Recent advances in surface functionalization of cardiovascular stents

Cardiovascular diseases (CVD) are the leading global threat to human health. The clinical application of vascular stents improved the survival rates and quality of life for patients with cardiovascular diseases. However, despite the benefits stents bring to patients, there are still notable complications such as thrombosis and in-stent restenosis (ISR). Surface modification techniques represent an effective strategy to enhance the clinical efficacy of vascular stents and reduce complications. This paper reviews the development strategies of vascular stents based on surface functional coating technologies aimed at addressing the limitations in clinical application, including the inhibition of intimal hyperplasia, promotion of re-endothelialization. These strategies have improved endothelial repair and inhibited vascular remodeling, thereby promoting vascular healing post-stent implantation. However, the pathological microenvironment of target vessels and the lipid plaques are key pathological factors in the development of atherosclerosis (AS) and impaired vascular repair after percutaneous coronary intervention (PCI). Therefore, restoring normal physiological environment and removing the plaques are also treatment focuses after PCI for promoting vascular repair. Unfortunately, research in this area is limited. This paper reviews the advancements in vascular stents based on surface engineering technologies over the past decade, providing guidance for the development of stents.

Safety, pharmacokinetics and pharmacodynamics of an original glycoprotein IIb/IIIa inhibitor in healthy volunteers: results of the clinical trial

Aim. To study the tolerability, safety, pharmacokinetics (PK) and pharmacodynamics of single intravenous infusions of Angipur in healthy male volunteers.

Material and methods. The Phase I trial included 20 healthy male volunteers (mean age, 30,8±7,7 years; mean body weight, 77,4±12,1 kg). Angipur (0,02% concentrate for solution for infusion) was administered to every subject in single doses 0,015, 0,05, 0,09 mg/kg for 3 consecutive days. Volunteers were divided in 6 groups (1, 1, 3, 5, 5, 5); every following group was recruited only after the previous one finished the study. The following were assessed: rate and severity of adverse events (AEs), key PK parameters of Angipur and its antiplatelet activity by impedance aggregometry.

Results. No moderate or severe AEs, as well as no serious AEs were reported according to obtained data of clinical and laboratory monitoring of healthy subjects. Totally 6 mild AEs were registered in 4 subjects. Four AEs (mild hematological deviations and episode of nose bleed) were classified as possibly related to study drug and 1 AE (positive fecal occult blood test)  — probably related. Key PK parameters of Angipur in single intravenous doses 0,015, 0,05 и  0,09 mg/kg were determined as follows: Cmax — 12,44±4,689, 46,10±14,295, 92,48±33,896 ng/ml; Vd  — 304,01±55,300, 299,67±64,244, 252,96±47,790 l; T1/2  — 6,72±1,290, 6,84±2,341, 6,06±2,287 h; Cl  — 32,19±6,919, 32,29±8,357, 31,55±10,113 l/h, respectively. Dose proportionality (linear PK) for parameters Cmax, AUC0-t and AUC0-∞ was established. Dose-dependent reduction of ADP-induced platelet aggregation degree and area under curve was revealed at period of 15 min to 2-4 h after Angipur infusion in doses 0,05 and 0,09 mg/kg.

Conclusion. Results of phase I clinical trial demonstrated good tolerability of single intravenous infusions of Angipur (0,015, 0,05 и 0,09 mg/kg) in healthy subjects. We determined key PK parameters and indicated dose-dependent antiplatelet activity of Angipur.

Combined Endothelialization Promoting and Surface Binding Chimeric Conjugate with Low Thrombogenicity

Endothelialization of blood contacting implants, e.g., vascular stents, is regarded as a prerequisite for an improved performance in terms of minimizing thrombogenicity and the inhibition of restenosis. Commonly used materials, such as Ti-based alloys, can be surface-modified in order to improve endothelial cell (EC) colonization as well as to reduce platelet adhesion. Standard modification techniques involve silanization and are laborious and time-consuming. We propose a novel single-step procedure based on a surface-recognizing peptide generated by phage display methodology. Combining this with a polyethylene glycol (PEG) spacer and an EC-specific sequence yielded a conjugate applicable for the modification of Ti surfaces.

Platelet integrin αIIbβ3: signal transduction, regulation, and its therapeutic targeting

Integrins are a family of transmembrane glycoprotein signaling receptors that can transmit bioinformation bidirectionally across the plasma membrane. Integrin αIIbβ3 is expressed at a high level in platelets and their progenitors, where it plays a central role in platelet functions, hemostasis, and arterial thrombosis. Integrin αIIbβ3 also participates in cancer progression, such as tumor cell proliferation and metastasis. In resting platelets, integrin αIIbβ3 adopts an inactive conformation. Upon agonist stimulation, the transduction of inside-out signals leads integrin αIIbβ3 to switch from a low- to high-affinity state for fibrinogen and other ligands. Ligand binding causes integrin clustering and subsequently promotes outside-in signaling, which initiates and amplifies a range of cellular events to drive essential platelet functions such as spreading, aggregation, clot retraction, and thrombus consolidation. Regulation of the bidirectional signaling of integrin αIIbβ3 requires the involvement of numerous interacting proteins, which associate with the cytoplasmic tails of αIIbβ3 in particular. Integrin αIIbβ3 and its signaling pathways are considered promising targets for antithrombotic therapy. This review describes the bidirectional signal transduction of integrin αIIbβ3 in platelets, as well as the proteins responsible for its regulation and therapeutic agents that target integrin αIIbβ3 and its signaling pathways.

