Abciximab inhibits the migration and invasion potential of human coronary artery smooth muscle cells

A monoclonal antibody against alphaVbeta3 integrin inhibits development of atherosclerotic lesions in diabetic pigs

Atherosclerotic lesions develop and progress more rapidly in diabetic patients than in nondiabetic individuals. This may be caused by accelerated lesion formation in the high-glucose environment of diabetes. Smooth muscle cells (SMCs) cultured in high glucose are more responsive to growth factors such as insulin-like growth factor-1 (IGF-1). This enhanced response to IGF-1 is due in part to increased activation of the alpha(V)beta(3) integrin. We tested whether alpha(V)beta(3) integrin activation was increased in diabetic animals and whether an antibody to beta(3) would inhibit IGF-1 action and development of atherosclerosis. Eight male pigs were made diabetic with streptozotocin and fed a high-fat diet. A F(ab)(2) antibody fragment directed at beta(3) was infused into one femoral artery, whereas the other artery received control F(ab)(2) for 3.5 months. There was a 65 +/- 8% reduction in atherosclerotic lesion area in the arteries treated with F(ab)(2) antibody to beta(3). Phosphorylation of beta(3) was reduced by 75 +/- 18% in vessels treated with the antibody. Shc and mitogen-activated protein kinase phosphorylation, which are required for IGF-1-stimulated SMC proliferation, were also significantly reduced. We conclude that activation of IGF-1 receptor and alpha(V)beta(3)-linked signaling pathways accelerates atherosclerosis in diabetes and that administration of an antibody to beta(3) to diabetic pigs inhibits alpha(V)beta(3) activation, IGF-1-stimulated signaling, and atherosclerotic lesion development. This approach offers a potential therapeutic approach to the treatment of this disorder.

Pharmacologic approaches to restenosis prevention

Despite significant advances in technology and technique, coronary restenosis remains the primary limitation of percutaneous transluminal coronary angioplasty (PTCA). Among patients undergoing PTCA, between 20% and 50% of patients who do not receive a stent and 10%-30% of those who do receive a stent develop restenosis within 6 months of the procedure. Drug-eluting stents, which release high local concentrations of antiproliferative or immunosuppressive agents directly into the vessel wall at the site of the lesion, have dramatically reduced the incidence of restenosis in patients undergoing PTCA. However, even with drug-eluting stents, a significant percentage of higher-risk patients develop in-stent restenosis. These data suggest that a role remains for effective, well-tolerated systemic pharmacologic therapies to further reduce the rate of restenosis. To date, the majority of systemic agents tested for restenosis prevention have failed to show significant benefit. Only 2 agents, probucol and cilostazol, have consistently demonstrated efficacy in preventing restenosis. In addition, the investigational agent AGI-1067 has demonstrated promising efficacy in early clinical trials. Together with drug-eluting stents, these therapies may for the first time reduce the rate of restenosis to near zero, even in high-risk patients, such as individuals with diabetes mellitus.

A Novel Drug-Eluting Stent Coated With an Integrin-Binding Cyclic Arg-Gly-Asp Peptide Inhibits Neointimal Hyperplasia by Recruiting Endothelial Progenitor Cells

OBJECTIVES

Novel stents loaded with an integrin-binding cyclic Arg-Gly-Asp peptide (cRGD) were analyzed for their potential to limit coronary neointima formation and to accelerate endothelialization by attracting endothelial progenitor cells (EPCs).

BACKGROUND

Re-endothelialization is important for healing after arterial injury.

METHODS

Effects of cRGD on EPC number, recruitment in flow, and invasion were analyzed in vitro. A durable polymer coating containing 67 microg cRGD per stent was developed for Guidant Tetra stents. Twelve cRGD-loaded polymer, 12 unloaded polymer, and 12 bare metal stents were deployed in porcine coronary arteries. Quantification of cRGD in peri-stent tissue was established by high-performance liquid chromatography (HPLC) and mass spectrometry (MS). Histomorphometry and immunostaining were performed after 4 and 12 weeks. Recruitment of labeled porcine EPCs was assessed 7 days after intracoronary infusion.

