Selective pressure-regulated retroinfusion of fibroblast growth factor-2 into the coronary vein enhances regional myocardial blood flow and function in pigs with chronic myocardial ischemia

OBJECTIVES: We sought to improve regional myocardial delivery and subsequent collateral perfusion induced by basic fibroblast growth factor-2 (FGF-2) using selective pressure-regulated retroinfusion of coronary veins for delivery. This hypothesis was tested in a newly developed pig model with percutaneous induction of chronic ischemia. BACKGROUND: Selective pressure-regulated retroinfusion of coronary veins is a catheter-based procedure that has been shown to provide effective regional delivery of drugs and gene vectors into ischemic myocardium. METHODS: A high-grade stenosis with subsequent progression to total occlusion within 28 days was induced by implanting a reduction stent graft into the left anterior descending artery (LAD). After seven days, a 30-min retroinfusion (anterior cardiac vein) was performed with (n = 7) or without (n = 7) 150 microg FGF-2 and compared with a 30-min antegrade infusion of 150 microg FGF-2 into the LAD (n = 7). Sonomicrometry to assess regional myocardial function at rest and during pacing, and microspheres to assess regional myocardial blood flow, were performed 28 days after implantation of the reduction stent. RESULTS: Retroinfusion of FGF-2 compared favorably with controls and with antegrade infusion of FGF-2 with regard to regional myocardial function at rest (18.5 +/- 4.1% vs. 5.7 +/- 2.9% vs. 7.9 +/- 1.8%, respectively, p < 0.05) and during pacing. Regional myocardial blood flow was also higher in the LAD territory after retroinfusion of FGF-2 (1.07 +/- 0.14 vs. 0.66 +/- 0.07 vs. 0.72 +/- 0.17 ml x min(-1) x g(-1), p < 0.05). CONCLUSIONS: Selective pressure-regulated retroinfusion increased tissue binding of FGF-2 and enhanced functionally relevant collateral perfusion compared with antegrade intracoronary delivery in pigs with chronic myocardial ischemia.     

Therapeutic angiogenesis in cardiology using protein formulations

Therapeutic angiogenesis in cardiovascular disease aims at improving myocardial function by increasing blood flow to ischemic myocardium that is not amenable to traditional forms of revascularization. Preclinical data have provided proof of the concept that angiogenic growth factors such as fibroblast growth factor 2 (FGF-2) and vascular endothelium growth factor (VEGF) may indeed improve myocardial flow and function when administered in ways that ensure prolonged tissue exposure to these short-lived molecules. Although other cytokines have been shown to enhance angiogenesis in vivo, FGF-2 and VEGF have been most widely studied and may serve as prototype proangiogenic drugs. Currently, several delivery techniques that are clinically applicable are being studied with respect to tissue distribution and retention as well as angiogenic efficacy of FGF-2 and VEGF. Although tissue distribution and retention of FGF-2 after intramyocardial injection compares favorably with other routes of administration, efficacy studies are not yet conclusive. At the same time, different protein- and gene-based formulations are being investigated. Arguments for and against protein and gene therapy are presented, showing that protein-based therapy seems to have advantages over gene therapy at the present time, although continuous efforts should be made to increase the tissue exposure time after a single administration of protein. While delivery systems and growth factor formulations are being improved, double-blind, placebo-controlled trials designed with existing animal data in mind, are needed to firmly establish the utility of therapeutic angiogenesis in cardiovascular disease.     

Effects of in vivo gene transfer of fibroblast growth factor-2 on cardiac function and collateral vessel formation in the microembolized rabbit heart

The effects of gene transfer of the secreted form of fibroblast growth factor-2 (FGF-2) were tested using an adenovirus vector in the microembolized rabbit heart. Japanese white rabbits underwent an intracoronary injection of 25-microm microspheres followed by recombinant adenovirus vectors encoding a secreted form of FGF-2 (FGF group), LacZ (LacZ group), or saline (saline group). Left ventricular (LV) systolic function was serially assessed by echocardiography. Vascular density was measured at 14 days with Azan and CD31 staining. The development of collateral vessels was assessed by measuring myocardial blood flow before and after the occlusion of the left anterior descending coronary artery. Percent fractional shortening (%FS) decreased after the microembolization, and improved gradually for 14 days in the FGF group only (41+/-1% (FGF) vs 32+/-1% (LacZ), 31+/-1% (saline), p<0.01). The vascular density and myocardial collateral blood flow were significantly higher in the FGF group in comparison with other groups. Transcoronary arterial gene transfer of the secreted form of FGF-2 was beneficial for the recovery of LV systolic function and development of collateral vessels in the microembolized rabbit heart.     

