Inflammation, oxidative stress and platelet activation in aspirin-treated critical limb ischaemia: beneficial effects of iloprost

Current Medical Therapy and Revascularization in Peripheral Artery Disease of the Lower Limbs: Impacts on Subclinical Chronic Inflammation

Peripheral artery disease (PAD), coronary artery disease (CAD), and cerebrovascular disease (CeVD) are characterized by atherosclerosis and inflammation as their underlying mechanisms. This paper aims to conduct a literature review on pharmacotherapy for PAD, specifically focusing on how different drug classes target pro-inflammatory pathways. The goal is to enhance the choice of therapeutic plans by considering their impact on the chronic subclinical inflammation that is associated with PAD development and progression. We conducted a comprehensive review of currently published original articles, narratives, systematic reviews, and meta-analyses. The aim was to explore the relationship between PAD and inflammation and evaluate the influence of current pharmacological and nonpharmacological interventions on the underlying chronic subclinical inflammation. Our findings indicate that the existing treatments have added anti-inflammatory properties that can potentially delay or prevent PAD progression and improve outcomes, independent of their effects on traditional risk factors. Although inflammation-targeted therapy in PAD shows promising potential, its benefits have not been definitively proven yet. However, it is crucial not to overlook the pleiotropic properties of the currently available treatments, as they may provide valuable insights for therapeutic strategies. Further studies focusing on the anti-inflammatory and immunomodulatory effects of these treatments could enhance our understanding of the mechanisms contributing to the residual risk in PAD and pave the way for the development of novel therapies.

Electroacupuncture Treats Myocardial Infarction by Influencing the Regulation of Substance P in the Neurovascular to Modulate PGI2/TXA2 Metabolic Homeostasis via PI3K/AKT Pathway: A Bioinformatics-Based Multiomics and Experimental Study

Acute myocardial infarction (AMI) is the most severe form of coronary heart disease caused by ischemia and hypoxia. The study is aimed at investigating the role of neuropeptides and the mechanism of electroacupuncture (EA) in acute myocardial infarction (AMI) treatment. Compared with the normal population, a significant increase in substance P (SP) was observed in the serum of patients with AMI. PGI2 expression was increased in the SP-treated AMI mouse model, and TXA2 expression was decreased. And PI3K pathway-related genes, including Pik3ca, Akt, and Mtor, were upregulated in myocardial tissue of SP-treated AMI patients. Human cardiomyocyte cell lines (HCM) treated with SP increased mRNA and protein expression of PI3K pathway-related genes (Pik3ca, Pik3cb, Akt, and Mtor). Compared to MI control and EA-treated MI rat models, Myd88, MTOR, Akt1, Sp, and Irak1 were differentially expressed, consistent with in vivo and in vitro studies. EA treatment significantly enriched PI3K/AKT signaling pathway genes within MI-associated differentially expressed genes (DEGs) according to Kyoto Encyclopedia of Genes and Genomes (KEGG). Furthermore, it was confirmed by molecular docking analysis that PIK3CA, AKT1, and mTOR form stable dockings with neuropeptide SP. PI3K/AKT pathway activity may be affected directly or indirectly by EA via SP, which corrects the PGI2/TXA2 metabolic imbalance in AMI. MI treatment is now better understood as a result of this finding.

Iloprost Attenuates Oxidative Stress-Dependent Activation of Collagen Synthesis Induced by Sera from Scleroderma Patients in Human Pulmonary Microvascular Endothelial Cells

Endothelial cell injury is an early event in systemic sclerosis (SSc) pathogenesis and several studies indicate oxidative stress as the trigger of SSc-associated vasculopathy. Here, we show that circulating factors present in sera of SSc patients increased reactive oxygen species (ROS) production and collagen synthesis in human pulmonary microvascular endothelial cells (HPMECs). In addition, the possibility that iloprost, a drug commonly used in SSc therapy, might modulate the above-mentioned biological phenomena has been also investigated. In this regard, as compared to sera of SSc patients, sera of iloprost-treated SSc patients failed to increased ROS levels and collagen synthesis in HPMEC, suggesting a potential antioxidant mechanism of this drug.

