Current therapies and investigational drugs for peripheral arterial disease

Racial and ethnic representation in peripheral artery disease randomized clinical trials

Clinical trial enrollment provides various benefits to study participants including early access to novel therapies that may potentially alter the trajectory of disease states. Trial sponsors benefit from enrolling demographically diverse trial participants enabling the trial outcomes to be generalizable to a larger proportion of the community at large. Despite these and other well-documented benefits, clinical trial enrollment for Black and Hispanic Americans as well as women continues to be low. Specific disease states such as peripheral artery disease (PAD) have a higher prevalence and clinical outcomes are relatively worse in Black Americans compared with non-Hispanic white Americans. The recruitment process for PAD clinical trials can be costly and challenging and usually comes at the expense of representation. Participant willingness and trust, engagement, and socioeconomic status play essential roles in the representation of under-represented minority (URM) groups. Despite the contrary belief, URM groups such as Blacks and Hispanics are just as willing to participate in a clinical trial as non-Hispanic Whites. However, financial burdens, cultural barriers, and inadequate health literacy and education may impede URMs' access to clinical trials and medical care. Clinical trials' enrollment sites often pose transportation barriers and challenges that negatively impact creating a diverse study population. Lack of diversity among a trial population can stem from the stakeholder level, where corporate sponsors of academic readers do not consider diversity in clinical trials a priority due to false cost-benefit assumptions. The funding source may also impact the racial reporting or the results of a given trial. Industry-based trials have always been criticized for over-representing non-Hispanic White populations, driven by the desire to reach high completion rates with minimum financial burdens. Real efforts are warranted to ensure adequate minorities' representation in the PAD clinical trials and to the process toward the ultimate goal of developing more durable and effective PAD treatments that fit the needs of real-world populations.

Effects of L-Ornithine-L-Aspartate on Angiogenesis and Perfusion in Subacute Hind Limb Ischemia: Preliminary Study

The current treatment options for peripheral arterial disease (PAD) are limited due to a lack of significant high-level evidence to inform clinical decisions and unfavorable outcomes in terms of cost-effectiveness and amputation rates. In order to suggest the use of the commercially available L-Ornithine-L-Aspartate (LOLA) for treating PAD, we induced hind limb ischemia (HLI) by unilaterally ligating the femoral artery in a rat model. The rats were randomly divided into three groups, with seven rats assigned to each group: group 1 (control), group 2 (sorbitol), and group 3 (LOLA). Intraperitoneal injections were administered five times on post-operative days (PODs) 3, 5, 7, 10, and 12. Perfusion imaging was conducted on PODs 7 and 14 and compared to pre-operative perfusion imaging. Immunohistochemistry staining and Western blotting were performed after the final perfusion imaging. Group 3 showed a significant increase in perfusion, high CD31-positive capillary lumen density, and substantial overexpression of VEGF in the ischemic limb during the subacute phase of HLI. In conclusion, this study provides the first documented evidence of angiogenesis and perfusion recovery in the subacute phase of the HLI model following the administration of LOLA. With LOLA readily available on the commercial market, the implementation of LOLA treatment for PAD in humans can be expedited compared to other therapies still in the developmental stage.

Exercise therapy for chronic symptomatic peripheral artery disease

All guidelines worldwide strongly recommend exercise as a pillar of the management of patients affected by lower extremity peripheral artery disease (PAD). Exercise therapy in this setting presents different modalities, and a structured programme provides optimal results. This clinical consensus paper is intended for clinicians to promote and assist for the set-up of comprehensive exercise programmes to best advice in patients with symptomatic chronic PAD. Different exercise training protocols specific for patients with PAD are presented. Data on patient assessment and outcome measures are narratively described based on the current best evidence. The document ends by highlighting disparities in access to supervised exercise programmes across Europe and the series of gaps for evidence requiring further research.

Exercise therapy for chronic symptomatic peripheral artery disease

All guidelines worldwide strongly recommend exercise as a pillar in the management of patients affected by lower extremity peripheral artery disease (PAD). Exercise therapy in this setting presents different modalities, and a structured programme provides optimal results. This clinical consensus paper is intended to promote and assist the set up of comprehensive exercise programmes and best advice for patients with symptomatic chronic PAD. Different exercise training protocols specific for patients with PAD are presented. Data on patient assessment and outcome measures are described based on the current best evidence. The document ends by highlighting supervised exercise programme access disparities across Europe and the evidence gaps requiring further research.

Exercise Therapy for Chronic Symptomatic Peripheral Artery Disease: A Clinical Consensus Document of the European Society of Cardiology Working Group on Aorta and Peripheral Vascular Diseases in Collaboration With the European Society of Vascular Medicine and the European Society for Vascular Surgery

All guidelines worldwide strongly recommend exercise as a pillar in the management of patients affected by lower extremity peripheral artery disease (PAD). Exercise therapy in this setting presents different modalities, and a structured programme provides optimal results. This clinical consensus paper is intended to promote and assist the set up of comprehensive exercise programmes and best advice for patients with symptomatic chronic PAD. Different exercise training protocols specific for patients with PAD are presented. Data on patient assessment and outcome measures are described based on the current best evidence. The document ends by highlighting supervised exercise programme access disparities across Europe and the evidence gaps requiring further research.

Angiogenesis-related proteins as biomarkers for peripheral artery disease

Background

Angiogenesis plays an important role in peripheral artery disease (PAD) and angiogenesis-related proteins may act as prognostic biomarkers. This study assesses the potential for angiogenesis-related proteins to predict adverse events associated with PAD.

Methods

This was a case-control study. Patients with PAD (n = 250) and without PAD (n = 125) provided blood samples and were followed prospectively for three years. Concentrations of 17 angiogenesis-related proteins were measured in plasma. The incidence of major adverse limb event (MALE), defined as a composite of major amputation or vascular intervention, was the primary outcome. Worsening PAD status, defined as a drop in ankle brachial index ≥ 0.15, was the secondary outcome. Multivariable regression adjusted for baseline characteristics was conducted to determine the prognostication value of angiogenesis-related proteins in predicting MALE.

Findings

Relative to patients without PAD, 8 proteins related to angiogenesis were expressed differentially in PAD patients. Worsening PAD status and MALE were observed in 52 (14%) and 83 (22%) patients, respectively. Hepatocyte growth factor (HGF) was the most reliable predictor of MALE (adjusted HR 0.79, 95% CI 0.15-0.86). Compared to individuals with high HGF, patients with low HGF had a decreased three-year freedom from MALE [66% vs 88%, p = 0.001], major amputation [93% vs 98%, p = 0.023], vascular intervention [68% vs 88%, p = 0.001], and worsening PAD status [81% vs 91%, p = 0.006].

