Catálogo de publicaciones - libros

Several vascular growth factors have the potential to induce angiogenesis in ischemic tissue. However, only vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF) have been tested in clinical studies of patients with coronary artery disease. Several small and unblinded studies with either recombinant growth factor proteins or genes encoding the growth factors have been performed in patients with severe CAD and results have been encouraging, demonstrating both clinical improvement and evidence of angiogenesis. However, a few larger double-blind randomised placebo-controlled studies have not been able to confirm the initial high efficacy of the growth factor therapy. Ongoing clinical trials with increased gene dose will demonstrate whether the used methodologies and genes are effective. In future trials one have to consider whether improved transfection vectors, combination of genes and stem cells or gene transfected cells will enhance the efficacy of the treatments. The conducted clinical studies with growth factor therapies have all been without any gene related adverse events, which supports the initiation of more large scaled clinical trials to evaluate whether vascular growth factor therapy either as a gene or recombinant slow-release protein formulation therapy could be a new treatment modality to patients with severe coronary artery disease, which cannot be treated with conventional revascularization

Viral vectors are essential for effective transgene expression . Revascularisation therapies of ischemic tissues with adenoviruses, the most commonly used vectors for gene therapy trials, encoding angiogenic growth factors remain an intriguing option for patients who cannot be treated with conventional revascularisation therapies. Adenoviruses yield very high, but transient, gene expression and are very effective in preclinical angiogenic gene therapy trials. Studies of angiogenic growth factors using adenoviral vectors in rabbit skeletal muscle have shown that even 30-fold increases in muscle perfusion can be achieved. Such increases have not been reported with any other vector or transfection technique. In clinical trials adenoviruses have been well tolerated and safe. However, only a very few positive results on clinical endpoints have been reported. In this chapter we summarise basic knowledge about adenoviruses, their strengths and weaknesses, and discuss how the strengths of adenoviruses could be better exploited to achieve positive results in future clinical trials

Diabetes mellitus (DM) leads to multiple alterations in nearly any organ and nearly any cell type. The most dramatic effects occur in vascular tissue leading to the development of diabetic macroangiopathy (accelerated atherosclerosis) and diabetic microangiopathy. The negative influences of DM leading to microangiopathy are largely based on mechanisms that negatively affect compensatory processes of vessel growth, namely angiogenesis and arteriogenesis, resulting in a reduced or impaired collateral circulation. This in turn is associated with a negative clinical outcome and prognosis. The DM-associated molecular changes include alterations in the extracellular milieu, dysbalance between proangiogenic and antiangiogenic growth factors and their receptors leading to defects in the angiogenic stimulus and resulting in cellular and vascular dysfunction.

Four main hypotheses have been put forward with regard to how DM and hyperglycaemia can cause vascular cell dysfunction and diabetic vascular complications: Most of the experimental evidence has been generated for endothelial cells (EC). The four hypotheses are: 1) increased polyol pathway flux; 2) increased advanced glycation end-product (AGE) formation; 3) activation of protein kinase C (PKC) isoforms; and 4) increased hexosamine pathway flux.

The current chapter provides a state-of-the-art review on DM-related changes in angiogenesis and arteriogenesis and their pathophysiological basis focusing on: the mechanisms of cellular dysfunction in DM; and how these mechanisms translate into alterations of vascular integrity and vessel growth

A major limitation of percutaneous revascularization procedures, including the modern drug eluting stent era, is the vascular response to injury characterized by the neointimal accumulation of vascular smooth muscle cells. Angiogenesis is the process of new capillary growth and is mediated by the proliferation, migration and recruitment of endothelial cells. Angiogenesis plays an integral role in diverse physiological and pathophysiological processes, including atherogenesis and restenosis. The role of activated endothelial cells in the healing response to endovascular procedures is a double-edged sword and remains unresolved. The rationale to accelerate endothelial repair to restore the protective properties of the luminal endothelium is offset by the potentially deleterious infiltration of neovessels to medial and adventitial layers of the vessel wall. Neovessels provide a conduit for inflammatory cells and a paracrine source of extracellular proteases (matrix metalloproteinases, cathepsins, serine proteases) and angiogenic growth factors that may propagate adverse remodeling. The degree of adventitial vasa vasorum neovascularization has been shown to positively correlate with neointimal thickening in numerous preclinical models of restenosis. This review will critically appraise the role of VEGF, as a tool to enhance endothelial cell activation, in the process of neointimal thickening. The potentially dichotomous and double-edged sword functionality of VEGF and other potent angiogenic growth factors in vessel wall remodeling has important consequences for their therapeutic use in myocardial neovascularization and vasculoprotection

Therapeutic angiogenesis is the induction of new blood vessels by the delivery of appropriate growth factors and is an attractive approach to the treatment of different ischemic conditions. The experience with initial clinical trials in the past decade has shown that this may be more complex than anticipated and highlights the need to incorporate current advancements in our understanding of the regulation of vessel growth in the design of novel strategies. The generation of new capillaries from neighboring microvasculature by angiogenesis can be represented as two-step process: 1) tube formation, in which endothelial cells respond to gradients of angiogenic factors, proliferate and migrate towards areas where increased blood flow is needed, and 2) vascular maturation, in which pericytes are recruited to proliferating endothelium and induce quiescence and stabilization of the new capillaries through cell-cell contact and paracrine factors. The formation of a new vascular network with normal morphology and physiological function requires a proper balance between these two processes.

Here we will review the current understanding of how the growth of normal or pathological blood vessels is determined by growth factor gradients in the microenvironment and what lessons can be learned to design more physiological strategies to achieve therapeutic angiogenesis for the treatment of ischemia. In particular, we will discuss the possibility to exploit vascular maturation as a target distinct from vessel induction, but capable of modulating the effects of angiogenic factors, and its implications for increasing safety and efficacy of therapeutic angiogenesis strategies.

