Instent neointimal hyperplasia after percutaneous intervention for ST-elevation myocardial infarction and treatment with granulocyte-colony stimulating factor. Results from the stem cells in myocardial infarction (STEMMI) trial.

BACKGROUND: Recombinant granulocyte-colony stimulating factor (G-CSF) mobilized pluripotent cells from the bone marrow are proposed to have a regenerative potential. Though, a report of excessive instent restenosis, in patients treated with G-CSF before percutaneous coronary intervention (PCI) warrants caution.

METHODS: Patients (n=59) enrolled in the STEMMI trial, a randomized and double blind study, comparing G-CSF and placebo after large ST-elevation myocardial infarctions, had an intracoronary ultrasound imaging at 6 months follow-up with a quantitative analysis of instent neointimal hyperplasia.

RESULTS: During G-CSF treatment leukocyte counts, and CD34+ and CD45-/CD34- cell fractions in peripheral blood increased markedly (p<0.0001 vs. placebo). At follow-up, there were no differences in intracoronary late lumen loss, expressed as neointima volume per mm of stent (1.6 mm(3)± 1.2 [G-CSF group] vs. 1.9 mm(3)± 1.3 [placebo group]; p=0.38), and in minimal instent lumen area (5.4 mm(2)± 2.4 vs. 5.3 mm(2)± 2.6, p=0.90). In the placebo group, plasma concentration of stromal cell-derived factor-1 (SDF-1) increased significantly after STEMI. This SDF-1 response was completely suppressed during G-CSF treatment. A rebound increase of SDF-1 was observed after withdrawal of G-CSF (p=0.001). Plasma concentration of SDF-1 at the time of stent implantation correlated positively to neointimal hyperplasia (p=0.025).

CONCLUSIONS: G-CSF treatment, initiated after PCI, does not lead to excessive instent neointimal hyperplasia or restenosis in patients with STEMI. The timing of G-CSF, in relation to the PCI, might be important, as G-CSF influences SDF-1.