RESULTS

The cRGD clearly supported the outgrowth, recruitment, and migration of EPCs in vitro. At 4 weeks, there was no difference for mean neointimal area and percent area stenosis in the cRGD-loaded, polymer, or bare metal stent group. At 12 weeks, neointimal area (2.2 +/- 0.3 mm2) and percent area stenosis (33 +/- 5%) were significantly reduced compared with polymer stents (3.8 +/- 0.4 mm2, 54 +/- 6%; p = 0.010) or bare metal stents (3.8 +/- 0.3 mm2, 53 +/- 3%; p < 0.001). The HPLC/MS confirmed cRGD tissue levels of 1 to 3 mug/stent at 4 weeks, whereas cRGD was not detectable at 12 weeks. Staining for CD34 and scanning electron microscopy indicated enhanced endothelial coverage on cRGD-loaded stents at 4 weeks associated with a significant increase in the early recruitment of infused EPCs.

CONCLUSIONS

Stent coating with cRGD may be useful for reducing in-stent restenosis by accelerating endothelialization.

Effects of abciximab on key pattern of human coronary restenosis in vitro: impact of the SI/MPL-ratio

Background

The significant reduction of angiographic restenosis rates in the ISAR-SWEET study (intracoronary stenting and antithrombotic regimen: is abciximab a superior way to eliminate elevated thrombotic risk in diabetes) raises the question of whether abciximab acts on clopidogrel-independent mechanisms in suppressing neointimal hyperplasia. The current study investigates the direct effect of abciximab on ICAM-1 expression, migration and proliferation.

Methods

ICAM-1: Part I of the study investigates in cytoflow studies the effect of abciximab (0.0002, 0.002, 0.02, 0.2, 2.0, and 20.0 μg/ml) on TNF-α induced expression of intercellular adhesion molecule 1 (ICAM-1). Migration: Part II of the study explored the effect of abciximab (0.0002, 0.002, 0.02, 0.2, 2.0, and 20.0 μg/ml) on migration of HCMSMC over a period of 24 h. Proliferation: Part III of the study investigated the effect of abciximab (0.0002, 0.002, 0.02, 0.2, 2.0, and 20.0 μg/ml) on proliferation of HUVEC, HCAEC, and HCMSMC after an incubation period of 5 days.

Results

ICAM-1: In human venous endothelial cells (HUVEC), human coronary endothelial cells (HCAEC) and human coronary medial smooth muscle cells (HCMSMC) no inhibitory or stimulatory effect on expression of ICAM-1 was detected. Migration: After incubation of HCMSMC with abciximab in concentrations of 0.0002 – 2 μg/ml a stimulatory effect on cell migration was detected, statistical significance was achieved after incubation with 0.002 μg/ml (p < 0.05), 0.002 μg/ml (p < 0.001), and 0.2 μg/ml (p < 0.05). Proliferation: Small but statistically significant antiproliferative effects of abciximab were detected after incubation of HUVEC (0.02 and 2.0 μg/ml; p = 0.01 and p < 0.01), HCAEC (2.0 and 20.0 μg/ml; p < 0.05 and p < 0,01), and HCMSMC (2.0 and 20.0 μg/ml; p < 0.05 and p < 0.05). The significant inhibition (SI) of cell proliferation found in HCAEC and HCMSMC was achieved with drug concentrations more than 10 times beyond the maximal plasma level (MPL), resulting in a SI/MPL-ratio > 1.

Conclusion

Thus, the anti-restenotic effects of systemically administered abciximab reported in the ISAR-SWEET-study were not caused by a direct inhibitory effect on ICAM-1 expression, migration or proliferation.