Interpretation

Measuring plasma levels of HGF in individuals with PAD can assist in identifying patients at elevated risk of adverse events related to PAD who may benefit from additional evaluation or treatment.

Targeted cell delivery of mesenchymal stem cell therapy for cardiovascular disease applications: a review of preclinical advancements

Cardiovascular diseases (CVD) continue to be the leading cause of morbidity and mortality globally and claim the lives of over 17 million people annually. Current management of CVD includes risk factor modification and preventative strategies including dietary and lifestyle changes, smoking cessation, medical management of hypertension and cholesterol lipid levels, and even surgical revascularization procedures if needed. Although these strategies have shown therapeutic efficacy in reducing major adverse cardiovascular events such as heart attack, stroke, symptoms of chronic limb-threatening ischemia (CLTI), and major limb amputation significant compliance by patients and caregivers is required and off-target effects from systemic medications can still result in organ dysfunction. Stem cell therapy holds major potential for CVD applications but is limited by the low quantities of cells that are able to traffic to and engraft at diseased tissue sites. New preclinical investigations have been undertaken to modify mesenchymal stem cells (MSCs) to achieve targeted cell delivery after systemic administration. Although previous reviews have focused broadly on the modification of MSCs for numerous local or intracoronary administration strategies, here we review recent preclinical advances related to overcoming challenges imposed by the high velocity and dynamic flow of the circulatory system to specifically deliver MSCs to ischemic cardiac and peripheral tissue sites. Many of these technologies can also be applied for the targeted delivery of other types of therapeutic cells for treating various diseases.

Label extension, single-arm, phase III study shows efficacy and safety of stempeucel® in patients with critical limb ischemia due to atherosclerotic peripheral arterial disease

BACKGROUND

Peripheral arterial disease (PAD) of lower extremities comprises a clinical spectrum that extends from asymptomatic patients to critical limb ischemia (CLI) patients. 10% to 40% of the patients are at the risk of primary amputation. This study was planned in "no-option" patients of CLI due to atherosclerotic PAD to assess the efficacy and safety of pooled, allogeneic, adult human bone marrow-derived mesenchymal stromal cells which is already approved for marketing in India for CLI due to Buerger's disease.

METHODS

This was a single-arm, multi-centric, phase III study where mesenchymal stromal cells was injected as 2 million cells/kg body weight in the calf muscle and around the ulcer. Twenty-four patients of lower extremity CLI due to PAD with Rutherford III-5 or III-6 and ankle-brachial pressure index ≤ 0.6 and having have at least one ulcer with area between 0.5 and 10 cm² were included in the study. These patients were evaluated over 12 months from drug administration.

RESULTS

Over a period of 12 months, statistical significant reduction of rest pain and ulcer size along with improvement in ankle-brachial pressure index and ankle systolic was observed. The quality of life of patients improved together with increase in total walking distance and major amputation-free survival time.

CONCLUSION

Mesenchymal stromal cells may be a feasible option to treat "no-option" patients with atherosclerotic PAD. Trial registration This study is registered prospectively in National Institutes of Health and Clinical Trials Registry-India (CTRI) website: CTRI/2018/06/014436. Registered 6th June 2018. http://ctri.nic.in/Clinicaltrials/pmaindet2.php?trialid=24050&EncHid=&userName=stempeutics .

Mesenchymal stem cell-based therapy for non-healing wounds due to chronic limb-threatening ischemia: A review of preclinical and clinical studies

Progressive peripheral arterial disease (PAD) can result in chronic limb-threatening ischemia (CLTI) characterized by clinical complications including rest pain, gangrene and tissue loss. These complications can propagate even more precipitously in the setting of common concomitant diseases in patients with CLTI such as diabetes mellitus (DM). CLTI ulcers are cutaneous, non-healing wounds that persist due to the reduced perfusion and dysfunctional neovascularization associated with severe PAD. Existing therapies for CLTI are primarily limited to anatomic revascularization and medical management of contributing factors such as atherosclerosis and glycemic control. However, many patients fail these treatment strategies and are considered "no-option," thereby requiring extremity amputation, particularly if non-healing wounds become infected or fulminant gangrene develops. Given the high economic burden imposed on patients, decreased quality of life, and poor survival of no-option CLTI patients, regenerative therapies aimed at neovascularization to improve wound healing and limb salvage hold significant promise. Cell-based therapy, specifically utilizing mesenchymal stem/stromal cells (MSCs), is one such regenerative strategy to stimulate therapeutic angiogenesis and tissue regeneration. Although previous reviews have focused primarily on revascularization outcomes after MSC treatments of CLTI with less attention given to their effects on wound healing, here we review advances in pre-clinical and clinical studies related to specific effects of MSC-based therapeutics upon ischemic non-healing wounds associated with CLTI.

Endothelial S1pr2 regulates post-ischemic angiogenesis via AKT/eNOS signaling pathway

Aims: It is important to understand the mechanism that regulates post-ischemic angiogenesis and to explore a new therapeutic target for an effective improvement of revascularization in peripheral artery disease (PAD) patients. Post-ischemic angiogenesis is a highly orchestrated process, which involves vascular endothelial cells (ECs) proliferation, migration and assembly into capillaries. We found a significant reduction of S1pr2 (sphingosine 1-phosphate receptor 2) in endothelial cells after hindlimb ischemia (HLI). We thus hypothesized that EC-S1pr2 might be involved in the regulation of post-ischemic angiogenesis and blood flow recovery during peripheral arterial disease (PAD). Methods and Results: We generated both EC-specific S1pr2 loss-of-function and S1pr2 gain-of-function mice. Our study showed that EC-specific S1pr2 loss-of-function significantly enhanced post-ischemic angiogenesis and improved blood flow recovery upon femoral artery ligation, whereas the EC-specific S1pr2 gain-of-function severely hindered post-ischemic angiogenesis and reduced blood flow recovery in ischemic limbs. We next identified that S1pr2 inhibited AKT/eNOS signaling pathway, and thus inhibited EC proliferation/migration and angiogenic activity. As expected, pharmacological inhibition of S1pr2 by JTE013 improved post-ischemic angiogenesis and improved blood flow perfusion after femoral artery ligation. Moreover, we developed RGD-peptide magnetic nanoparticles packaging S1pr2-siRNA which specifically targeted ECs and achieved an efficient silencing of S1pr2 expression in ECs in vivo. This EC-targeted strategy to dampen S1pr2 significantly enhanced post-ischemic angiogenesis and boosted blood perfusion after HLI, supplying a novel therapy target for patients with peripheral arterial disease. Conclusions: This present study demonstrates that EC-expressing S1pr2 tightly controls post-ischemic angiogenesis and blood flow perfusion recovery. This research provides a novel strategy for EC-target knockdown of S1pr2 as a new therapeutic intervention for patients with peripheral artery disease.

