Site-specific therapeutic angiogenesis after systemic administration of vascular endothelial growth factor

Plasma Exosomes Loaded pH-Responsive Carboxymethylcellulose Hydrogel Promotes Wound Repair by Activating the Vascular Endothelial Growth Factor Signaling Pathway in Type 1 Diabetic Mice

Chronic wound healing plagues thousands of diabetic patients and brings social and economic burdens. Plasma exosomes (P-Exos), regarded as nanosized therapeutic agents, have shown therapeutic efficacy in promoting diabetic wound healing. The present work prepared the P-Exos-loaded pH-responsive carboxymethylcellulose (P-Exos-loaded CMC) hydrogel to investigate its ability to accelerate diabetic wound healing and to explore its underlying mechanisms. The results showed that the P-Exos-loaded CMC hydrogel was an effective therapeutic agent for accelerating diabetic wound repair. It promoted the local wound healing process in diabetic type 1 mice and enhanced angiogenesis and re-epithelialization via activating angiogenesis-related pathways mediated by vascular endothelial growth factor (VEGF).

Proangiogenic Effect of 2A-Peptide Based Multicistronic Recombinant Constructs Encoding VEGF and FGF2 Growth Factors

Coronary artery disease remains one of the primary healthcare problems due to the high cost of treatment, increased number of patients, poor clinical outcomes, and lack of effective therapy. Though pharmacological and surgical treatments positively affect symptoms and arrest the disease progression, they generally exhibit a limited effect on the disease outcome. The development of alternative therapeutic approaches towards ischemic disease treatment, especially of decompensated forms, is therefore relevant. Therapeutic angiogenesis, stimulated by various cytokines, chemokines, and growth factors, provides the possibility of restoring functional blood flow in ischemic tissues, thereby ensuring the regeneration of the damaged area. In the current study, based on the clinically approved plasmid vector pVax1, multigenic constructs were developed encoding vascular endothelial growth factor (VEGF), fibroblast growth factors (FGF2), and the DsRed fluorescent protein, integrated via picornaviruses' furin-2A peptide sequences. In vitro experiments demonstrated that genetically modified cells with engineered plasmid constructs expressed the target proteins. Overexpression of VEGF and FGF2 resulted in increased levels of the recombinant proteins. Concomitantly, these did not lead to a significant shift in the general secretory profile of modified HEK293T cells. Simultaneously, the secretome of genetically modified cells showed significant stimulating effects on the formation of capillary-like structures by HUVEC (endothelial cells) in vitro. Our results revealed that when the multicistronic multigene vectors encoding 2A peptide sequences are created, transient transgene co-expression is ensured. The results obtained indicated the mutual synergistic effects of the growth factors VEGF and FGF2 on the proliferation of endothelial cells in vitro. Thus, recombinant multicistronic multigenic constructs might serve as a promising approach for establishing safe and effective systems to treat ischemic diseases.

Collagen/heparin scaffold combined with vascular endothelial growth factor promotes the repair of neurological function in rats with traumatic brain injury

The objective of this study was to evaluate the therapy effects of a novel biological scaffold containing heparin, collagen and vascular endothelial growth factor (VEGF) in treating traumatic brain injury (TBI).

Notoginsenoside R1 activates the Ang2/Tie2 pathway to promote angiogenesis

BACKGROUND

Therapeutic angiogenesis is a novel strategy for the treatment of ischemic diseases that involves promotion of angiogenesis in ischemic tissues via the use of proangiogenic agents. However, effective proangiogenic drugs that activate the Ang2/Tie2 signaling pathway remain scarce.

PURPOSE

We aimed to investigate the proangiogenic activity of notoginsenoside R1 (NR1) isolated from total saponins of Panax notoginseng with regard to activation of the Ang2/Tie2 signaling pathway.

METHODS

We examined the proangiogenic effects of NR1 by assessing the effects of NR1 on the proliferation, migration, invasion and tube formation of human umbilical vein endothelial cells (HUVECs). The aortic ring assay and vascular endothelial growth factor receptor inhibitor (VRI)-induced vascular regression in the zebrafish model were used to confirm the proangiogenic effects of NR1 ex vivo and in vivo. Furthermore, the molecular mechanism was investigated by Western blot analysis.

RESULTS

We found that NR1 promoted the proliferation, mobility and tube formation of HUVECs in vitro. NR1 also increased the number of sprouting vessels in rat aortic rings and rescued VRI-induced vascular regression in zebrafish. NR1-induced angiogenesis was dependent on Tie2 receptor activation mediated by increased autocrine Ang2 in HUVECs, and inhibition of the Ang2/Tie2 pathway abrogated the proangiogenic effects of NR1.

CONCLUSIONS

Our results suggest that NR1 promotes angiogenesis by activating the Ang2/Tie2 signaling pathway. Thus, NR1-induced activation of the Ang2/Tie2 pathway is an effective proangiogenic approach. NR1 may be useful agent for the treatment of ischemic diseases.