Efficacy and safety of iloprost in trauma patients with haemorrhagic shock-induced endotheliopathy-Protocol for the multicentre randomized, placebo-controlled, blinded, investigator-initiated shine-trauma trial

BACKGROUND

Traumatic injury accounts for 800 000 deaths in the European Union annually. The main causes of deaths in trauma patients are exsanguination and multiple organ failure (MOF). We have studied >1000 trauma patients and identified shock-induced endotheliopathy (SHINE), the pathophysiological mechanism responsible for MOF and high mortality. Pilot studies indicate that low-dose iloprost (1 ng/kg/min) improves endothelial functionality in critically ill patients suggesting this intervention may improve patient outcome in traumatic SHINE.

MATERIAL AND METHODS

This is a multicentre, randomized, blinded clinical investigator-initiated phase 2B trial in trauma patients with haemorrhagic shock-induced endotheliopathy. Patients are randomized 1:1 to 72 hours infusion of iloprost 1 ng/kg/min or Placebo (equal volume of saline). A total of 220 trauma patients will be included. The primary endpoint is the number of intensive care unit (ICU)-free days, within 28 days of admission. Secondary endpoints include 28- and 90-day all-cause mortality, hospital length of stay, vasopressor-free days in the intensive care unit (ICU) within 28 days, ventilator-free days in the ICU within 28 days, renal replacement-free days in the ICU within 28 days, number of serious adverse reactions and serious adverse events within the first 4 days of admission.

DISCUSSION

This trial will test the safety and efficacy of administration of iloprost vs placebo for 72 hours in trauma patients with haemorrhagic shock-induced endotheliopathy. Trial endpoints focus on the potential effect of iloprost to reduce the need for ICU stay secondary to mitigation of organ failure.

TRIAL REGISTRATION

SHINE-TRAUMA trial-EudraCT no. 2019-000936-24-Clinicaltrials.gov: NCT03903939 Ethics Committee no. H-19014482.

Acute effect of inhaled iloprost on exercise dynamic hyperinflation in COPD patients: A randomized crossover study

BACKGROUND AND OBJECTIVE

We tested whether the prostacyclin analog inhaled iloprost modulates dead space, dynamic hyperinflation (DH), and systemic inflammation/oxidative stress during maximal exercise in subjects with chronic obstructive pulmonary disease (COPD) who were not selected based on pulmonary hypertension (PH).

METHODS

Twenty-four COPD patients with moderate-severe obstruction (age 59 ± 7 years, FEV₁ 53 ± 13% predicted) participated in a randomized, double-blind, placebo-controlled crossover trial. Each subject received a single nebulized dose of 5.0 μg iloprost or placebo on non-consecutive days followed by maximal cardiopulmonary exercise tests. The primary outcome was DH quantified by end-expiratory lung volume/total lung capacity ratio (EELV/TLC) at metabolic isotime.

RESULTS

Inhaled iloprost was well-tolerated and reduced submaximal alveolar dead-space fraction but did not significantly reduce DH (0.70 ± 0.09 vs 0.69 ± 0.07 following placebo and iloprost, respectively, p = 0.38). Maximal exercise time (9.1 ± 2.3 vs 9.3 ± 2.2 min, p = 0.31) and peak oxygen uptake (17.4 ± 6.3 vs 17.9 ± 6.9 mL/kg/min, p = 0.30) were not significantly different following placebo versus iloprost.

CONCLUSIONS

A single dose of inhaled iloprost was safe and reduced alveolar dead space fraction; however, it was not efficacious in modulating DH or improving exercise capacity in COPD patients who were not selected for the presence of PH.

Routine Intraoperative Inhaled Milrinone and Iloprost Reduces Inotrope Use in Patients Undergoing Cardiac Surgery: A Retrospective Cohort Pilot Study

BACKGROUND

Catecholamine inotropes are frequently used after cardiopulmonary bypass (CPB) but may have undesirable effects. The aim was to identify whether the routine use of inhaled pulmonary vasodilators might reduce the requirement for inotrope drugs after cardiac surgery.