Efficacy of intracoronary or intravenous VEGF165 in a pig model of chronic myocardial ischemia

OBJECTIVES: We sought to optimize vascular endothelial growth factor (VEGF) treatment for therapeutic angiogenesis in myocardial ischemia, we explored the efficacy of five different regimens. BACKGROUND: Although VEGF165 is one of the most potent pro-angiogenic growth factors, VEGF165 treatment for myocardial ischemia has been hampered by low efficacy and dose-limiting hypotension after systemic or intracoronary delivery. METHODS: This study evaluated the effect of intravenous or intracoronary rhVEGF165 in the presence or absence of nitric oxide (NO) synthase inhibition in a porcine model of chronic myocardial ischemia. Forty-two Yorkshire pigs with chronically occluded left circumflex coronary arteries were randomly assigned to receive 10 microg/kg of VEGF165: 1) rapid (40 min) intravenous VEGF165 0.25 microg/kg/min, 2) slow (200 min) intravenous VEGF165 0.05 microg/kg/min, 3) rapid intracoronary VEGF165 0.25 microg/kg/min, 4) rapid intracoronary VEGF165 0.25 microg/kg/min + nitro-L-arginine methyl ester hydrochloride (L-NAME) or 5) rapid vehicle infusion. RESULTS: Intracoronary and intravenous VEGF165 induced hypotension. Intracoronary VEGF-induced hypotension was blocked by L-NAME. Coronary angiography three weeks after treatment showed improvement in collateral index in both intracoronary groups but not the intravenous VEGF165 groups. Likewise, myocardial blood flow and microvascular function in the ischemic territory improved in both intracoronary groups but not in the intravenous groups. Global and regional myocardial function showed no significant improvements in any groups. CONCLUSIONS: Intracoronary infusion of VEGF165 significantly improves blood flow to the ischemic myocardium. Concomitant administration of L-NAME inhibits VEGF-induced hypotension while most likely preserving VEGF-induced angiogenesis. Intravenous infusion of VEGF165 was not effective in augmenting either myocardial flow or function in this model.     

Intramyocardial injection of fibroblast growth factor-2 plus heparin suppresses cardiac failure progression in rats with hypertensive heart disease

A reduction of coronary flow reserve has been reported in patients with hypertensive heart disease (HHD), which suggests that myocardial ischemia may contribute to the progression to cardiac failure in HHD. Therefore, we evaluated whether fibroblast growth factor (FGF)-2 and/or heparin, which induce angiogenesis, may affect cardiac function in the setting of HHD. We used Dahl salt sensitive (DS) rats as an HHD model. Direct intramyocardial injection of 100 microg of FGF-2 plus 1.28 microg of heparin (n = 6), 100 microg of FGF-2 (n = 6), 1.28 microg of heparin (n = 6) or saline (n = 6) were performed in 9-week-old rats. Echocardiography was performed to evaluate cardiac function at 9, 11, and 13 weeks of age. Plasma atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) concentrations were measured at 8 and 13 weeks of age. DS rats were killed 4 weeks after myocardial injection (at 13 weeks of age), and myocardial capillary density was assessed by von Willebrand factor staining. Injection of FGF-2 plus heparin significantly decreased left ventricular end-diastolic diameter (P < 0.0001) and left ventricular end-systolic diameter (P < 0.0001), significantly improved the reduction of left ventricular fractional shortening (P = 0.0005), significantly decreased plasma ANP (P < 0.0001) and BNP (P = 0.016) concentrations, and significantly increased myocardial capillary density (P = 0.0002) compared with injection of saline. These findings indicate that intramyocardial injection of FGF-2 plus heparin suppresses the progression of cardiac failure in DS rats. FGF-2 plus heparin administration may be a new therapeutic strategy for the treatment of HHD.     

VEGF gene delivery for treatment of ischemic cardiovascular disease

There are increasing numbers of patients with ischemic myocardial disease not amenable to traditional methods of revascularization. These patients may benefit from new research into the use of naturally occurring angiogenic compounds, such as vascular endothelial growth factor (VEGF) for re-establishing blood flow into regions of hibernating myocardium. Animal studies and human clinical trials evaluating VEGF demonstrate increases in myocardial perfusion after treatment, with some patients reporting improvement in anginal symptoms. Further research into the ideal form of VEGF therapy (protein, plasmid, or adenoviral) and delivery method (intracoronary, intramyocardial, or epicardial) seems justified.     