Vascular toxicity associated with anti-angiogenic drugs

Over the past two decades, the treatment of cancer has been revolutionised by the highly successful introduction of novel molecular targeted therapies and immunotherapies, including small-molecule kinase inhibitors and monoclonal antibodies that target angiogenesis by inhibiting vascular endothelial growth factor (VEGF) signaling pathways. Despite their anti-angiogenic and anti-cancer benefits, the use of VEGF inhibitors (VEGFi) and other tyrosine kinase inhibitors (TKIs) has been hampered by potent vascular toxicities especially hypertension and thromboembolism. Molecular processes underlying VEGFi-induced vascular toxicities still remain unclear but inhibition of endothelial NO synthase (eNOS), reduced nitric oxide (NO) production, oxidative stress, activation of the endothelin system, and rarefaction have been implicated. However, the pathophysiological mechanisms still remain elusive and there is an urgent need to better understand exactly how anti-angiogenic drugs cause hypertension and other cardiovascular diseases (CVDs). This is especially important because VEGFi are increasingly being used in combination with other anti-cancer dugs, such as immunotherapies (immune checkpoint inhibitors (ICIs)), other TKIs, drugs that inhibit epigenetic processes (histone deacetylase (HDAC) inhibitor) and poly (adenosine diphosphate-ribose) polymerase (PARP) inhibitors, which may themselves induce cardiovascular injury. Here, we discuss vascular toxicities associated with TKIs, especially VEGFi, and provide an up-to-date overview on molecular mechanisms underlying VEGFi-induced vascular toxicity and cardiovascular sequelae. We also review the vascular effects of VEGFi when used in combination with other modern anti-cancer drugs.

In Vitro Angiogenic Properties of Plasmid DNA Encoding SDF-1α and VEGF165 Genes

The stromal-derived factor-1 alpha (SDF-1α) and vascular endothelial growth factor (VEGF) play an important role in angiogenesis and exert a significant trophic function. SDF-1α is a chemoattractant for endothelial progenitor cells derived from bone marrow and promotes new blood vessel formation. VEGF regulates all types of vascular growth, stimulates angiogenesis, and is involved in the induction of lymphangiogenesis. The possibility of using these growth factors for regenerative medicine is currently under investigation. The angiogenic potential of a pBud-SDF-1α-VEGF165 bicistronic plasmid construct which simultaneously encodes VEGF165 and SDF-1α genes cDNA was evaluated in this study. The conditioned medium collected from HEK293T cells transfected with the pBud-SDF-1α-VEGF165 plasmid was shown to stimulate the formation of capillary-like structures by human umbilical vein-derived endothelial cells (HUVEC) on Matrigel and to increase the proliferative activity of these cells in vitro. Thus, the pBud-SDF-1α-VEGF165 plasmid exhibits angiogenic properties in cell cultures in vitro. As interest in the development of non-viral techniques for regenerative medicine increases, this plasmid which simultaneously expresses VEGF165 and SDF-1α may provide a platform for advanced methods of stimulating therapeutic angiogenesis.

Tissue Engineering of the Microvasculature

The ability to generate new microvessels in desired numbers and at desired locations has been a long-sought goal in vascular medicine, engineering, and biology. Historically, the need to revascularize ischemic tissues nonsurgically (so-called therapeutic vascularization) served as the main driving force for the development of new methods of vascular growth. More recently, vascularization of engineered tissues and the generation of vascularized microphysiological systems have provided additional targets for these methods, and have required adaptation of therapeutic vascularization to biomaterial scaffolds and to microscale devices. Three complementary strategies have been investigated to engineer microvasculature: angiogenesis (the sprouting of existing vessels), vasculogenesis (the coalescence of adult or progenitor cells into vessels), and microfluidics (the vascularization of scaffolds that possess the open geometry of microvascular networks). Over the past several decades, vascularization techniques have grown tremendously in sophistication, from the crude implantation of arteries into myocardial tunnels by Vineberg in the 1940s, to the current use of micropatterning techniques to control the exact shape and placement of vessels within a scaffold. This review provides a broad historical view of methods to engineer the microvasculature, and offers a common framework for organizing and analyzing the numerous studies in this area of tissue engineering and regenerative medicine. © 2019 American Physiological Society. Compr Physiol 9:1155-1212, 2019.

Local pharmacological induction of angiogenesis: Drugs for cells and cells as drugs

The past decades have seen significant advances in pro-angiogenic strategies based on delivery of molecules and cells for conditions such as coronary artery disease, critical limb ischemia and stroke. Currently, three major strategies are evolving. Firstly, various pharmacological agents (growth factors, interleukins, small molecules, DNA/RNA) are locally applied at the ischemic region. Secondly, preparations of living cells with considerable bandwidth of tissue origin, differentiation state and preconditioning are delivered locally, rarely systemically. Thirdly, based on the notion, that cellular effects can be attributed mostly to factors secreted in situ, the cellular secretome (conditioned media, exosomes) has come into the spotlight. We review these three strategies to achieve (neo)angiogenesis in ischemic tissue with focus on the angiogenic mechanisms they tackle, such as transcription cascades, specific signalling steps and cellular gases. We also include cancer-therapy relevant lymphangiogenesis, and shall seek to explain why there are often conflicting data between in vitro and in vivo. The lion's share of data encompassing all three approaches comes from experimental animal work and we shall highlight common technical obstacles in the delivery of therapeutic molecules, cells, and secretome. This plethora of preclinical data contrasts with a dearth of clinical studies. A lack of adequate delivery vehicles and standardised assessment of clinical outcomes might play a role here, as well as regulatory, IP, and manufacturing constraints of candidate compounds; in addition, completed clinical trials have yet to reveal a successful and efficacious strategy. As the biology of angiogenesis is understood well enough for clinical purposes, it will be a matter of time to achieve success for well-stratified patients, and most probably with a combination of compounds.