Pro-angiogenic approach for skeletal muscle regeneration

The angiogenesis process is a phenomenon in which numerous molecules participate in the stimulation of the new vessels' formation from pre-existing vessels. Angiogenesis is a crucial step in tissue regeneration and recovery of organ and tissue function. Muscle diseases affect millions of people worldwide overcome the ability of skeletal muscle to self-repair. Pro-angiogenic therapies are key in skeletal muscle regeneration where both myogenesis and angiogenesis occur. These therapies have been based on mesenchymal stem cells (MSCs), exosomes, microRNAs (miRs) and delivery of biological factors. The use of different calls of biomaterials is another approach, including ceramics, composites, and polymers. Natural polymers are use due its bioactivity and biocompatibility in addition to its use as scaffolds and in drug delivery systems. One of these polymers is the natural rubber latex (NRL) which is biocompatible, bioactive, versatile, low-costing, and capable of promoting tissue regeneration and angiogenesis. In this review, the advances in the field of pro-angiogenic therapies are discussed.

A Swine Hind Limb Ischemia Model Useful for Testing Peripheral Artery Disease Therapeutics

Currently, there is no large animal model of sustained limb ischemia suitable for testing novel angiogenic therapeutics for peripheral artery disease (PAD) such as drugs, genes, materials, or cells. We created a large animal model suitable for efficacy assessment of these therapies by testing 3 swine hind limb ischemia (HLI) variations and quantifying vascular perfusion, muscle histology, and limb function. Ligation of the ipsilateral external and bilateral internal iliac arteries produced sustained gait dysfunction compared to isolated external iliac or unilateral external and internal iliac artery ligations. Hyperemia-dependent muscle perfusion deficits, depressed limb blood pressure, arteriogenesis, muscle atrophy, and microscopic myopathy were quantifiable in ischemic limbs 6 weeks post-ligation. Porcine mesenchymal stromal cells (MSCs) engineered to express a reporter gene were visualized post-administration via positron emission tomography (PET) in vivo. These results establish a preclinical platform enabling better optimization of PAD therapies, including cellular therapeutics, increasing bench-to-bedside translational success. A preclinical platform for porcine studies of peripheral artery disease therapies including (1) a hind limb ischemia model and (2) non-invasive MSC viability and retention assessment via PET.

Freezing of cell sheets using a 3D freezer produces high cell viability after thawing

In cell therapy, transplanting an appropriate number of cells to the target site is crucial. One way to achieve this is to transplant cell sheets. Transplantation of cell sheets has already been utilized for various diseases in clinical practice. However, reducing the cost of cell sheet utilization is essential so as to facilitate the spread of regenerative medicine. Several ways to reduce costs are available, one of which is the use of allogenic cells. Another alternative is the use of cell sheets, which necessitates the development of methods for freezing cell sheets. This is the first study to report the use of a 3D Freezer for freezing cells. 3D Freezers have been used in the field of food processing and technology for a long time. The 3D Freezer freezes objects using cold air at a uniform temperature from all directions. In this study, we analyzed the cooling speed of human fibroblast sheets in 11 cell preservation solutions using a 3D Freezer and a Program Freezer. The cooling speed was −2 °C per min in the 3D Freezer. Supercooling in 10 cell preservation solutions was lower in the 3D Freezer than in the Program Freezer. Cell viability after freeze–thaw of the cell sheets using 3D Freezer was more than 70% in five cell preservation solutions. The levels of hepatocyte growth factor and transforming growth factor-β1 were the same not only in the fibroblast sheets frozen using the five cell preservation solutions but also in the non-frozen fibroblast sheets. These results suggest that the 3D Freezer can freeze implantable cell sheets immediately after thawing.

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3D Freezer operates using cold air with uniform temperature directed at an object from all directions.

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3D Freezer was trialed for freezing 3D cell sheets for the first time.

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3D Freezer can generate high cell viability after freezing and thawing for cell therapy.

Real World Treatment Practices for Chronic Lymphocytic Leukemia in Japan: An Observational Database Research Study (CLIMBER-DBR)

There are limited real-world data on the treatment practices and healthcare resource utilization associated with chronic lymphocytic leukemia (CLL) in Japan. In this study (CLIMBER-DBR), we performed retrospective analyses of the Japanese Medical Data Vision database, and extracted data for 2562 patients with newly diagnosed CLL (CLL-1 cohort) and 930 patients receiving CLL treatment (CLL-2 cohort) registered between March 1, 2013 and February 28, 2018. The median follow-up in the CLL-1 cohort was 721 (quartile 1-3: 363-1267) days and the median time to initial (first-line) treatment was 1331 (quartile 1-3: 189-not reached) days. In the CLL-2 cohort, the most frequently used regimens were fludarabine alone (17.7%), cyclophosphamide alone (13.7%), and bendamustine/rituximab (8.2%). The median (quartile 1-3) times to second-line and third-line treatments were 1066 (273-not reached) and 1795 (631-not reached) days, respectively. The CLIMBER-DBR was the first database research study to assess current treatment practices for CLL in Japan, where the treatment patterns were driven by the approval/reimbursement status of drugs in the study period. Our study provides an important benchmark for future studies of CLL in Japan.

