Anti-inflammatory effect of abciximab-coated stent in a porcine coronary restenosis model

Preclinical Evaluation of a Novel Polymer-free Everolimus-eluting Stent in a Mid-term Porcine Coronary Restenosis Model

BACKGROUND

Titanium dioxide films exhibit good biocompatibility and may be effective as drug-binding matrices for drug-eluting stents. We conducted a mid-term evaluation of a novel polymer-free everolimus-eluting stent using nitrogen-doped titanium dioxide film deposition (TIGEREVOLUTION^®) in comparison with a commercial durable polymer everolimus-eluting stent (XIENCE Alpine^®) in a porcine coronary restenosis model.

METHODS

Twenty-eight coronary arteries from 14 mini-pigs were randomly allocated to TIGEREVOLUTION^® stent and XIENCE Alpine^® stent groups. The stents were implanted in the coronary artery at a 1.1-1.2:1 stent-to-artery ratio. Eleven stented coronary arteries in each group were finally analyzed using coronary angiography, optical coherence tomography, and histopathologic evaluation 6 months after stenting.

RESULTS

Quantitative coronary analysis showed no significant differences in the pre-procedural, post-procedural, and 6-month lumen diameters between the groups. In the volumetric analysis of optical coherence tomography at 6 months, no significant differences were observed in stent volume, lumen volume, and percent area stenosis between the groups. There were no significant differences in injury score, inflammation score, or fibrin score between the groups, although the fibrin score was zero in the TIGEREVOLUTION^® stent group (0 vs. 0.07 ± 0.11, P = 0.180).

CONCLUSION

Preclinical evaluation, including optical coherence tomographic findings 6 months after stenting, demonstrated that the TIGEREVOLUTION^® stent exhibited efficacy and safety comparable with the XIENCE Alpine^® stent, supporting the need for further clinical studies on the TIGEREVOLUTION^® stent.

Development of Novel Drug-Eluting Stents for Acute Myocardial Infarction

Delayed arterial healing at culprit sites after drug-eluting stent (DES) placement for acute myocardial infarction (AMI) is associated with increased risk of late stent thrombosis. The Korea Acute Myocardial Infarction Registry was established in commemoration of the 50^th anniversary of Korea Circulation Society. Between November 2005 and December 2016, more than 62,000 patients were registered from 50 primary percutaneous coronary intervention (PCI) centers in Korea. DES in AMI may be safe and effective, however, there is concern about increased stent thrombosis after DES implantation in AMI patients, requiring longer-term dual anti-platelet therapy to reduce the risk of late stent thrombosis. Device innovation is needed to overcome issues such as stent thrombosis and restenosis by using new coating materials with biocompatible polymers, different coating methods using non-polymer techniques, bioabsorbable stents and pro-healing stents. In this review article, we describe the current usage of DES in AMI in Korea and introduce novel DES uses in development for patients with AMI. We have developed many types of DES in our research laboratory. Abciximab-coated stents inhibited platelet thrombi and restenosis. Furthermore, anti-oxidants (carvedilol, probucol and alpha-lipoic acid) were used for stent coating. Currently we are developing novel DESs using polymer-free and natural binding techniques, peptide coating stents, gene-and-drug delivery, bioabsorbable stents using 3D printing, endothelial progenitor cell capturing stents to promote reendothelialization and reduce stent thrombosis. New DESs in development may be safe and effective in preventing late stent thrombosis and restenosis in patients with AMI.

Zedoary Guaiane-Type Sesquiterpenes-Eluting Stents Accelerate Endothelial Healing Without Neointimal Hyperplasia in a Porcine Coronary Artery Model

Objective:

The effects of zedoary guaiane-type sesquiterpenes (ZGS)-based eluting stent (ZES) in accelerating reendothelialization and inhibiting neointimal hyperplasia were examined in a porcine coronary artery model.

Methods:

The ZES was prepared by polymer-free 316L stainless metal stents. Sirolimus-eluting stents (SES) and bare metal stents (BMS) with identical platforms were used as controls. Stents with 15 mm in length and 2.0 to 3.5 mm in diameter were implanted in porcine coronary arteries. Scanning electron microscopy (SEM) and histopathology were performed to assess the reendothelialization and neointimal hyperplasia. The 3-(4, 5-dimethylthiazol-2yl)-2, 5-diphenyl-2H-tetrazoliumbromide assay and flow cytometry were used to assess the influence of ZGS on human umbilical vascular endothelial cells (HUVECs).

Results:

At 7 days, SEM showed that percentage of endothelial coverage area was 94.04% ± 5.01% for ZES, 47.59% ± 19.91% for SES ( P < .01 for ZES vs SES), and 59.58% ± 19.61% for BMS ( P < .05 for ZES vs BMS). At 28 days, the percentage of coverage area was 98.51% ± 1.86% for ZES, 86.18% ± 8.16% for SES ( P < .05 for ZES vs SES), and 94.26% ± 5.58% for BMS. Neointimal area and stenosis were significantly lower in ZES (1.07 ± 0.48 mm2, 27.66% ± 12.20%) compared to BMS (1.73 ± 0.69 mm2, 44.08% ± 15.03%, both P < .01, respectively), with no difference in SES (0.94 ± 0.12 mm2, 28.87% ± 6.00%, both P > .05, respectively). The ZGS also promoted HUVECs viability and improved HUVECs proliferation compared to sirolimus.