Heparin Functionalized Injectable Cryogel with Rapid Shape-Recovery Property for Neovascularization

Cryogel based scaffolds have high porosity with interconnected macropores that may provide cell compatible microenvironment. In addition, cryogel based scaffolds can be utilized in minimally invasive surgery due to its sponge-like properties, including rapid shape recovery and injectability. Herein, we developed an injectable cryogel by conjugating heparin to gelatin as a carrier for vascular endothelial growth factor (VEGF) and fibroblasts in hindlimb ischemic disease. Our gelatin/heparin cryogel showed gelatin concentration-dependent mechanical properties, swelling ratios, interconnected porosities, and elasticities. In addition, controlled release of VEGF led to effective angiogenic responses both in vitro and in vivo. Furthermore, its sponge-like properties enabled cryogels to be applied as an injectable carrier system for in vivo cells and growth factor delivery. Our heparin functionalized injectable cryogel facilitated the angiogenic potential by facilitating neovascularization in a hindlimb ischemia model.

Sustained-released mixture of vascular endothelial growth factor 165 and fibrin glue strengthens healing of ileal anastomoses in a rabbit model with intraperitoneal infection

Purpose

To investigate the effects of a sustained-released mixture of vascular endothelial growth factor 165 (VEGF165) and fibrin glue (FG) local administration on postoperative rabbit ileal anastomoses.

Methods

One hundred twenty-eight male and female New Zealand white rabbits underwent intraperitoneal infection subsequent ileal anastomosis surgery were divided randomly into 4 groups, including 32 animals in each, applied with saline solution, FG, rhVEGF165 and a mixture of rhVEGF165 with FG (VEGF + FG) on the anastomoses, respectively. The incidences of anastomotic leakage were observed. Histopathological examination for inflammatory infiltration, fibroblast proliferation, and capillary vascular proliferation were performed. Then, bursting pressure and hydroxyproline concentrations were assessed in anastomoses sits on postoperative days 3, 5, 7, and 14.

Results

Rabbits in VEGF + FG group had the lowest incidence of leakage (P < 0.05). Histological evaluations revealed that granulation tissue was formed on days 5 after anastomosis; fibroblast proliferation and capillary vascular proliferation were significantly increased on days 7 and 14 in VEGF + FG group. Furthermore, there was a statistically significant difference in the mean bursting pressures between VEGF + FG group and other groups on days 7 and 14 (P < 0.05), and rabbits in VEGF + FG group exhibited a higher concentration than VEGF group (P < 0.05) and FG group (P < 0.05) on day 14.

Conclusion

Administration of VEGF165 mixed with FG to ileal anastomosis accelerates wound healing and enhances the anastomosis by increased angiogenesis.

Biodegradable Carriers for Delivery of VEGF Plasmid DNA for the Treatment of Critical Limb Ischemia

The safe and efficient delivery of therapeutic nucleic acid is a prerequisite for an effective DNA therapy. In this study, we condensed the low molecular weight polyethylenimine (PEI, 1.8k Da) with 2,6-pyridinedicarboxaldehyde (PDA), both of which are degradable in vivo, to synthesize a biodegradable polycationic material (PDAPEI) to deliver vascular endothelial growth factor (VEGF) plasmid DNA (pDNA). Particle size and zeta potential of this novel degradable PEI derivatives-pDNA nanoparticle were investigated and in vitro cytotoxicity was estimated on human umbilical vein endothelial cells (HUVECs). Using pDNA-encoding VEGF-A and green fluorescence protein (GFP), we also checked transfection efficiency of the vector (PDAPEI) and found its excellent performance at 40 w/w ratio. We successfully established peripheral ischemia animal model on C57/BL6J mice to evaluate the therapeutic effect of PDAPEI/pVEGF-A polyplex system on ischemic disease and a conclusion was made that PDAPEI is a promising gene vector in the treatment of peripheral ischemic artery disease (PAD).

