Endothelial Progenitor Cells and Their Potential Clinical Applications in Peripheral Arterial Disease

TWEAK promotes endothelial progenitor cell vasculogenesis to alleviate acute myocardial infarction via the Fn14-NF-κB signaling pathway

Acute myocardial infarction (AMI) remains one of the leading causes of mortality worldwide; however, endothelial progenitor cell (EPC) transplantation has been proposed as a promising treatment strategy for EPC. High levels of tumor necrosis factor-related weak inducer of apoptosis (TWEAK) have been reported in AMI, although its effect on EPCs has not been reported. In the present study, immunofluorescence and flow cytometry were performed to assess the effect of TWEAK in isolated mouse EPCs. Echocardiography was used to evaluate the cardiac function of murine hearts following EPC treatment in the AMI model, while collagen synthesis within the heart tissue was assessed using Masson's trichrome staining. A tube formation assay and Transwell migration assay were performed to investigate the effects of TWEAK on vessel formation and EPC migration in vitro. Angiogenesis and arteriogenesis were assessed in vivo using immunohistochemistry and western blotting was performed to determine the effect of TWEAK-mediated nuclear factor (NF)-κB pathway activation in EPCs. The results revealed that TWEAK promotes EPC migration, tube formation and viability in vitro. Furthermore, TWEAK treatment resulted in improved cardiac function, decreased heart collagen and vasculogenesis in mice with AMI, which was mediated by the TWEAK- fibroblast growth factor-inducible 14 (Fn14)-NF-κB signaling pathway, as determined using Fn14 small interfering (si)RNA and Bay 11–7082 (an NF-κB inhibitor). In summary, the results of the present study suggest that activation of the TWEAK-Fn14-NF-κB signaling pathway exerts a beneficial effect on EPCs for the treatment of AMI.

Scaffolds and Cell-Based Tissue Engineering for Blood Vessel Therapy

The increasing morbidity of cardiovascular diseases in modern society has made it crucial to develop a small-caliber blood vessel. In the absence of appropriate autologous vascular grafts, an alternative prosthesis must be constructed for cardiovascular disease patients. The aim of this article is to describe the advances in making cell-seeded cardiovascular prostheses. It also discusses the combinations of types of scaffolds and cells, especially autologous stem cells, which are suitable for application in tissue-engineered vessels with the favorable properties of mechanical strength, antithrombogenicity, biocompliance, anti-inflammation, fatigue resistance and long-term durability. This article highlights the advancements in cellular tissue-engineered vessels in recent years.

Stem cell mediated cardiovascular repair

Recent increase in the interest in stem and progenitor cells may be attributed to their behavioural characteristics. A consensus has been reached that embryonic or adult stem cells have therapeutic potential. As cardiovascular health issues are still the major culprits in many developed countries, stem and progenitor cell driven approaches may give the clinicians a new arsenal to tackle many significant health issues. However, stem and progenitor cell mediated cardiovascular regeneration can be achieved via complex and dynamic molecular mechanisms involving a variety of cells, growth factors, cytokines, and genes. Functional contributions of transplanted cells on target organs and their survival are still critical problems waiting to be resolved. Moreover, the regeneration of contracting myocardial tissue has controversial results in human trials. Thus, moderately favourable clinical results should be interpreted carefully. Determining the behavioural programs, genetic and transcriptional control of stem cells, mechanisms that determine cell fate, and functional characteristics are the primary targets. In addition, ensuring the long-term follow-up of cells with efficient imaging techniques in human clinical studies may provide a resurgence of the initial enthusiasm, which has faded over time. Here, we provide a brief historical perspective on stem cell driven cardiac regeneration and discuss cardiac and vascular repair in the context of translational science.

ECM-based materials in cardiovascular applications: Inherent healing potential and augmentation of native regenerative processes

The in vivo healing process of vascular grafts involves the interaction of many contributing factors. The ability of vascular grafts to provide an environment which allows successful accomplishment of this process is extremely difficult. Poor endothelisation, inflammation, infection, occlusion, thrombosis, hyperplasia and pseudoaneurysms are common issues with synthetic grafts in vivo. Advanced materials composed of decellularised extracellular matrices (ECM) have been shown to promote the healing process via modulation of the host immune response, resistance to bacterial infections, allowing re-innervation and reestablishing homeostasis in the healing region. The physiological balance within the newly developed vascular tissue is maintained via the recreation of correct biorheology and mechanotransduction factors including host immune response, infection control, homing and the attraction of progenitor cells and infiltration by host tissue. Here, we review the progress in this tissue engineering approach, the enhancement potential of ECM materials and future prospects to reach the clinical environment.