Pharmacological treatment for prevention of restenosis

Coronary artery disease (CAD) is the leading cause of mortality and morbidity among adults in the Western world. Coronary artery bypass grafting and percutaneous coronary interventions (PCI) have gained widespread acceptance for the treatment of symptomatic CAD. There has been an explosive growth worldwide in the utilisation of PCI, such as balloon angioplasty and stenting, which now accounts for over 50% of coronary revascularisation. Despite the popularity of PCI, the problem of recurrent narrowing of the dilated artery (restenosis) continues to vex investigators. In recent years, significant advances have occurred in the understanding of restenosis. Two processes seem to contribute to restenosis: remodelling (vessel size changes) and intimal hyperplasia (vascular smooth muscle cell [VSMC] proliferation and extracellular matrix [ECM] deposition). Despite considerable efforts, pharmacological approaches to decrease restenosis have been largely unsuccessful and the only currently applied modality to reduce the restenosis rate is stenting. However, stenting only prevents remodelling and does not inhibit intimal hyperplasia. Several potential targets for inhibiting restenosis are currently under investigation including platelet activation, the coagulation cascade, VSMC proliferation and migration, and ECM synthesis. In addition, new approaches for local drug therapy, such as drug eluting stents, are currently being evaluated in preclinical and clinical studies. In this article, we critically review the current status of drugs that are being evaluated for restenosis at various stages of development (in vitro, preclinical animal models and human trials).

The long-term clinical results of a platelet glycoprotein IIb/IIIa receptor blocker (Abciximab: Reopro) coated stent in patients with coronary artery disease

BACKGROUND

Previously, the inhibition of coronary restenosis with Abciximab (ReoPro)-coated stent in a porcine model was reported. ReoPro inhibits platelet aggregation, the proliferation of vascular smooth muscle cells and the inflammatory reaction.

METHODS

A prospective randomized trial was performed to compare two types of stent for revascularization in the native coronary artery. The primary effective end points were major adverse coronary events (MACE): cardiac death, acute myocardial infarction, target vessel revascularization (TVR) and restenosis at the 6-month clinical and angiographic follow-ups.

RESULTS

One hundred and fifty-five patients were enrolled between August 2001 and June 2003. The mean ages (56.0 +/- 10.0 vs. 56.9 +/- 10.8 years), baseline diameter of stenosis and minimal luminal diameter were no different between the two groups. There was one myocardial infarction and revascularization during the hospital stay in control stent group. During the clinical follow-up there were two myocardial infarctions in control group. Follow-up coronary angiograms were performed in 62.3% (48/77) and 65.4% (51/78) of the coated and control groups, respectively. The diameter of stenosis and late loss were significantly less in the ReoPro-coated stent group compared with the controls (16.4 +/- 5.8% vs. 34.3 +/- 6.1%, p = 0.009; and 0.33 +/- 0.28 mm vs. 0.88 +/- 0.41 mm; p = 0.002). The restenosis and TVR rates of the ReoPro-coated stent were relatively lower compared with the control stent [14.6% (7/48) vs. 29.4% (15/51), p = 0.062; and 9.2% (7/76) vs. 14.7% (11/75); p = 0.327].

CONCLUSION

A ReoPro-coated stent is safe, and may be effective in the prevention of coronary restenosis.

A randomized trial comparing phosphorylcholine-coated stenting with balloon angioplasty as well as abciximab with placebo for restenosis reduction in small coronary arteries

OBJECTIVE

The objective of this randomized trial was to assess the antirestenotic effects of phosphorylcholine (PC)-coated stents as well as of abciximab in small coronary arteries when compared with percutaneous transluminal coronary angioplasty (PTCA) and placebo respectively.

BACKGROUND

Stent coating with PC has been shown to reduce protein absorption and platelet activation which may reduce the risk of restenosis. Furthermore, on the basis of nondedicated studies abciximab is believed to reduce the risk of restenosis after coronary interventions.

METHODS

A total of 502 patients with lesions situated in small coronary arteries (vessel diameter </=2.5 mm) were randomly assigned to be treated with either PC-coated stents (n = 253) or PTCA (n = 249) and with either abciximab (n = 251) or placebo (n = 251) with the use of a 2 x 2 factorial design. All patients were pretreated with 600 mg clopidogrel. The primary end-point was the incidence of angiographic restenosis (>/=50% diameter stenosis) at follow-up; death or myocardial infarction, and target vessel revascularization (TVR), were assessed as secondary end-points.

RESULTS

Angiographic restenosis did not differ between patients treated with PC-coated stents or with PTCA (39.0% vs. 34.2%; P = 0.30) and between patients receiving abciximab or placebo (39.3% vs. 34.3%; P = 0.29). Similarly, the need for TVR at 1-year follow-up did not differ between patients receiving PC-coated stents or PTCA (20.2% vs. 20.5%; P = 0.98) as well as between patients treated with abciximab or placebo (18.7% vs. 21.9%; P = 0.44).

