Effects of tacrolimus or sirolimus on proliferation of vascular smooth muscle and endothelial cells

Efficacy and Safety Evaluation of Tacrolimus-Eluting Stent in a Porcine Coronary Artery Model

BACKGROUND

A drug-eluting stent (DES) is a highly beneficial medical device used to widen or unblock narrowed blood vessels. However, the drugs released by the implantation of DES may hinder the re-endothelialization process, increasing the risk of late thrombosis. We have developed a tacrolimus-eluting stent (TES) that as acts as a potent antiproliferative and immunosuppressive agent, enhancing endothelial regeneration. In addition, we assessed the safety and efficacy of TES through both in vitro and in vivo tests.

METHODS

Tacrolimus and Poly(lactic-co-glycolic acid) (PLGA) were applied to the metal stent using electrospinning equipment. The surface morphology of the stent was examined before and after coating using a scanning electron microscope (SEM) and energy dispersive X-rays (EDX). The drug release test was conducted through high-performance liquid chromatography (HPLC). Cell proliferation and migration assays were performed using smooth muscle cells (SMC). The stent was then inserted into the porcine coronary artery and monitored for a duration of 4 weeks.

RESULTS

SEM analysis confirmed that the coating surface was uniform. Furthermore, EDX analysis showed that the surface was coated with both polymer and drug components. The HPCL analysis of TCL at a wavelength of 215 nm revealed that the drug was continuously released over a period of 4 weeks. Smooth muscle cell migration was significantly decreased in the tacrolimus group (54.1% ± 11.90%) compared to the non-treated group (90.1% ± 4.86%). In animal experiments, the stenosis rate was significantly reduced in the TES group (29.6% ± 7.93%) compared to the bare metal stent group (41.3% ± 10.18%). Additionally, the fibrin score was found to be lower in the TES group compared to the group treated with a sirolimus-eluting stent (SES).

CONCLUSION

Similar to SES, TES reduces neointimal proliferation in a porcine coronary artery model, specifically decreasing the fibrins score. Therefore, tacrolimus could be considered a promising drug for reducing restenosis and thrombosis.

Comparative analysis of antiproliferative and vasodilator effects of drugs for pulmonary hypertension: Extensive in vitro study in rats and human

An effective pulmonary hypertension (PH) treatment should combine antiproliferative and vasodilator effects. We characterized a wide-range of drugs comparing their anti-proliferative vs vasodilator effects in human and rat pulmonary artery smooth muscle cells (PASMC). Key findings: 1) Approved PH drugs (PDE5 inhibitors, sGC stimulators and PGI2 agonists) are preferential vasodilators. 2) cGMP stimulators were more effective in cells derived from hypertensive rats. 3) Nifedipine acted equally as vasodilator and antiproliferative. 4) quercetin and imatinib were potent dual vasodilator/antiproliferative drugs. 5) Tacrolimus and levosimendan lacked antiproliferative effects. 6) Forskolin, pinacidil and hydroxyfasudil were more effective as antiproliferative in human cells.

In Vivo and Clinical Studies of Natural Products Targeting the Hallmarks of Cancer

Despite more than 200 approved anticancer agents, cancer remains a leading cause of death worldwide due to disease complexity, tumour heterogeneity, drug toxicity, and the emergence of drug resistance. Accordingly, the development of chemotherapeutic agents with higher efficacy, a better safety profile, and the capability of bypassing drug resistance would be a cornerstone in cancer therapy. Natural products have played a pivotal role in the field of drug discovery, especially for the pharmacotherapy of cancer, infectious, and chronic diseases. Owing to their distinctive structures and multiple mechanistic activities, natural products and their derivatives have been utilized for decades in cancer treatment protocols. In this review, we delve into the potential of natural products as anticancer agents by targeting cancer's hallmarks, including sustained proliferative signalling, evading growth suppression, resisting apoptosis and cell death, enabling replicative immortality, inducing angiogenesis, and activating invasion and metastasis. We highlight the molecular mechanisms of some natural products, in vivo studies, and promising clinical trials. This review emphasizes the significance of natural products in fighting cancer and the need for further studies to uncover their fully therapeutic potential.

Nanofiber-coated, tacrolimus-eluting sutures inhibit post-operative neointimal hyperplasia in rats

Post-operative complications of vascular anastomosis procedures remain a significant clinical challenge and health burden globally. Each year, millions of anastomosis procedures connect arteries and/or veins in vascular bypass, vascular access, organ transplant, and reconstructive surgeries, generally via suturing. Dysfunction of these anastomoses, primarily due to neointimal hyperplasia and the resulting narrowing of the vessel lumen, results in failure rates of up to 50% and billions of dollars in costs to the healthcare system. Non-absorbable sutures are the gold standard for vessel anastomosis; however, damage from the surgical procedure and closure itself causes an inflammatory cascade that leads to neointimal hyperplasia at the anastomosis site. Here, we demonstrate the development of a novel, scalable manufacturing system for fabrication of high strength sutures with nanofiber-based coatings composed of generally regarded as safe (GRAS) polymers and either sirolimus, tacrolimus, everolimus, or pimecrolimus. These sutures provided sufficient tensile strength for maintenance of the vascular anastomosis and sustained drug delivery at the site of the anastomosis. Tacrolimus-eluting sutures provided a significant reduction in neointimal hyperplasia in rats over a period of 14 days with similar vessel endothelialization in comparison to conventional nylon sutures. In contrast, systemically delivered tacrolimus caused significant weight loss and mortality due to toxicity. Thus, drug-eluting sutures provide a promising platform to improve the outcomes of vascular interventions without modifying the clinical workflow and without the risks associated with systemic drug delivery.

Pharmacological prevention of intimal hyperplasia: A state-of-the-art review

Intimal hyperplasia (IH) occurs in a considerable number of cases of blood vessel reconstruction by stenting or balloon angioplasty, venous bypass grafting, and arteriovenous dialysis accesses. It is triggered by endothelial injury during the vascular intervention and leads to vessel restenosis with life-threatening consequences for patients. To date, the drugs used for IH prevention in clinics-paclitaxel and rapalog drugs-have been focusing primarily on the vascular smooth muscle cell (VSMC) proliferation pathway of IH development. Limitations, such as endothelial toxicity and inappropriate drug administration timing, have spurred the search for new and efficient pharmacological approaches to control IH. In this state-of-the-art review, we present the pathways of IH development, focusing on the key events and actors involved in IH. Subsequently, we discuss different drugs and drug combinations interfering with these pathways based on their effect on peripheral circulation IH models in animal studies, or on clinical reports. The reports were obtained through an extensive search of peer-reviewed publications in Pubmed, Embase, and Google Scholar, with search equations composed based on five concepts around IH and their various combinations. To improve vascular intervention outcomes, rethinking of conventional therapeutic approaches to IH prevention is needed. Exploring local application of drugs and drug combinations acting on different pathophysiological pathways of IH development has the potential to provide effective and safe restenosis prevention.

Keratosis pilaris rubra successfully treated with topical sirolimus: Report of a case and review of the literature

Keratosis pilaris rubra (KPR) is a subtype of keratosis pilaris (KP) presenting with numerous "grainlike" follicular papules in a background of confluent erythema most often affecting the face and upper extremities with persistence beyond puberty. Treatment has remained challenging with inconsistent benefit from topical therapies such as emollients, keratolytics, corticosteroids, and retinoids, though case reports documenting success with pulsed dye laser therapy have been found. We present a case of KPR in a 15-year-old boy who was successfully treated with topical sirolimus 1% cream.

Late polymicrobial transjugular intrahepatic portosystemic shunt infection in a liver transplant patient: A case report

BACKGROUND

Infection of a transjugular intrahepatic portosystemic shunt (TIPS) stent is a rare and serious complication that most commonly occurs during TIPS creation and revision. Patients typically present with recurrent bacteremia due to shunt occlusion or vegetation. To date there are approximately 58 cases reported. We present a patient diagnosed with late polymicrobial TIPS infection five years following TIPS creation.