Blood Outgrowth Endothelial Cells as a Vehicle for Transgene Expression of Hepatocyte-Secreted Proteins viaSleeping Beauty

The therapeutic use of autologous cells with the capacity for extensive in vitro expansion and manipulation prior to host administration has been an area of significant investigation over the last decade. Blood outgrowth endothelial cells (BOECs) are derived from the circulation and exhibit proliferative growth, in vivo engraftment, and survival characteristics for long-term expression of endogenously secreted proteins, such as factor VIII (FVIII). The authors describe a modified method for the isolation, culture, and expansion of these cells that is readily accomplished using standard laboratory methods. Using a commercially available transfection reagent, approximately 30% of these primary cells can be routinely transfected with the nonviral Sleeping Beauty transposon for long-term, stable transgene expression. Moreover, the results indicate that these cells have the ability to secrete functionally active proteins that are synthesized endogenously by hepatocytes and require post-translational modification including alpha1-antitrypsin and clotting factors VII and IX. This, coupled with their notably long half-life of years, suggests that these cells may provide an appropriate vehicle for secretion of a variety of proteins produced by different cell types in vivo. Thus, BOECs have the potential to provide clinically relevant secreted proteins for diseases other than those of endothelial origin.

Late outgrowth endothelial cells derived from Wharton jelly in human umbilical cord reduce neointimal formation after vascular injury: involvement of pigment epithelium-derived factor

OBJECTIVE

The number of endothelial progenitor cells (EPCs) that can be obtained from adult bone marrow and peripheral blood to treat cardiovascular diseases is limited. The goal was to examine the endothelial potential of Wharton jelly in human umbilical cord (WJC)-derived stem cells and evaluate their potential to affect neointimal formation after vascular injury.

METHODS AND RESULTS

Mesenchymal cells (MCs) were isolated from WJC and cultured in endothelial growth medium. Differentiation into late outgrowth endothelial cells (WJC-OECs) was demonstrated by incorporation of acetylated low-density lipoprotein and expression of the endothelial-specific markers. Transplantation of these cells into wire-injured femoral arteries in mice led to rapid reendothelialization. At 4 weeks after injury, the neointima/media area ratio was reduced and strong expression of pigment epithelium-derived factor (PEDF) compared to saline-or MC- or cord blood-OEC-treated mice. WJC-OECs-conditioned medium has an extremely strong capacity to inhibit the migration and proliferation of smooth muscle cells. The effects were inhibited by neutralizing antibody for PEDF and by siRNA silencing of PEDF.

CONCLUSIONS

We firstly demonstrated the presence of a cell population within WJC that has the potential to differentiate into OECs. Transplantation of WJC-OECs may play a crucial role in reestablishing endothelial integrity in injured vessels, thereby inhibiting neointimal hyperplasia. These findings have implications for a novel and practical cell-based therapy for vascular diseases.

Endothelial function, arterial stiffness and lipid lowering drugs

The endothelium is a dynamic organ that plays a pivotal role in cardiovascular homeostasis. Alteration in endothelial function precedes the development of atherosclerosis and contributes to its initiation, perpetuation and clinical manifestations. It has been suggested that the assessment of endothelial function could represent a barometer of vascular health that could be used to gauge cardiovascular risk. This review summarises the various methods used to assess endothelium-dependent vasodilatation and their potential prognostic implications. In addition, the techniques used to evaluate arterial stiffness are discussed. The latter is to some extent controlled by the endothelium and has been the subject of considerable research in recent years. This paper also discusses the effects of lipid lowering treatment on both endothelial function and arterial stiffness.

Statins and Peripheral Arterial Disease: Potential Mechanisms and Clinical Benefits

Peripheral arterial disease (PAD) is a manifestation of widespread atherosclerosis. Lipid modification (especially with statins) is a component of the treatment of patients with PAD since this condition is considered a coronary heart disease equivalent. This review considers the mechanism of action of statins in PAD. Statins have been shown to reduce the incidence of new coronary events in patients with PAD. However, surveys suggest that many such patients remain undertreated. Statins can also increase walking distance in patients with PAD. There is also evidence that statins can improve renal function in these patients. Several other actions of statins are considered in this review. PAD patients have an increased morbidity and mortality, largely due to myocardial infarction and stroke. Recognizing and treating these high-risk patients as early as possible should be a priority.