Oroxylin a Attenuates Limb Ischemia by Promoting Angiogenesis via Modulation of Endothelial Cell Migration

Oroxylin A (OA) has been shown to simultaneously increase coronary flow and provide a strong anti-inflammatory effect. In this study, we described the angiogenic properties of OA. OA treatment accelerated perfusion recovery, reduced tissue injury, and promoted angiogenesis after hindlimb ischemia (HLI). In addition, OA regulated the secretion of multiple cytokines, including vascular endothelial growth factor A (VEGFA), angiopoietin-2 (ANG-2), fibroblast growth factor-basic (FGF-2), and platelet derived growth factor BB (PDGF-BB). Specifically, those multiple cytokines were involved in cell migration, cell population proliferation, and angiogenesis. These effects were observed at 3, 7, and 14 days after HLI. In skeletal muscle cells, OA promoted the release of VEGFA and ANG-2. After OA treatment, the conditioned medium derived from skeletal muscle cells was found to significantly induce endothelial cell (EC) proliferation. OA also induced EC migration by activating the Ras homolog gene family member A (RhoA)/Rho-associated coiled-coil kinase 2 (ROCK-II) signaling pathway and the T-box20 (TBX20)/prokineticin 2 (PROK2) signaling pathway. In addition, OA was able to downregulate the number of macrophages and neutrophils, along with the secretion of interleukin-1β, at 3 days after HLI. These results expanded current knowledge about the beneficial effects of OA in angiogenesis and blood flow recovery. This research could open new directions for the development of novel therapeutic intervention for patients with peripheral artery disease (PAD).

Combined Analysis of Clinical Data on HGF Gene Therapy to Treat Critical Limb Ischemia in Japan

OBJECTIVE

The objective of this combined analysis of data from clinical trials in Japan, using naked plasmid DNA encoding hepatocyte growth factor (HGF), was to document the safety and efficacy of intramuscular HGF gene therapy in patients with critical limb ischemia (CLI).

METHODS

HGF gene transfer was performed in 22 patients with CLI in a single-center open trial at Osaka University; 39 patients in a randomized, placebo-controlled, multi-center phase III trial, 10 patients with Buerger's disease in a multi-center open trial; and 6 patients with CLI in a multi-center open trial using 2 or 3 intramuscular injections of naked HGF plasmid at 2 or 4 mg. Resting pain on a visual analogue scale (VAS) and wound healing as primary endpoints were evaluated at 12 weeks after the initial injection. Serious adverse events caused by gene transfer were detected in 7 out of 77 patients (9.09%). Only one patient experienced peripheral edema (1.30%), in contrast to those who had undergone treatment with VEGF. At 12 weeks after gene transfer, combined evaluation of VAS and ischemic ulcer size demonstrated a significant improvement in HGF gene therapy group as compared to the placebo group (P=0.020).

RESULTS

The long-term analysis revealed a sustained decrease in the size of ischemic ulcer in HGF gene therapy group. In addition, VAS score over 50 mm at baseline (total 27 patients) demonstrated a tendency (P=0.059), but not significant enough, to improve VAS score in HGF gene therapy as compared to the placebo group.

CONCLUSION

The findings indicated that intramuscular injection of naked HGF plasmid tended to improve the resting pain and significantly decreased the size of the ischemic ulcer in the patients with CLI who did not have any alternative therapy, such as endovascular treatment (EVT) or bypass graft surgery. An HGF gene therapy product, CollategeneTM, was recently launched with conditional and time-limited approval in Japan to treat ischemic ulcer in patients with CLI. Further clinical trials would provide new therapeutic options for patients with CLI.

Mesenchymal Stem Cell-Based Therapy for Diabetes Mellitus: Enhancement Strategies and Future Perspectives

Diabetes mellitus (DM), a chronic disorder of carbohydrate metabolism, is characterized by the unbridled hyperglycemia resulted from the impaired ability of the body to either produce or respond to insulin. As a cell-based regenerative therapy, mesenchymal stem cells (MSCs) hold immense potency for curing DM duo to their easy isolation, multi-differentiation potential, and immunomodulatory property. However, despite the promising efficacy in pre-clinical animal models, naive MSC administration fails to exhibit clinically satisfactory therapeutic outcomes, which varies greatly among individuals with DM. Recently, numbers of innovative strategies have been applied to improve MSC-based therapy. Preconditioning, genetic modification, combination therapy and exosome application are representative strategies to maximize the therapeutic benefits of MSCs. Therefore, in this review, we summarize recent advancements in mechanistic studies of MSCs-based treatment for DM, and mainly focus on the novel approaches aiming to improve the anti-diabetic potentials of naive MSCs. Additionally, the potential directions of MSCs-based therapy for DM are also proposed at a glance.

Targeted Delivery of a Matrix Metalloproteinases-2 Specific Inhibitor Using Multifunctional Nanogels to Attenuate Ischemic Skeletal Muscle Degeneration and Promote Revascularization

Critical limb ischemia (CLI) is a severe form of peripheral artery disease (PAD). It is featured by degenerated skeletal muscle and poor vascularization. During the development of CLI, the upregulated matrix metalloproteinase-2 (MMP-2) degrades muscle extracellular matrix to initiate the degeneration. Meanwhile, MMP-2 is necessary for blood vessel formation. It is thus hypothesized that appropriate MMP-2 bioactivity in ischemic limbs will not only attenuate muscle degeneration but also promote blood vessel formation. Herein, we developed ischemia-targeting poly(N-isopropylacrylamide)-based nanogels to specifically deliver an MMP-2 inhibitor CTTHWGFTLC (CTT) into ischemic limbs to tailor MMP-2 bioactivity. Besides acting as an MMP-2 inhibitor, CTT promoted endothelial cell migration under conditions mimicking the ischemic limbs. The nanogels were sensitive to the pH of ischemic tissues, allowing them to largely aggregate in the injured area. To help reduce nanogel uptake by macrophages and increase circulation time, the nanogels were cloaked with a platelet membrane. An ischemia-targeting peptide CSTSMLKA (CST) was further conjugated on the platelet membrane for targeted delivery of nanogels into the ischemic area. CTT gradually released from the nanogels for 4 weeks. The nanogels mostly accumulated in the ischemic area for 28 days. The released CTT preserved collagen in the muscle and promoted its regeneration. In addition, CTT stimulated angiogenesis. Four weeks after CLI, the blood flow and vessel density of the ischemic limbs treated with the nanogels were remarkably higher than the control groups without CTT release. These results demonstrate that the developed nanogel-based CTT release system has the potential to stimulate ischemic limb regeneration.