CONCLUSIONS

PC-coated stents and abciximab failed to reduce the incidence of angiographic restenosis after percutaneous coronary intervention of small coronary arteries. These data strengthen the belief that future studies on prevention of restenosis in small coronary arteries should focus on drug-eluting stents.

Beta3-integrin mediates smooth muscle cell accumulation in neointima after carotid ligation in mice

BACKGROUND

Pharmacological blockade of beta3-integrins inhibits neointimal lesion formation in nonmouse animal models of arterial injury. In contrast, beta3-integrin-deficient (beta3-/-) mice are not protected from neointimal lesion formation after arterial injury. We investigated this discrepancy in beta3-/- and wild-type (beta3+/+) mice using different models of injury.

METHODS AND RESULTS

After disruption of the carotid with a transluminal probe, there was no significant difference in neointimal thickening between beta3-/- and beta3+/+ mice. However, after ligation of the carotid without medial disruption, there was reduced neointimal thickening in beta3-/- mice compared with beta3+/+ mice at intervals up to 3 months. Lesion reduction in beta3-/- mice was associated with fewer intimal smooth muscle cells (SMCs) without a difference in SMC apoptosis or proliferation rate compared with beta3+/+ mice, consistent with reduced SMC migration from the media into the intima of beta3-/- mice. Moreover, combined eccentric medial disruption and ligation of the carotid in beta3-/- mice resulted in neointimal lesion formation only at the site of medial disruption. Transplantation of bone marrow cells harvested from beta3+/+ mice into irradiated beta3-/- mice resulted in reduced neointimal lesion formation after carotid ligation injury, confirming the importance of alpha(v)beta3 and not alpha(IIb)beta3 in the attenuated response.

CONCLUSIONS

The alpha(v)beta3-integrin mediates intimal SMC accumulation that contributes to neointimal thickening in the setting of arterial ligation.

Antiproliferative coatings for the treatment of coronary heart disease:. what are the targets and which are the tools?

Since the advent of percutaneous coronary intervention (PCI) for stenosing coronary disease, restenosis has remained a clinical problem. Despite the emergence and evolution of coronary stents, the rate of restenosis following PCI is still 10-20%, and above 50% in high risk subgroups. With increased understanding of the pathophysiology of this process, a number of potential therapeutic targets have been identified, allowing the development of novel therapies against restenosis, which can now be delivered locally using stent platforms. Some of the reported clinical trial data utilizing drug-eluting stents (DES) have produced such profound reductions in clinical and angiographic restenosis that we have been tempted to believe we are on the brink of eradicating this process completely. As the initial excitement subsides, however, there is a need to decide whether these tools will remain effective in real-world interventional practice. In this article we review the pathophysiology of the restenotic process, and the biological targets of the DES therapies currently available in clinical practice. We attempt to define clinical target populations for DES therapy, and assess the impact on outcomes thus far. We consider the advantages that newly emergent stent coatings might offer, and whether targeting specific patient subgroups with unique antiproliferative agents may provide the best chance of limiting restenosis in high risk subgroups. Finally, we consider future strategies to prevent restenosis, with a movement away from the antiproliferative approach, and toward accelerating endothelialization.

Abciximab: an updated review of its therapeutic use in patients with ischaemic heart disease undergoing percutaneous coronary revascularisation