A Short Half-Life αIIbβ₃ Antagonist ANTP266 Reduces Thrombus Formation

Integrin α_IIbβ₃ plays a pivotal role in platelet aggregation. Three α_IIbβ₃ antagonists have been approved by the Food and Drug Administration (FDA) for the treatment of cardiovascular diseases. Unfortunately, all of these three drugs can cause the side effect of severe bleeding. Therefore, developing a new α_IIbβ₃ antagonist with low bleeding was needed. In the present study, we screened compounds by using a fibrinogen/integrin α_IIbβ₃ enzyme-linked immunosorbent assay (ELISA), and a novel α_IIbβ₃ antagonist ANTP266 was attained. The antithrombotic effects of ANTP266 were estimated by using two animal models, the bleeding risk was estimated by using a mice tail cutting assay, and the plasma half-life time was tested by LC-MS/MS. The results showed that ANTP266 potently decreased thrombosis formation, while not prolonging bleeding time at its effective dosage. The bleeding of ANTP266 reduced rapidly as time went on from 5 to 60 min, but tirofiban produced high bleeding continuously. The plasma half-life of ANTP266 in rats was 10.8 min. Taken together, ANTP266 is an effective antithrombotic agent with a low bleeding risk. The shorter bleeding time benefits from its short plasma half-life. ANTP266 could be a candidate for developing the α_IIbβ₃ antagonist of rapid elimination for a patient undergoing percutaneous coronary intervention.

rLj-RGD3, a novel recombinant toxin protein from Lampetra japonica, prevents coronary thrombosis-induced acute myocardial infarction by inhibiting platelet functions in rats

Recombinant Lampetra japonica RGD-peptide (rLj-RGD3), a soluble protein containing three RGD sequences, was acquired from the oral salivary glands of Lampetra japonica using recombinant DNA technology. The aim of this study was to investigate the protective effects of rLj-RGD3 against acute myocardial infarction (AMI) induced by coronary artery thrombosis, as well as the underlying mechanisms. A rat model of AMI caused by ferric chloride-induced thrombosis on the surface of the left anterior descending (LAD) coronary artery was successfully established. Rats were given various doses of rLj-RGD3 (12 μg/kg, 24 μg/kg and 48 μg/kg) via sublingual intravenous delivery 10 min before AMI. ST segment elevation was recorded by electrocardiogram (ECG) until the end of the model. Left ventricular Evans blue content and histopathological changes were examined. Blood samples were collected to determine 5-hydroxytryptamine (5-HT), β-thromboglobulin (β-TG), platelet factor 4 (PF4) and cAMP levels. The effects of rLj-RGD3 on platelet aggregation, adhesion and intracellular calcium concentrations were also measured. rLj-RGD3 significantly reduced ST segment elevation, prevented thrombus formation in the coronary artery and decreased Evans blue content in the left ventricular myocardium. Meanwhile, rLj-RGD3 exerted an inhibitory effect on adenosine diphosphate (ADP)-induced platelet aggregation and blocked platelet adhesion to collagen. Treatment with rLj-RGD3 prevented 5-HT, β-TG and PF4 release and significantly elevated intracellular cAMP levels in a dose-dependent manner but decreased the level of cytosolic-free Ca²⁺, an aggregation-inducing molecule. These results show that rLj-RGD3 can effectively reduce coronary thrombosis in AMI rats by strongly inhibiting platelet function, indicating that the recombinant RGD toxin protein rLj-RGD3 may serve as a potent clinical therapeutic agent for AMI.

Design, synthesis and evaluation of 1,4-benzodioxine derivatives as novel platelet aggregation inhibitors

AIM

To find novel platelet aggregation inhibitors, two new series of 1,4-benzodioxine derivatives were synthesized and screened for the ability to inhibit platelet aggregation.

MATERIALS & METHODS

The synthesized compounds were evaluated for antiplatelet aggregation activity using human blood platelet and GPIIb/IIIa antagonistic activity.

RESULTS

Compound 9-2p showed significant antiplatelet activity with the IC₅₀ values of 41.7 and 22.2 μM induced by ADP and thrombin, respectively, more potent than that of LX2421. Compound 9-2p exhibited GPIIb/IIIa antagonistic activity with the IC₅₀ value of 2.3 μM, as potent as RGDs. In vivo study showed that 9-2p displayed remarkable antithrombotic activity, more effective than LX2421, but less effective than tirofiban.

CONCLUSION

Compound 9-2p showed moderate antiplatelet activity and antithrombotic activity, which could be further optimized based on the target of GPIIb/IIIa.

The progress in the research of antiplatelet agents (1995-2017)

Antiplatelet therapy displays a critical role in the treatment and prevention of antithrombotic disorders. Many new antiplatelet agents have been developed following the emergence of various clinical limitations of classical antiplatelet drugs. This review covers mainly the recent advances in the development of P2Y₁₂ antagonists and GPIIb/IIIa antagonists. Meanwhile, it summarizes promising approaches to new platelet surface receptors such as prostanoid EP3 receptor, thromboxane A₂ prostanoid receptor, protease-activated receptors, GPIb-IX-V receptor and P-selectin. In addition, PI3K_β, a critical protein at the inside signaling pathway of platelet activation is also mentioned as an important antiplatelet target. Moreover, the development of respective drug candidates is discussed in detail.