Conclusion:

The ZES accelerated reendothelialization and suppressed neointimal hyperplasia in a porcine coronary artery model, with beneficial effects on HUVECs.

Computational drug repositioning for peripheral arterial disease: prediction of anti-inflammatory and pro-angiogenic therapeutics

Peripheral arterial disease (PAD) results from atherosclerosis that leads to blocked arteries and reduced blood flow, most commonly in the arteries of the legs. PAD clinical trials to induce angiogenesis to improve blood flow conducted in the last decade have not succeeded. We have recently constructed PADPIN, protein-protein interaction network (PIN) of PAD, and here we combine it with the drug-target relations to identify potential drug targets for PAD. Specifically, the proteins in the PADPIN were classified as belonging to the angiome, immunome, and arteriome, characterizing the processes of angiogenesis, immune response/inflammation, and arteriogenesis, respectively. Using the network-based approach we predict the candidate drugs for repositioning that have potential applications to PAD. By compiling the drug information in two drug databases DrugBank and PharmGKB, we predict FDA-approved drugs whose targets are the proteins annotated as anti-angiogenic and pro-inflammatory, respectively. Examples of pro-angiogenic drugs are carvedilol and urokinase. Examples of anti-inflammatory drugs are ACE inhibitors and maraviroc. This is the first computational drug repositioning study for PAD.

Comparison of reendothelialization and neointimal formation with stents coated with antibodies against endoglin and CD34 in a porcine model

Anti-CD34 coated stents are the only commercialized antibody-coated stents currently used for coronary artery diseases with various limitations. Endoglin plays important roles in the proliferation of endothelial cells and vascular remodeling and could be an ideal target surface molecule. The objective of this study was to investigate the efficacy of stents coated with anti-endoglin antibodies (ENDs) in terms of endothelial recovery and the reduction of neointimal formation. The performance of ENDs was evaluated by comparing with stents coated with anti-CD34 antibodies (CD34s), sirolimus-eluting stents (SESs), and bare metal stents (BMSs). Stents were randomly assigned and placed in the coronary arteries of juvenile pigs. Histomorphometric analysis and scanning electron microscopy were performed after stent implantation. Our results showed at 14 days after stent implantation, the neointima area and percent area stenosis in ENDs and CD34s were remarkably decreased compared with those in BMSs and SESs (P<0.05). Moreover, the percentage of reendothelialization was significantly higher in ENDs and CD34s than that in SESs or BMSs at both 7 and 14 days (P<0.05). There was no difference in the neointima area, percent area stenosis, and percentage of reendothelialization in ENDs compared with CD34s. The artery injury and the inflammation scores were similar in all groups at both 7 and 14 days. Our results demonstrate that the performance of ENDs is similar to the commercial CD34s, without the disadvantages of CD34s, and both are better than SESs and BMSs. ENDs potentially offer an alternative approach to reduce restenotic process and enhance reendothelialization after stent implantation.

Effect of pretreatment of ezetimibe/simvastatin on arterial healing and endothelialization after drug-eluting stent implantation in a porcine coronary restenosis model

Background and Objectives

We sought to evaluate the effect of the early use of ezetimibe/simvastatin (Vytorin®) on arterial healing and endothelialization after the implantation of a drug-eluting stent (DES) in a porcine model of coronary restenosis.

Materials and Methods

A total of 20 pigs (40 coronary arteries) were randomly allocated to a pretreatment or no treatment group. The pretreatment group (n=20) received oral ezetimibe/simvastatin (10/20 mg) daily for 7 days before stenting and the no pretreatment group (n=20) did not. All pigs were treated with ezetimibe/simvastatin (10/20 mg) daily after stenting for 4 weeks. Stenting was performed using a bare-metal stent (BMS, n=10) and three types of DES: biolimus A9-eluting stent (BES, n=10), zotarolimus-eluting stent (ZES, n=10), and everolimus-eluting stents (EES, n=10). Four weeks later, pigs underwent a follow-up coronary angiography and were sacrificed for histopathologic analysis.

Results

There were no significant differences between the pretreatment and no pretreatment groups in the internal elastic lamina area, lumen area, neointima area, stenotic area, injury score, fibrin score, and inflammation score. In both groups, the fibrin score was higher in pigs with DES than in BMS, particularly in ZES and EES. The inflammatory score was not different between DES and BMS.

Conclusion

In a porcine model of coronary restenosis, pretreatment with ezetimibe/simvastatin before DES implantation failed to improve arterial healing and endothelialization compared to treatment after stenting.

