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(Arteriosclerosis, Thrombosis, and Vascular Biology. 2009;29:1817.)
© 2009 American Heart Association, Inc.

Integrative Physiology/Experimental Medicine

Stimulation of Coronary Collateral Growth by Granulocyte Stimulating Factor

Role of Reactive Oxygen Species

Ana Catarina R. Carrão; William M. Chilian; June Yun; Christopher Kolz; Petra Rocic; Kerstin Lehmann; Jeroen P.H.M. van den Wijngaard; Pepijn van Horssen; Jos A.E. Spaan; Vahagn Ohanyan; Yuh Fen Pung; Ivo Buschmann

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.

Correspondence to William M. Chilian, PhD, Department of Integrative Medical Sciences, Northeastern Ohio University College of Medicine, 4209 State Route 44, Rootstown, OH 44272. 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.

We hypothesized that G-CSF stimulates coronary collateral growth (CCG) via production of ROS. G-CSF increased CCG with or without myocardial ischemia. G-CSF–induced ROS production occurred in cardiomyocytes but not in granulocytes. We conclude G-CSF stimulates ROS production in cardiomyocytes, which elicits growth of coronary collaterals via stimulation of angiogenic factors.

Key Words: G-CSF • coronary collateral circulation • ROS • cardiomyocytes