CASE SUMMARY

A 63-year-old female status-post liver transplant with recurrent cirrhosis and portal hypertension presented with sepsis and recurrent extended-spectrum beta-lactamase Escherichia coli bacteremia. Computed tomography of the abdomen revealed an occluded TIPS with thrombus extension into the distal right portal vein, and focal thickening of the cecum and ascending colon. Colonoscopy revealed patchy ulcers in these areas with histopathology demonstrating ulcerated colonic mucosa with fibrinopurulent exudate. Shunt thrombectomy and revision revealed infected-appearing thrombus. Patient initially cleared her infection with antibacterial therapy and TIPS revision; however, soon after, she developed Enterobacter cloacae bacteremia and Candida glabrata and C. albicans fungemia with recurrent TIPS thrombosis. She remained on antifungal therapy indefinitely and later developed vancomycin-resistant Enterococcus faecium with recurrent TIPS thrombosis. The option of liver re-transplant for removal of the infected TIPS was not offered given her critical illness and complex shunt anatomy. The patient became intolerant to linezolid and elected hospice care.

CONCLUSION

Clinicians should be aware that TIPS superinfection may occur as long as five years following TIPS creation in an immunocompromised patient.

Pimecrolimus interferes the therapeutic efficacy of human mesenchymal stem cells in atopic dermatitis by regulating NFAT-COX2 signaling

Background

Human mesenchymal stem cells (hMSCs) therapy has recently been considered a promising treatment for atopic dermatitis (AD) due to their immunomodulation and tissue regeneration ability. In our previous studies, we demonstrated that hMSCs alleviate allergic inflammation in murine AD model by inhibiting the activation of mast cells and B cells. Also our phase I/IIa clinical trial showed clinical efficacy and safety of hMSCs in moderate-to-severe adult AD patients. However, hMSCs therapy against atopic dermatitis have had poor results in clinical field. Therefore, we investigated the reason behind this result. We hypothesized that drug–cell interaction could interfere with the therapeutic efficacy of stem cells, and investigated whether coadministration with pimecrolimus, one of the topical calcineurin inhibitors, could influence the therapeutic potential of human umbilical cord blood mesenchymal stem cells (hUCB-MSCs) in AD.

Methods

hUCB-MSCs were subcutaneously injected to AD-induced mice with or without pimecrolimus topical application. To examine whether pimecrolimus influenced the immunomodulatory activity of hUCB-MSCs, hUCB-MSCs were treated with pimecrolimus.

Results

Pimecrolimus disturbed the therapeutic effect of hUCB-MSCs when they were co-administered in murine AD model. Moreover, the inhibitory functions of hUCB-MSCs against type 2 helper T (Th2) cell differentiation and mast cell activation were also deteriorated by pimecrolimus treatment. Interestingly, we found that pimecrolimus decreased the production of PGE₂, one of the most critical immunomodulatory factors in hUCB-MSCs. And we demonstrated that pimecrolimus downregulated COX2-PGE₂ axis by inhibiting nuclear translocation of NFAT3.

Conclusions

Coadministration of pimecrolimus with hMSCs could interfere with the therapeutic efficacy of hMSCs in atopic dermatitis, and this is the first study that figured out the interaction of hMSCs with other drugs in cell therapy of atopic dermatitis. Therefore, this study might give rise to improvement of the clinical application of hMSCs therapy and facilitate the widespread application of hMSCs in clinical field.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02547-8.

Natriuretic Peptide Clearance Receptor (NPR-C) Pathway as a Novel Therapeutic Target in Obesity-Related Heart Failure With Preserved Ejection Fraction (HFpEF)

Heart failure (HF) with preserved ejection fraction (HFpEF) is a major public health problem with cases projected to double over the next two decades. There are currently no US Food and Drug Administration–approved therapies for the health-related outcomes of HFpEF. However, considering the high prevalence of this heterogeneous syndrome, a directed therapy for HFpEF is one the greatest unmet needs in cardiovascular medicine. Additionally, there is currently a lack of mechanistic understanding about the pathobiology of HFpEF. The phenotyping of HFpEF patients into pathobiological homogenous groups may not only be the first step in understanding the molecular mechanism but may also enable the development of novel targeted therapies. As obesity is one of the most common comorbidities found in HFpEF patients and is associated with many cardiovascular effects, it is a viable candidate for phenotyping. Large outcome trials and registries reveal that being obese is one of the strongest independent risk factors for developing HFpEF and that this excess risk may not be explained by traditional cardiovascular risk factors. Recently, there has been increased interest in the intertissue communication between adipose tissue and the heart. Evidence suggests that the natriuretic peptide clearance receptor (NPR-C) pathway may play a role in the development and pathobiology of obesity-related HFpEF. Therefore, therapeutic manipulations of the NPR-C pathway may represent a new pharmacological strategy in the context of underlying molecular mechanisms.

Anti-Thrombogenicity Study of a Covalently-Attached Monolayer on Stent-Grade Stainless Steel

Implantable devices fabricated from austenitic type 316L stainless steel have been employed significantly in medicine, principally because the material displays excellent mechanical characteristics and corrosion resistance. It is well known, however, that interaction of exposure of such a material to blood can initiate platelet adhesion and blood coagulation, leading to a harmful medical condition. In order to prevent undesirable surface platelet adhesion on biomaterials employed in procedures such as renal dialysis, we developed an ultrathin anti-thrombogenic covalently attached monolayer based on monoethylene glycol silane chemistry. This functions by forming an interstitial hydration layer which displays restricted mobility in the prevention of surface fouling. In the present work, the promising anti-thrombogenic properties of this film are examined with respect to platelet aggregation on 316L austenitic stainless steel exposed to whole human blood. Prior to exposure with blood, all major surface modification steps were examined by X-ray photoelectron spectroscopic analysis and surface free-angle measurement by contact angle goniometry. End-stage anti-thrombogenicity detection after 20 min of blood exposure at 100 s^-1, 300 s^-1, 600 s^-1, 750 s^-1, and 900 s^-1 shear rates revealed that a significant reduction (>90%) of platelet adhesion and aggregation was achieved for surface-modified steel, compared with untreated material. This result is confirmed by experiments conducted in real time for 60-minute exposure to blood at 100 s^-1, 600 s^-1, and 900 s^-1 shear rates.

Tacrolimus inhibits oral carcinogenesis through cell cycle control

Tacrolimus (TAC, FK506) is a major calcineurin inhibitor and has been commonly used in treatments of patients with organ transplants and immune diseases. Moreover, tacrolimus is recommended by the treatment guidelines for oral potentially malignant disorders (OPMDs) such as oral lichen planus (OLP). However, whether tacrolimus increases the risk of cancer remains controversial. We observed that in a 4-Nitroquinoline N-oxide (4NQO)-induced oral carcinogenesis model, tacrolimus treatment was associated with a significantly lower ratio of cancer formation (52.94% vs. 90%) and a lower proportion of Ki67 and proliferation cell nuclear antigen (PCNA) -positive cells in lesion areas (P < 0.001). Liver, kidney, and lung functions of rats and the tumor immune microenvironment of the tongue were not affected. These observations suggest that tacrolimus blocked oral carcinogenesis through epithelial cell proliferation inhibition, independent of its immunosuppressive effects. As a processing factor, tacrolimus decreased tumor formation and cell proliferation in different stages of oral squamous cell carcinoma (OSCC) progression in vivo and in vitro. Furthermore, we investigated effects on the cell cycle and expression of related proteins. Tacrolimus induced G1/S phase arrest and significantly downregulated the expression of cyclinD1, cyclinE1, and c-Myc. These results suggest that tacrolimus induces G1/S phase arrest via inhibition of cyclinD1, cyclinE1, and c-Myc expression and retards oral cell carcinogenesis in vitro and in vivo. Thus, application of tacrolimus is a safe therapeutic strategy for treating OPMDs.

Do we really understand how drug eluted from stents modulates arterial healing?

The advent of drug-eluting stents (DES) has revolutionised the treatment of coronary artery disease. These devices, coated with anti-proliferative drugs, are deployed into stenosed or occluded vessels, compressing the plaque to restore natural blood flow, whilst simultaneously combating the evolution of restenotic tissue. Since the development of the first stent, extensive research has investigated how further advancements in stent technology can improve patient outcome. Mathematical and computational modelling has featured heavily, with models focussing on structural mechanics, computational fluid dynamics, drug elution kinetics and subsequent binding within the arterial wall; often considered separately. Smooth Muscle Cell (SMC) proliferation and neointimal growth are key features of the healing process following stent deployment. However, models which depict the action of drug on these processes are lacking. In this article, we start by reviewing current models of cell growth, which predominantly emanate from cancer research, and available published data on SMC proliferation, before presenting a series of mathematical models of varying complexity to detail the action of drug on SMC growth in vitro. Our results highlight that, at least for Sodium Salicylate and Paclitaxel, the current state-of-the-art nonlinear saturable binding model is incapable of capturing the proliferative response of SMCs across a range of drug doses and exposure times. Our findings potentially have important implications on the interpretation of current computational models and their future use to optimise and control drug release from DES and drug-coated balloons.

