Published ahead of print on June 9, 2005, doi:10.1164/rccm.200409-1280OC Am. J. Respir. Crit. Care Med., Volume 172, Number 5, September 2005, 581-589 A more recent version of this article appeared on September 1, 2005
Submitted on September 26, 2004 Adrenomedullin Regenerates Alveoli and Vasculature in Elastase-induced Pulmonary Emphysema in MiceShinsuke Murakami1,1 Department of Regenerative Medicine and Tissue Engineering, National Cardiovascular Center Research Institute, Osaka, Japan; Second Department of Internal Medicine, Nara Medical University, Nara, Japan, 2 Department of Regenerative Medicine and Tissue Engineering, National Cardiovascular Center Research Institute, Osaka, Japan; Department of Internal Medicine, National Cardiovascular Center, Osaka, Japan, 3 Department of Regenerative Medicine and Tissue Engineering, National Cardiovascular Center Research Institute, Osaka, Japan, 4 Department of Transfusion Medicine, Hyogo College of Medicine, Hyogo, Japan, 5 Second Department of Internal Medicine, Nara Medical University, Nara, Japan, 6 Department of Biochemistry, National Cardiovascular Center Research Institute, Osaka, Japan * To whom correspondence should be addressed. E-mail: nnagaya{at}ri.ncvc.go.jp.
Rationale: Adrenomedullin, a potent vasodilator peptide, regulates cell growth and survival. However, whether adrenomedullin contributes to lung regeneration remains unknown. Objectives: To investigate whether adrenomedullin influences the kinetics of bone marrow cells, and whether adrenomedullin promotes regeneration of alveoli and vasculature and thereby improves lung structure and function in elastase-induced emphysema in mice. Methods: Adrenomedullin or vehicle was randomly administered to C57BL/6 mice for five days. We counted the numbers of mononuclear cells and stem cell antigen-1-positive cells in circulating blood. After intratracheal injection of elastase or saline, mice were randomized to receive continuous infusion of adrenomedullin or vehicle for 14 days. Functional and histological analyses were performed 28 days after treatment. Measurements and Main Results: Twenty-eight days after elastase injection, destruction of the alveolar walls was observed. However, adrenomedullin infusion significantly inhibited the increase in lung volume, static lung compliance, and mean linear intercept in mice given elastase. Adrenomedullin increased the numbers of mononuclear cells and stem cell antigen-1-positive cells in circulating blood. Adrenomedullin significantly increased the number of bone marrow-derived cells incorporated into the elastase-treated lung. Some of these cells were positive for cytokeratin or von Willebrand factor. Infusion of adrenomedullin after the establishment of emphysema also had beneficial effects on lung structure and function. In vitro, addition of adrenomedullin attenuates elastase-induced cell death in alveolar epithelial cells and endothelial cells. Conclusions: Adrenomedullin improved elastase-induced emphysema at least in part through mobilization of bone marrow cells and the direct protective effects on alveolar epithelial cells and endothelial cells. Key words: bone marrow cells, differentiation, mobilization, regeneration
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