METHODS

Retrospective cohort study of sequential patients undergoing cardiac surgery at the Royal Melbourne Hospital performed by a single surgeon and anesthesia care team, within 14 months before and after routine implementation of inhaled pulmonary vasodilators, August 2017. Milrinone 4 mg and iloprost 20 µg were inhaled using a vibrating mesh nebulizer (Aerogen) before initiation of CPB and at chest closure. Other aspects of clinical management were unaltered over the time period. Two investigators blinded to each other extracted data from electronic and written medical records. The primary outcome was any use of inotropes in the perioperative period; a Fisher exact test was used to analyze any differences between the 2 groups. Demographic data, hemodynamic data, and use of inotropes and vasopressors were collected from induction of anesthesia to 36 hours postoperative in the intensive care unit (ICU). Hospital and ICU length of stay, cost, and complications were collected.

RESULTS

Any use of inotropes was significantly lower with inhaled pulmonary dilators (62.5% vs 86.8%, odds ratio [95% confidence interval {CI}], 0.253 (0.083-0.764); P = .011), including intraoperative inotrope use (37.5% vs 86.8%, odds ratio [95% CI], 0.091 (0.03-0.275); P < .001). ICU length of stay was significantly lower with inhaled pulmonary dilators (45 hours, interquartile range [IQR], 27-65 vs 50 hours, IQR, 45-74; P = .026). There were no significant differences among major postoperative complications or costs between groups.

CONCLUSIONS

Routine use of inhaled milrinone 4 mg and iloprost 20 µg before and after CPB is associated with reduced postoperative inotrope use.

Medical adjunctive therapy for patients with chronic limb-threatening ischemia: a systematic review

INTRODUCTION

The aim of this article is to systematically review the literature on medical adjunctive therapy for patients with chronic limb-threatening ischemia (CLTI).

EVIDENCE ACQUISITION

MEDLINE, Embase, and Cochrane Database of Systematic Reviews were searched for studies published between January 1st, 2009, and June 1st, 2019. Articles that studied medical treatment of CLTI patients and reported clinical outcomes were eligible. Main exclusion criteria were case reports <20 patients, incorrect publication type, and CLTI caused by Buerger disease. The primary end point was major amputation (above the ankle) in studies with a follow-up of ≥6 months. Secondary end points were other clinical end points such as death and wound healing. Study quality was assessed according to the Downs and Black checklist.

EVIDENCE SYNTHESIS

Included were 42 articles: four focused on antiplatelet therapy, five on antihypertensive medication, 6 on lipid-lowering therapy, 16 on stem cell therapy, three on growth factors, five on prostanoids, and one study each on cilostazol, glucose-lowering therapy, spinal cord stimulation, sulodexide, and hemodilution. Calcium channel blockers, iloprost, cilostazol, and hemodilution showed significant improvement of limb salvage, but data are limited. Stem cell therapy showed no significant improvement of limb salvage but could potentially improve wound healing. Antiplatelets, antihypertensives, and statins showed significantly lower cardiovascular events rates but not evident lower major amputation rates. The quality of the studies was fair to good.

CONCLUSIONS

Certain medical therapies serve to improve limb salvage next to revascularization in CLTI patients, whereas others are important in secondary prevention. Because high quality evidence is limited, further research is needed.

Iloprost treatment on top of infrapopliteal angioplasty accelerates wound healing in critical leg ischemia

Objectives

This study aimed to examine the efficacy of the concomitant use of infrapopliteal drug-eluting balloon angioplasty and a medical treatment (iloprost) in the treatment of critical leg ischemia.

Methods

Eighty-seven patients that underwent infrapopliteal drug-eluting balloon angioplasty for critical leg ischemia were included in this retrospective study. For analyses, patients were allocated into one of the two groups: 55 patients that underwent drug-eluting balloon angioplasty alone (drug-eluting balloon Group), and 32 patients that received intravenous iloprost for one week after drug-eluting balloon (DEB-I Group). Demographic, perioperative and follow-up clinical data were extracted retrospectively and analyzed.

Results

Duration of hospitalization was significantly longer in the DEB-I group (9.7 vs. 3.1 days, p < 0.001); however, the two groups were similar in terms of other clinical outcomes including early postoperative mortality, and primary patency, wound healing, reintervention, mortality, and amputation rates at one year ( p > 0.05 for all). Primary patency was similar across groups. Wound healing occurred earlier in the DEB-I group when compared to drug-eluting balloon group, in the subgroup of patients with ischemic wound at baseline. Mean time to wound healing was 3.0 ± 0.6 and 4.4 ± 0.6 months in DEB-I and drug-eluting balloon groups, respectively ( p = 0.037).