Assessing the influence of atherosclerosis on drug coated balloon therapy using computational modelling

Interventional therapies such as drug-eluting stents (DES) and drug-coated balloons (DCB) have significantly improved the clinical outcomes of patients with coronary occlusions in recent years. Despite this marked improvement, ischemic cardiovascular disease remains the most common cause of death worldwide. To address this, research efforts are focused on improving the safety and efficacy of the next generation of these devices. However, current experimental methods are unable to account for the influence of atherosclerotic lesions on drug uptake and retention. Therefore, in this study, we used an integrated approach utilizing both in vitro and in silico methods to assess the performance of DCB therapy. This approach was validated against existing in vivo results before being used to numerically estimate the effect of the atheroma. A bolus release of sirolimus was observed with our coating matrix. This, coupled with the rapid saturation of specific and non-specific binding sites observed in our study, indicated that increasing the therapeutic dose coated onto the balloons might not necessarily result in greater uptake and/or retention. Additionally, our findings alluded to an optimal exposure time, dependent on the coating matrix, for the DCBs to be expanded against the vessel. Moreover, our findings suggest that a biphasic drug release profile might be beneficial for establishing and maintaining the saturation of bindings sites within severely occluded vessels. Ultimately, we have demonstrated that computational methods may be capable of assessing the efficacy of DCB therapy as well as predict the influence of atherosclerotic lesions on said efficacy.

Fas ligand and nitric oxide combination to control smooth muscle growth while sparing endothelium

Metallic stents cause vascular wall damage with subsequent smooth muscle cell (SMC) proliferation, neointimal hyperplasia, and treatment failure. To combat in-stent restenosis, drug-eluting stents (DES) delivering mTOR inhibitors such as sirolimus or everolimus have become standard for coronary stenting. However, the relatively non-specific action of mTOR inhibitors prevents efficient endothelium recovery and mandates dual antiplatelet therapy to prevent thrombosis. Unfortunately, long-term dual antiplatelet therapy leads to increased risk of bleeding/stroke and, paradoxically, myocardial infarction. Here, we took advantage of the fact that nitric oxide (NO) increases Fas receptors on the SMC surface. Fas forms a death-inducing complex upon binding to Fas ligand (FasL), while endothelial cells (ECs) are relatively resistant to this pathway. Selected doses of FasL and NO donor synergistically increased SMC apoptosis and inhibited SMC growth more potently than did everolimus or sirolimus, while having no significant effect on EC viability and proliferation. This differential effect was corroborated in ex vivo pig coronaries, where the neointimal formation was inhibited by the drug combination, but endothelial viability was retained. We also deployed FasL-NO donor-releasing ethylene-vinyl acetate copolymer (EVAc)-coated stents into pig coronary arteries, and cultured them in perfusion bioreactors for one week. FasL and NO donor, released from the stent coating, killed SMCs close to the stent struts, even in the presence of flow rates mimicking those of native arteries. Thus, the FasL-NO donor-combination has a potential to prevent intimal hyperplasia and in-stent restenosis, without harming endothelial restoration, and hence may be a superior drug delivery strategy for DES.

The comparison of early healing 1-month after PCI among CoCr-everolimus-eluting stent (EES), biodegradable polymer (BP)-EES and BP-sirolimus-eluting stent: Insights from OFDI and coronary angioscopy

Background

Third-generation stents with abluminal biodegradable polymer (BP) might facilitate early healing. Therefore, we compared early healing between second-generation and third-generation stents using coronary angioscopy (CAS) and optical frequency domain imaging [OFDI].

Methods

We prospectively enrolled 30 consecutive patients with stent implantation for acute coronary syndrome (cobalt‑chromium [CoCr] everolimus-eluting stent [EES] [n = 10], BP-EES [n = 10], and BP-sirolimus eluting stent [SES] [n = 10]). All patients underwent CAS and OFDI 1 month after initial percutaneous coronary intervention. On OFDI, the stent coverage (SC), thrombus, and peri-strut low intensity area (PLIA) were assessed. CAS findings were recorded for the grade of SC, grade of yellow color (YC), and grade of the thrombus (TG).

Results

On OFDI, the incidences of any thrombus at the 1-month follow-up were 70%, 80%, and 80% in the CoCr-EES, BP-EES, and BP-SES groups, respectively. The percentage of coverage was comparable among the groups (CoCr-EES 79.8 vs. BP-EES 79.9 vs. BP-SES 80.1%, P = 0.96). However, the number of struts with PLIA was numerically higher in the BP-SES group than in the CoCr-EES and BP-EES groups (46.4 ± 25.1 vs. 21.6 ± 13.2 vs. 22.0 ± 7.2%, P = 0.08). In the CoCr-EES, BP-EES, and BP-SES groups, mean grades of SC were 1.25 ± 0.5, 1.25 ± 0.5, and 0.85 ± 0.70 (P = 0.60); mean grades of YC were 0.75 ± 0.5, 0.80 ± 0.45, and 0.88 ± 0.37 (P = 0.65), and mean grades of TG were 1.00 ± 1.00, 1.20 ± 0.83, and 0.88 ± 0.64 (P = 0.75), respectively.

Conclusion

Third-generation stents are not inferior to second-generation stents regarding stent coverage. However, PLIA on OFDI was often observed with BP-SESs, indicating involvement of the fibrin component.

Long non‑coding RNA SENCR alleviates the inhibitory effects of rapamycin on human umbilical vein endothelial cells

Rapamycin (RPM) is frequently used as the drug coating in drug‑eluting stents (DESs) as it can inhibit the growth of smooth muscle cells. However, RPM also inhibits the proliferation and migration of vascular endothelial cells, and impairs reendothelialization in DES implantation. Therefore, the development of a strategy to protect vascular endothelial cells after DES implantation is of great importance. Long non‑coding RNAs (lncRNAs) metastasis‑associated lung adenocarcinoma transcript 1 (MALAT1) and smooth muscle and endothelial cell‑enriched migration/differentiation‑associated lncRNA (SENCR) are able to enhance the proliferation, migration and angiogenesis of endothelial cells, which suggests that they may have potential as antagonists of the adverse effects of RPM in DES. However, the relationship between RPM and lncRNAs in endothelial cells during the intervention is not fully understood at present. The current study investigated the role and potential mechanism of the lncRNA SENCR on the activity of human umbilical vein endothelial cells (HUVECs) after RPM treatment. The proliferation, migration, angiogenic capacity and cell cycle progression of lncRNA SENCR‑overexpressing HUVECs following RPM treatment was examined. The proliferation‑related proteins of lncRNA SENCR‑modified HUVECs were evaluated to understand the mechanism of action. LncRNA SENCR significantly alleviated the inhibition of proliferation, migration, angiogenesis and cell cycle progression of HUVECs caused by RPM by activating extracellular signal‑regulated kinase 1/2 and mammalian target of RPM. The lncRNA SENCR could alleviate the inhibitory effects of RPM on HUVECs and may be useful as a new combinative agent to avoid the disadvantages of RPM in DES implantation.

Consensus Document ANMCO/ANCE/ARCA/GICR-IACPR/GISE/SICOA: Long-term Antiplatelet Therapy in Patients with Coronary Artery Disease

Dual antiplatelet therapy (DAPT) with aspirin and a P2Y12 receptor inhibitor is the cornerstone of pharmacologic management of patients with acute coronary syndrome (ACS) and/or those receiving coronary stents. Long-term (>1 year) DAPT may further reduce the risk of stent thrombosis after a percutaneous coronary intervention (PCI) and may decrease the occurrence of non-stent-related ischaemic events in patients with ACS. Nevertheless, compared with aspirin alone, extended use of aspirin plus a P2Y12 receptor inhibitor may increase the risk of bleeding events that have been strongly linked to adverse outcomes including recurrent ischaemia, repeat hospitalisation and death. In the past years, multiple randomised trials have been published comparing the duration of DAPT after PCI and in ACS patients, investigating either a shorter or prolonged DAPT regimen. Although the current European Society of Cardiology guidelines provide a backup to individualised treatment, it appears to be difficult to identify the ideal patient profile which could safely reduce or prolong the DAPT duration in daily clinical practice. The aim of this consensus document is to review contemporary literature on optimal DAPT duration, and to guide clinicians in tailoring antiplatelet strategies in patients undergoing PCI or presenting with ACS.

