Therapeutic angiogenesis in Buerger's disease: reviewing the treatment landscape

Thromboangiitis obliterans, also known as Buerger's disease, is a rare inflammatory vasculitis that predominantly develops in smokers and characteristically affects the small- and medium-sized peripheral arteries and veins. Patients typically present with extremity claudication, but symptoms may progress to rest pain and tissue loss, especially in those unable to abstain from tobacco use. Unfortunately, traditional medical treatments are largely ineffective and due to the small caliber of affected vessels and lack of suitable distal targets or venous conduits, endovascular and open surgical approaches are often not possible. Eventually, a significant number of patients require major amputation. For these reasons, much research effort has been made in developing techniques of therapeutic angiogenesis to improve limb perfusion, both for atherosclerotic peripheral arterial disease and the smaller subset of patients with critical limb ischemia due to Buerger's disease. Neovascularization in response to ischemia relies on a complex interplay between the local tissue microenvironment and circulating stem and progenitor cells. To date, studies of therapeutic angiogenesis have therefore focused on exploiting known angiogenic factors and stem cells to induce neovascularization in ischemic tissues. This review summarizes the available clinical data regarding the safety and efficacy of various angiogenic therapies, notably injection of naked DNA plasmids, viral gene constructs, and cell-based preparations, and describes techniques for potentiating in vivo efficacy of gene- and cell-based therapies as well as ongoing developments in exosome-based cell-free approaches for therapeutic angiogenesis.

Plain Language Title and Summary

A review of available and emerging treatments for improving blood flow and wound healing in patients with Buerger's disease, a rare disorder of blood vessels Buerger's disease is a rare disorder of the small- and medium-sized blood vessels in the arms and legs that almost exclusively develops in young smokers. Buerger's disease causes inflammation in arteries and veins, which leads to blockage of these vessels and reduces blood flow to and from the extremities. Decreased blood flow to the arms and legs can lead to development of nonhealing wounds and infection for which some patients may eventually require amputation. Unfortunately, traditional medical and surgical treatments are not effective in Buerger's disease, so other methods for improving blood flow are needed for these patients. There are several different ways to stimulate new blood vessel formation, both in humans and animal models. The most common treatments involve injection of DNA or viruses that express genes related to blood vessel formation or, alternatively, stem cell-based treatments that help regenerate blood vessels and repair wound tissue. This review explores how safe and effective these various treatments are and describes recent research developments that may lead to better therapies for patients with Buerger's disease and other vascular disorders.

Risk Factors, Mechanisms and Treatments of Thromboangiitis Obliterans: An Overview of Recent Research

BACKGROUND

Thromboangiitis obliterans (TAO) is a nonatherosclerotic thromboticocclusive vasculitis that affects the vessels of the small and medium-sized extremities. No explicit etiology or pathogenesis of TAO has been proven, and more effective treatments are needed.

OBJECTIVE

The study aimed to summarize and present an overview of recent advances regarding the risk factors, mechanisms and treatments of TAO and to organize the related information in figures to provide a comparatively complete reference.

METHODS

We searched PubMed for English-language literature about TAO without article type limits, including articles about the risk factors, pathological mechanisms and treatments of TAO in the last 10 years with essential supplements (references over ranges and English abstracts of Russian literature).

RESULTS

After screening content of works of literature, 99 references were evaluated. We found that risk factors of TAO include smoking, gene factors and periodontal diseases. The underlying mechanism of TAO involves oxidative stress, immunity, hemodynamic changes, inflammation and so on. Moreover, similarities in genetic factors and cigarette relevance existed between periodontal diseases and TAO, so further study of relationship was required. For TAO treatment, medicine, endovascular intervention and revascularization surgery, autologous cell therapy and novel therapies were also mentioned. Besides, a hypothesis that infection triggers autoimmunity in TAO could be speculated, in which TLR4 plays a key role.

CONCLUSION

1. A hypothesis is put forward that infections can trigger autoimmunity in TAO development, in which TLR4, as a key agent, can activate immune signaling pathways and induce autoimmune cytokines expression. 2. It is suggested to reconsider the association between periodontal diseases and TAO, as they share the same high-risk population. Controlling periodontal disease severity in TAO studies may provide new clues. 3. For TAO treatment, endovascular intervention and autologous cell therapy both showed promising long-term therapeutic effectiveness, in which autologous cell therapy is becoming more popular, although more clinical comparisons are needed.