Conclusions

Iloprost add-on treatment in patients undergoing drug-eluting balloon angioplasty for critical limb ischemia seems to have additional benefits, at least in terms of accelerated wound healing. Further large prospective studies are warranted.

Significance of urinary 11-dehydro-thromboxane B2 in age-related diseases: Focus on atherothrombosis

Platelet activation plays a key role in atherogenesis and atherothrombosis. Biochemical evidence of increased platelet activation in vivo can be reliably obtained through non-invasive measurement of thromboxane metabolite (TXM) excretion. Persistent biosynthesis of TXA₂ has been associated with several ageing-related diseases, including acute and chronic cardio-cerebrovascular diseases and cardiovascular risk factors, such as cigarette smoking, type 1 and type 2 diabetes mellitus, obesity, hypercholesterolemia, hyperhomocysteinemia, hypertension, chronic kidney disease, chronic inflammatory diseases. Given the systemic nature of TX excretion, involving predominantly platelet but also extraplatelet sources, urinary TXM may reflect either platelet cyclooxygenase-1 (COX-1)-dependent TX generation or COX-2-dependent biosynthesis by inflammatory cells and/or platelets, or a combination of the two, especially in clinical settings characterized by low-grade inflammation or enhanced platelet turnover. Although urinary 11-dehydro-TXB₂ levels are largely suppressed with low-dose aspirin, incomplete TXM suppression by aspirin predicts the future risk of vascular events and death in high-risk patients and may identify individuals who might benefit from treatments that more effectively block in vivo TX production or activity. Several disease-modifying agents, including lifestyle intervention, antidiabetic drugs and antiplatelet agents besides aspirin have been shown to reduce TX biosynthesis. Taken together, these aspects may contribute to the development of promising mechanism-based therapeutic strategies to reduce the progression of atherothrombosis. We intended to critically review current knowledge on both the pathophysiological significance of urinary TXM excretion in clinical settings related to ageing and atherothrombosis, as well as its prognostic value as a biomarker of vascular events.

Systemic lupus erythematosus and systemic sclerosis: All roads lead to platelets

Systemic lupus erythematosus (SLE) and systemic sclerosis (SSc) are two phenotypically distincts inflammatory systemic diseases. However, SLE and SSc share pathogenic features such as interferon signature, loss of tolerance against self-nuclear antigens and increased tissue damage such as fibrosis. Recently, platelets have emerged as a major actor in immunity including auto-immune diseases. Both SLE and SSc are characterized by strong platelet system activation, which is likely to be both the witness and culprit in their pathogenesis. Platelet activation pathways are multiple and sometimes redundant. They include immune complexes, Toll-like receptors activation, antiphospholipid antibodies and ischemia-reperfusion associated with Raynaud phenomenon. Once activated, platelet promote immune dysregulation by priming interferon production by immune cells, providing CD40L supporting B lymphocyte functions and providing a source of autoantigens. Platelets are actively implicated in SLE and SSc end-organ damage such as cardiovascular and renal disease and in the promotion of tissue fibrosis. Finally, after understanding the main pathogenic implications of platelet activation in both diseases, we discuss potential therapeutics targeting platelets.

Investigation of Asymmetric and Symmetric Dimethylarginine Levels after Iloprost Treatment in Patients with Buerger's Disease

OBJECTIVE

The aim of this study was to compare the levels of acetyl-dimethylarginine (ADMA), symmetric dimethylarginine (SDMA), and the l-arginine/ADMA ratio before and after iloprost treatment in patients with Buerger's disease.

METHODS

Between January 2011 and December 2015, data from 44 patients (36 males, 8 females, mean age 48.7 ± 18.1 years) with the diagnosis of Fontaine Stage III-IV Buerger's disease were included. Iloprost infusion was administered intravenously through the forearm veins for 7 days at a dose of 0.5-1.5 ng/kg/min over 16 h. Blood samples were collected before and after treatment for measurement of ADMA, SDMA, and l-arginine. ADMA, SDMA, l-arginine levels were measured using high performance liquid chromatography (HPLC).