Effects of Tacrolimus or Sirolimus on the adhesion of vascular wall cells: Controlled in-vitro comparison study

In drug eluting stents the cytostatic drugs Sirolimus or Tacrolimus are used to inhibit blood vessel restenosis by limiting the proliferation of smooth muscle cells. However, the cytostatic activity of both drugs was shown to be not cell specific and could also affect the stent endothelialisation, respectively. Currently, only limited in vitro data are available about the impact of Sirolimus and Tacrolimus on endothelial cell proliferation over a broad concentration range. To answer this question the following study was performed.Commercially obtained HUVEC were expanded with DMEM cell culture medium (GIBCO, Germany) supplemented with 5 vol% fetal calf serum on non-coated regular polystyrene-based 24-multiwell plates. For drug testings 2×104 cells/cm2 were seeded and grown for 24 h until 30-40% of the multiwell surfaces were covered and then exposed to Sirolimus (1.0×10-11 - 1.0×10-5 mol/l) or Tacrolimus (2.0×10-8 - 6.2×10-5 mol/l), both dissolved in DMSO. 12, 24 and 48 h after adding the drugs cell numbers per area were quantified by counting the cells in six wells with four fields of view per well, representing 0.6 mm2, using a confocal laser microscope.After 48 h of cell growth in the drug-free cell culture medium, the HUVEC number increased from 2.0×104 to 3.55×104 cells/cm2 (mean cell doubling time: 53.6 h, n = 6). At lower concentrations (≤2.0×10-6 mol/l) Tacrolimus reduced the number of adherent HUVEC significantly less than Sirolimus (p < 0.05). However, at higher concentrations (≥2.07×10-5 mol/l) the effect of Tacrolimus on the number of adherent endothelial cells was significantly greater than that of Sirolimus (p < 0.05). At the highest concentration applied (6.22×10-5 mol/l), Tacrolimus induced detachment of all HUVECs within 12 h after drug application. The number of adherent HUVEC decreased only slightly (about 9%) after Sirolimus application at the highest concentration (1.09×10-5 mol/l).These data show that in a non-flow model the cytostatic drug Tacrolimus reduced the number of adherent endothelial cells less than Sirolimus, as long as the drug concentration did not surpass 10-6 mol/l. At the limits of solubility, Sirolimus (1×10-5 mol/l) reduced the number of adherent endothelial cells less than Tacrolimus (6×10-5 mol/l), which induced detachment of endothelial cells.

Rhombic-Shaped Channel Stent with Enhanced Drug Capacity and Fatigue Life

A drug-eluting stent with rhombic-shaped drug reservoirs is proposed, aimed at providing long-term drug delivery and enhanced fatigue life. Unique rhombic-shaped reservoirs or channels on the stent struts can increase the total drug capacity and improve the stress distribution for longer fatigue life, without compromising other important clinical attributes. Our rhombic-shaped channel stent increases the total drug capacity by multiple times. Its fatigue safety factor, even with the large rhombic cutouts on the stent struts, could be 50% higher than that of the conventional drug-eluting stent. A pulsed fiber-optic laser and a series of expansions and heat treatments were used to make the first prototype of our rhombic-shaped channel stent. This new concept may open up a wide variety of new treatment options and opportunities for the medical industry in the future.

Nanomaterials for treating cardiovascular diseases: A review

Nanomaterials such as nanostructured surfaces, nanoparticles, and nanocomposites represent new viable sources for future therapeutics for cardiovascular diseases. The special properties of nanomaterials such as their intrinsic physiochemical properties, surface energy and surface topographies could actively enhance desirable cellular responses within the cardiovascular system, projecting a growing potential for clinical translation. Recent progress on nanomaterials opened up new opportunities for treating cardiovascular diseases. Successful translation of nanomaterials into cardiovascular applications requires a comprehensive understanding of both nanomaterials and biomedicine, and, thus, it is critical to stress current advancements on both sides. In this review, the authors introduced crucial fabrication techniques for promising nanomaterials for cardiovascular applications. This review highlighted the key elements to consider for their fabrication, properties and applications. The important concerns relevant to cardiovascular nanomaterials, such as cellular responses to nanomaterials and the toxicity of nanomaterials, are also discussed. This review provided an overview of necessary knowledge and key concerns on nanomaterials specific for treating cardiovascular diseases, from the perspectives of both material science and biomedicine.

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Reviewed current progress of nanomaterials and their cardiovascular applications.

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Mainly focused on nanostructured surfaces, nanoparticles and nanocomposites.

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Discussed important topics of nanomaterials for cardiovascular applications.

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Comparatively reviewed the fabrication of nanomaterials.

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Informative to researchers in the field of biomaterials and nanomaterials.

The Mammalian Target of Rapamycin and DNA methyltransferase 1 axis mediates vascular endothelial dysfunction in response to disturbed flow

The earliest atherosclerotic lesions preferentially develop in arterial regions experienced disturbed blood flow, which induces endothelial expression of pro-atherogenic genes and the subsequent endothelial dysfunction. Our previous study has demonstrated an up-regulation of DNA methyltransferase 1 (DNMT1) and a global hypermethylation in vascular endothelium subjected to disturbed flow. Here, we determined that DNMT1-specific inhibition in arterial wall ameliorates the disturbed flow-induced atherosclerosis through, at least in part, targeting cell cycle regulator cyclin A and connective tissue growth factor (CTGF). We identified the signaling pathways mediating the flow-induction of DNMT1. Inhibition of the mammalian target of rapamycin (mTOR) suppressed the DNMT1 up-regulation both in vitro and in vivo. Together, our results demonstrate that disturbed flow influences endothelial function and induces atherosclerosis in an mTOR/DNMT1-dependent manner. The conclusions obtained from this study might facilitate further evaluation of the epigenetic regulation of endothelial function during the pathological development of atherosclerosis and offer novel prevention and therapeutic targets of this disease.

Evolving Significance and Future Relevance of Anti-Angiogenic Activity of mTOR Inhibitors in Cancer Therapy

mTOR inhibitors have demonstrated remarkable anti-tumor activity in experimental models, mainly by reducing cancer cell growth and tumor angiogenesis. Their use in cancer patients as monotherapy has, however, generated only limited benefits, increasing median overall survival by only a few months. Likewise, in other targeted therapies, cancer cells develop resistance mechanisms to overcome mTOR inhibition. Hence, novel therapeutic strategies have to be designed to increase the efficacy of mTOR inhibitors in cancer. In this review, we discuss the present and future relevance of mTOR inhibitors in cancer therapy by focusing on their effects on tumor angiogenesis.

Tacrolimus therapy for dermal arteritis of the nasal philtrum refractory to surgery and anti-inflammatory therapy (doxycycline/niacinamide and topical fluocinolone) in a dog

BACKGROUND

Dermal arteritis of the nasal philtrum is a rarely reported condition commonly affecting large breed dogs.

OBJECTIVE

To describe the effective treatment of nasal philtrum arteritis with topical tacrolimus in one dog.

ANIMAL

A 9-year-old, intact male German shorthair pointer dog was presented with well-demarcated deep erythematous ulcers targeting exclusively the skin of the nasal philtrum, accompanied by frequent series of haemorrhage.

METHODS

Complete blood count, serum chemistry profile, urinalysis, histopathological examination and immunohistochemistry of skin biopsies.

RESULTS

The presence of a V-shaped ulcer with subendothelial spindle cell proliferation resulting in stenosis of dermal arteries and arterioles on histological evaluation, together with a well-demarcated deep nasal philtrum ulcer was consistent with arteritis of the nasal philtrum. Treatment was initiated with twice daily oral doxycycline and niacinamide in conjunction with topical fluocinolone cream. Over the course of two years, the lesions progressed with frequent bleeding episodes. A novel surgical approach provided deep resection of all grossly affected tissue; four months later a recurrence of fissures and occasional mild bleeding from the original site was noted and there was no improvement after another two months of oral doxycycline/niacinamide and topical fluocinolone treatment. Topical application of 0.1% tacrolimus twice daily resulted in complete healing of the ulceration and normalization of the epidermis. Over the subsequent 15 months, the dog's lesions remained in remission with topical tacrolimus application twice daily.