Deletion of TXNIP Mitigates High-Fat Diet-Impaired Angiogenesis and Prevents Inflammation in a Mouse Model of Critical Limb Ischemia

Background: Previous work demonstrated that high-fat diet (HFD) triggered thioredoxin-interacting protein (TXNIP) and that silencing TXNIP prevents diabetes-impaired vascular recovery. Here, we examine the impact of genetic deletion of TXNIP on HFD-impaired vascular recovery using hind limb ischemia model. Methods: Wild type mice (WT, C57Bl/6) and TXNIP knockout mice (TKO) were fed either normal chow diet (WT-ND and TKO-ND) or 60% high-fat diet (WT-HFD and TKO-HFD). After four weeks of HFD, unilateral hind limb ischemia was performed and blood flow was measured using Laser doppler scanner at baseline and then weekly for an additional three weeks. Vascular density, nitrative stress, infiltration of CD68+ macrophages, and expression of inflammasome, vascular endothelial growth factor (VEGF), VEGF receptor-2 were examined by slot blot, Western blot and immunohistochemistry. Results: By week 8, HFD caused similar increases in weight, cholesterol and triglycerides in both WT and TKO. At week 4 and week 8, HFD significantly impaired glucose tolerance in WT and to a lesser extent in TKO. HFD significantly impaired blood flow and vascular density (CD31 labeled) in skeletal muscle of WT mice compared to ND but not in TKO. HFD and ischemia significantly induced tyrosine nitration, and systemic IL-1β and infiltration of CD68+ cells in skeletal muscle from WT but not from TKO. HFD significantly increased cleaved-caspase-1 and IL-1 β compared to ND. Under both ND, ischemia tended to increase VEGF expression and increased VEGFR2 activation in WT only but not TKO. Conclusion: Similar to prior observation in diabetes, HFD-induced obesity can compromise vascular recovery in response to ischemic insult. The mechanism involves increased TXNIP-NLRP3 (nucleotide-binding oligomerization domain-like receptor protein 3) inflammasome activation, nitrative stress and impaired VEGFR2 activation. Deletion of TXNIP restored blood flow, reduced nitrative stress and blunted inflammasome-mediated inflammation; however, it did not impact VEGF/VEGFR2 in HFD. Targeting TXNIP-NLRP3 inflammasome can provide potential therapeutic target in obesity-induced vascular complication.

Angiogenesis: Bench to Bedside, Have We Learned Anything?

End-stage ischemic cardiomyopathy patients are an ever-increasing group of coronary artery disease patients, often with no options in our current treatment armamentarium. Angiogenesis therapy pre-clinical and phase I clinical trials showed great promise, however, the benefits of single growth factor treatments have not been borne out in the larger phase II randomized trials. The complexity of angiogenesis process and the challenges in creating animal models to replicate and study this process in ischemic adult human myocardium have been major limitations to progress in this field. In addition failure to control for the powerful placebo effect in the clinical trials and inadequate methods of outcomes measures assessment have created difficult to overcome road blocks in establishing the efficacy of angiogenic strategies. Herein we review the challenges of angiogenesis research and development of treatment strategies. We also propose a structured model for further investigations of angiogenic therapies. The adherence to such a regimented approach as proposed here is, in our opinion, the only way to achieve success in angiogenesis approach development to treatment of patients with end-stage cardiac ischemia refractory to other established therapies.

Limb ischemia and vessel regeneration: Is there a role for VEGF?

Vascular endothelial growth factor (VEGF), as an endothelial cell-specific mitogen, is crucial for new blood vessels formation. Atherosclerosis affecting the cardiovascular system causes ischemia and functio laesa in tissues supplied by the occluded vessels. When such a situation occurs in the lower extremities, it causes critical limb ischemia (CLI) often requiring leg amputation. Low oxygen tension leads to upregulation of hypoxia-regulated genes (i.e. VEGF), that should help to restore the impaired blood flow. In CLI these rescue mechanisms are, however, often inefficient. Moreover, there are many contradictory reports showing either induction, no changes or even down-regulation of VEGF in specimens taken from patients with CLI, as well as in samples collected from animals subjected to hindlimb ischemia. Additionally, taking into account numerous experimental and clinical data demonstrating rather insufficient therapeutic potential of VEGF, we called into question the role of this protein in limb ischemia and vessel regeneration. In this review we are also summarizing several aspects which can influence VEGF expression and its measurement in the ischemic tissues.

Biomaterials for hollow organ tissue engineering

Tissue engineering is a rapidly advancing field that is likely to transform how medicine is practised in the near future. For hollow organs such as those found in the cardiovascular and respiratory systems or gastrointestinal tract, tissue engineering can provide replacement of the entire organ or provide restoration of function to specific regions. Larger tissue-engineered constructs often require biomaterial-based scaffold structures to provide support and structure for new tissue growth. Consideration must be given to the choice of material and manufacturing process to ensure the de novo tissue closely matches the mechanical and physiological properties of the native tissue. This review will discuss some of the approaches taken to date for fabricating hollow organ scaffolds and the selection of appropriate biomaterials.

[Hemodynamic effects of succinate-containing dialyzing solution]

AIM

To assess the results of using an acetate-free succinate-containing dialyzing solution (SDS) against natremia and blood pressure (BP) in patients on chronic hemodialysis (HD).

SUBJECTS AND METHODS

Ninety-two patients were transferred from 3 Saint Petersburg HD centers to 3-month HD treatment using SDS. The investigators measured blood biochemical indicators immediately before and 1 and 3 months after the investigation, BP before and after a successive HD session, and the patients' weight and its gain in the period between HD sessions. Hypotensive and hypertensive episodes were recorded during HD sessions throughout the investigation.