RESULTS

After iloprost treatment, ADMA and SDMA levels significantly decreased (p = .001). The increase in the l-arginine levels was not significant (p = .16). However, the l-arginine/ADMA ratio increased significantly (p = .001).

CONCLUSION

Iloprost treatment decreases ADMA and SDMA, which are associated with endothelial dysfunctions in patients with Buerger's disease. Of note, the still higher than normal range of SDMA levels after iloprost treatment suggests that treatment should continue until SDMA levels are within the normal range in this patient population.

Endothelial Dysfunction in Resuscitated Cardiac Arrest (ENDO-RCA): safety and efficacy of low-dose prostacyclin administration and blood pressure target in addition to standard therapy, as compared to standard therapy alone, in post-cardiac arrest syndrome patients: study protocol for a randomized controlled trial

BACKGROUND

Morbidity and mortality following initial survival of cardiac arrest remain high despite great efforts to improve resuscitation techniques and post-resuscitation care, in part due to the ischemia-reperfusion injury secondary to the restoration of the blood circulation. Patients resuscitated from cardiac arrest display evidence of endothelial injury and coagulopathy (hypocoagulability, hyperfibrinolysis), which in associated with poor outcome. Recent randomized controlled trials have revealed that treatment with infusion of prostacyclin reduces endothelial damage after major surgery and AMI. Thus, a study is pertinent to investigate if prostacyclin infusion as a therapeutic intervention reduces endothelial damage without compromising, or even improving, the hemostatic competence in resuscitated cardiac arrest patients. Post-cardiac arrest patients frequently have a need for vasopressor therapy (catecholamines) to achieve the guideline-supported blood pressure goals. To evaluate a possible catecholamine interaction with the primary endpoints of this study, included patients will be randomized into two different blood pressure goals within guideline-recommended targets.

METHODS/DESIGN

A randomized, placebo-controlled, double-blind investigator-initiated pilot trial in 40 out-of-hospital-cardiac-arrest (OHCA) patients will be conducted. Patients will be randomly assigned to either the active treatment group (48 hours of active study drug (iloprost, 1 ng/kg/min) or to the control group [placebo (saline) infusion]. Target mean blood pressure levels will be allocated 1:1 to 65 mmHg or approximately 75 mmHg, which gives four different permutations, namely: (i) iloprost/65 mHg, (ii) iloprost/75 mmHg, (iii) placebo/65 mmHg, and (iv) placebo/75 mmHg. All randomized patients will be treated in accordance with state-of-the art therapy including targeted temperature management. The primary endpoint of this study is change in biomarkers indicative of endothelial activation and damage, [soluble thrombomodulin (sTM), sE-selectin, syndecan-1, soluble vascular endothelial growth factor (sVEGF), nucleosomes] and sympathoadrenal over activation (epinephrine/norepinephrine) from baseline to 48 hours post-randomization. The secondary endpoints of this trial will include: (1) the hemostatic profile [change in functional hemostatic blood test (thrombelastography (TEG) and whole blood platelet aggregometry (multiplate)) blood cell and endothelial cell-derived microparticles]; (2) feasibility of blood pressure target intervention (target 90 %); (3) interaction of primary endpoints and blood pressure target; (4) levels of neuron-specific enolase at 48 hours post-inclusion according to blood pressure targets.

DISCUSSION

The ENDO-RCA study is a pilot study trial that investigates safety and efficacy of low-dose infusion of prostacyclin administration as compared to standard therapy in post-cardiac arrest syndrome patients.

TRIAL REGISTRATION

Trial registration at ClinicalTrials.gov (identifier NCT02685618 ) on 18 February 2016.

Comparison of hyperbaric oxygen versus iloprost treatment in an experimental rat central retinal artery occlusion model

PURPOSE

Central retinal artery occlusion (CRAO) is one of the serious ophthalmological emergencies with poor visual prognosis. Iloprost is a stable prostacyclin analogue and has prominent anti-edema, anti-inflammatory, vasodilatory, and antiagregant effects. The main objective of this work was to investigate iloprost as an alternative agent versus hyperbaric oxygen (HBO) in the treatment of CRAO.