CONCLUSIONS AND CLINICAL IMPORTANCE

Topical tacrolimus ointment appeared effective at inducing and maintaining lesion remission in this dog with nasal philtrum arteritis.

Inhibition effect of tacrolimus and platelet-derived growth factor-BB on restenosis after vascular intimal injury

Excessive proliferation and migration of vascular smooth muscle cells(VSMCs) and delayed proliferation and migration of endothelial cells(ECs) were the main cause of restenosis after endovascular interventional therapy. Since tacrolimus has proved to be more sensitive to inhibiting VSMCs' proliferation,and platelet-derived growth factor-BB(PDGF-BB) benefitted ECs' and VSMCs' proliferation, this study was aimed to identify combined effect of tacrolimus and PDGF-BB, investigate any mechanisms underneath and demonstrate combined effect of two drugs in vivo. As the results showed we confirmed differential effect of PDGF-BB and tacrolimus on ECs and VSMCs. On the concentration level of 2-5μg/ml tacrolimus plus 10ng/ml PDGF-BB, combination of drugs could effectively promote ECs proliferation and migration, and meanwhile inhibit VSMCs proliferation and migration, and the inhibition of p-mTOR's expression within VSMCs played an important role in this differentiated effect. Raising concentration level of PDGF-BB would weaken inhibitory effect of tacrolimus on both kinds of cell. For injured intima, the mix solution of two drugs could promote intima healing and suppress excessive intimal hyperplasia.

Collagen-binding nanoparticles for extracellular anti-inflammatory peptide delivery decrease platelet activation, promote endothelial migration, and suppress inflammation

Peripheral artery disease is an atherosclerotic stenosis in the peripheral vasculature that is typically treated via percutaneous transluminal angioplasty. Deployment of the angioplasty balloon damages the endothelial layer, exposing the underlying collagen and allowing for the binding and activation of circulating platelets which initiate an inflammatory cascade leading to eventual restenosis. Here, we report on collagen-binding sulfated poly(N-isopropylacrylamide) nanoparticles that are able to target to the denuded endothelium. Once bound, these nanoparticles present a barrier that reduces cellular and platelet adhesion to the collagenous surface by 67% in whole blood and 59% in platelet-rich plasma under biologically relevant shear rates. In vitro studies indicate that the collagen-binding nanoparticles are able to load and release therapeutic quantities of anti-inflammatory peptides, with the particles reducing inflammation in endothelial and smooth muscle cells by 30% and 40% respectively. Once bound to collagen, the nanoparticles increased endothelial migration while avoiding uptake by smooth muscle cells, indicating that they may promote regeneration of the damaged endothelium while remaining anchored to the collagenous matrix and locally releasing anti-inflammatory peptides into the injured area. Combined, these collagen-binding nanoparticles have the potential to reduce inflammation, and the subsequent restenosis, while simultaneously promoting endothelial regeneration following balloon angioplasty.

STATEMENT OF SIGNIFICANCE

In this manuscript, we present our work on the development and characterization of a novel temperature sensitive collagen-binding nanoparticle system. We demonstrate that when bound to a collagenous matrix, the nanoparticles are able to promote endothelial migration while avoiding cellular uptake. We also show that the nanoparticles are able to reduce inflammation via the release of anti-inflammatory peptides which, when combined with its ability to inhibit platelet binding, could lead to reduced intimal hyperplasia following balloon angioplasty. The drug delivery platform presented represents a unique dual therapy biomaterial wherein the nanoparticle itself plays a crucial role in the system's overall therapeutic potential while simultaneously releasing anti-inflammatory peptides.

Rapamycin-loaded nanoporous α-Fe2O3 as an endothelial favorable and thromboresistant coating for biodegradable drug-eluting Fe stent applications

Iron and its alloys can be potentially employed to fabricate advanced degradable cardiovascular stents due to their excellent mechanical and biocompatibility properties. However, their clinical applications are hindered by their inherent slow degradation rate, the formation of thrombosis and in-stent restenosis. In this study, vertically oriented and orderly arranged α-Fe₂O₃ (hematite) nanotubes with diameters ranging from 30 nm to 70 nm were successfully fabricated on iron substrates using an anodic oxidation approach. These nanotubular coatings acted as drug depots by being loaded with anti-proliferation drug rapamycin to accelerate the re-endothelialization process and being coated by PLGA through a simple spin-coating process to control the drug release rate. The static immersion test showed that the 50 nm-Fe₂O₃ nanotube arrays displayed a faster corrosion rate than pristine Fe, and the PLGA coating effectively reduced the initial burst release of the loaded drug and extended the rapamycin release time to 30 days. The CCK-8 assay and immunofluorescence staining analysis results indicated that the endothelial cells (ECs) on the coated samples showed higher cell viability than the vascular smooth muscle cells (VSMCs), with possible outcomes to promote re-endothelialization and decrease VSMC proliferation. In addition, the surface modified iron exhibited very good hemocompatibility. The current findings suggested that fabricating rapamycin-loaded and PLGA coated Fe₂O₃ nanotubes on a pure iron surface may be a promising method to improve the corrosion rate and accelerate the re-endothelialization of the iron for biodegradable cardiovascular stent applications.

Angiogenic Factors Correlate with T Cell Immune Reconstitution and Clinical Outcomes after Double-Unit Umbilical Cord Blood Transplantation in Adults

Umbilical cord blood (UCB) is a valuable graft source for allogeneic hematopoietic stem cell transplantation (HSCT) in patients who lack adult donors. UCB transplantation (UCBT) in adults results in delayed immune reconstitution, leading to high infection-related morbidity and mortality. Angiogenic factors and markers of endothelial dysfunction have biologic and prognostic significance in conventional HSCT, but their role in UCBT has not been investigated. Furthermore, the interplay between angiogenesis and immune reconstitution has not been studied. Here we examined whether angiogenic cytokines, angiopoietin-1 (ANG-1) and vascular endothelial growth factor (VEGF), or markers of endothelial injury, thrombomodulin (TM) and angiopoietin-2 (ANG-2), associate with thymic regeneration as determined by T cell receptor excision circle (TREC) values and recovery of T cell subsets, as well as clinical outcomes in adult recipients of UCBT. We found that plasma levels of ANG-1 significantly correlated with the reconstitution of naive CD4+CD45RA+ and CD8+CD45RA+ T cell subsets, whereas plasma levels of VEGF displayed a positive correlation with CD4+CD45RO+ T cells and regulatory T cells and a weak correlation with TRECs. Assessment of TM and ANG-2 revealed a strong inverse correlation of both factors with naive T cells and TRECs. The angiogenic capacity of each patient's plasma, as determined by an in vitro angiogenesis assay, positively correlated with VEGF levels and with reconstitution of CD4+ T cell subsets. Higher VEGF levels were associated with worse progression-free survival and higher risk of relapse, whereas higher levels of TM were associated with chronic graft-versus-host disease and nonrelapse mortality. Thus, angiogenic factors may serve as valuable markers associated with T cell reconstitution and clinical outcomes after UCBT.

Drug loaded nanoparticle coating on totally bioresorbable PLLA stents to prevent in-stent restenosis

Biodegradable polymer poly (dl-lactide) (PDLLA) has been used as drug coating material for drug-eluting stents due to its excellent biocompatibility and sustained drug release ability. However, the uniform thin layer drug eluting coating on a stent not only inhibits the blood vessel's smooth muscle cell overgrowth but also delay the endotheliation process which is often associated with the occurrence of acute thrombosis. Therefore, in this study, we developed a novel coating method using PDLLA nanoparticles (NPs) as a coating to overcome this issue. The average 300 nm sized sirolimus-loaded PDLLA nanoparticles were prepared by a conventional emulsion solvent evaporation method. A low temperature plasma polymerization technology to graft hydrophilic polymers on to poly (l-lactide) stent was used to increase the surface coating efficiency of nanoparticles on the stent. Results showed that sirolimus-loaded nanoparticles can be successfully coated on to the stents with sustained drug release properties. In vitro cell culture study showed the drug loaded nanoparticle coating effectively inhibited the proliferation of smooth muscle cells while still allowed a faster proliferation of endothelial cells, suggesting that the new NP coated bioresorbable stents have the potential to reduce both the occurrence of in-stent restenosis and acute thrombosis. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 88-95, 2018.