RESULTS

Following 3-month treatment using SDS, there were statistically significant decreases in blood sodium levels and systolic BP (SBP) prior to a HD session. At the same time, patients with a baseline pre-HD SBP of less than 100 mm Hg were observed to have a statistically significant increase in this indicator by the end of the investigation. Pre-dialysis diastolic BP (DBP) and post- dialysis SBP and DBP substantially unchanged. After 3 months of SDS use, there was a statistically significant reduction in weight gain in the period between HD sessions. When SDS was administered, the frequency of hypertensive episodes tended to decline after a HD session.

CONCLUSION

The use of SDS causes a drop in pre-dialysis blood sodium levels, ensuring adequate dehydration in patients and improving hypertension control. In doing so, SDS prevents hypotension during a HD session.

Stimulation of angiogenesis and survival of endothelial cells by human monoclonal Tie2 receptor antibody

Angiopoietin-1 (Ang1) and its endothelium-specific receptor, tyrosine kinase with Ig and epidermal growth factor homology domain 2 (Tie2), play critical roles in vascular development. Although the Ang1/Tie2 system has been considered a promising target for therapeutic neovascularization, several imitations of large-scale production have hampered the development of recombinant Ang1 for therapeutics. In this study, we produced a fully human agonistic antibody against Tie2, designated 1-4h, and tested the applicability of 1-4h as an alternative to native Ang1 in therapeutic angiogenesis. 1-4h significantly enhanced the phosphorylation of Tie2 in a dose- and time-dependent manner in human Tie2-expressing HEK293 cells and human umbilical vein endothelial cells. Moreover, 1-4h induced the activation of Tie2-mediated intracellular signaling such as AKT, eNOS, MAPK, and Focal Adhesion Kinase p125(FAK). In addition, 1-4h increased the chemotactic motility and capillary-like tube formation of endothelial cells in vitro and enhanced the survival of serum-deprived endothelial cells. Taken together, our data clearly suggest that a human Tie2 agonistic antibody is a potentially useful therapeutic approach for the treatment of several ischemic diseases including delayed-wound healing and ischemic heart and limb diseases.

Clinical application of growth factors and cytokines in wound healing

Wound healing is a complex and dynamic biological process that involves the coordinated efforts of multiple cell types and is executed and regulated by numerous growth factors and cytokines. There has been a drive in the past two decades to study the therapeutic effects of various growth factors in the clinical management of nonhealing wounds (e.g., pressure ulcers, chronic venous ulcers, diabetic foot ulcers). For this review, we conducted an online search of Medline/PubMed and critically analyzed the literature regarding the role of growth factors and cytokines in the management of these wounds. We focused on currently approved therapies, emerging therapies, and future research possibilities. In this review, we discuss four growth factors and cytokines currently being used on and off label for the healing of wounds. These include granulocyte-macrophage colony-stimulating factor, platelet-derived growth factor, vascular endothelial growth factor, and basic fibroblast growth factor. While the clinical results of using growth factors and cytokines are encouraging, many studies involved a small sample size and are disparate in measured endpoints. Therefore, further research is required to provide definitive evidence of efficacy.

Postischemic revascularization: from cellular and molecular mechanisms to clinical applications

After the onset of ischemia, cardiac or skeletal muscle undergoes a continuum of molecular, cellular, and extracellular responses that determine the function and the remodeling of the ischemic tissue. Hypoxia-related pathways, immunoinflammatory balance, circulating or local vascular progenitor cells, as well as changes in hemodynamical forces within vascular wall trigger all the processes regulating vascular homeostasis, including vasculogenesis, angiogenesis, arteriogenesis, and collateral growth, which act in concert to establish a functional vascular network in ischemic zones. In patients with ischemic diseases, most of the cellular (mainly those involving bone marrow-derived cells and local stem/progenitor cells) and molecular mechanisms involved in the activation of vessel growth and vascular remodeling are markedly impaired by the deleterious microenvironment characterized by fibrosis, inflammation, hypoperfusion, and inhibition of endogenous angiogenic and regenerative programs. Furthermore, cardiovascular risk factors, including diabetes, hypercholesterolemia, hypertension, diabetes, and aging, constitute a deleterious macroenvironment that participates to the abrogation of postischemic revascularization and tissue regeneration observed in these patient populations. Thus stimulation of vessel growth and/or remodeling has emerged as a new therapeutic option in patients with ischemic diseases. Many strategies of therapeutic revascularization, based on the administration of growth factors or stem/progenitor cells from diverse sources, have been proposed and are currently tested in patients with peripheral arterial disease or cardiac diseases. This review provides an overview from our current knowledge regarding molecular and cellular mechanisms involved in postischemic revascularization, as well as advances in the clinical application of such strategies of therapeutic revascularization.