Catheter-based ventricle-coronary vein bypass.

The goal of this study was to investigate the feasibility of a catheter-based ventricle-to-coronary vein bypass (VPASS) in order to achieve retrograde myocardial perfusion by a conduit (VSTENT) from the left ventricle (LV) to the anterior interventricular vein (AIV). Percutaneous coronary venous arterialization has been proposed as a potential treatment strategy for otherwise untreatable coronary artery disease. In an acute setting, the VSTENT implant was deployed percutaneously using the VPASS procedure in five swine. Coronary venous flow and pressure patterns were measured before and after VSTENT implant deployment with and without AIV and left anterior descending artery (LAD) occlusion. In a separate chronic pilot study, the VPASS procedure was completed on two animals that had a mid-LAD occlusion or LAD stenosis. At day 30 post-VPASS procedure, left ventriculography and magnetic resonance imaging (MRI) were performed to assess the patency and myocardial viability of the VSTENT implants. Pre-VSTENT implantation, the mid-AIV systolic wedge pressure was significantly lower than LV systolic pressure during AIV blockage (46 +/- 19 vs. 90 +/- 16 mm Hg; P < 0.01). The VSTENT implant deployment was performed without complication and achieved equalization of the AIV and LV systolic pressures and creation of retrograde flow in the distal AIV (maximal flow velocity: 37 +/- 7 cm/sec). At day 30 post-VPASS procedure, left ventriculography showed VSTENT implant patency. MRI perfusion images demonstrated myocardial viability even with an LAD occlusion. Coronary retrograde perfusion using the VPASS procedure is feasible and may represent a potential technique for end-stage myocardial ischemia.     

Effects of acidic fibroblast growth factor on normal and ischemic myocardium.

We sought to determine the effects of acidic fibroblast growth factor (FGF) on ischemic and normal myocardium and to determine whether direct application of acidic FGF to the heart could promote angiogenesis. Eighteen dogs underwent placement of an ameroid constrictor on the left anterior descending coronary artery (LAD). Three weeks later, a left internal mammary artery (IMA) pedicle was positioned over the LAD territory, with a sponge saturated with acidic FGF (n = 12) or saline (n = 4) interposed between the pedicle and the heart. Polytetrafluoroethylene fiber or collagen I sponges were used to deliver the acidic FGF. Weekly angiography of the IMA was performed in all dogs, but significant IMA to coronary collaterals were not demonstrable in any dog. Eight dogs had histological evidence of subendocardial infarction in the LAD territory (five acidic FGF, three control, p = NS). Striking smooth muscle cell hyperplasia was present in arterioles and small arteries exclusively in areas of subendocardial infarction in all of the acidic FGF-treated dogs but in none of the control dogs (p less than 0.05). Noninfarcted myocardium appeared normal in all dogs. In two additional dogs, ameroid constrictors were not placed on the LAD, such that acidic FGF-treated sponges were placed on normally perfused myocardium of the LAD territory. Histological evaluation of those hearts revealed normal myocardium, without evidence of myocardial infarction or smooth muscle cell hyperplasia. Thus, when acidic FGF is delivered to the myocardium via an epicardial sponge in dogs whose coronary flow is compromised, acidic FGF does not cause an angiogenic response in viable myocardium but causes vascular smooth muscle cell hyperplasia in areas subjected to ischemic injury.     

A porcine model of ischemic heart failure produced by intracoronary injection of ethyl alcohol