Injectable thermosensitive chitosan-based hydrogel containing ferulic acid for treating peripheral arterial disease

Peripheral arterial disease (PAD) affects more than 200 million people worldwide. Recent studies suggest that oxidative stress-related inflammation can lead to the initiation and progression of PAD. Ferulic acid (FA) is a natural phenolic compound and has been proven to have antioxidant and angiogenesis effects. In this study, thermosensitive chitosan-gelatin-based hydrogel was used as a delivery vehicle of FA. The effects of hydrogel encapsulating FA (FA-gel) have been demonstrated in vitro and in vivo. The results revealed that the developed hydrogel with porous structure could provide a sustained release of FA. Post-treatment of FA-gel effectively decreased the oxidative stress-induced damage in human umbilical vein endothelial cells via decreasing endogenous reactive oxygen species production, inflammation-related gene expression and apoptosis level. In the mouse hindlimb ischemia model, the results revealed that FA-gel could improve blood flow, muscle regeneration and decreases inflammation in veins. These results suggested that FA-gel may have a therapeutic potential in PAD.

Efficacy of nonviral gene transfer of human hepatocyte growth factor (HGF) against ischemic-reperfusion nerve injury in rats

Ischemic neuropathy is common in subjects with critical limb ischemia, frequently causing chronic neuropathic pain. However, neuropathic pain caused by ischemia is hard to control despite the restoration of an adequate blood flow. Here, we used a rat model of ischemic-reperfusion nerve injury (IRI) to investigate possible effects of hepatocyte growth factor (HGF) against ischemic neuropathy. Hemagglutinating virus of Japan (HVJ) liposomes containing plasmids encoded with HGF was delivered into the peripheral nervous system by retrograde axonal transport following its repeated injections into the tibialis anterior muscle in the right hindlimb. First HGF gene transfer was done immediately after IRI, and repeated at 1, 2 and 3 weeks later. Rats with IRI exhibited pronounced mechanical allodynia and thermal hyperalgesia, decreased blood flow and skin temperature, and lowered thresholds of plantar stimuli in the hind paw. These were all significantly improved by HGF gene transfer, as also were sciatic nerve conduction velocity and muscle action potential amplitudes. Histologically, HGF gene transfer resulted in a significant increase of endoneurial microvessels in sciatic and tibial nerves and promoted nerve regeneration which were confirmed by morphometric analysis. Neovascularization was observed in the contralateral side of peripheral nerves as well. In addition, IRI elevated mRNA levels of P2X3 and P2Y1 receptors, and transient receptor potential vanilloid receptor subtype 1 (TRPV1) in sciatic nerves, dorsal root ganglia and spinal cord, and these elevated levels were inhibited by HGF gene transfer. In conclusion, HGF gene transfer is a potent candidate for treatment of acute ischemic neuropathy caused by reperfusion injury, because of robust angiogenesis and enhanced nerve regeneration.

Comparison of long-term outcomes after directional versus rotational atherectomy in peripheral artery disease

INTRODUCTION

The rate of atherectomy utilization in peripheral artery diseases (PAD) is growing. The two atherectomy devices available on the market and used most frequently are the directional and rotational ones. Nonetheless, there is a lack of direct comparison between these two types of atherectomy in PAD.

AIM

To compare the long-term outcomes after PAD endovascular revascularization with two types of atherectomies: rotational (AR) (Phoenix Philips) and directional (AD) (SilverHawk Medtronic).

MATERIAL AND METHODS

This was a single-center, retrospective study of obstructive and symptomatic PAD patients who underwent revascularization with atherectomy. The endpoints were considered as target lesion revascularization (TLR), death, amputations and bailout stenting (BS).

RESULTS

The AR group consisted of 97 patients, while the AD group consisted of 85 individuals. There were no significant differences between the groups in terms of baseline characteristics except for an increased critical limb ischemia (CLI) prevalence in the AR group. The mean follow-up for AD and AR was 282.6 ±147.4 and 255.7 ±186.1 days, respectively (p = 0.44). There were no significant differences in the death rate (AD: 1 (1.7%) vs. AR: 5 (5.7%); p = 0.54), amputations (AD: 2 (2.3%) vs. AR: 5 (5.7%); p = 0.45) or bailout stenting (AD: 2 (2.3%) vs. AR: 3 (3.2%); p = 0.74), whereas TLR was more frequent in the AD group (AD: 25 (29%) vs. AR: 15 (15.9%; p = 0.03). The Kaplan-Meier analysis showed no significant differences between the groups in time to TLR, amputation or death.

CONCLUSIONS

In this hypothesis-generating study the AR had a lower rate of TLR when compared to the AD. Nevertheless, this should be confirmed in further controlled randomized trials.

Tumor Angiogenesis and Anti-Angiogenic Strategies for Cancer Treatment

Angiogenesis is the process through which novel blood vessels are formed from pre-existing ones and it is involved in both physiological and pathological processes of the body. Furthermore, tumor angiogenesis is a crucial factor associated with tumor growth, progression, and metastasis. In this manner, there has been a great interest in the development of anti-angiogenesis strategies that could inhibit tumor vascularization. Conventional approaches comprise the administration of anti-angiogenic drugs that target and block the activity of proangiogenic factors. However, as their efficacy is still a matter of debate, novel strategies have been focusing on combining anti-angiogenic agents with chemotherapy or immunotherapy. Moreover, nanotechnology has also been investigated for the potential of nanomaterials to target and release anti-angiogenic drugs at specific sites. The aim of this paper is to review the mechanisms involved in angiogenesis and tumor vascularization and provide an overview of the recent trends in anti-angiogenic strategies for cancer therapy.

Comparison of efficacy between trimetazidine and cilostazol in the treatment of arteriosclerosis obliterans in lower extremity

This study compared the efficacy and long-term survival rate of trimetazidine and cilostazol in the treatment of lower extremity arteriosclerosis obliterans (ASO). A retrospectively analysis on the medical records of 206 patients with ASO who were admitted to The Central Hospital of Wuhan from January 2011 to May 2013 was performed, including 94 patients treated with trimetazidine (group A) and 112 patients treated with cilostazol (group B). On the basis of the same basic treatment, both groups were applied with these two drugs after two courses of treatments. Then the efficacy of clinical treatment, dorsal artery blood flow, anterior femoral artery, posterior tibial artery blood flow, brachial artery index, toe-brachial index, painless walking distance, maximum walking distance, adverse reactions, 5-year survival rates were compared. The total effective rate of clinical efficacy in group B was higher than group A (P<0.05). After the first course of treatment, the above indicators increased in both groups (P<0.05). After the end of the second course of treatment, the above-mentioned index values in both groups were significantly increased (P<0.05). The improvement of the above indicators in group B were better than the trimetazidine group in both the first and second treatment courses (P<0.05). In group A, there were 15 cases of patients with lethargy and hypodynamia and 9 cases of dizziness and headache. There were significant differences between the 7th and 3rd cases of patients when compared to group B (P<0.05). The 5-year survival rate of group A was lower than group B (P<0.05). The clinical efficacy of cliostazol in the treatment of ASO had a good effect, and there was only a few adverse reactions and the long-term survival rate was high. It is worthy of being promoted in clinical practice.