Abciximab (Reopro) is an antibody fragment that dose-dependently inhibits platelet aggregation and leucocyte adhesion by binding to the glycoprotein (GP) IIb/IIIa, vitronectin and Mac-1 receptors. Abciximab (0.25 mg/kg bolus plus infusion of 0.125 micro g/kg/min for 12 hours) showed greater efficacy than tirofiban in reducing the 30-day composite endpoint of death, nonfatal myocardial infarction (MI) or urgent target-vessel revascularisation in the randomised, double-blind TARGET study in patients scheduled for stent placement. In addition, the beneficial effects of treatment with abciximab previously observed in the randomised, multicentre, placebo-controlled EPILOG and EPISTENT studies have been maintained to 1 year, with a significantly reduced incidence of ischaemic complications relative to placebo consistently observed across a range of subgroups including age, sex, bodyweight and indication for revascularisation. The incidence of the composite endpoint was reduced in patients presenting with acute MI of <48 hours' duration in comparison with either fibrinolytic therapy or stenting alone in the randomised STOPAMI and ADMIRAL trials, primarily because of a reduced requirement for urgent repeat revascularisation and reduced incidence of mortality. In the randomised, nonblind, multicentre CADILLAC trial in patients with acute myocardial infarction (MI), stenting alone was superior to percutaneous transluminal coronary angioplasty (PTCA) and stenting alone was not inferior to PTCA plus abciximab. Recent large randomised, multicentre studies (ASSENT-3 and GUSTO-V) have shown higher efficacy (on various ischaemic endpoints) of abciximab in combination with either a reduced dose of tenecteplase or reteplase compared with the fibrinolytic drug alone. TIMI grade 3 flow rates at 60 and 90 minutes in the TIMI-14 and SPEED trials were higher in patients who received abciximab in combination with either alteplase or reteplase than abciximab alone and were similar to that seen with the full-dose fibrinolytic alone. In the randomised, multicentre GUSTO IV-ACS study, no significant differences in any of the ischaemic endpoints at either 7 or 30 days in patients with acute coronary syndromes who were not scheduled to undergo early revascularisation (within 12 hours of end of infusion) were apparent between those who received abciximab (bolus and either 24- or 48-hour infusion) and those who received placebo in addition to aspirin and heparin. The most common adverse events associated with the use of abciximab are bleeding complications and thrombocytopenia, although the risk of major bleeding can be limited through adhering to current administration protocols. Treatment costs are generally higher in both stent plus abciximab and angioplasty plus abciximab groups than stent plus placebo, primarily because of the acquisition cost of abciximab. Abciximab appeared most cost beneficial in high-risk patients undergoing elective percutaneous coronary revascularisation; among lower risk patients, abciximab therapy has been associated with higher total in-hospital and 6-month medical costs than eptifibatide.

CONCLUSION

The GP IIb/IIIa receptor antagonist abciximab, when used with aspirin and heparin, has demonstrated efficacy in reducing the short- and long-term risk of ischaemic complications in patients with ischaemic heart disease undergoing percutaneous coronary intervention, when used with aspirin and heparin. High-risk patients (including those with diabetes mellitus) derive particular benefits from abciximab treatment. Abciximab remains an important therapeutic option for the prevention of complications in patients with ischaemic heart disease.

Upregulation of the cytoskeletal-associated protein Moesin in the neointima of coronary arteries after balloon angioplasty: a new marker of smooth muscle cell migration?

Migrating cells like coronary smooth muscle cells in restenosis change their cell shape and form cellular protrusions called filopodia. A prerequisite for filopodia formation is the rearrangement of the actin cytoskeleton. An essential role of the 78-kDa protein Moesin is described for Rho- and Rac-dependent assembly of actin filaments. In vivo Moesin is not observed in mature smooth muscle cells. The objective of this study was to demonstrate that Moesin is upregulated in migrating coronary smooth muscle cells during restenosis development. In vivo expression of Moesin was upregulated in neointimal coronary smooth muscle cells of dilated porcine coronary arteries compared to the undilated left circumflex coronary artery of the same swine. Concordant to these results Moesin expression was upregulated in migrating and invading human arterial smooth muscle cells in vitro analyzed by FACS, Western blotting and RT-PCR. In addition, the invasive potential of Moesin-positive Mel Im cells transfected with Moesin sense DNA increased by 28% as compared to mock-transfected control, whereas antisense transfected cells had a decreased invasive potential of 32%. Transfection of Moesin-negative HepG2 with Moesin sense cDNA increased the invasive potential by 43%. Finally, transfection of human arterial smooth muscle cells with Moesin sense cDNA caused an increased invasive potential of 30%. Transfection of haSMCs with antisense cDNA decreased the invasive potential by 37% in comparison to mock-transfected control. These results demonstrate for the first time an upregulation of Moesin expression in coronary smooth muscle cells of the neointima after arterial injury. The increased migrative and invasive potential of cells transfected with Moesin confirmed the functional role of Moesin in cell migration. This indicates an important role of Moesin during restenosis development.