Vascular-targeted therapies for Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is the most common muscular dystrophy and an X-linked recessive, progressive muscle wasting disease caused by the absence of a functional dystrophin protein. Dystrophin has a structural role as a cytoskeletal stabilization protein and protects cells against contraction-induced damage. Dystrophin also serves a signaling role through mechanotransduction of forces and localization of neuronal nitric oxide synthase (nNOS), which produces nitric oxide (NO) to facilitate vasorelaxation. In DMD, the signaling defects produce inadequate tissue perfusion caused by functional ischemia due to a diminished ability to respond to shear stress induced endothelium-dependent dilation. Additionally, the structural defects seen in DMD render myocytes with an increased susceptibility to mechanical stress. The combination of both defects is necessary to generate myocyte damage, which induces successive rounds of myofiber degeneration and regeneration, loss of calcium homeostasis, chronic inflammatory response, fibrosis, and myonecrosis. In individuals with DMD, these processes inevitably cause loss of ambulation shortly after the first decade and an abbreviated life with death in the third or fourth decade due to cardio-respiratory anomalies. There is no known cure for DMD, and although the culpable gene has been identified for more than twenty years, research on treatments has produced few clinically relevant results. Several recent studies on novel DMD therapeutics are vascular targeted and focused on attenuating the inherent functional ischemia. One approach improves vasorelaxation capacity through pharmaceutical inhibition of either phosphodiesterase 5 (PDE5) or angiotensin-converting enzyme (ACE). Another approach increases the density of the underlying vascular network by inducing angiogenesis, and this has been accomplished through either direct delivery of vascular endothelial growth factor (VEGF) or by downregulating the VEGF decoy-receptor type 1 (VEGFR-1 or Flt-1). The pro-angiogenic approaches also seem to be pro-myogenic and could resolve the age-related decline in satellite cell (SC) quantity seen in mdx models through expansion of the SC juxtavascular niche. Here we review these four vascular targeted treatment strategies for DMD and discuss mechanisms, proof of concept, and the potential for clinical relevance associated with each therapy.

[Genic and cellular therapy for peripheral arterial diseases]

Late evolution of peripheral arterial disease consists in the apparition of critical limb ischemia. Surgical treatments allow to treat these patients during long time; however, in most patients, especially the diabetic ones, there a very few options and the clinical evolution is rapidly dramatic. For these reasons, the critical limb ischemia is one of the first diseases treated by genic or cellular therapies aiming to improve blood flow perfusion in the lower-limbs. In this short review, we describe the main clinical trials of genic therapy; most of them have been abandoned because serious side effects, modest effects and major risks. Different types of stem cells are now used for cell therapy: endothelial progenitor cells, early or late, activated or not, mesenchymal stem cells, embryonic stem cells and human induced pluripotent stem cells. Problems of characterization are described and the results of the most important clinical trials are reported.

Therapeutic angiogenesis for revascularization in peripheral artery disease

Therapeutic angiogenesis for peripheral artery disease (PAD), achieved by gene and cell therapy, has recently raised a great deal of hope for patients who cannot undergo standard revascularizing treatment. Although pre-clinical studies gave very promising data, still clinical trials of gene therapy have not provided satisfactory results. On the other hand, cell therapy approach, despite several limitations, demonstrated more beneficial effects but initial clinical studies must be constantly validated by larger randomized, multi-center, double-blinded, placebo-controlled trials. This review focuses on previous and recent gene and cell therapy studies for limb ischemia, including both experimental and clinical research, and summarizes some important papers published in this field. Moreover, it provides a short comment on combined gene and cell therapy approach on the example of heme oxygenase-1 overexpressing cells with therapeutic properties.

Fragmin/protamine microparticles to adsorb and protect HGF and to function as local HGF carriers in vivo

The clinical efficacy of hepatocyte growth factor (HGF) in tissue repair can be greatly enhanced by high affinity, biocompatible drug carriers that maintain the bioactivity and regulate release at the target site. We produced 0.5-3.0 μm fragmin (low molecular weight heparin)/protamine microparticles (F/P MPs) as carriers for the controlled release of HGF. F/P MPs immobilized more than 3 μg of HGF per mg of MPs and gradually released the absorbed HGF into the medium with a half-release time of approximately 5 days. Compared with HGF alone, HGF-containing F/P MPs substantially enhanced the mitogenic effect of HGF on cultured human microvascular endothelial cells, by prolonging the biological half-life, and its conjugation to F/P MPs protected HGF from heat and proteolytic inactivation. F/P MPs disappeared 8 days after subcutaneous injection in mice, suggesting that they are rapidly biodegraded. Furthermore, the number of large (diameter ≥200 μm or containing ≥ 100 erythrocytes) and medium (diameter 20-200 μm or containing 10-100 erythrocytes) lumen capillaries 8 days after injection of HGF-containing F/P MPs was significantly higher than that after injection of HGF or F/P MPs alone. Furthermore, the number of small (diameter ≤ 20 μm or containing 1-10 erythrocytes) lumen capillaries was significantly higher 4 days after injection of HGF-containing F/P MPs. This increased angiogenic activity of HGF in vivo is probably due to both sustained local release and protection against biodegradation by the F/P MPs. Thus, F/P MPs may be useful and safe HGF carriers that facilitate cell proliferation and vascularization at sites of tissue damage.