METHODS

Twenty-eight healthy Wistar albino male rats were randomly assigned into control (n = 7, sham operation), HBO (n = 7), iloprost (n = 7), and sham groups (n = 7). CRAO model was created through optic nerve exploration and ligation. Full-thickness retina (FTR), outer nuclear layer (ONL), inner nuclear layer (INL) and ganglion cell layer (GCL) thickness were measured on Hematoxylin/Eosin (H&E) stained retinal sections and immunohistochemical analysis including terminal deoxynucleotidyl transferase-mediated biotindeoxyuridine triphosphate nick-end labeling (TUNEL) assay was performed to determine the apoptotic index (AI).

RESULTS

AI values of HBO (0.204 ± 0.067) and iloprost (0.197 ± 0.052) groups were significantly lower than sham (0.487 ± 0.046) group (p < 0.001). Any significant difference was found between the HBO and iloprost groups in terms of AI (p = 0.514). A statistically significant increase in thickness of FTR, ONL, INL and GCL was detected in HBO, iloprost and sham groups compared to the control group (p = 0.002). FTR, ONL, INL and GCL thickness were significantly thinner in HBO and iloprost groups than in the sham group (p = 0.002). A significant lesser increase was observed in all the retinal layers thickness in iloprost group versus HBO group (p = 0.002) except for INL (p = 0.665).

CONCLUSIONS

The study results demonstrated anti-edema, neuroprotective, and anti-apoptotic effects of iloprost quantitatively; thus, iloprost may be a beneficial alternative agent in the treatment of CRAO.

Normal platelet activation profile in patients with peripheral arterial disease on aspirin

BACKGROUND

Peripheral arterial disease (PAD) is a progressive vascular disease associated with a high risk of cardiovascular morbidity and death. Antithrombotic prevention is usually applied by prescribing the antiplatelet agent aspirin. However, in patients with PAD aspirin fails to provide protection against myocardial infarction and death, only reducing the risk of ischemic stroke. Platelets may play a role in disease development, but this has not been tested by proper mechanistic studies. In the present study, we performed a systematic evaluation of platelet reactivity in whole blood from patients with PAD using two high-throughput assays, i.e. multi-agonist testing of platelet activation by flow cytometry and multi-parameter testing of thrombus formation on spotted microarrays.

METHODS

Blood was obtained from 40 patients (38 on aspirin) with PAD in majority class IIa/IIb and from 40 age-matched control subjects. Whole-blood flow cytometry and multiparameter thrombus formation under high-shear flow conditions were determined using recently developed and validated assays.

RESULTS

Flow cytometry of whole blood samples from aspirin-treated patients demonstrated unchanged high platelet responsiveness towards ADP, slightly elevated responsiveness after glycoprotein VI stimulation, and decreased responsiveness after PAR1 thrombin receptor stimulation, compared to the control subjects. Most parameters of thrombus formation under flow were similarly high for the patient and control groups. However, in vitro aspirin treatment caused a marked reduction in thrombus formation, especially on collagen surfaces. When compared per subject, markers of ADP- and collagen-induced integrin activation (flow cytometry) strongly correlated with parameters of collagen-dependent thrombus formation under flow, indicative of a common, subject-dependent regulation of both processes.

CONCLUSION

Despite of the use of aspirin, most platelet activation properties were in the normal range in whole-blood from class II PAD patients. These data underline the need for more effective antithrombotic pharmacoprotection in PAD.

The effect of iloprost on renal function in patients with critical limb ischemia

BACKGROUND

Iloprost, which has efficacy in the microvascular space, is shown to have beneficial effects on the kidney, which has an extensive microvascular network.

OBJECTIVE

We aimed to evaluate the effect of iloprost treatment on kidney functions in patients with critical limb ischemia.

METHODS

Forty-eight patients with critical limb ischemia who were not suitable for revascularization and who were treated with iloprost were evaluated prospectively in our clinic between September 2010 and December 2012. The patients were divided into 2 groups as patients with chronic renal dysfunction (Group I) and patients with normal renal function (Group II). Urine albumin:creatinine ratio and glomerular filtration rate (GFR) calculated using serum creatinine and serum cystatin C (GFRcyc) were used to establish the presence of renal dysfunction. The decrease analgesic requirement, walking distance, reduction in ulcer diameter, the increase in ankle-brachial index, and changes in The Society of Vascular Surgery/International Society of Cardiovascular Surgery criteria were used in the evaluation of treatment response.