Paclitaxel-eluting stents versus sirolimus-eluting stents in patients with diabetes mellitus undergoing percutaneous coronary intervention: a systematic review and meta-analysis of randomized controlled trials

Uncertainties exist with regard to the efficacy of paclitaxel-eluting stents (PES) versus sirolimus-eluting stents (SES) in diabetes patients undergoing percutaneous coronary intervention (PCI). We performed a meta-analysis of randomized controlled trials (RCTs) to investigate the outcome of PES versus SES in diabetes patients undergoing PCI. A literature search was started, and we found all studies conducted from 2005 to 2016. We systematically searched the literature through the MEDLINE, Cochrane library, and EMBASE. Quality assessments were evaluated with the Jadad scale. Data were extracted considering the characteristics of efficacy and the safety of the designs. 12 RCTs satisfy the inclusion criteria. There is a significant decrease of target lesion revascularization (TLR) (MD = 0.65, 95 % CI = 0.42-1.00, P = 0.05) in a year and more than 1 year (MD = 0.54, 95 % CI = 0.37-0.78, P = 0.00010). A significant decrease of target vessel revascularization (TVR) in more than 1 year is (MD = 0.62, 95 % CI = 0.47-0.81, P = 0.0004). A significant decrease of major adverse cardiac events (MACE) in more than 1 year is (MD = 0.73, 95 % CI = 0.60-0.89, P = 0.002). Nevertheless, there is no significant difference in mortality (MD = 0.85, 95 % CI = 0.66-1.11, P = 0.24), stent thrombosis (ST) (MD = 0.65, 95 % CI = 0.35-1.21, P = 0.18), or myocardial infarction (MD = 1.04, 95 % CI = 0.71-1.51, P = 0.84). SES may be more significant in decreasing TLR, TVR, and MACE than PES without significantly increasing mortality, ST and MI in diabetes patients.

Prevention of Collagen-Induced Platelet Binding and Activation by Thermosensitive Nanoparticles

Peripheral artery disease is an atherosclerotic occlusion in the peripheral vasculature that is typically treated via percutaneous transluminal angioplasty. Unfortunately, deployment of the angioplasty balloon damages the endothelial layer, exposing the underlying collagen and allowing for the binding and activation of circulating platelets, which initiate an inflammatory cascade leading to eventual restenosis. Here, we report on the development of poly(NIPAm-MBA-AMPS-AAc) nanoparticles that have a collagen I-binding peptide crosslinked to their surface allowing them to bind to exposed collagen. Once bound, these particles mask the exposed collagen from circulating platelets, effectively reducing collagen-mediated platelet activation. Using collagen I-coated plates, we demonstrate that these particles are able to bind to collagen at concentrations above 0.5 mg/mL. Once bound, these particles inhibit collagen-mediated platelet activation by over 60%. Using light scattering and zeta potential measurements, we investigated the potential of the nanoparticles as a drug delivery platform. We have verified that the collagen-binding nanoparticles retain the temperature sensitivity common to poly(NIPAm)-based nanoparticles while remaining colloidally stable in aqueous environments. We also demonstrate that they are able to passively load and release anti-inflammatory cell penetrating peptides. Combined, we have developed a collagen-binding nanoparticle that has dual therapy potential, preventing collagen-mediated platelet activation while delivering water-soluble therapeutics directly to the damaged area.

Optimization of Drug Delivery by Drug-Eluting Stents

Drug-eluting stents (DES), which release anti-proliferative drugs into the arterial wall in a controlled manner, have drastically reduced the rate of in-stent restenosis and revolutionized the treatment of atherosclerosis. However, late stent thrombosis remains a safety concern in DES, mainly due to delayed healing of the endothelial wound inflicted during DES implantation. We present a framework to optimize DES design such that restenosis is inhibited without affecting the endothelial healing process. To this end, we have developed a computational model of fluid flow and drug transport in stented arteries and have used this model to establish a metric for quantifying DES performance. The model takes into account the multi-layered structure of the arterial wall and incorporates a reversible binding model to describe drug interaction with the cells of the arterial wall. The model is coupled to a novel optimization algorithm that allows identification of optimal DES designs. We show that optimizing the period of drug release from DES and the initial drug concentration within the coating has a drastic effect on DES performance. Paclitaxel-eluting stents perform optimally by releasing their drug either very rapidly (within a few hours) or very slowly (over periods of several months up to one year) at concentrations considerably lower than current DES. In contrast, sirolimus-eluting stents perform optimally only when drug release is slow. The results offer explanations for recent trends in the development of DES and demonstrate the potential for large improvements in DES design relative to the current state of commercial devices.

Decorin mimic promotes endothelial cell health in endothelial monolayers and endothelial-smooth muscle co-cultures

Non-specific cytotoxins, including paclitaxel and sirolimus analogues, currently utilized as anti-restenotic therapeutics, affect not only smooth muscle cells (SMCs) but also neighbouring vascular endothelial cells (ECs). These drugs inhibit the formation of an intact endothelium following vessel injury, thus emphasizing the critical need for new candidate therapeutics. Utilizing our in vitro models, including EC monolayers and both hyperplastic and quiescent EC-SMC co-cultures, we investigated the ability of DS-SILY₂₀ , a decorin mimic, to promote EC health. DS-SILY₂₀ increased EC proliferation and migration by 1.5- and 2-fold, respectively, which corresponded to increased phosphorylation of ERK-1/2. Interestingly, IL-6 secretion and the production of both E-selectin and P-selectin were reduced in the presence of 10 μm DS-SILY₂₀ , even in the presence of the potent pro-inflammatory cytokine platelet-derived growth factor (PDGF). In hyperplastic and quiescent EC-SMC co-cultures, DS-SILY₂₀ treatment reduced the secretion of IFNγ, IL-1β, IL-6 and TNFα, corresponding to a 23% decrease in p38 phosphorylation. E-selectin and P-selectin expression was further reduced following DS-SILY₂₀ treatment in both co-culture models. These results indicate that DS-SILY₂₀ promotes EC health and that this decorin mimic could serve as a potential therapeutic to promote vessel healing following percutaneous coronary intervention (PCI). Copyright © 2015 John Wiley & Sons, Ltd.

Effect of imatinib mesylate and rapamycin on the preformed intimal hyperplasia in rat carotid injury model

PURPOSE

Intimal hyperplasia (IH) is the main cause of restenosis or occlusion after vascular procedures. Imatinib mesylate and rapamycin are known to prevent IH. The purpose of this study was to evaluate the effect of these drugs on the regression of preformed IH in rat carotid injury model.

METHODS

IH was established in rat carotid arteries using a balloon catheter. The drug effects were assessed in vitro on proliferation, migration, and apoptosis of vascular smooth muscle cells (VSMC) in the neointima. And in vivo studies were carried out in 4 groups: imatinib, rapamycin, combined, and no medication. After 2-week oral medication, morphometric analysis evaluated the number and density of neointimal cells, intima-to-media (I/M) ratio and cross-sectional area. Cell proliferation, apoptosis, and collagen changes were also investigated by immunohistochemical staining (IHCS).

RESULTS

Imatinib and rapamycin significantly inhibited VSMC proliferation and migration, and promoted apoptosis in vitro. In morphometric analysis, the number and density of neointimal cells decreased significantly in all medication groups compared with control group (P < 0.01). However, there was no significant difference in neointimal cross-sectional area and I/M ratio among groups. In IHCS, imatinib and rapamycin inhibited neointimal cell proliferation significantly. However, there was no significant change in cell apoptosis and collagen composition.

CONCLUSION

Combined treatment of with imatinib and rapamycin induced reduction of cell mass in preformed intimal hyperplasia, but failed to induce regression of intimal mass in this short-term medication study. Further studies will be needed with additional strategies of inducing lysis of the extracellular matrix.

Tacrolimus prevents laryngotracheal stenosis in an acute-injury rat model

OBJECTIVES/HYPOTHESIS

Acquired laryngotracheal stenosis is a challenging problem for otolaryngologists. Several studies suggest tacrolimus may inhibit post-transplant airway stenosis that occurs with coronary drug-eluting stents. The objective of the present study was to determine whether tacrolimus modulates wound healing of the airway mucosa and prevents laryngotracheal stenosis in an acute injury animal model.

STUDY DESIGN

Basic science.

METHODS

The laryngotracheal mucosa of rats was scraped with a nylon brush through the tracheostoma. Tacrolimus (0.2 mg/kg or 1.0 mg/kg) was systemically administered intramuscularly for 5 days. Nine days after scraping, the pathological changes and the degree of stenosis were assessed by hematoxylin and eosin staining or by immunohistochemical staining for nuclear factor of activated T cell and interleukin 2.