A Low-Molecular-Weight Polyethylenimine/pDNA-VEGF Polyplex System Constructed in a One-Pot Manner for Hindlimb Ischemia Therapy

Peripheral arterial disease (PAD) is often characterized by continued reduction in blood flow supply to limbs. Advanced therapeutic strategies like gene therapy could potentially be applied to limb ischemia therapy. However, developing a gene delivery system with low toxicity and high efficiency remains a great challenge. In this study, a one-pot construction was used to integrate vector synthesis and polyplex fabrication simultaneously in a simple and robust manner. We fabricated an interpenetrating gene delivery network through the physical interaction between low-molecular-weight polyethylenimine (PEI 1.8 kDa) and plasmid DNA (pDNA) and the chemical bonding between PEI and glutaraldehyde (GA), which was named the glutaraldehydelinked-branched PEI (GPEI) polyplex. The final GPEI polyplex system was pH-responsive and biodegradable due to the imine linkage and it could successfully deliver desired vascular endothelial growth factor (VEGF) pDNA. Compared with PEI (25 kDa)/pDNA polyplexes, GPEI polyplexes showed lower cytotoxicity and higher transfection efficiency both in vitro and in vivo. In addition, we demonstrated that GPEI polyplexes could efficiently promote the formation of new capillaries in vivo, which may provide a practicable strategy for clinical hindlimb ischemia therapy in the future.

The TRPC5 channel regulates angiogenesis and promotes recovery from ischemic injury in mice

Ischemia-related diseases are a leading cause of death worldwide, and promoting therapeutic angiogenesis is key for effective recovery from hypoxia-ischemia. Given the limited success of angiogenic factors, such as vascular endothelial growth factor, in clinical trials, it is important to find more promising angiogenic targets. Here, using both cell- and tissue-based assays and a mouse model of injury-induced ischemia, we investigated the involvement of the transient receptor potential canonical 5 (TRPC5) ion channel in angiogenesis and the effects of a TRPC5 activator, the Food and Drug Administration-approved drug riluzole, on recovery from ischemic injury. We demonstrate that TRPC5 is involved in endothelial cell sprouting, angiogenesis, and blood perfusion in an oxygen-induced retinopathy model and a hind limb ischemia model. We found a potential regulatory link between nuclear factor of activated T cell isoform c3 and angiopoietin-1 that could provide the mechanistic basis for the angiogenic function of TRPC5. Importantly, treatment with riluzole, which can activate TRPC5 in endothelial cells, improved recovery from ischemia in mice. Our study reveals TRPC5 as a potential angiogenic target and suggests riluzole as a promising drug for managing ischemic diseases.

Long term outcomes in diabetic patients treated with atherectomy for peripheral artery disease

BACKGROUND

The prevalence of diabetes has increased significantly in well-developed countries during the last decade and it continues to grow. Diabetes increases the risk of restenosis in patients treated percutaneously for peripheral artery disease. The present study sought to compare outcomes of atherectomy treatment in diabetic (DM) vs. non-diabetic (nDM) patients suffering from peripheral artery disease.

METHOD

Between 2008 and 2012, 204 revascularization atherectomy procedures were performed on arteries of the lower extremities. The endpoints included target lesion revascularization (TLR), amputation and death. The type of atherectomy (excisional-soft plaque, orbital-calcified plaque, with active aspiration - with a thrombus) was left to operator discretion.

RESULTS

This study contains 132 DM (66% male, age 68 ± 11.2 years) and 72 nDM (63% male, age 75 ± 11.3 years) subjects. DM were younger but had a higher prevalence of coronary artery disease (DM: 91% vs. nDM: 62%, p < 0.0001) and end-stage renal disease (DM: 22% vs. nDM: 2.5%, p < 0.0001). There were no differences in critical limb ischemia between the groups (DM: 21% vs. nDM: 12%, p = = 0.13). Mean time of follow-up was 384 and 411 days in DM and nDM, respectively (p = 0.43). There were no significant differences in TLR (DM: 15.2% vs. nDM: 22.2%, p = 0.249), amputations (DM: 3.0% vs. nDM: 1.5%, p = NS) or death rates (DM: 2.2% vs. nDM: 2.7%, p = NS). Kaplan-Mayer analysis showed no significant differences between the groups in the time to TLR, amputation or death.

CONCLUSIONS

Plaque modification with adjusted atherectomy appears to have similar outcomes in diabetic as well as in non-diabetic patients. Nonetheless, a randomized study would be warranted to confirm the findings of the current study.

Medical Resource Consumption and Quality of Life in Peripheral Arterial Disease in Korea: PAD Outcomes (PADO) Research

BACKGROUND AND OBJECTIVES

We aimed to investigate the history of medical resource consumption and quality of life (QoL) in peripheral arterial disease (PAD) patients in Korea.

METHODS

This was a prospective, multi-center (23 tertiary-hospitals, division of cardiology), non-interventional study. Adult patients (age ≥20 years) suffering from PAD for the last 12-month were enrolled in the study if they met with any of following; 1) ankle-brachial index (ABI) ≤0.9, 2) lower-extremity artery stenosis on computed tomography angiography ≥50%, or 3) peak-systolic-velocity-ratio (PSVR) on ultrasound ≥2.0. Medical chart review was used to assess patient characteristics/treatment patterns while the history of medical resource consumption and QoL data were collected using a patient survey. QoL was measured using EuroQoL-5-dimensions-3-level (EQ-5D-3L) score system, and the factors associated with QoL were analyzed using multiple linear regression analysis.