Osteoarthritis synovial fluid activates pro-inflammatory cytokines in primary human chondrocytes

PURPOSE

Two of the most common joint diseases are rheumatoid arthritis (RA) and osteoarthritis (OA). Cartilage degradation and erosions are important pathogenetic mechanisms in both joint diseases and have presently gained increasing interest. The aim of the present study was to investigate the effects of the synovial fluid environment of OA patients in comparison with synovial fluids of RA patients on human chondrocytes in vitro.

METHODS

Primary human chondrocytes were incubated in synovial fluids gained from patients with OA or RA. The detection of vital cell numbers was determined by histology and by using the Casy Cell Counter System. Cytokine and chemokine secretion was determined by a multiplex suspension array.

RESULTS

Microscopic analysis showed altered cell morphology and cell shrinkage following incubation with synovial fluid of RA patients. Detection of vital cells showed a highly significant decrease of vital chondrocyte when treated with RA synovial fluids in comparison with OA synovial fluids. An active secretion of cytokines such as vascular endothelial growth factor (VEGF) of chondrocytes treated with OA synovial fluids was observed.

CONCLUSIONS

Significantly increased levels of various cytokines in synovial fluids of RA, and surprisingly of OA, patients were shown. Activation of pro-inflammatory cytokines of human chondrocytes by synovial fluids of OA patient supports a pro-inflammatory process in the pathogenesis of OA.

Exercise training and peripheral arterial disease

Peripheral arterial disease (PAD) is a common vascular disease that reduces blood flow capacity to the legs of patients. PAD leads to exercise intolerance that can progress in severity to greatly limit mobility, and in advanced cases leads to frank ischemia with pain at rest. It is estimated that 12 to 15 million people in the United States are diagnosed with PAD, with a much larger population that is undiagnosed. The presence of PAD predicts a 50% to 1500% increase in morbidity and mortality, depending on severity. Treatment of patients with PAD is limited to modification of cardiovascular disease risk factors, pharmacological intervention, surgery, and exercise therapy. Extended exercise programs that involve walking approximately five times per week, at a significant intensity that requires frequent rest periods, are most significant. Preclinical studies and virtually all clinical trials demonstrate the benefits of exercise therapy, including improved walking tolerance, modified inflammatory/hemostatic markers, enhanced vasoresponsiveness, adaptations within the limb (angiogenesis, arteriogenesis, and mitochondrial synthesis) that enhance oxygen delivery and metabolic responses, potentially delayed progression of the disease, enhanced quality of life indices, and extended longevity. A synthesis is provided as to how these adaptations can develop in the context of our current state of knowledge and events known to be orchestrated by exercise. The benefits are so compelling that exercise prescription should be an essential option presented to patients with PAD in the absence of contraindications. Obviously, selecting for a lifestyle pattern that includes enhanced physical activity prior to the advance of PAD limitations is the most desirable and beneficial.

Treatment of mouse limb ischemia with an integrative hypoxia-responsive vector expressing the vascular endothelial growth factor gene

Constitutive vascular endothelial growth factor (VEGF) gene expression systems have been extensively used to treat peripheral arterial diseases, but most of the results have not been satisfactory. In this study, we designed a plasmid vector with a hypoxia-responsive element sequence incorporated into it with the phiC31 integrative system (pVHAVI) to allow long-term VEGF gene expression and to be activated under hypoxia. Repeated activations of VEGF gene expression under hypoxia were confirmed in HEK293 and C2C12 cells transfected with pVHAVI. In limb ischemic mice, the local administration of pVHAVI promoted gastrocnemius mass and force recovery and ameliorated limb necrosis much better than the group treated with hypoxia-insensitive vector, even this last group had produced more VEGF in muscle. Histological analyses carried out after four weeks of gene therapy showed increased capillary density and matured vessels, and reduced number of necrotic cells and fibrosis in pVHAVI treated group. By our study, we demonstrate that the presence of high concentration of VEGF in ischemic tissue is not beneficial or is less beneficial than maintaining a lower but sufficient and long-term concentration of VEGF locally.

Coronary collateral growth--back to the future

The coronary collateral circulation is critically important as an adaptation of the heart to prevent the damage from ischemic insults. In their native state, collaterals in the heart would be classified as part of the microcirculation, existing as arterial-arterial anastomotic connections in the range of 30 to 100 μM in diameter. However, these vessels also show a propensity to remodel into components of the macrocirculation and can become arteries larger than 1000 μM in diameter. This process of outward remodeling is critically important in the adaptation of the heart to ischemia because the resistance to blood flow is inversely related to the fourth power of the diameter of the vessel. Thus, an expansion of a vessel from 100 to 1000 μM would reduce resistance (in this part of the circuit) to a negligible amount and enable delivery of flow to the region at risk. Our goal in this review is to highlight the voids in understanding this adaptation to ischemia-the growth of the coronary collateral circulation. In doing so we discuss the controversies and unknown aspects of the causal factors that stimulate growth of the collateral circulation, the role of genetics, and the role of endogenous stem and progenitor cells in the context of the normal, physiological situation and under more pathological conditions of ischemic heart disease or with some of the underlying risk factors, e.g., diabetes. The major conclusion of this review is that there are many gaps in our knowledge of coronary collateral growth and this knowledge is critical before the potential of stimulating collateralization in the hearts of patients can be realized. This article is part of a Special Issue entitled "Coronary Blood Flow".