Activation of IP and EP(3) receptors alters cAMP-dependent cell migration

Migration of vascular smooth cells from the media to the intima essentially contributes to neointima formation after percutaneous transluminal angioplasty and stent implantation. The stable prostacyclin mimetic iloprost has been shown to inhibit neointima formation in experimental restenosis, but it is currently unknown whether this may be caused by an antimigratory effect. Hence, the present study analyses (i) the influence of G(s)-coupled prostacyclin (IP) receptors on cell migration and (ii) verifies whether EP(3) receptors with opposite (i.e., G(i)) coupling may conversely stimulate cell migration. In a modified Boyden chamber model, it was shown that iloprost dose-dependently inhibits the migration of primary human arterial smooth muscle cells, which constitutively express the IP receptor. On the other hand, human arterial smooth muscle cell migration was stimulated by the EP(3) receptor agonist M&B 28.767. To independently study the effects of these receptors, IP or EP(3) receptors were stably overexpressed in chinese hamster ovary cells (CHO-IP and CHO-EP(3)). Chemotaxis of CHO cells transfected with G(s)-coupled IP receptors was concentration-dependently inhibited by iloprost (2-100 nM), while there was no effect of iloprost on mock-transfected CHO. By contrast, CHO-cells that overexpressed EP(3) receptors showed a significant, concentration dependent (1-100 nM) increase of cell migration in presence of the selective EP(3) agonist M&B 28.767. It is concluded that the prostacyclin mimetic iloprost inhibits vascular cell migration, which probably depends on a G(s)-mediated increase of intracellular cAMP. EP(3) receptors conversely stimulate CHO migration.

Synthesis of highly potent and selective hetaryl ureas as integrin alpha(V)beta3-receptor antagonists

Solid-phase synthesis and SAR of integrin alpha(V)beta3-receptor antagonists containing a urea moiety as non-basic guanidine mimetic are described. The most potent compounds exhibited IC(50) values towards alpha(V)beta3 in the nanomolar range and high selectivity versus related integrins like alpha(IIb)beta3. For selected examples efficacy in functional cellular assays is demonstrated.

Efficient transfection method for primary cells

Transfection of primary cells and stem cells is a problem in the laboratory routine and further in tissue engineering and gene therapy. Most methods working effectively for cell lines in culture fail to transfect primary cells. Here we describe the use of the Nucleofector technology developed by amaxa biosystems. We were able to transfect primary human melanocytes, human coronary smooth muscle cells, human chondrocytes, and human mesenchymal stem cells with high efficiencies (28.9-45.3%). All primary cell types failed to be transfected satisfactorily by methods based on liposome-mediated transfection in our hands. The viability of the transfected cells varied between 11.2% and 75% in comparison to untreated cells. Only 200,000 cells per transfection sample were needed. In summary, this method presents an effective and fast mean for transfection of primary and stem cells demonstrated by four cell types which are only transfected with low efficiency by other methods.

Platelet aggregation inhibitors for use in peripheral vascular interventions: what can we learn from the experience in the coronary arteries?

During the last decade, an enormous amount of information has been gathered about the function of the platelet and its impact on percutaneous vascular interventions. With the discovery of the GP IIb/IIIa receptor, which is responsible for platelet aggregation, new drug antagonists have been developed to prevent platelet aggregation that may result in arterial thrombosis or platelet microembolization. These drugs include the three GP IIb/IIIa receptor antagonists approved by the Food and Drug Administration: abciximab (ReoPro), eptifibatide (Integrilin), and tirofiban (Aggrastat). These drugs have been used in several large studies to improve the outcome of coronary interventions and in conjunction with plasminogen activators to accelerate thrombolysis. In addition, because no oral GP IIb/IIIa inhibitor exists, other oral regimens have been developed with use of the thienopyridines, ticlopidine (Ticlid) and clopidogrel (Plavix), in combination with aspirin to prevent platelet aggregation and thrombosis. Because the majority of investigations have been performed in patients undergoing coronary interventions, knowledge of these data is necessary to attempt to translate the use of these antiplatelet drugs to peripheral vascular interventions. The goal of this article is to review the use of these agents in the percutaneous treatment of coronary artery disease and give insight to their potential utility in noncoronary interventions.