RESULTS

This study included 1,260 patients (age: 69.8 years, male: 77.0%). The most prevalent comorbidities were hypertension (74.8%), hyperlipidemia (51.0%) and diabetes-mellitus (50.2%). The 94.1% of the patients took pharmacotherapy including aspirin (76.2%), clopidogrel (53.3%), and cilostazol (33.6%). The 12.6% of the patients were receiving smoking cessation education/pharmacotherapy. A considerable number of patients (500 patients, 40.0%) had visit history to another hospital before diagnosis/treatment at the current hospital, with visits to orthopedic units (50.4%) being the most common. At the time, 29% (or higher) of the patients were already experiencing symptoms of critical limb ischemia. Baseline EQ-5D index and EQ VAS were 0.64±0.24 and 67.49±18.29. Factors significantly associated with QoL were pharmacotherapy (B=0.05053; p=0.044) compared to no pharmacotherapy, and Fontaine stage improvement/maintain stage I (B=0.04448; p<0.001) compared to deterioration/maintain stage II-IV.

CONCLUSIONS

Increase in disease awareness for earlier diagnosis and provision of adequate pharmacotherapy is essential to reduce disease burden and improve QoL of Korean PAD patients.

Molecular Regulation of Sprouting Angiogenesis

The term angiogenesis arose in the 18th century. Several studies over the next 100 years laid the groundwork for initial studies performed by the Folkman laboratory, which were at first met with some opposition. Once overcome, the angiogenesis field has flourished due to studies on tumor angiogenesis and various developmental models that can be genetically manipulated, including mice and zebrafish. In addition, new discoveries have been aided by the ability to isolate primary endothelial cells, which has allowed dissection of various steps within angiogenesis. This review will summarize the molecular events that control angiogenesis downstream of biochemical factors such as growth factors, cytokines, chemokines, hypoxia-inducible factors (HIFs), and lipids. These and other stimuli have been linked to regulation of junctional molecules and cell surface receptors. In addition, the contribution of cytoskeletal elements and regulatory proteins has revealed an intricate role for mobilization of actin, microtubules, and intermediate filaments in response to cues that activate the endothelium. Activating stimuli also affect various focal adhesion proteins, scaffold proteins, intracellular kinases, and second messengers. Finally, metalloproteinases, which facilitate matrix degradation and the formation of new blood vessels, are discussed, along with our knowledge of crosstalk between the various subclasses of these molecules throughout the text. Compr Physiol 8:153-235, 2018.

Periodontitis deteriorates peripheral arterial disease in Japanese population via enhanced systemic inflammation

Peripheral arterial disease (PAD) is a common manifestation of arterial stenosis of the extremity that reduces arterial flow. While patients with periodontitis are at a high risk of PAD, little causal information has been provided to date. To clarify the relationship, we conducted this cross-sectional study. The oral condition of patients with or without PAD, who attended Tokyo Medical and Dental University Hospital, was evaluated. Blood examinations and dental clinical measurements, including number of teeth, probing pocket depth (PPD), bleeding on probing (BOP) and clinical attachment level (CAL) were performed. Chi-square test was performed to compare gender, smoker rate, prevalence of DM, hypertension and dyslipidemia and edentulous rate. Wilcoxon test was used to compare bacterial counts and anti-bacterial antibodies and Student's t test was used to compare the other numerical values. The subjects were patients with (n = 34) or without (n = 956) PAD. We revealed that the PAD patients had more missing teeth (17.5 ± 11.0), a higher rate of edentulism (18%), and higher serum inflammatory factor levels than non-PAD patients (10.9 ± 8.7, 5%, respectively). On the other hand, there was no significant difference between hypertension, dyslipidemia, smoking status, HbA1c, bacterial antibody titers, and bacterial counts between the groups. In conclusion, we clarified that PAD patients had decreased tooth number and worsened oral and periodontal condition with enhanced systemic inflammation.

WBC count predicts the risk of new-onset peripheral arterial disease in a Chinese community-based population

This longitudinal cohort study investigated whether peripheral WBC counts could predict peripheral arterial disease (PAD) incidence after a 2.3-year follow-up in a Chinese community-based population without PAD at baseline. A total of 3555 Chinese subjects without fever and PAD at baseline from an atherosclerosis cohort were included in our analysis. The ankle brachial index (ABI) was measured, and PAD was defined as an ABI <0.9. Multivariate regression models were used to evaluate the association of WBC count and new-onset PAD. The mean (±s.d.) baseline WBC count was 6.11±1.54 × 10⁹ l^-1, the mean (±s.d.) ABI was 1.11±0.08 at baseline and the incidence of PAD was 2.7% over 2.3 years. WBC counts were significantly associated with PAD incidence (odds ratio (OR)=1.27, 95% confidence interval (CI): 1.14-1.41, P<0.0001) with every 1 × 10⁹ l^-1 increase in WBC count. This relationship remained significant (OR=1.21, 95% CI: 1.08-1.36, P=0.0014) even after adjusting for other variables. The highest WBC quartile group had increased risk when compared with the lowest quartile group (OR=2.14, 95% CI: 1.09-4.22, P=0.027) in a multivariate logistic model. Furthermore, we did not find significant heterogeneity among the analyzed subgroups based on sex (male or female), age (<60 or ⩾60 years old), body mass index (BMI, <25 or ⩾25 kg m^-2), current smoking, current drinking, hypertension, diabetes mellitus, dyslipidemia or cardiovascular disease. In conclusion, elevated WBC counts independently predict the risk of new-onset PAD in a Chinese community-based population, supporting the hypothesis that systemic inflammation plays an important role in PAD development.

Long-Term Outcomes After Percutaneous Lower Extremity Arterial Interventions With Atherectomy vs. Balloon Angioplasty - Propensity Score-Matched Registry

BACKGROUND

The impact of endovascular revascularization of the lower extremity arteries with atherectomy (AT) compared with percutaneous transluminal angioplasty (PTA) is still unclear. Therefore, the aim of the study was to compare long-term outcomes after percutaneous PTA and AT in patients requiring endovascular revascularization.

METHODS AND RESULTS

This was a single-center, retrospective registry of obstructive and symptomatic PAD patients who underwent endovascular revascularization. PTA was performed in 215 patients, and AT in 204 (Silver Hawk, EV3, n=125; CSI 360°, n=66; Pathway Medical Technologies, n=13). There were no significant between-group differences in baseline characteristics except for increased CAD, dialysis and CLI prevalence in the PTA group. Following propensity score analysis 131 well-matched pairs were included in analysis. Bail-out stenting was more frequent in the reference group (PTA, 6.1% vs. AT, 0%; P=0.004). At 6- and 12-month follow-up there were no differences in TLR between the groups (PTA, 8.3% vs. AT, 5.3%; P=0.47; and PTA, 16.7% vs. AT, 13.7%; P=0.73, respectively). The difference was in favor of AT at 24-month follow-up (PTA, 29.0% vs. AT, 16.7%; P=0.05). No difference was observed in amputation rate (PTA, 0.7% vs AT, 1.5%; P=0.62). On Kaplan-Meier analysis there were no significant differences between groups in time to TLR, amputation or death.