We have developed a porcine model of acute myocardial infarction (AMI) and ischemic heart failure by transcatheter intracoronary injection of ethyl alcohol and observed pathologic changes induced in the alcohol-injured coronary artery and infarcted myocardium. In a total of 12 female pigs, anteroseptal AMI was induced by transcatheter delivery of 1 mL of 99.9% ethyl alcohol using a 2.5 mm diameter over-the-wire balloon catheter in the left anterior descending artery (LAD). Another five pigs underwent the sham operation, and the differences in left ventricular (LV) dimension and LV ejection fraction between these pigs and those injected with ethyl alcohol were evaluated. Follow-up coronary and LV angiography, echocardiography and histopathology were performed at 4 weeks after the procedure. Myocardial SPECT using ²⁰¹Tl (and ^99mTc-MIBI) and triphenyl tetrazolium chloride (TTC) stain were performed and compared. Procedure-related death occurred in two pigs with proximal LAD occlusion. Four pigs suffered from ventricular tachycardia, which converted to sinus rhythm by DC cardioversion. Follow-up coronary angiography at 4 weeks revealed persistent total occlusion in all pigs. Echocardiogram showed decreased apicoanteroseptal wall motion with an ejection fraction of 46.5 ± 3.3% and nonsignificantly changed LV dimensions. Myocardial SPECT revealed a perfusion defect in the apicoanterior wall in all subjects (percent area of the perfusion defect = 22.1 ± 2.50%). The percentage of myocardium not stained by TTC was 23.1 ± 2.25%. Histologic examination revealed severe fibrosis in the infarcted myocardium and massive thrombus with organization and calcification in the alcohol-injured coronary artery. The porcine model of AMI obtained by intracoronary alcohol injection provides a safe and reproducible method for the research and development of new therapeutic modalities for MI and end-stage heart failure.     

Induction of myocardial neoangiogenesis by human growth factors. A new therapeutic approach in coronary heart disease

Currently available approaches for treating human coronary heart disease aim to relieve symptoms and the risk of myocardial infarction either by reducing myocardial oxygen demand, preventing further disease progression, restoring coronary blood flow pharmacologically or mechanically, or bypassing the stenotic lesions and obstructed coronary artery segments. Gene therapy, especially using angiogenic growth factors, has emerged recently as a potential new treatment for cardiovascular disease. Following extensive experimental research on angiogenic growth factors, the first clinical studies on patients with coronary heart disease and peripheral vascular lesions have been performed. The polypeptides fibroblast growth factor (FGF) and vascular endothelial growth factor (VEGF) appear to be particularly effective in initiating neovascularization (neoangiogenesis) in hypoxic or ischemic tissues. The first clinical study on patients with coronary heart disease treated by local intramyocardial injection of FGF-1 showed a 3-fold increase of capillary density mediated by the growth factor. Also, angiogenic growth factor injection intramyocardially as sole therapy for end-stage coronary disease showed an improvement of myocardial perfusion in the target areas as well as a reduction of symptoms and an increase in working capacity. Angiogenic therapy of the human myocardium introduces a new modality of treatment for coronary heart disease in terms of regulation of blood vessel growth. Beyond drug therapy, angioplasty and bypass surgery, this new approach may evolve into a fourth principle of treatment of atherosclerotic cardiovascular disease.     

Coronary flow reserve is reflective of myocardial perfusion status in acute anterior myocardial infarction.

Our objective was to determine whether coronary vasodilatory reserve (CVR) correlates with the perfusion state of infarct zone in early recovery phase of acute anterior myocardial infarction (AMI). We studied 14 patients (11 males; mean age, 46 years) who had AMI and 6 control subjects who had chest pain but normal coronary angiograms. All patients underwent successful percutaneous revascularization of left anterior descending (LAD) coronary artery. Coronary flow velocity was measured using intracoronary (IC) Doppler at baseline and following IC injection of 18 microg of adenosine. Myocardial perfusion was evaluated by myocardial contrast echocardiography (MCE). CVR was higher in patients without a perfusion defect on MCE than in those with (2.48 +/- 0.21 vs. 1.66 +/- 0.13, P = 0.001). Subjects with a perfusion defect had a lower CVR than controls (1.66 +/- 0.13 vs.2.40 +/- 0.18, P < 0.05). CVR was > 2.0 in all subjects without a perfusion defect. There was a strong correlation between the magnitude of myocardial opacification in the LAD territory and CVR (r = 0.80, P < 0.01). Increase in peak diastolic flow velocity after adenosine infusion, but not systolic flow velocity, correlated with myocardial opacification index (r = 0.63, P = 0.016). CVR of infarct-related artery correlated closely with the perfusion status of the myocardium in infarct zone and those with a CVR > 2.0 had normal myocardial perfusion. These data suggest that CVR may be used to determine the perfusion state of the myocardium in the infarct zone, which is a known predictor of myocardial viability. Cathet. Cardiovasc. Intervent. 51:281-286, 2000.     

