The effects of granulocyte-colony stimulating factor in bare stent and sirolimus-eluting stent in pigs following myocardial infarction

Deletion of Smooth Muscle Lethal Giant Larvae 1 Promotes Neointimal Hyperplasia in Mice

Vascular smooth muscle cell (VSMC) proliferation and migration contribute to neointimal hyperplasia after injury, which causes vascular remodeling related to arteriosclerosis, hypertension, and restenosis. Lethal giant larvae 1 (LGL1) is a highly conserved protein and plays an important role in cell polarity and tumor suppression. However, whether LGL1 affects neointimal hyperplasia is still unknown. In this study, we used smooth muscle-specific LGL1 knockout (LGL1^SMKO) mice generated by cross-breeding LGL1^flox/flox mice with α-SMA-Cre mice. LGL1 expression was significantly decreased during both carotid artery ligation in vivo and PDGF-BB stimulation in vitro. LGL1 overexpression inhibited the proliferation and migration of VSMCs. Mechanistically, LGL1 could bind with signal transducer and activator of transcription 3 (STAT3) and promote its degradation via the proteasomal pathway. In the carotid artery ligation animal model, smooth muscle-specific deletion of LGL1 accelerated neointimal hyperplasia, which was attenuated by the STAT3 inhibitor SH-4-54. In conclusion, LGL1 may inhibit neointimal hyperplasia by repressing VSMC proliferation and migration via promoting STAT3 proteasomal degradation.

Effects of granulocyte colony‑stimulating factor on rabbit carotid and porcine heart models of chronic obliterative arterial disease

Previous studies suggest that granulocyte colony-stimulating factor (G-CSF) can promote bone marrow derived progenitor cells to mediate cardiovascular repair, potentially reversing mechanical dysfunction in chronic ischaemic heart disease and post myocardial infarction. Two models were used in the present study both using a surgical ameroid constrictor to induce arterial stenosis. The first model used the carotid artery of rabbits. They were divided into high fat diet (inducing atherosclerosis) or normal fat diet (control) groups. Each was subdivided into surgical exposure group without constrictor, ameroid constrictor receiving normal saline or receiving G-CSF 15 µg/kg/day. Endothelial markers of endothelial nitric oxide synthase and endothelin 1 were increased by the use of ameroid constrictor in both atherosclerotic and non-atherosclerotic mice, however were not further altered by G-CSF. Scanning electron microscopy indicated that ameroid constrictor application altered endothelial morphology from an oval shape to a round shape and this was more prominent in the atherosclerotic compared with the non-atherosclerotic group. G-CSF injection increased the number of endothelial cells in all groups. The second model used the left coronary artery of pigs. They were equally divided into following groups, receiving normal saline (control), G-CSF 2.5 µg/kg/day (low dose), 5 µg/kg/day (medium dose) and 10 µg/kg/day (high dose) for 5 days. G-CSF at a low or high dose worsened intimal hyperplasia however at a medium dose improved it. In conclusion, G-CSF had no effect in a rabbit carotid artery model of atherosclerosis. Its effects on the porcine heart were dose-dependent; arterial disease worsened at a low or high dose, but improved at a medium dose.

Erythropoietin Induces Excessive Neointima Formation: A Study in a Rat Carotid Artery Model of Vascular Injury

A therapeutic strategy that would mitigate the events leading to hyperplasia and facilitate re-endothelialization of an injured artery after balloon angioplasty could be effective for a long-term patency of the artery. It is hypothesized that erythropoietin (EPO), which has both anti-inflammatory and antiapoptotic properties, will prevent hyperplasia, and its ability to proliferate and mobilize endothelial progenitor cells will re-endothelialize the injured artery. To test this hypothesis, EPO (5000 IU/kg) in solution was injected intraperitoneally 6 hours before vascular injury and then on every alternate day for a week or as a single dose (5000 IU/kg) in a sustained release gel formulation 1 week before the vascular injury. Morphometric analysis revealed nearly continuous re-endothelialization of the injured artery in EPO solution-treated animals (90% vs less than 20% in saline control); however, the treatment also caused excessive neointima formation (intima/media ratio, 2.10 ± 0.09 vs 1.60 ± 0.02 saline control, n = 5, P < .001). The EPO gel also induced similar excessive neointima formation. Immunohistochemical analysis of the injured arteries from the animals treated with EPO solution demonstrated a significant angiogenic response in adventitia and media, thus explaining the formation of excessive neointima. Although the results are in contrast to expectation, they explain a greater degree of stenosis seen in hemodialysis access fistulas in patients who are on EPO therapy for anemic condition. The results also caution the use of EPO, particularly in patients who are at a risk of vascular injury or are suffering from an atherosclerotic condition.

Endothelial progenitor cells: what use for the cardiologist?

Endothelial Progenitor Cells (EPC) were first described in 1997 and have since been the subject of numerous investigative studies exploring the potential of these cells in the process of cardiovascular damage and repair. Whilst their exact definition and mechanism of action remains unclear, they are directly influenced by different cardiovascular risk factors and have a definite role to play in defining cardiovascular risk. Furthermore, EPCs may have important therapeutic implications and further understanding of their pathophysiology has enabled us to explore new possibilities in the management of cardiovascular disease. This review article aims to provide an overview of the vast literature on EPCs in relation to clinical cardiology.

The effect of G-CSF in a myocardial ischemia reperfusion model rat

PURPOSE

It has been reported that G-CSF administration improves cardiac function by reducing the area of the infarct in a myocardial infarction model rat. In the present study, myocardial infarction model rats, produced by ligation of the left anterior coronary artery, were prepared. The G-CSF effect for treating cardiac muscle cell disorders by ischemia reperfusion was studied.

METHODS

Myocardial infarction model rats were produced by ligation of the left anterior descending coronary artery in 12-week-old Wistar rats. G-CSF was administered subcutaneously daily at a dose of 100 microg/kg/day for 5 days to rats with a complete ligation (MI-G group, n=6) and rats in which the ligated coronary artery was reperfused 30 minutes after the ligation (R-G group, n=6). Physiological saline was subcutaneously administered to rats with a complete ligation and reperfusion (MI-C and R-C groups, respectively, n=6 each), as controls. After 4 weeks, the infarct area ratio (%), cardiac function on echocardiography (left ventricular ejection fraction), and a myocardial histopathological diagnosis were carried out and the results compared among the groups.

RESULTS

No significant differences were found in the proportion of the residual heart muscle in the infarct lesion, myocardial wall thickness, or left ventricular ejection fraction between the MI-G and MI-C groups. In contrast, the infarct area, myocardial wall thickness, and left ventricular ejection fraction were significantly improved in the R-G group compared to the R-C group (p<0.05).

CONCLUSIONS

Any inhibitory effect of G-CSF on the infarct lesion was found in the myocardial infarction reperfusion model rat, but only a small effect was found in rats with a complete ligation-induced myocardial infarction. The findings in the present study, therefore, suggest that G-CSF is effective for treating cardiac muscle cell disorders by ischemia reperfusion.