CONCLUSIONS

AT was associated with lower risk of TLR, and this should be confirmed in randomized controlled trials.

Therapeutic strategies for cell-based neovascularization in critical limb ischemia

Critical limb ischemia (CLI) causes severe ischemic rest pain, ulcer, and gangrene in the lower limbs. In spite of angioplasty and surgery, CLI patients without suitable artery inflow or enough vascular bed in the lesions are often forced to undergo amputation of a major limb. Cell-based therapeutic angiogenesis has the potential to treat ischemic lesions by promoting the formation of collateral vessel networks and the vascular bed. Peripheral blood mononuclear cells and bone marrow-derived mononuclear cells are the most frequently employed cell types in CLI clinical trials. However, the clinical outcomes of cell-based therapeutic angiogenesis using these cells have not provided the promised benefits for CLI patients, reinforcing the need for novel cell-based therapeutic angiogenesis strategies to cure untreatable CLI patients. Recent studies have demonstrated the possible enhancement of therapeutic efficacy in ischemic diseases by preconditioned graft cells. Moreover, judging from past clinical trials, the identification of adequate transplant timing and responders to cell-based therapy is important for improving therapeutic outcomes in CLI patients in clinical settings. Thus, to establish cell-based therapeutic angiogenesis as one of the most promising therapeutic strategies for CLI patients, its advantages and limitations should be taken into account.

Ghrelin, MicroRNAs, and Critical Limb Ischemia: Hungering for a Novel Treatment Option

Critical limb ischemia (CLI) is the most severe manifestation of peripheral artery disease. It is characterized by chronic pain at rest, skin ulcerations, and gangrene tissue loss. CLI is a highly morbid condition, resulting in a severely diminished quality of life and a significant risk of mortality. The primary goal of therapy for CLI is to restore blood flow to the affected limb, which is only possible by surgery, but is inadvisable in up to 50% of patients. This subset of patients who are not candidates for revascularisation are referred to as "no-option" patients and are the focus of investigation for novel therapeutic strategies. Angiogenesis, arteriogenesis and vasculogenesis are the processes whereby new blood vessel networks form from the pre-existing vasculature and primordial cells, respectively. In therapeutic angiogenesis, exogenous stimulants are administered to promote angiogenesis and augment limb perfusion, offering a potential treatment option for "no option" patients. However, to date, very few clinical trials of therapeutic angiogenesis in patients with CLI have reported clinically significant results, and it remains a major challenge. Ghrelin, a 28-amino acid peptide, is emerging as a potential novel therapeutic for CLI. In pre-clinical models, exogenous ghrelin has been shown to induce therapeutic angiogenesis, promote muscle regeneration, and reduce oxidative stress via the modulation of microRNAs (miRs). miRs are endogenous, small, non-coding ribonucleic acids of ~20-22 nucleotides which regulate gene expression at the post-transcriptional level by either translational inhibition or by messenger ribonucleic acid cleavage. This review focuses on the mounting evidence for the use of ghrelin as a novel therapeutic for CLI, and highlights the miRs which orchestrate these physiological events.

Modulation of VEGF receptor 2 signaling by protein phosphatases

Phosphorylation of serines, threonines, and tyrosines is a central event in signal transduction cascades in eukaryotic cells. The phosphorylation state of any particular protein reflects a balance of activity between kinases and phosphatases. Kinase biology has been exhaustively studied and is reasonably well understood, however, much less is known about phosphatases. A large body of evidence now shows that protein phosphatases do not behave as indiscriminate signal terminators, but can function both as negative or positive regulators of specific signaling pathways. Genetic models have also shown that different protein phosphatases play precise biological roles in health and disease. Finally, genome sequencing has unveiled the existence of many protein phosphatases and associated regulatory subunits comparable in number to kinases. A wide variety of roles for protein phosphatase roles have been recently described in the context of cancer, diabetes, hereditary disorders and other diseases. In particular, there have been several recent advances in our understanding of phosphatases involved in regulation of vascular endothelial growth factor receptor 2 (VEGFR2) signaling. The receptor is the principal signaling molecule mediating a wide spectrum of VEGF signal and, thus, is of paramount significance in a wide variety of diseases ranging from cancer to cardiovascular to ophthalmic. This review focuses on the current knowledge about protein phosphatases' regulation of VEGFR2 signaling and how these enzymes can modulate its biological effects.

Effect of long-term treatment with melatonin on vascular markers of oxidative stress/inflammation and on the anticontractile activity of perivascular fat in aging mice

Some reports have suggested that inflammation in perivascular adipose tissue (PVAT) may be implicated in vascular dysfunction by causing the disappearance of an anticontractile effect. The aim of this study was to investigate the effects of chronic melatonin treatment on the functional responses of the small mesenteric arteries and on the expression of markers of inflammation/oxidative stress in the aortas of senescence-accelerated prone mice (SAMP8), a model of age-related vascular dysfunction. We investigated seven SAMP8 and seven control senescence-accelerated resistant mice (SAMR1) treated for 10 months with melatonin, as well as equal numbers of age-matched untreated SAMP8 and SAMR1. The mesenteric small resistance arteries were dissected and mounted on a wire myograph, and the concentration-response to norepinephrine was evaluated in vessels with intact PVAT and after the removal of the PVAT. The expression of markers of oxidative stress, inflammation and aging in the aortas was evaluated by immunostaining. In addition, the adiponectin content and the expression of adiponectin receptor 1 were evaluated in the visceral adipose tissue. In untreated SAMP8 mice, we observed an overexpression of oxidative stress and inflammatory markers in the vasculature compared with the controls. No anticontractile effect of the PVAT was observed in untreated SAMP8 mice. Long-term treatment of SAMP8 mice with melatonin increased the expression of some markers of vasoprotection, decreased oxidative stress and inflammation and restored the anticontractile effect of the PVAT. Decreased expression of adiponectin and adiponectin receptor 1 was also observed in visceral fat of untreated SAMP8, whereas a significant increase was observed after melatonin treatment.