Delivery strategies to achieve therapeutic myocardial angiogenesis

The use of recombinant genes or growth factors to enhance myocardial collateral blood vessel function may represent a new approach to the treatment of cardiovascular disease. Proof of concept has been demonstrated in animal models of myocardial ischemia, and clinical trials are underway. Currently, it is unknown which is the safest and most effective delivery strategy to induce clinically important therapeutic angiogenic responses in ischemic myocardium. Most strategies for transcatheter delivery of angiogenic factors have used an intracoronary route, which may have limitations because of imprecise localization of genes or proteins and systemic delivery to noncardiac tissue. The effect of direct intraoperative intramyocardial injection of angiogenic factors on collateral function has been reported in experimental models, and angiogenesis is being studied after direct intramyocardial injection of angiogenic peptides or plasmid vectors during open heart surgery in patients. Catheter-based transendocardial injection of angiogenic factors may provide equivalent benefit without the need for surgery. Intrapericardial delivery of angiogenic factors may offer a theoretical advantage of prolonged exposure of either coronary or myocardial tissue to the administered drug as result of a reservoir function of the pericardium. In this article, we review the different modes of administration for therapeutic myocardial angiogenesis therapy.     

Responsiveness of the coronary circulation to brief vs sustained alpha-adrenergic stimulation

The effects of brief and sustained pharmacologic alpha-adrenergic stimulation on the coronary arterial circulation were compared in awake pigs. Phenylephrine was administered into the left anterior descending coronary artery (LAD) either as a bolus (eight pigs) or as a 15-minute infusion (eight pigs), with myocardial blood flow measured by the radioactive microsphere technique. Flow in the distribution in the LAD was compared with flow in myocardium perfused by the left circumflex coronary artery (LCF) as the ratio LAD/LCF. This technique corrects for systemic factors capable of modifying oxygen demand, and hence myocardial blood flow, in both zones. After a phenylephrine bolus (50-100 microgram), LAD/LCF fell significantly, whereas no change was observed after the sustained infusion (5-10 and 50-100 microgram/min). Four additional pigs were pretreated with i.v. adenosine to raise myocardial blood flow in excess of demand before sustained stimulation. In this setting LAD/LCF fell significantly during the sustained phenylephrine infusion. Brief alpha-adrenergic stimulation could overcome normal flow regulatory mechanisms and resulted in constriction of coronary resistance vessels. Such changes did not occur after sustained stimulation and suggest an ability of the coronary circulation to offset chronic vasoconstrictive effects. When the myocardium is overperfused, sustained alpha-adrenergic stimulation does not jeopardize myocardial oxygenation and its vasoconstriction potential is unmasked.     

Intravenous injection of phagocytes transfected ex vivo with FGF4 DNA/biodegradable gelatin complex promotes angiogenesis in a rat myocardial ischemia/reperfusion injury model

Conventional gene therapies still present difficulties due to poor tissue-targeting, invasiveness of delivery, method, or the use of viral vectors. To establish the feasibility of using non-virally ex vivo transfected phagocytes to promote angiogenesis in ischemic myocardium, gene-transfection into isolated phagocytes was performed by culture with positively charged gelatin impregnated with plasmid DNA. A high rate of gene transfection was achieved in rat macrophages and human monocytes, but not in mouse fibroblasts. The efficiency was 68 +/- 11% in rat macrophages and 78 +/- 8% in human monocytes. Intravenously injected phagocytes accumulated predominantly in ischemic tissue (13 +/- 8%) and spleen (84 +/- 6%), but negligibly in other organs in rodents. The efficiency of accumulation in the target ischemic tissue reached more than 86% on direct local tissue injection. In a rat model of myocardial ischemia-reperfusion, intravenous injection of fibroblast growth factor 4 (FGF4)-gene-transfected macrophages significantly increased regional blood flow in the ischemic myocardium (78 +/- 7.1 % in terms of flow ratio of ischemic/non-ischemic myocardium) compared with intravenous administration of saline (36 +/- 11%) or nontransfected macrophages (42 +/- 12 %), or intramuscular administration of naked DNA encoding FGF4 (75 +/- 18 %). Enhanced angiogenesis in the ischemic tissue we confirmed histologically. Similarly, intravenous injection of FGF4-gene-transfected monocytes enhanced regional blood flow in an ischemic hindlimb model in mice (93 +/- 22 %), being superior to the three other treatments described above (38 +/- 12, 39 +/- 15, and 55 +/- 12%, respectively).Phagocytes transfected ex vivo with FGF4 DNA/gelatin promoted angiogenesis. This approach might have potential for non-viral angiogenic gene therapy.     