Targeting the ischemic myocardium in the setting of coronary artery disease is usually hampered by the impaired arterial perfusion of the region of interest. Retroinfusion of the coronary veins has gained attention for therapeutic approaches which target drugs, genes or cells to ischemic myocardium. Besides anatomy of the coronary venous system, the pressure flow relationship during retroinfusion and the efficacy of pressure-regulated selective retroinfusion for targeted delivery of drugs is reported. Moreover, we describe adenoviral and liposomal gene transfer into ischemic and non-ischemic myocardium, outline studies in chronic ischemic preclinical models treated by retroinfusion of pro-angiogenic agents and discuss the impact of retroinfusion for cell-based regenerative therapy of the diseased myocardium

Repair and regeneration of the vasculature in patients with advanced ischemic disease, or therapeutic neovascularization, can be achieved through the enhancement of both - the development of capillaries and - the remodeling of pre-existing arterioles into larger vessels. The regulation of both of these processes is extremely complex and as a result, only modest success has been achieved in most clinical trials using single angiogenic growth factors whether administered as recombinant proteins or as therapeutic transgenes. Alternative strategies include the co-delivery of two or more angiogenic cytokines or the induction of multiple pro-angiogenic signaling cascades through the administration of a single gene. One such candidate is Hypoxia-Inducible Factor-1 (HIF-1), a heterodimeric transcription factor composed of HIF- 1α and HIF- 1β subunits. Activity of HIF-1 is regulated by oxygen concentration through regulation of protein stability and transcriptional activity of the HIF- 1α subunit. Because HIF-1 regulates the expression of a variety of genes involved in angiogenesis, therapeutic strategies targeting this factor hold promise for the generation and growth of morphologically and physiologically normal vessels. In this review, we provide information on the scientific rationale, enabling experimental animal data, and early clinical trial experience of a constitutively active form of HIF-1 α

Therapeutic angiogenesis is the induction of new blood vessels by the delivery of appropriate growth factors and is an attractive approach to the treatment of different ischemic conditions. The experience with initial clinical trials in the past decade has shown that this may be more complex than anticipated and highlights the need to incorporate current advancements in our understanding of the regulation of vessel growth in the design of novel strategies. The generation of new capillaries from neighboring microvasculature by angiogenesis can be represented as two-step process: 1) tube formation, in which endothelial cells respond to gradients of angiogenic factors, proliferate and migrate towards areas where increased blood flow is needed, and 2) vascular maturation, in which pericytes are recruited to proliferating endothelium and induce quiescence and stabilization of the new capillaries through cell-cell contact and paracrine factors. The formation of a new vascular network with normal morphology and physiological function requires a proper balance between these two processes.

Here we will review the current understanding of how the growth of normal or pathological blood vessels is determined by growth factor gradients in the microenvironment and what lessons can be learned to design more physiological strategies to achieve therapeutic angiogenesis for the treatment of ischemia. In particular, we will discuss the possibility to exploit vascular maturation as a target distinct from vessel induction, but capable of modulating the effects of angiogenic factors, and its implications for increasing safety and efficacy of therapeutic angiogenesis strategies.

Two key events during evolution allowed vertebrates to develop specialized tissues able to perform complex tasks: the formation of a highly branched vascular system ensuring that all tissues receive adequate blood supply, and the development of a nervous system in which nerves branches to transmit electrical signal to peripheral organs. Both networks are laid down in a complex and stereotyped manner, which is tightly controlled by a series of shared developmental cues. Vessels and nerves use similar signals and principles to grow, differentiate and navigate toward their final targets. Moreover, the vascular and the nervous system cross-talk and, when deregulated, they contribute to medically relevant diseases. The emerging evidence that both systems share several molecular pathways not only provides an important link between vascular biology and neuroscience, but also promises to accelerate the discovery of new pathogenetic insights and therapeutic strategies

Antimicrobial peptides (AMPs) are effector molecules of the innate immune system. In addition their direct antimicrobial activity AMPs modulate angiogenesis. This chapter reviews the current knowledge about the link between AMPs and angiogenesis. A variety of AMPs have been isolated from species of all kingdoms and are classified based on their structure and amino acid motifs. AMPs have a broad antimicrobial spectrum and lyse microbial cells by interaction with biomembranes. Cathelicidins are characterized by a conserved N-terminal cathelin domain and a variable C-terminal antimicrobial domain that can be released from the precursor protein after cleavage by proteinases. LL-37 is the C-terminal part of the only human cathelicidin identified to date called human cationic antimicrobial protein (hCAP-18) and was first isolated from polymorphonuclear leukocytes but is also expressed by lymphocytes, macrophages and epithelial cells. LL-37 inactivates microorganisms by interaction with biomembranes. Beside the antimicrobial activity LL-37 modulates inflammation and displays different important cellular activities such as acting as chemotractant or activator of epithelial or immune cells. LL-37 interacts with endothelial cells and stimulates angiogenesis both in vitro and in vivo. LL-37 stimulates collateral formation in a rabbit hind-limb model of ischemia. Mice deficient for the murine analogue of LL-37/hCAP-18 showed decreased neovascularization of skin lesions as compared to wild-type controls. The angiogenic actions of LL-37 seem to be receptor-mediated by interaction with formyl peptide receptor–like 1 (FPRL1) that is expressed on endothelial cells. Cathelicidin is an example that AMPs serve as multifunctional host defense molecules and link antibiotic activity, repair and angiogenesis