneumocytes / up to 20%, bronchial epithelium / 4% | Y chromosome FISH, surfactant B mRNA | [31] |
Animal, in-vivo | Radiation pneumonitis | Whole bone marrow | Type II pneumocytes, bronchial epithelium / up to 20% of type II cells | Y chromosome FISH, surfactant B mRNA | [25] |
Animal, in-vivo | BMT | Whole bone marrow/EGFP retrovirus | Type II pneumocytes / 1–7% | EGFP, keratin immunostain, surfactant protein B FISH | [33] |
Animal, in-vivo | BMT and parabiotic animals | HSC | Hematopoietic chimerism but exceedingly rare lung cell types | EGFP | [32] |
Animal, in-vivo | Bleomycin fibrosis | MSC | Type II pneumocytes / ~1% | Y chromosome FISH | [22] |
Animal, in-vivo | Radiation fibrosis | MSC or whole bone marrow | Fibroblasts / common | EGFP, Y chromosome FISH, vimentin immunostain | [26] |
Animal, in-vivo | BMT | Bone marrow, EGFP labeled | Fibroblasts, Type I pneumocyte / occasional to rare | Flow cytometry | [34] |
Animal, in-vitro and in-vivo | Hypoxia-induced pulmonary hypertension | Circulating BM-derived c-kit positive | c-kit positive cells in pulmonary artery vessel wall; In hypoxia, circulating cells generate endothelial and smooth muscle cells in-vitro | Flow cytometry and immunohistochemistry | [27] |
Animal, in-vivo | Ablative radiation and elastase induced emphysema | GFP + fetal liver | Alveolar epithelium and endothelium; frequency not reported but increased by G-CSF and retinoic acid | Immunohistochemistry for CD45-, GFP+ cells | [28] |
Animal, in-vivo | Bleomycin fibrosis | Whole marrow GFP+ | GFP+ type I collagen expressing | Flow cytometry and immunohistochemistry, RT-PCR | [24] |
Human, in-vitro | Heat shock in cell culture | MSC and SAEC | Cell fusion / common | Immunostaining, microarray | [39] |
Animal, in-vivo Human, in-vivo | OVA-sensitized mouse model Allergen – sensitized asthmatics | CD34 positive, collagen I expressing fibrocytes CD34 positive, collagen I expressing fibrocytes | Myofibroblasts / ? Myofibroblasts / ? | CD34-positive, collagen I, α-smooth muscle actin CD34-positive, collagen I, α-smooth muscle actin | [29] |
Human, in-vivo | Human heart and lung transplant | Sex-mismatched donor lung or heart | No lung cell types of recipient origin | X and Y chromosome FISH, antibody stain for hematopoeitic cells | [36] |
Human, in-vivo | Human lung transplant Human BMT | Sex-mismatched donor lung Sex-mismatched donor bone marrow | Bronchial epithelium, type II pneumocytes, glands of recipient origin / 9 – 24% No lung cell types of donor origin | Y chromosome FISH, short tandem repeat PCR Y chromosome FISH, short tandem repeat PCR | [35] |
Human, in-vivo | Human BMT | Sex-mismatched donor bone marrow | Lung epithelium and endothelium of donor origin / up to 43% | X and Y chromosome FISH, keratin and PECAM immunostain | [38] |
Human, in-vivo | Human BMT | Sex-mismatched donor bone marrow | No nasal epithelium of donor origin | Y chromosome FISH, cytokeratin immunostain | [37] |