Validation of local venous sampling within the at risk left anterior descending artery vascular bed in the canine left ventricle

The validity of using blood sampled from the anterior interventricular vein (AIV), anatomically located within the myocardium perfused by the left anterior descending (LAD) coronary artery, to represent venous drainage originating from the LAD vascular territory was studied in eight anaesthetised, open chest dogs. The LAD was cannulated and perfused from a blood reservoir isolated from the systemic circulation. To determine the presence of blood from non-LAD sources that appears in the AIV sample, 51Cr-labelled red blood cells were injected into the left atrium and distributed in the systemic circulation while the LAD was perfused by non-radioactive blood. The percentage spillover of red blood cells from non-LAD sources into the AIV drainage was determined under control, reduced LAD flow, ischaemia, and reperfusion conditions as 100 X (AIV chromium content/arterial chromium content). Spillover of red blood cells into AIV blood samples averaged only 1.5(1.3)% under control conditions and increased insignificantly to 8.6(3.5)% during reduced LAD flow. During ischaemia red blood cells in AIV blood increased insignificantly to 98.3(5.0)% but decreased to 1.9(1.3)% after reperfusion. Studies in five dogs with microspheres showed that a portion of this admixture from non-LAD sources originated from precapillary nutritional collateral or overlapping blood flow.(ABSTRACT TRUNCATED AT 250 WORDS)     

Dynamic intracoronary thrombosis does not cause significant downstream platelet embolization

OBJECTIVE: A mural intracoronary thrombus is a potential source of platelet emboli that may obstruct downstream microvessels, but this phenomenon has not been characterized. The present study aimed to assess the magnitude of myocardial platelet accumulation downstream of a mural intracoronary thrombus and its modification by a concomitant transient coronary occlusion (OC) or by treatment with aspirin. METHODS: The myocardial content of 99mTc-labelled platelets was analyzed in 26 pigs submitted to intimal injury of the left anterior descending coronary artery (LAD) followed by no intervention (n=6), 25-min OC (n=6), or 48-min OC preceded (n=8) or not (n=6) by intravenous administration of 250 mg aspirin. RESULTS: After 2 h, 24 animals had had 12+/-1 cyclic flow reductions (CFRs) reflecting dynamic LAD thrombosis. Myocardial platelet content in the inferior region was similar among groups. Platelet content in the LAD region was not significantly different to that in the inferior region (129+/-19%, P=NS) in the no intervention group, but was increased following OC (172+/-20 and 312+/-71% after 25- and 48-min OC, respectively, P<0.05). Pre-treatment with aspirin lessened the number of CFRs but did not reduce platelet accumulation in LAD myocardium (483+/-148%). Myocardial platelet accumulation was not associated with the magnitude of platelet deposition in the LAD nor with the number of CFRs, but was correlated with myeloperoxidase activity (r=0.91, P<0.001) and with infarct size (r=0.52, P=0.05). Histological analysis frequently showed sparse platelets or small platelet or leukoplatelet aggregates in small vessels, but arteriolar emboli were rare. In none of seven additional experiments coronary angiography showed obstructions of arterial branches during CFRs. CONCLUSION: The magnitude of platelet embolization from a mural intracoronary thrombus into downstream myocardium is small despite the presence of repetitive CFRs.     

采用OTW球囊经冠状静脉逆行灌注骨髓间充质干细胞的安全性和有效性

目的 探讨采用over-the-wire(OTW)球囊经冠状静脉逆行灌注骨髓间充质干细胞(MSCs)的安全性及有效性.方法 杂种犬12 只,体重(23.0±1.9)kg,采用开胸直视下完全结扎前降支(LAD)中段建立急性心梗模型.1 周后采用OTW 球囊将1×108 EGFP 标记的MSCs 灌注到与LAD 平行的前室间静脉(AIV)中段.所有实验动物分别在灌注后1 h(n=4)、14 d(n=4)、28 d(n=4)取材,比较LAD 结扎部位缺血心肌和LCX区域非缺血心肌组织中EGFP 阳性细胞的数量.结果 经冠状静脉逆行灌注成功率为100%(12/12),术中及术后未发生死亡、心包填塞及恶性心律失常.免疫荧光结果显示,所有时间点LAD 区域内EGFP 阳性细胞数均明显高于LCX 区域(均P<0.05),细胞在LAD 区域内的分布也更均匀.结论 采用OTW 球囊经冠状静脉逆行灌注MSCs 安全可行,靶向性高,细胞在缺血心肌内的分布也较为均匀、持久.     

