Combined iNO and endothelial progenitor cells improve lung alveolar and vascular structure in neonatal rats exposed to prolonged hyperoxia.
BACKGROUND
Stem cells or inhaled nitric oxide (iNO) are reported to improve lung structures in bronchopulmonary dysplasia (BPD) models. We hypothesized that combined iNO and transplanted endothelial progenitor cells (EPCs) might restore lung structure in rats after neonatal hyperoxia.


METHODS
Litters were separated into eight groups: room air, hyperoxia, hyperoxia + iNO, hyperoxia + iNO + L-NAME, hyperoxia + EPCs, hyperoxia + EPCs + L-NAME, hyperoxia + EPCs + iNO, and hyperoxia + EPCs + iNO + L-NAME. Litters were exposed to hyperoxia from the 21st day, then, sacrificed. EPCs were injected on the 21st day. L-NAME was injected daily for 7 d from the 21st day. Serum vascular endothelial growth factor (VEGF), radial alveolar count (RAC), VIII factor, EPCs engraftment, lung VEGF, VEGFR2, endothelial nitric oxide (eNOS) and SDF-1 expression, and NO production were examined.


RESULTS
Hyperoxia exposure led to air space enlargement, loss of lung capillaries, and low expression of VEGF and eNOS. Transplanted EPCs, when combined with iNO, had significantly increased engraftment in lungs, compared to EPCs alone, upon hyperoxia exposure. There was improvement in alveolarization, microvessel density, and upregulation of VEGF and eNOS proteins in the hyperoxia-exposed EPCs with iNO group, compared to hyperoxia alone.


CONCLUSIONS
Combined EPCs and iNO improved lung structures after neonatal hyperoxia. This was associated with the upregulation of VEGF and eNOS expression.
Department of Respiratory, Children's Hospital of Fudan University, Shanghai, P. R. China.
Aizhen
A
Lu
Department of the Respiratory laboratory, Children's Hospital of Fudan University, Shanghai, P. R. China.
Bo
B
Sun
Department of Respiratory, Children's Hospital of Fudan University, Shanghai, P. R. China.
Liling
L
Qian
D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D001808:Blood Vessels / Q000166:cytology / Q000187:drug effects*; D015153:Blotting, Western; D001973:Bromodeoxyuridine; D017931:DNA Primers / Q000235:genetics; D066026:Endothelial Progenitor Cells / Q000502:physiology* / Q000637:transplantation; D004797:Enzyme-Linked Immunosorbent Assay; D018496:Hyperoxia / Q000473:pathology*; D007150:Immunohistochemistry; D019331:NG-Nitroarginine Methyl Ester / Q000008:administration & dosage; D009569:Nitric Oxide / Q000008:administration & dosage / Q000494:pharmacology*; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D011650:Pulmonary Alveoli / Q000098:blood supply / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D060888:Real-Time Polymerase Chain Reaction; D042461:Vascular Endothelial Growth Factor A / Q000097:blood / Q000378:metabolism; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism
D017931:DNA Primers; D042461:Vascular Endothelial Growth Factor A; D009569:Nitric Oxide; D052250:Nitric Oxide Synthase Type III; C496316:Nos3 protein, rat; D040301:Vascular Endothelial Growth Factor Receptor-2; D001973:Bromodeoxyuridine; D019331:NG-Nitroarginine Methyl Ester