Background Experimental studies demonstrate that granulocyte colony stimulating factor (G-CSF) promotes neovascularisation and confers cardioprotection.

Objective To assess the efficacy of repeated low dose G-CSF plus exercise on myocardial ischaemia in patients with severe chronic ischaemic heart disease.

Methods 18 patients with Canadian Cardiovascular Society class III–IV angina completed a randomised, double blind, crossover study of dose adjusted G-CSF versus placebo. Exercise was commenced 6 weeks prior and continued for the duration of the study. G-CSF or placebo was administered daily for 5 consecutive days at fortnightly intervals for three cycles, followed by crossover after 6 weeks. Primary outcome was myocardial perfusion by cardiac magnetic resonance imaging (MRI). Secondary outcomes were: Seattle Angina and Utility Based Quality of Life Heart Questionnaire (SAQ/UBQ-H), Exercise Stress Test (EST) and quantification of endothelial progenitor cells (EPC) by flow cytometry and angiogenic cytokines by immunoassay.

Results Compared with placebo, G-CSF had no effect on myocardial ischaemia by cardiac MRI, EST or SAQ/UBQ-H, despite effective EPC mobilisation (peak fold increase: CD34⁺=19, CD34⁺CD133⁺=37, CD34⁺ vascular endothelial growth factor receptor 2 (VEGFR-2)⁺=5, CD34⁺CD133⁺VEGFR-2⁺=3; all p<0.05 vs placebo). Plasma levels of stromal cell derived factor 1, angiopoietin 1, interleukin 8 and tumour necrosis factor α decreased after a symptom limited EST while vascular endothelial growth factor and platelet derived growth factor remained unchanged. All cytokines were unchanged following G-CSF. Seven troponin I positive events occurred with G-CSF compared with three with placebo (p=0.289). High sensitivity C reactive protein and N terminal prohormone brain natriuretic peptide increased with G-CSF (both p<0.01 vs placebo).

Conclusion In patients with chronic ischaemic heart disease, G-CSF mobilises EPCs but does not improve myocardial perfusion or angina. G-CSF increases plasma levels of adverse prognostic cardiac biomarkers.

Clinical trial registration information Australian New Zealand Clinical Trials Registry: http://www.anzctr.org.au. Unique identifier: ACTRN012607000354482.