Cardiac accumulation of bone marrow mononuclear progenitor cells after intracoronary or intravenous injection in pigs subjected to acute myocardial infarction with subsequent reperfusion.

OBJECTIVE: The purpose of the present study was to compare the efficacy of intracoronary and intravenous injection of autologous progenitor cells for homing to the acutely infarcted but reperfused myocardium in pigs. METHODS: Myocardial infarction was induced in 11 anesthetized pigs by 60-min balloon inflation in the mid LAD. After balloon deflation, reperfusion was verified and autologous CD31(+) progenitor cells, or bone marrow mononuclear cells, labeled with PKH67, were injected either intracoronarily (n=6) or intravenously (n=3). By autopsy, 4-5 days after induction of infarction, tissue from the heart and other organs was obtained for fluorescence microscopy. RESULTS: In the heart, PKH(+) cells were detected throughout the reperfused infarcted myocardium, and the number of PKH(+) cells was significantly higher after intracoronary than after intravenous injection (3.2+/-0.55 vs. 0.33+/-0.17 cells/high-power field/10(6) cells injected, P=.01). Few PKH(+) cells were detected in the spleen, lung, mesenteric lymph node, and bone marrow. In an additional animal with a coil placed in the mid LAD, progenitor cells were not detected in the infarcted myocardium or in the normal myocardium. CONCLUSION: Autologous mononuclear and CD31(+) cells from bone marrow accumulated in the infarcted myocardium when injected intracoronarily or intravenously after established reperfusion, and the accumulation of cells was significantly greater after intracoronary injection than after intravenous injection. Accumulation of PKH(+) cells did not appear in the normal myocardium or in the nonreperfused infarcted myocardium. PKH(+) cells were detected in spleen, lung, and bone marrow but to a lesser degree than in the infarcted myocardium.     

Impact of different topical negative pressure levels on myocardial microvascular blood flow

BACKGROUND: We have previously shown that a myocardial topical negative pressure (TNP) of -50 mmHg significantly increases microvascular blood flow in the underlying myocardium in normal, ischemic, and reperfused porcine myocardium. The present study was designed to elucidate the effect of different TNP levels between -50 and -150 mmHg on microvascular flow in normal and ischemic myocardium. MATERIALS AND METHODS: Seven pigs underwent median sternotomy. The microvascular blood flow in the myocardium was recorded, before and after the application of TNP, using laser Doppler velocimetry. Analyses were performed before left anterior descending artery (LAD) occlusion (normal myocardium) and after 20 min of LAD occlusion (ischemic myocardium). RESULTS: A TNP of -50 mmHg significantly increased microvascular blood flow in both normal (from 320.0+/-56.1 PU before TNP application to 435.7+/-65.5 PU after TNP application, P=.028) and ischemic myocardium (from 110.0+/-36.7 PU before TNP application to 194.3+/-56.2 PU after TNP application, P=.012). TNP between -75 and -150 mmHg showed no significant increase in microvascular blood flow in normal or ischemic myocardium. CONCLUSIONS: Of pressures between -50 and -150 mmHg, a TNP of -50 mmHg seems to be the most effective negative pressure concerning significant increase in microvascular blood flow in both normal and ischemic myocardium.     

Selective regional myocardial infiltration by the percutaneous coronary venous route: A novel technique for local drug delivery.

Recent advances in the treatment of heart disease, in particular cardiovascular gene therapy and therapeutic angiogenesis, highlight the need for efficient and practical local delivery methods for the heart. We assessed the feasibility of percutaneous selective coronary venous cannulation and injection as a novel approach to local myocardial drug delivery. In anesthetized swine, the coronary sinus was cannulated percutaneously and a balloon-tipped catheter advanced to the anterior interventricular vein (AIV) or middle cardiac vein (MCV). During balloon occlusion, venous injection of radiographic contrast caused regional infiltration of targeted myocardial regions. Complete AIV occlusion had no impact on LAD flow parameters. Videodensitometric analysis following venous injection showed that radiographic contrast persisted for at least 30 min. Selective regional myocardial infiltration is feasible by this approach, targeting selected myocardial beds, including the apex, anterior wall, septum, and inferoposterior wall. This novel technique has potential application for local myocardial drug or growth factor delivery. Cathet. Cardiovasc. Intervent. 51:358-363, 2000.