RESULTS

Lumen stenosis resulted from hyperplasia of the airway epithelium and a thickened submucosal layer with extensive fibrosis, angiogenesis, and collagen deposition. There was a significant preventive effect on airway stenosis at the tracheal and cricoid levels in the low-dose (0.2 mg/kg) tacrolimus-treated animals, compared to the untreated animals (P < .05). This effect was insignificant with treatment by high-dose tacrolimus (1.0 mg/kg). Immunohistochemistry showed that, after tacrolimus treatment, the expressions of nuclear factor of activated T cell and interleukin 2 were downregulated in submucosal fibroblasts, neovascular cells, and glandular cells.

CONCLUSIONS

This study suggests that low-dose systemic tacrolimus has a preventive effect on laryngotracheal stenosis by inhibiting the activation of immune cells in the injured airway mucosa via the calcineurin/nuclear factor of activated T cell/interleukin 2 pathway.

LEVEL OF EVIDENCE

NA.

Myocardial drug distribution generated from local epicardial application: potential impact of cardiac capillary perfusion in a swine model using epinephrine

Prior studies in small mammals have shown that local epicardial application of inotropic compounds drives myocardial contractility without systemic side effects. Myocardial capillary blood flow, however, may be more significant in larger species than in small animals. We hypothesized that bulk perfusion in capillary beds of the large mammalian heart not only enhances drug distribution after local release, but also clears more drug from the tissue target than in small animals. Epicardial (EC) drug releasing systems were used to apply epinephrine to the anterior surface of the left heart of swine in either point-sourced or distributed configurations. Following local application or intravenous (IV) infusion at the same dose rates, hemodynamic responses, epinephrine levels in the coronary sinus and systemic circulation, and drug deposition across the ventricular wall, around the circumference and down the axis, were measured. EC delivery via point-source release generated transmural epinephrine gradients directly beneath the site of application extending into the middle third of the myocardial thickness. Gradients in drug deposition were also observed down the length of the heart and around the circumference toward the lateral wall, but not the interventricular septum. These gradients extended further than might be predicted from simple diffusion. The circumferential distribution following local epinephrine delivery from a distributed source to the entire anterior wall drove drug toward the inferior wall, further than with point-source release, but again, not to the septum. This augmented drug distribution away from the release source, down the axis of the left ventricle, and selectively toward the left heart follows the direction of capillary perfusion away from the anterior descending and circumflex arteries, suggesting a role for the coronary circulation in determining local drug deposition and clearance. The dominant role of the coronary vasculature is further suggested by the elevated drug levels in the coronary sinus effluent. Indeed, plasma levels, hemodynamic responses, and myocardial deposition remote from the point of release were similar following local EC or IV delivery. Therefore, the coronary vasculature shapes the pharmacokinetics of local myocardial delivery of small catecholamine drugs in large animal models. Optimal design of epicardial drug delivery systems must consider the underlying bulk capillary perfusion currents within the tissue to deliver drug to tissue targets and may favor therapeutic molecules with better potential retention in myocardial tissue.

Macromolecular approaches to prevent thrombosis and intimal hyperplasia following percutaneous coronary intervention

Cardiovascular disease remains one of the largest contributors to death worldwide. Improvements in cardiovascular technology leading to the current generation of drug-eluting stents, bioresorbable stents, and drug-eluting balloons, coupled with advances in antirestenotic therapeutics developed by pharmaceutical community, have had a profound impact on quality of life and longevity. However, these procedures and devices contribute to both short- and long-term complications. Thus, room for improvement and development of new, alternative strategies exists. Two major approaches have been investigated to improve outcomes following percutaneous coronary intervention including perivascular delivery and luminal paving. For both approaches, polymers play a major role as controlled research vehicles, carriers for cells, and antithrombotic coatings. With improvements in catheter delivery devices and increases in our understanding of the biology of healthy and diseased vessels, the time is ripe for development of novel macromolecular coatings that can protect the vessel lumen following balloon angioplasty and promote healthy vascular healing.

Concentration-dependent differential effects of udenafil on viability, proliferation, and apoptosis in vascular endothelial and smooth muscle cells

OBJECTIVES

Local strategies directed against vascular smooth muscle cell (VSMC) proliferation, such as drug-eluting stents (DES), reduce the occurrence of restenosis. However, these approaches may also inhibit vascular endothelial cell (VEC) proliferation and impair reendothelialization, and hence, increase susceptibility to late thrombosis. In this study we examined the differential effects of various concentrations of the type 5 phosphodiesterase (PDE-5) inhibitor, udenafil, on viability, proliferation, and apoptosis of VEC and VSMC, in order to identify the optimal concentration of udenafil that minimizes inhibition of VEC survival and growth, and maximizes inhibition of VSMC survival and growth.

MATERIALS AND METHODS

VEC from human umbilical veins and VSMC from human aorta were exposed to various concentrations of udenafil (1, 10, and 100 μmol/l and 1 mmol/l) for 24 h, and its effects on cell viability, proliferation, and apoptosis were studied using 5-bromo-2'- deoxyuridine (BrdU), methylthiazoletetrazolium (MTT) assay, trypan blue dye exclusion, and flow cytometry.

RESULTS

Udenafil inhibited the survival and growth of VEC and VSMC in a concentration-dependent manner over a range of concentrations. At 100 μmol/l, udenafil, inhibited VEC proliferation significantly less than VSMC proliferation (P < 0.05), and could significantly induce VEC apoptosis less than VSMC apoptosis (P < 0.05).

CONCLUSIONS

Udenafil has a differential effect on survival and growth in VEC and VSMC. The maximal differential effect, with minimal inhibition of VEC and maximal inhibition of VSMC, occurs at 100 μmol/l. This characteristic suggests that udenafil is a promising agent for use in DES.

Drug-eluting metallic stents in urology

Drugeluting metal stents (DESs) have been extensively used in coronary and vascular disease. This type of stents has been proven to provide significantly lower restenosis rates due to the reduction of neo-intimal hyperplasia in comparison to the traditionally used bare metal stents (BMSs). The latter stents have been evaluated for more than a decade in urological practice in an attempt to provide permanent relief of urethral or ureteral obstruction. Although the initial results were promising, long-term experience revealed significant complications, which are mainly attributed to stent-related hyperplastic reaction compromising stent patency. The favorable experience of vascular DESs led to the application of DESs in both the urethra and ureter of animal models. These experimental results demonstrated a reduction of hyperplastic reaction of DESs in comparison to BMSs. Nevertheless, clinical data are currently not available. Considering the fact that DESs are under continuous development, the use of DESs in urology holds promise for the future and seems to be an intriguing field.

PI3K/p110α inhibition selectively interferes with arterial thrombosis and neointima formation, but not re-endothelialization: potential implications for drug-eluting stent design

BACKGROUND

Impaired re-endothelialization and stent thrombosis are a safety concern associated with drug-eluting stents (DES). PI3K/p110α controls cellular wound healing pathways, thereby representing an emerging drug target to modulate vascular homoeostasis after injury.

METHODS AND RESULTS

PI3K/p110α was inhibited by treatment with the small molecule inhibitor PIK75 or a specific siRNA. Arterial thrombosis, neointima formation, and re-endothelialization were studied in a murine carotid artery injury model. Proliferation and migration of human vascular smooth muscle cell (VSMC) and endothelial cell (EC) were assessed by cell number and Boyden chamber, respectively. Endothelial senescence was evaluated by the β-galactosidase assay, endothelial dysfunction by organ chambers for isometric tension. Arterial thrombus formation was delayed in mice treated with PIK75 when compared with controls. PIK75 impaired arterial expression and activity of tissue factor (TF) and plasminogen activator inhibitor-1 (PAI-1); in contrast, plasma clotting and platelet aggregation did not differ. In VSMC and EC, PIK75 inhibited expression and activity of TF and PAI-1. These effects occurred at the transcriptional level via the RhoA signalling cascade and the transcription factor NFkB. Furthermore, inhibition of PI3K/p110α with PIK75 or a specific siRNA selectively impaired proliferation and migration of VSMC while sparing EC completely. Treatment with PIK75 did not induce endothelial senescence nor inhibit endothelium-dependent relaxations. In line with this observation, treatment with PIK75 selectively inhibited neointima formation without affecting re-endothelialization following vascular injury.

