Peripheral arterial disease (PAD) usually results from atherosclerosis and associated thrombosis and limits blood supply to the lower limbs. Common presenting symptoms include intermittent claudication (IC), rest pain and tissue loss. When limb viability is threatened, known as critical limb ischaemia (CLI), surgical and endovascular interventions are frequently undertaken; however, these are not always successful and ultimately major amputation may be required. There is significant interest in developing new therapeutic approaches to manage PAD which can be applied to patients unlikely to benefit from interventional approaches. Many of the therapeutic agents successful in inducing angiogenesis and arteriogenesis in pre-clinical animal models of PAD have failed to have efficacy in human randomized control trials. One possible reason for this inability to translate findings to patients could be the type of pre-clinical animal models used. In the present review, we describe currently available pre-clinical models of PAD and discuss the advantages and disadvantages of the available models. A detailed assessment of the currently available pre-clinical animal models shows major limitations such as variability in the surgical procedure used to induce limb ischaemia, variability in the strains of rodents used, lack of risk factors incorporated into the model and lack of standardized functional outcomes. The most commonly used outcome assessments in studies within pre-clinical models differ from those employed in clinical trials within PAD patients. Most current pre-clinical models are designed to produce acute ischaemia which leads to muscle necrosis and inflammation. Patients, however, most commonly present with chronic ischaemia suggesting that more representative models are needed to evaluate therapeutic modalities that can be potentially translated to clinical practice.

peripheral arterial disease (pAD) develops due to the narrowing or blockage of arteries supplying blood to the lower limbs. Surgical and endovascular interventions are the main treatments for advanced pAD but alternative and adjunctive medical therapies are needed. currently the main preclinical experimental model employed in pAD research is based on induction of acute hind limb ischemia (HLI) by a 1-stage procedure. Since there are concerns regarding the ability to translate findings from this animal model to patients, we aimed to develop a novel clinically relevant animal model of pAD. HLi was induced in male Apolipoprotein e (ApoE −/− ) deficient mice by a 2-stage procedure of initial gradual femoral artery occlusion by ameroid constrictors for 14 days and subsequent excision of the femoral artery. This 2-stage HLI model was compared to the classical 1-stage HLI model and sham controls. ischemia severity was assessed using Laser Doppler perfusion imaging (LDpi). Ambulatory ability was assessed using an open field test, a treadmill test and using established scoring scales. Molecular markers of angiogenesis and shear stress were assessed within gastrocnemius muscle tissue samples using quantitative polymerase chain reaction. HLI was more severe in mice receiving the 2-stage compared to the 1-stage ischemia induction procedure as assessed by LDPI (p = 0.014), and reflected in a higher ischemic score (p = 0.004) and lower average distance travelled on a treadmill test (p = 0.045). Mice undergoing the 2-stage HLI also had lower expression of angiogenesis markers (vascular endothelial growth factor, p = 0.004; vascular endothelial growth factor-receptor 2, p = 0.008) and shear stress response mechano-transducer transient receptor potential vanilloid 4 (p = 0.041) within gastrocnemius muscle samples, compared to animals having the 1-stage HLI procedure. Mice subjected to the 2-stage HLI receiving an exercise program showed significantly greater improvement in their ambulatory ability on a treadmill test than a sedentary control group. this study describes a novel model of HLi which leads to more severe and sustained ischemia than the conventionally used model. Exercise therapy, which has established efficacy in PAD patients, was also effective in this new model. this new model maybe useful in the evaluation of potential novel pAD therapies.Peripheral arterial disease (PAD) leads to impaired lower limb blood supply usually as a result of atherosclerosis and associated thrombosis 1 . In 2010 an estimated 200 million people worldwide were living with PAD, an increase of ~30% since 2000 which has been referred to as a PAD pandemic 2,3 . The burden of PAD is increasing worldwide and particularly within low and middle-income countries 4 . PAD is associated with significant morbidity including intense leg pain during walking (intermittent claudication, IC), impaired walking ability, poor health-related quality of life and risk of serious complications such as major leg amputation and death 1 . Medical management of PAD is ...

This meta-analysis suggests that low levels of circulating 25(OH)D are associated with PAD presence, particularly in patients presenting with CLI. These data suggest the possibility that vitamin D insufficiency may contribute to the development of more advanced PAD although this remains to be confirmed.

Diets rich in flavonoids have been reported to have beneficial effects in the primary prevention of cardiovascular events. There are limited data, however, on the cardiovascular benefits of purified flavonoids. The aim of this systematic review and meta-analysis was to examine the reported effects of isolated flavonoids on aortic atherosclerosis in a mouse model. Medline, Pubmed, Science direct and Web of Science were searched to identify studies which examined the effect of isolated flavonoids on aortic atherosclerosis in apolipoprotein E deficient mice. A meta-analysis was performed to determine the overall effect of the flavonoids, and sub-analyses were performed to compare the effects of the flavonols and flavan-3-ols. Eleven studies, which examined a total of 208 mice receiving a flavonoid and 126 control mice, were included. Overall the flavonoids significantly reduced aortic atherosclerosis (SMD 1.10, 95% CI 0.69, 1.51). Of the 18 flavonoid interventions examined 12 were flavonols and 3 were flavan-3-ols. Sub-analyses suggested that the flavonols (SMD 1.31, 95% CI 0.66, 1.91) but not the flavan-3-ols (SMD 0.33, 95% CI -0.19, 0.85) significantly decreased atherosclerosis area. Of the eleven studies, only one examined histological markers of atherosclerosis plaque stability. Most studies did not report blinding of outcome assessors or reproducibility of the primary outcome, and did not justify the sample size used and flavonoid dose administered. Based on the included studies, the flavonols appear to be the most effective flavonoids for reducing aortic atherosclerotic lesion area in apolipoprotein E deficient mice.

The identified studies suggest that ETSCs improve recovery of limb blood supply within current animal HLI models. Improved study quality is, however, needed to provide support for the likelihood of translating these findings to patients with PAD.