on June 18, 2009
Published online before print June 18, 2009, doi: 10.1161/ATVBAHA.109.186445
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Submitted on February 14, 2009
Accepted on June 3, 2009
Stimulation of Coronary Collateral Growth by Granulocyte Stimulating Factor. Role of Reactive Oxygen Species
Ana Catarina R. Carrão ;
From the Centre for Cardiovascular Research (A.C.R.C., K.L., I.B.), Charité Medical University, Berlin, Germany; Department for Cardiology (I.B.), University of Freiburg, Germany; Department of Integrative Medical Sciences (W.M.C., J.Y., C.K., V.O., Y.F.P.), NEOUCOM, Northeastern Ohio University College of Medicine, Rootstown, Ohio; Department of Biochemistry and Molecular Biology (P.R.), University of South Alabama, Mobile; Department of Biomedical Engineering and Physics (J.P.H.M.v.d.W., P.v.H., J.A.E.S.), Academic Medical Centre, Amsterdam, Netherlands.
* To whom correspondence should be addressed. E-mail: wchilian{at}neoucom.edu.
Objective—The purpose of this study was to determine whether G-CSF promotes coronary collateral growth (CCG) and decipher the mechanism for this stimulation.
Methods and Results—In a rat model of repetitive episodic myocardial ischemia (RI, 40 seconds LAD occlusion every 20 minutes for 2 hours and 20 minutes, 3 times/d for 5 days) CCG was deduced from collateral-dependent flow (flow to LAD region during occlusion). After RI, G-CSF (100 µg/kg/d) increased CCG (P<0.01) (0.47±0.15) versus vehicle (0.14±0.06). Surprisingly, G-CSF treatment without RI increased CCG (0.57±0.18) equal to G-CSF+RI. We evaluated ROS by dihydroethidine (DHE) fluorescence (LV injection, 60 µg/kg, during two episodes of ischemia). DHE fluorescence was double in G-CSF+RI versus vehicle+RI (P<0.01), and even higher in G-CSF without RI (P<0.01). Interestingly, the DHE signal did not colocalize with myeloperoxidase (immunostaining, neutrophil marker) but appeared in cardiac myocytes. The study of isolated cardiac myocytes revealed the cytokine stimulates ROS which elicit production of angiogenic factors. Apocynin inhibited G-CSF effects both in vivo and in vitro.
Conclusions—G-CSF stimulates ROS production directly in cardiomyocytes, which plays a pivotal role in triggering adaptations of the heart to ischemia including growth of the coronary collaterals.
Key words: G-CSF • coronary collateral circulation • ROS • cardiomyocytes