A novel stent coated with antibodies to endoglin inhibits neointimal formation of porcine coronary arteries

Endoglin/CD105 is an accessory protein of the transforming growth factor-β receptor system that plays a critical role in proliferation of endothelial cells and neovasculature. Here, we aimed to assess the effect of novel stents coated with antibodies to endoglin (ENDs) on coronary neointima formation. Thirty ENDs, thirty sirolimus-eluting stents (SESs), and thirty bare metal stents (BMSs) were randomly assigned and placed in the coronary arteries in 30 juvenile pigs. Histomorphometric analysis and scanning electron microscopy were performed after stent implantation. Our results showed that after 7 days, there was no difference in the neointimal area and percent area stenosis in ENDs compared with SMSs or BMSs. After 14 days, the neointima area and percent area stenosis in ENDs were markedly decreased than those in BMSs or SESs (P < 0.05). Moreover, the percentage of reendothelialization was significantly higher in ENDs than that in SESs or BMSs (P < 0.01) at 7 and 14 days. The artery injury and the inflammation scores were similar in all groups at 7 and 14 days. In conclusion, our results demonstrated for the first time to our knowledge that endoglin antibody-coated stents can markedly reduce restenosis by enhancing reendothelialization in the porcine model and potentially offer a new approach to prevent restenosis.

A bumpy and winding but right path to domestic drug-eluting coronary stents

Restenosis and stent thrombosis remain major concerns after percutaneous coronary intervention for the treatment of coronary artery disease. The present review was undertaken in order to highlight the various coronary stents that have been investigated in our Heart Research Center, and how far we have come from the first heparin-coated stent first used in the late 1990s. Thereafter, from the abciximab-coated stent to the current gene-delivery stent and other newer agents, our group has applied a range of techniques in this field. However, in groups similar to ours, the restenosis rates of such stents are still high for second-generation drug-eluting stents (DESs). Moreover, our nation imports almost all of these types of stents from other countries. Thus, we need to develop domestic coronary stents. Research into newer DESs are warranted in Korea so as to achieve improved safety and efficacy outcomes.

Integrin αIIbβ3: from discovery to efficacious therapeutic target

From the initial description of platelets in 1882, their propensity to aggregate and to contribute to thrombosis was apparent. Indeed, excessive platelet aggregation is associated with myocardial infarction and other thrombotic diseases whereas Glanzmann thrombasthenia, in which platelet aggregation is reduced, is a bleeding syndrome. Over the last half of the 20th century, many investigators have provided insights into the cellular and molecular basis for platelet aggregation. The major membrane protein on platelets, integrin αIIbβ3, mediates this response by rapidly transiting from its resting to an activated state in which it serves as a receptor for ligands that can bridge platelets together. Monoclonal antibodies, natural products, and small peptides were all shown to inhibit αIIbβ3 dependent platelet aggregation, and these inhibitors became the forerunners of antagonists that proceeded through preclinical testing and into large patient trials to treat acute coronary syndromes, particularly in the context of percutaneous coronary interventions. Three such αIIbβ3 antagonists, abciximab, eptifibatide, and tirofiban, received Food and Drug Administration approval. Over the past 15 years, millions of patients have been treated with these αIIbβ3 antagonists and many lives have been saved by their administration. With the side effect of increased bleeding and the development of new antithrombotic drugs, the use of αIIbβ3 antagonists is waning. Nevertheless, they are still widely used for the prevention of periprocedural thrombosis during percutaneous coronary interventions. This review focuses on the biology of αIIbβ3, the development of its antagonists, and some of the triumphs and shortcomings of αIIbβ3 antagonism.

Impact of heterogeneous overlapping drug-eluting stents on the arterial responses of rabbit iliac arteries: a comparison with overlapping bare metal stents

Background and Objectives

Although the use of heterogeneous overlapping drug-eluting stents (DES) is not uncommon in clinical practice, whether the implantation sequences of heterogeneous DES will influence the endothelialization or arterial responses differently remains unclear.

Materials and Methods

Twenty-one rabbits were randomized to receive overlapping stents in the iliac artery for 3 months {distal sirolimus-eluting stent (SES, Cypher™)+proximal paclitaxel-eluting stent (PES, Taxus™) (C+T, n=7), distal Taxus+proximal Cypher (T+C, n=7) and bare metal stent (BMS)+BMS (B+B, n=7)}. Endothelial function was evaluated by the acetylcholine provocation test during follow-up angiography. Histopathological changes in proximal, overlapped, and distal stented segments were evaluated.

Results

Although the overall angiographic outcomes were comparable, late loss (mm) in the distal stented segment was higher in the B+B (0.39±0.07) and C+T (0.40±0.20) than that in the T+C (0.06±0.02) group (p<0.001). The incidence of acetylcholine-induced spasm was higher in the DES groups compared with BMS, regardless of the implantation sequences (85.7% in C+T vs. 14.3% in B+B vs. 71.4% in T+C, p=0.017). Notably, only the distal Cypher implantation group (C+T) had three cases of stent fracture. A histopathological analysis showed that despite similar arterial injury scores, Taxus and Cypher stents had higher inflammatory reactions at the overlapped and distal segments compared with those of BMS.

Conclusion

Despite similar arterial injury, higher inflammatory reactions were observed in overlapping DES segments regardless of the implantation sequence compared with that of BMS. Moreover, DES was associated with impaired endothelial function on the adjacent non-stented segments.