[Effects of hRAMP1 modified mesenchymal stem cells on restenosis and heart function in rabbit model of carotid angioplasty and myocardial infarction].

OBJECTIVE: To observe the effects of mesenchymal stem cells (MSC) modified by human receptor activity-modifying protein 1 (hRAMP1) on restenosis and cardiac function post-myocardial infarction (MI) and explore the therapeutic safety for gene modification of MSC. METHODS: The double-injury rabbit model with MI reperfusion and sacculus damaged atherosclerotic carotid were established according to the previous study. MSC were transfected with adenovirus vector with enhanced green fluorescence protein (EGFP) and then introduced into rabbit model. The animals were randomly divided into Ad-EGFP-hRAMP1-MSC transfection group (hRAMP1-MSC group, n = 24) and Ad-EGFP-MSC transfection group (MSC group, n = 24), and PBS transfection group (C group, n = 24). At Day 28 post-transplantation, the injured carotid arteries and infarction myocardium were harvested to detect the expression of EGFP-positive MSC and assess organization morphology by hematoxylin and eosin, triphenyltetrazolium chloride or immunohistochemical stains and heart function by echocardiography. RESULTS: On flow cytometry, most cells expressed CD29 and CD90 while few ones expressed CD45. MSC with EGFP and a continuous expression of CD31 were found in intima of damaged carotid of both hRAMP1-MSC and MSC, but the expression of EGFP was not found in the control group. At Day 28 post-transplantation, the improvement of heart function and the decrease of infarct size were found in the hRAMP1-MSC and MSC groups compared with that in the control group(EF: 60.6% ± 1.5%,50.8% ± 3.2% vs 38.2% ± 2.0%, infarct size: 20.7% ± 1.4%, 33.2% ± 3.7% vs 35.6% ± 2.7%, all P < 0.05), especially much higher in hRAMP1-MSC group. At Day 28 post-transplantation, the area of intima hyperplasia and the rate of neointima and media in the hRAMP1-MSC group were lower than those in the MSC and C groups (0.15 ± 0.05 and 0.33 ± 0.08 vs 0.77 ± 0.11, 0.24 ± 0.07 and 0.51 ± 0.11 vs 1.09 ± 0.23, all P < 0.05). Also the expression of α-SMA was found in the hyperplasia intima. The expression of proliferating cell nuclear antigen significantly decreased in the hRAMP1-MSC group than those of the MSC and control groups (0.120 ± 0.028 vs 0.366 ± 0.013 and 0.627 ± 0.049, both P < 0.05). And it was much lower in the MSC group than that in the control group. CONCLUSIONS: Compared with MSC alone, hRAMP1-modified MSC have the potency not only of more improvement on cardiac function and the recovery of damaged endothelium, but also of significant inhibition of the proliferation of vascular smooth muscle cells. The recombinant hRAMP1 adenovirus vectors do not affect the differentiation potential MSC into endothelial cells.

[Establishing an animal model for carotid artery stenosis in rabbits].

OBJECTIVE: To establish an animal model for carotid artery stenosis in rabbits. METHODS: Forty New Zealand White rabbits were randomly divided into two groups, for 4-week and 8-week experiment, respectively. All rabbits were fed with a diet with 1.5% cholesterol for one week before the experiment started. The right common carotid arteries (RCCA) of the rabbits were then injured with nitrogen gas (100 mL/min x 5 min), with the left common carotid arteries (LCCA) serving as a control (self control). An additional 5 rabbits were fed with high cholesterol diet only without exposure to nitrogen gas (control group). Angiography and pathology tests were performed to evaluate the stenosis of carotid arteries. RESULTS: Four weeks after exposure to nitrogen gas, early atheromatosis appeared, with lesions showing fatty streak and fibrous plaque, and thickened focal arterial walls. The lumens showed light-stenosis. The angiography showed 20%-30% artery stenosis. Eight weeks after exposure to nitrogen gas, the lesions proceeded to mature fibrous plaque or atheromatous plaque stages, with entire arterial walls thickened and remarkable lumens stenosis. The angiography showed 60% -80% artery stenosis, and two arteries were totally occluded. No artherosclerosis and stenosis were seen in the self control arteries and control groups. CONCLUSION: The animal model for carotid artery stenosis can be effectively established in rabbits with nitrogen gas injury along with high cholesterol-feeding.

[rhG-CSF promotes re-endothelialization and attenuates intima hyperplasia in carotid artery of rabbits post balloon catheter injury].

OBJECTIVE: To investigate the effect of rhG-CSF on mobilizing bone marrow-MSCs, re-endothelialization and intima hyperplasia in carotid artery of rabbits post balloon catheter injury. METHODS: Rabbits were treated with rhG-CSF (25 microg/kg, twice daily, i.p, n = 35) or saline (n = 32) for 5 days, then, carotid arteries of rabbits were injured by balloon catheter. The number of peripheral MSCs was detected with FACS. The morphology of injured artery was examined with hematoxylin and eosin stain, PCNA was determined with immunohistochemistry. RESULTS: (1) Number of peripheral MSCs was similar at baseline and significantly increased at 24 hours and peaked at 7 days and remained increased till 14 days post rhG-CSF. (2) Significant endothelial cell deletion was evidenced in the control group, while scatter endothelial cells was observed in the rhG-CSF group at 1 week post injury. Two weeks after injury, new endothelial area was significantly higher in rhG-CSF group compared to control group. At 4 weeks post injury, endothelial connection was evidenced and regularly displayed in rhG-CSF treated group. (3) PCNA-positive cells in the tunica intima were significantly lower in rhG-CSF treated rabbits at 7, 14 and 28 days compared that in control rabbits (all P < 0.01). CONCLUSION: rhG-CSF could mobilize the bone marrow-MSCs and promote re-endothelialization and attenuate intima hyperplasia post balloon catheter injury in carotid arteries of rabbits.