CONCLUSION

Following vascular injury, PI3K/p110α inhibition selectively interferes with arterial thrombosis and neointima formation, but not re-endothelialization. Hence, PI3K/p110α represents an attractive new target in DES design.

Transjugular intrahepatic portosystemic shunts in liver transplant recipients

The insertion of a transjugular intrahepatic portosystemic shunt (TIPS) is a minimally invasive procedure used to relieve the signs and symptoms of portal hypertension in patients with liver disease. The most common indications for placement are refractory ascites and variceal hemorrhage. In properly selected candidates, TIPS placement can serve as a bridge to liver transplantation. Expertise in TIPS placement after transplantation has significantly increased, which has allowed the procedure to become a viable option for retransplant candidates suffering the consequences of recurrent portal hypertension due to portal vein thrombosis, recurrent liver disease, or hepatic venous outflow obstruction (HVOO). However, TIPSs in liver transplant recipients are associated with a lower clinical response rate and a higher rate of complications in comparison with patients with native liver disease, and they are, therefore, generally reserved for patients with a Model for End-Stage Liver Disease (MELD) score ≤ 15 and ≤ 12 in patients with HCV. The role of TIPS placement in nonliver transplant recipients has been well studied in large trials, and it translates well into clinical applicability to candidates for orthotopic liver transplantation (OLT). However, the experience with OLT recipients is heterogeneous and restricted to small series. Thus, we focus here on reviewing the current literature and discussing the proper use of TIPSs in liver transplant recipients.

Exercise limitation following transplantation

Organ transplantation is one of the medical miracles or the 20th century. It has the capacity to substantially improve exercise performance and quality of life in patients who are severely limited with chronic organ failure. We focus on the most commonly performed solid-organ transplants and describe peak exercise performance following recovery from transplantation. Across all of the common transplants, evaluated significant reduction in VO2peak is seen (typically renal and liver 65%-80% with heart and/or lung 50%-60% of predicted). Those with the lowest VO2peak pretransplant have the lowest VO2peak posttransplant. Overall very few patients have a VO2peak in the normal range. Investigation of the cause of the reduction of VO2peak has identified many factors pre- and posttransplant that may contribute. These include organ-specific factors in the otherwise well-functioning allograft (e.g., chronotropic incompetence in heart transplantation) as well as allograft dysfunction itself (e.g., chronic lung allograft dysfunction). However, looking across all transplants, a pattern emerges. A low muscle mass with qualitative change in large exercising skeletal muscle groups is seen pretransplant. Many factor posttransplant aggravate these changes or prevent them recovering, especially calcineurin antagonist drugs which are key immunosuppressing agents. This results in the reduction of VO2peak despite restoration of near normal function of the initially failing organ system. As such organ transplantation has provided an experiment of nature that has focused our attention on an important confounder of chronic organ failure-skeletal muscle dysfunction.

Decorin mimic inhibits vascular smooth muscle proliferation and migration

Over the past 10 years, the number of percutaneous coronary intervention procedures performed in the United States increased by 33%; however, restenosis, which inhibits complete functional recovery of the vessel wall, complicates this procedure. A wide range of anti-restenotic therapeutics have been developed, although many elicit non-specific effects that compromise vessel healing. Drawing inspiration from biologically-relevant molecules, our lab developed a mimic of the natural proteoglycan decorin, termed DS-SILY, which can mask exposed collagen and thereby effectively decrease platelet activation, thus contributing to suppression of vascular intimal hyperplasia. Here, we characterize the effects of DS-SILY on both proliferative and quiescent human SMCs to evaluate the potential impact of DS-SILY-SMC interaction on restenosis, and further characterize in vivo platelet interactions. DS-SILY decreased proliferative SMC proliferation and pro-inflammatory cytokine secretion in vitro in a concentration dependent manner as compared to untreated controls. The addition of DS-SILY to in vitro SMC cultures decreased SMC migration and protein synthesis by 95% and 37%, respectively. Furthermore, DS-SILY decreased platelet activation, as well as reduced neointimal hyperplasia by 60%, in vivo using Ossabaw swine. These results indicate that DS-SILY demonstrates multiple biological activities that may all synergistically contribute to an improved treatment paradigm for balloon angioplasty.

In vitro study of dual drug-eluting stents with locally focused sirolimus and atorvastatin release

Within the context of novel stent designs we developed a dual drug-eluting stent (DDES) with an abluminally focussed release of the potent anti-proliferative drug sirolimus and a luminally focussed release of atorvastatin with stabilizing effect on atherosclerotic deposits and stimulating impact on endothelial function, both from biodegradable poly(L-lactide)-based stent coatings. With this concept we aim at simultaneous inhibition of in-stent restenosis as a result of disproportionally increased smooth muscle cell proliferation and migration as well as thrombosis due to failed or incomplete endothelialisation. The especially adapted spray-coating processes allowed the formation of smooth form-fit polymer coatings at the abluminal and luminal side with 70% respectively 90% of the drug/polymer solution being deposited at the intended stent surface. The impacts of tempering, sterilization, and layer composition on drug release are thoroughly discussed making use of a semi-empirical model. While tempering at 80 °C seems to be necessary for the achievement of adequate and sustained drug release, the coating sequence for DDES should be rather abluminal-luminal than luminal-abluminal, as reduction of the amount of sirolimus eluted luminally could then potentially minimize the provocation of endothelial dysfunction. In vitro proliferation and viability assays with smooth muscle and endothelial cells underline the high potential of the developed DDES.

Water soluble polymer films for intravascular drug delivery of antithrombotic biomolecules

Over the past 10 years, the number of percutaneous coronary intervention (PCI) procedures performed in the United States has increased by 33%; however, restenosis, which inhibits complete functional recovery of the vessel wall, remains a complication of this procedure. To traverse the complications associated with PCI, the investigation of therapeutic delivery has become an integral topic in modern research. One such therapeutic, a mimic of the proteoglycan decorin, termed DS-SILY, can mask exposed collagen and thereby effectively decrease platelet activation, has recently been developed by our lab. Drawing inspiration from coating technologies developed by the pharmaceutical industry, a fast-dissolving polymer film has been developed to deliver active therapeutic agents from a balloon catheter during PCI. This research investigates the release of DS-SILY from fast-dissolving polymer films composed of poly(vinyl alcohol) (PVA) and poly(ethylene glycol) (PEG). Thin, uniform polymer films were produced via spin coating technique. The dissolution speed of the polymer films was found to be dependent on the concentration of polymer solution, where at least 65% of the films were shown to dissolve into nanometer sized polymer fragments within 2 min. DS-SILY, up to 6.26 μg/cm(2), was loaded into the films and functional release of the mimic was demonstrated by its successful binding to collagen upon release. Furthermore, DS-SILY released from films resulted in increased platelet inhibition. These results indicate that use of fast-dissolving polymer films allow for the successful release of biomolecules and further investigation of their use for localized drug delivery during PCI procedures is warranted.

Antirestenotic mechanisms of everolimus on human coronary artery smooth muscle cells: inhibition of human coronary artery smooth muscle cell proliferation, but not migration

Everolimus, a pharmaceutical component of drug-eluting stents, inhibits coronary vessel restenosis, but the antirestenotic mechanisms of action remain unclear. Here, we describe the effects of everolimus on key contributors to vessel restenosis, smooth muscle cell proliferation, and migration. In a dose-dependent fashion, everolimus reduced human coronary artery smooth muscle cell (HCASMC) proliferation without toxicity in a bimodal fashion, with accentuated potency occurring at 10 μM. Everolimus arrested the majority of HCASMCs in G1-phase, whereas it reduced the fraction of cells in S-phase at doses that inhibited DNA synthesis (bromodeoxyuridine incorporation). Consistent with this, Western blotting demonstrated that everolimus reduced activation and expression of G1-phase cell cycle progression factors, including p70S6K and cyclin D, respectively, decreased levels of proliferating cell nuclear antigen, and attenuated growth factor/serum-induced phosphorylation of the cell cycle phase transition intermediate, retinoblastoma protein. Everolimus did not, however, affect HCASMC migration. These observations suggest that everolimus acts as an antiproliferative, but not antimigratory, compound to account for at least some of the clinical efficacy exhibited by this drug as an antirestenotic agent. Moreover, everolimus-induced inhibition of the mammalian target of rapamycin complex 1 and regulation of cyclin-mediated cell cycle progression actions likely account for the antiproliferative effects of this compound on HCASMCs.