The Imbalance among Oxidative Biomarkers and Antioxidant Defense Systems in Thromboangiitis Obliterans (Winiwarter-Buerger Disease)

(1) Background: Thromboangiitis obliterans or Winiwarter-Buerger disease (WBD), is an inflammatory, thrombotic occlusive, peripheral vascular disease, usually occurring in young smokers. The pathophysiological mechanisms underlying the disease are not clearly understood. The aim of this study is to investigate the imbalance between oxidants and antioxidants occurring in these patients. (2) Patients and Methods: In this cross-sectional study, 22 male patients with WBD and 20 healthy male smoking habit matched control group were included. To evaluate the possible sources of oxidative stress, the antioxidant biomarkers, and the markers of lipid peroxidation and protein oxidation, serum samples were analyzed for total oxidative status (TOS), total antioxidant capacity (TAC), myeloperoxidase (MPO), coenzyme Q10 (CoQ10), superoxide dismutase (SOD), glutathione reductase (GR), malondialdehyde (MDA), and protein carbonyl (PC) activity and/or content. (3) Results: The circulating levels of TOS, TAC, and CoQ10 were significantly higher in WBD patients, with respect to healthy smokers as controls. No significant difference was found among the serum level of PC, total cholesterol, MPO, and GR activity in WBD patients and healthy smoker controls. The activity of SOD and the mean serum level of MDA were significantly lower in WBD patients, with respect to healthy smoker controls. (4) Conclusion: Considerably high levels of oxidative stress were detected in WBD patients, which were greater than the antioxidant capacity. The low level of MDA may be associated with the enzymatic degradation of lipid peroxidation products. High levels of CoQ10 and low levels of SOD may be related to a harmful oxidative cooperation, leading to the vasoconstriction of WBD, representing a promising tool to discern possible different clinical risks of this poorly understood peripheral occlusive disease.

A Non-smoking Woman with Anti-phospholipid Antibodies Proved to Have Thromboangiitis Obliterans

A 48-year-old woman with severe pain and numbness of her right leg and foot was admitted to our hospital. She had never smoked and had little exposure to passive smoking. Initially, polyarteritis nodosa with anti-phospholipid antibodies was considered. Combination therapy with methylprednisolone pulse therapy, intravenous cyclophosphamide pulse therapy, vasodilators, antiplatelet agents, and anticoagulants was not effective. Vasculopathy was progressive, and she presented with gangrene of the toes. She required amputation of her right leg. The pathological findings of the amputated leg revealed thromboangiitis obliterans (TAO). TAO should be considered even in non-smoking women. Non-response to immunosuppressant and anticoagulant therapies may be a clue to the diagnosis of TAO.

Molecular mechanisms regulating immune responses in thromboangiitis obliterans: A comprehensive review

Thromboangiitis obliterans (TAO) is a thrombotic-occlusive as well as an inflammatory peripheral vascular disease with unknown etiology. Recent evidence has supported the immunopathogenesis of the disease, however, the factors contributing to the altered immune function and vascular tissue inflammation are still unclear. This review was intended to collate the more current knowledge on the regulatory molecules involved in TAO from an immunoreactive perspective. The homeostasis of the immune system as well as a variety of progenitor cell populations appear to be affected during TAO and these alterations are associated with intrinsic signaling defects that are directing to an improved understanding of the crosstalk between angiogenesis and the immune system, as well as the potential of new co-targeting strategies applying both immunotherapy and angiogenic therapy.

Shenfu injection protects human ECV304 cells from hydrogen peroxide via its anti-apoptosis way

ETHNOPHARMACOLOGICAL RELEVANCE

The pathogenesis of thromboangiitis obliterans (TAO) has not been fully elucidated until now. Shenfu injection (SFI), a traditional Chinese formula has been widely used clinically for the treatment of cardiovascular diseases for more than two decade. Our previous results first suggested that SFI can cause a significant therapeutic effect on experimental TAO model rats. This experiment was designed to further investigate the protective effect of SFI on VEC damaged by hydrogen peroxide (H2O2) oxidative stress in vitro.

METERIALS AND METHODS

The cell viability was evaluated by the MTT assay, the activities of SOD and GSH-PX and the content of MDA in the supernatants of the cultured ECV304 cells were evaluated by a colorimetry method, cell apoptosis was detected by flow cytometry and an AO/EB double staining method. The protein expressions of Bcl2, Bax and caspase-3 were examined by Western blotting.

RESULTS

When compared with control group, lower survival rate of ECV304 cells was observed in H2O2 group (p<0.01) ; 20μl/ml, 30μl/ml and 40μl/ml SFI increased the survival rate of ECV304 cells under H2O2 oxidative stress (p<0.05 and p<0.01). The activities of SOD and GSH-PX were higher and MDA level was lower in H2O2 group than those in control group. These effects of H2O2 on SOD, GSH-PX activities and MDA content were reversed by SFI in concentration-dependent way (p<0.05 and p<0.01). Flow cytometry and AO-EB double staining discovered that SFI pretreatment inhibited the ECV304 cells apoptosis. The protein expression of caspase3 in 30μl/ml and 40μl/ml SFI groups significantly decreased whereas Bcl2 protein expressions in 20μl/ml, 30μl/ml and 40μl/ml SFI groups were higher than H2O2 group, with Bax protein expression much lower than H2O2 group (p<0.05 and p<0.01).

CONCLUSIONS

Our findings suggest that SFI could prevent the ECV304 cells against H2O2 oxidative-stress by enhancing antioxidant enzyme activities, reducing the membrane lipid peroxidation, as well as upregulating antiapoptotic and downregulating apoptosis protein expressions.