RESULTS

Opioid analgesic requirement and decubitus pain disappeared after treatment in 58.3% (n = 28) of subjects. Walking distance increased in 66.6% (n = 32). Iloprost treatment significantly increased ankle-brachial index (P < 0.01). In Group I the levels of serum urea, creatinine, and cystatin C significantly decreased (P < 0.05), whereas GFRcyc and GFR calculated using the equation of the Chronic Kidney Disease Epidemiology Collaboration (ie, GFR expressed for specified race, sex, and serum creatinine in milligrams per deciliter) was increased significantly compared with pretreatment levels (P < 0.05). No significant change was observed in urine albumin:creatinine ratio (P > 0.05).

CONCLUSIONS

The use of iloprost in critical limb ischemia can slow down the progress of early stage renal damage. GFRcyc and cystatin C, which are indicators of early stage chronic renal dysfunction, can be used for the evaluation of treatment response.

Autologous bone marrow cell therapy for peripheral arterial disease

Inadequate blood supply to tissues caused by obstruction of arterioles and/or capillaries results in ischemic injuries – these injuries can range from mild (eg, leg ischemia) to severe conditions (eg, myocardial infarction, stroke). Surgical and/or endovascular procedures provide cutting-edge treatment for patients with vascular disorders; however, a high percentage of patients are currently not treatable, owing to high operative risk or unfavorable vascular involvement. Therapeutic angiogenesis has recently emerged as a promising new therapy, promoting the formation of new blood vessels by the introduction of bone marrow–derived stem and progenitor cells. These cells participate in the development of new blood vessels, the enlargement of existing blood vessels, and sprouting new capillaries from existing blood vessels, providing evidence of the therapeutic utility of these cells in ischemic tissues. In this review, the authors describe peripheral arterial disease, an ischemic condition affecting the lower extremities, summarizing different aspects of vascular regeneration and discussing which and how stem cells restore the blood flow. The authors also present an overview of encouraging results from early-phase clinical trials using stem cells to treat peripheral arterial disease. The authors believe that additional research initiatives should be undertaken to better identify the nature of stem cells and that an intensive cooperation between laboratory and clinical investigators is needed to optimize the design of cell therapy trials and to maximize their scientific rigor. Only this will allow the results of these investigations to develop best clinical practices. Additionally, although a number of stem cell therapies exist, many treatments are performed outside international and national regulations and many clinical trials have been not registered on databases such as ClinicalTrials.gov or EudraCT. Therefore, more rigorous clinical trials are required to confirm the first hopeful results and to address the challenging issues.

Critical limb ischemia

Critical limb ischemia (CLI) represents the most advanced clinical stage of peripheral arterial disease. It is usually caused by obstructive atherosclerotic arterial disease and is associated with very high morbidity and mortality. The pathophysiology of CLI is a complex and chronic process affecting the macrovascular and microvascular circulation of the muscle and non-muscle tissues of the lower limbs. In particular, the atherosclerosis-related vascular remodelling, angiogenesis and arteriogenesis are central phenomena in the process. The most common clinical manifestations of CLI are limb pain at rest, with or without trophic skin changes or tissue loss. Diagnosis of CLI is based on physical examination, ankle-brachial index measurement, duplex-ultrasound and angiography; transcutaneous oxygen may also help. Risk factor control is recommended for all patients with CLI. Individuals with minimal or no skin breakdown or in whom comorbid conditions avoid revascularization can be treated with medical therapy (antiplatelet agents, intravenous prostanoids, rheologic agents). Treatment of infection is mandatory to decrease the metabolic demands that hamper wound healing. Therapeutic angiogenesis has been pursued with several approaches ranging from gene therapy to the use of bone marrow-derived progenitor cells, but further phase II and III trials are needed. Finally, the evaluation of the risk, benefit and optimal timing of revascularization lesions or the decision about amputation and its extension is a complex decision that requires a multidisciplinary approach.