Abstract 537: Granulocyte Colony-Stimulating Factor in the Cardiac Interstitium is Increased in the Early Phase of Acute Myocardial Infarction
Granulocyte colony-stimulating factor (G-CSF) is a hematopoietic growth factor that regulates the production and differentiation of neutrophils. Recently, G-CSF has been reported to mobilize bone marrow stem cells, which may differentiate into cardiac myocytes after acute myocardial infarction (AMI). Several angiogenic growth factors were reported to be accumulated at high concentrations in the pericardial fluid (PF) in patients with ischemic heart disease (IHD). However, it remains unclear how and to what degree the endogenous G-CSF is mobilized in patients with IHD, especially after the onset of AMI. We measured G-CSF levels in the plasma and PF obtained from 70 IHD patients who underwent coronary artery bypass graft surgery (CABG) using specific enzyme immunoassay (EIA) kits. Among 70 patients, 24 had AMI and the other 46 angina pectoris (AP). All patients with AMI underwent emergency CABG within 24 hours after the onset of AMI. G-CSF level in PF was markedly increased in patients with AMI (58.9±8.0 pg/ml) compared with patients with AP (4.2±0.2 pg/ml, p<0.01). Also, the plasma level of G-CSF was higher in patients with AMI (7.3±0.2 pg/ml) than in those with AP (4.0±0.2 pg/ml, p<0.01). In patients with AMI, G-CSF level in PF was increased by 8-fold compared with that in the plasma, whereas in patients with AP, there was no difference between the plasma and PF levels. In patients with AMI, G-CSF level in PF was positively correlated with that in the plasma (r=0.73, p<0.01). In another group of 20 patients with AMI, we collected blood samples on days 1, 2, 3, 5, 7 and 14 after the onset of AMI, and measured the plasma level of G-CSF and the mobilization of CD34 positive mononuclear cells (MNCCD34+) using flow cytometry. G-CSF level peaked at day 1, was decreased at day 5, and thereafter remained constant. The mobilization of MNCCD34+ was increased from 3.3±0.4 /μl on day 1 to 4.3±1.0 /μl on day 3 (p=0.08). In conclusion, the endogenous G-CSF level in the cardiac interstitium is markedly increased in the early phase of AMI, and may play an important role in the mobilization of MNCCD34+.