Summary
Background: The dysfunction of vascular endothelial cells plays a key role in starting arterial restenosis. The circulating endothelial progenitor cells (EPCs) can be mobilised by cytokines and are recruited to sites of injury, where they may participate in intima repair and the recovery of endothelial function. In the present study, we examined the hypothesis that mobilisation of EPCs by exogenous recombinant human granulocyte-colony stimulating factor (rhG-CSF) can promote vascular proliferation, reduce vascular inflammation and decrease the rate of restenosis.
Methods: Male rats were randomly divided into the rhG-CSF and control groups. The animals were injected daily with 30 µg/kg rhG-CSF or 0.9% NaCl subcutaneously for 7 days, then the animals underwent balloon angioplasty of the common carotid artery. The animals were euthanased at 2 or 4 weeks after injury, and the carotid arteries were harvested and processed for immunohistochemistry, scanning electron microscopy (SEM), morphometric analysis of endothelialisation and neointimal formation at 1 hour, and 3, 7, 14 and 28 days after injury. Immunohistochemistry for proliferation cell nuclear antigen (PCNA) and reverse transcriptase polymerase chain reaction (RT-PCR) for endothelial nitric oxide synthase (eNOS) mRNA were also conducted for evaluating the proliferation of cells of the vessel wall and the possible mechanism of the repairing.
Results: Four weeks after balloon damage, SEM showed increased re-endothelialisation of the denuded vessels in the G-CSF treated animals compared with the control animals [(60.6 ± 7.3)% versus (41.6 ± 3.3)%, p < 0.01]. Re-endothelialisation was paralleled by a decrease in inflammation in the vessel wall. Histological examination showed that neointimal formation, vascular smooth muscle cells and fibrous tissue of the G-CSF group were less than those of the control group. Morphometry showed the lumen area of the G-CSF group was larger than that of the control group, and the neointimal area and percent of intimal hyperplasia were significantly smaller than those of the control group. Immunohistochemical staining for PCNA positive cells was less in the G-CSF treated animals compared with the control animals (42.9% versus 72.8%, p < 0.01).
Conclusion: rhG-CSF-induced mobilisation of EPCs regenerated endothelium and inhibited neointimal hyperplasia after vascular injury. This cytokine therapy may be a feasible strategy for the promotion of re-endothelialisation after angioplasty.