An investigation of the antiplatelet effects of succinobucol (AGI-1067)

Intra-arterial injection of mesenchymal stem cells to accelerate neointima formation after endovascular stenting in a rabbit model

OBJECTIVE

Delayed neointima formation over a neurovascular stent is associated with thrombotic complications that can lead to stroke. The purpose of this study was to evaluate whether an intra-arterial injection of mesenchymal stem cells (MSCs) after stent placement leads to improved neointima and reduced thrombus formation over the device.

METHODS

Solitaire stents were placed into the aortas of rabbits that were divided into MSC and control groups. The MSC group received an intra-arterial injection of MSCs through the same microcatheter used for stent deployment. Optical coherence tomography (OCT) was used to evaluate and compare neointima and thrombus formation in a blinded fashion. Explanted specimens were also imaged with scanning electron microscopy (SEM) and evaluated by observers blinded to group allocation using an endothelialization scoring system.

RESULTS

The 3-day MSC group was similar to the 7-day controls in terms of stent strut coverage ratio and maximum neointimal thickness, but these values were significantly higher than the 3-day control group based on a hierarchical mixed-effects linear regression analysis. SEM revealed a significantly higher endothelialization score for the MSC group compared with controls at the same time point. There was no difference in thrombus formation between any of the groups.

CONCLUSIONS

The intra-arterial injection of MSCs after endovascular stenting accelerated early neointima formation but had no effect on thrombus formation in this study. Larger studies are required to verify these findings and determine the durability and mechanism of this effect.

Heparin-Tagged PLA-PEG Copolymer-Encapsulated Biochanin A-Loaded (Mg/Al) LDH Nanoparticles Recommended for Non-Thrombogenic and Anti-Proliferative Stent Coating

Drug-eluting stents have been widely implanted to prevent neointimal hyperplasia associated with bare metal stents. Conventional polymers and anti-proliferative drugs suffer from stent thrombosis due to the non-selective nature of the drugs and hypersensitivity to polymer degradation products. Alternatively, various herbal anti-proliferative agents are sought, of which biochanin A (an isoflavone phytoestrogen) was known to have anti-proliferative and vasculoprotective action. PLA-PEG diblock copolymer was tagged with heparin, whose degradation releases heparin locally and prevents thrombosis. To get a controlled drug release, biochanin A was loaded in layered double hydroxide nanoparticles (LDH), which are further encapsulated in a heparin-tagged PLA-PEG copolymer. LDH nanoparticles are synthesized by a co-precipitation process; in situ as well as ex situ loading of biochanin A were done. PLA-PEG-heparin copolymer was synthesized by esterification reaction, and the drug-loaded nanoparticles are coated. The formulation was characterized by FTIR, XRD, DSC, DLS, and TEM. In vitro drug release studies, protein adhesion, wettability, hemocompatibility, and degradation studies were performed. The drug release was modeled by mathematical models to further emphasize the mechanism of drug release. The developed drug-eluting stent coating is non-thrombogenic, and it offers close to zero-order release for 40 days, with complete polymer degradation in 14 weeks.

Antiplatelet activity of new derivatives of benzimidazole containing sterically hindered phenolic group in their structure

Introduction: Cardiovascular diseases are currently the leading cause of global disability and mortality. According to the centers for disease control and prevention, the average life expectancy of a person would be 10 years longer but for a high prevalence of cardiovascular diseases, and if antiplatelet drugs and special therapy were used.

Materials and methods: Antiplatelet activity of the novel benzimidazole derivatives containing a sterically hindered phenolic group in their structure has been investigated in vitro, using a model of ADP-induced platelet aggregation of rabbit’s plasma. The compounds exhibiting high antiplatelet activity and acetylsalicylic acid, as a reference drug, were examined for antioxidant properties in an ascorbate-dependent model of lipid peroxidation.

Results: It was established that the compounds with high antiplatelet activity demonstrated the pronounced antioxidant action. The compound RU-1144 (1-(3,5-ditretbutyl-4-hydroxyphenyl) -1-hydroxypropyl)-phenyl-pyrimidobenzimidazole hydrochloride), in in vitro experiments, had a pronounced antiplatelet activity, surpassing the reference drug acetylsalicylic acid by 21.8 times; in the study of antioxidant activity, the leader compound was inferior to the reference drug dibunol by 1.7 times. By inhibiting intravascular platelet aggregation in vivo, this compound exceeded acetylsalicylic acid by 1.5 times and was slightly inferior to clopidogrel by 1.4 times.

Discussion: Benzimidazole derivatives with a hindered phenolic substituent in their structure exhibited antiplatelet and antioxidant properties. It was established that the compounds with high antiplatelet activity demonstrated the pronounced antioxidant action.

Conclusion: The chemical class of benzimidazole derivatives with a hindered phenolic substituent in their structure is promising for the search for new antiaggregant and antioxidant drugs.

Novel ASK1 inhibitor AGI-1067 improves AGE-induced cardiac dysfunction by inhibiting MKKs/p38 MAPK and NF-κB apoptotic signaling

Heart failure has been identified as one of the clinical manifestations of diabetic cardiovascular complications. Excessive myocardium apoptosis characterizes cardiac dysfunctions, which are correlated with an increased level of advanced glycation end products (AGEs). In this study, we investigated the participation of reactive oxygen species (ROS) and the involvements of apoptosis signal-regulating kinase 1 (ASK1)/mitogen-activated protein kinase (MAPK) kinases (MKKs)/p38 MAPK and nuclear factor κB (NF-κB) pathways in AGE-induced apoptosis-mediated cardiac dysfunctions. The antioxidant and therapeutic effects of a novel ASK1 inhibitor, AGI-1067, were also studied. Myocardium and isolated primary myocytes were exposed to AGEs and treated with AGI-1067. Invasive hemodynamic and echocardiographic assessments were used to evaluate the cardiac functions. ROS formation was evaluated by dihydroethidium fluorescence staining. A terminal deoxynucleotidyl transferase dUTP nick end labelling assay was used to detect the apoptotic cells. ASK1 and NADPH activities were determined by kinase assays. The association between ASK1 and thioredoxin 1 (Trx1) was assessed by immunoprecipitation. Western blotting was used to evaluate the phosphorylation and expression levels of proteins. Our results showed that AGE exposure significantly activated ASK1/MKKs/p38 MAPK, which led to increased cardiac apoptosis and cardiac impairments. AGI-1067 administration inhibited the activation of MKKs/p38 MAPK by inhibiting the disassociation of ASK1 and Trx1, which suppressed the AGE-induced myocyte apoptosis. Moreover, the NF-κB activation as well as the ROS generation was inhibited. As a result, cardiac functions were improved. Our findings suggested that AGI-1067 recovered AGE-induced cardiac dysfunction by blocking both ASK1/MKKs/p38 and NF-κB apoptotic signaling pathways.