Therapeutic angiogenesis for myocardial ischemia revisited: basic biological concepts and focus on latest clinical trials

Therapeutic angiogenesis is based on the premise that the development of new blood vessels can be augmented by exogenous administration of the appropriate growth factors. Over the last years, successful preclinical studies and promising results of early clinical trials have created great excitement about the potential of therapeutic angiogenesis for patients with advanced ischemic heart disease. The authors provide an overview of the biology of angiogenesis, the basic characteristics of angiogenic factors, and the different routes of their delivery. They discuss experimental studies in animal models of myocardial ischemia and outline available clinical studies on therapeutic angiogenesis for myocardial ischemia. Related safety issues are also addressed followed by a critical perspective about the future of proangiogenic therapies for ischemic cardiovascular disorders. Despite the established proof of concept and reasonable safety, however, results of the latest trials on therapeutic angiogenesis for myocardial ischemia have provided inconsistent results and the definite means of inducing clinically useful therapeutic angiogenesis remain elusive. More studies are required to gain further insights into the biology of angiogenesis and address pharmacological limitations of current approaches of angiogenic therapy. The authors hope and envisage that in the not-too-distant future, these investigative efforts will lead to important new strategies for treatment of myocardial ischemic syndromes. Means of non-invasive individualized pharmacological therapeutic neovascularization may be the next major advance in the treatment of ischaemic heart disease.

Mitotic and antiapoptotic effects of nanoparticles coencapsulating human VEGF and human angiopoietin-1 on vascular endothelial cells

BACKGROUND

Research towards the application of nanoparticles as carrier vehicles for the delivery of therapeutic agents is increasingly gaining importance. The angiogenic growth factors, human vascular endothelial growth factor (VEGF) and human angiopoietin-1 are known to prevent vascular endothelial cell apoptosis and in fact to stimulate human vascular endothelial cell (HUVEC) proliferation. This paper aims to study the combined effect of these bioactive proteins coencapsulated in human serum albumin nanoparticles on HUVECs and to evaluate the potential application of this delivery system towards therapeutic angiogenesis.

METHODS AND RESULTS

The angiogenic proteins, human VEGF and human angiopoietin-1, were coencapsulated in albumin nanoparticles for better controlled delivery of the proteins. The application of a nanoparticle system enabled efficient and extended-release kinetics of the proteins. The size of the nanoparticles crosslinked with glutaraldehyde was 101.0 ± 0.9 nm and the zeta potential was found to be -18 ± 2.9 mV. An optimal concentration of glutaraldehyde for the nanoparticle coating process was determined, and this provided stable and less toxic nanoparticles as protein carriers. The results of the study indicate that nanoparticles crosslinked with glutaraldehyde produced nanoparticles with tolerable toxicity which provided efficient and controlled release of the coencapsulated proteins. The nanoparticles were incubated for two weeks to determine the release profiles of the proteins. At the end of the two-week incubation period, it was observed that 49% ± 1.3% of human angiopoietin-1 and 59% ± 2.1% of human VEGF had been released from the nanoparticles. The proliferation and percent apoptosis of the HUVECs in response to released proteins was observed.

CONCLUSION

The results indicate that the released proteins were biologically active and the combined application of both the proteins demonstrated a significant highly proliferative and antiapoptotic effect on HUVECs as compared with the effect demonstrated by the individual proteins released. These studies could serve as a basis to encourage further research into the potential in vivo application of these protein-loaded nanoparticles in the field of therapeutic angiogenesis.

Synergistic effect of vascular endothelial growth factor and granulocyte colony-stimulating factor double gene therapy in mouse limb ischemia

BACKGROUND

Vascular endothelial growth factor (VEGF) has mostly been tested to treat ischemic diseases, although the outcomes obtained are not satisfactory. Our hypothesis is that the local transient expression of VEGF and stem cell mobilizer granulocyte colony-stimulating factor (G-CSF) genes in ischemic limbs can complement their activities and be more efficient for limb recovery.

METHODS

Limb ischemia was surgically induced in mice and 50 microg of VEGF and/or G-CSF genes were locally transferred by electroporation. After 3-4 weeks, evidence of necrosis by visual inspection, capillary density, muscle mass, muscle force and hematopoietic cell mobilization were evaluated.

RESULTS

After 4 weeks, 70% and 90% of the animals of the ischemic group (IG) and VEGF-treated group (VG), respectively, presented limb necrosis, in contrast to only 10% observed in the group of mice treated with both VEGF and G-CSF genes (VGG). Recovery of muscle mass and muscle force was higher than 60% in the VGG compared to the non-ischemic group. The mobilization of Sca1+ cells and neutrophils was also higher in the VGG, which may explain the lower level of necrosis observed in this group (22%, in contrast to 70% in the IG). Capillary density and degree of fibrosis were determined in weeks 3 and 4, and also showed a clear benefit as a result of the use of the G-CSF and VEGF genes together.

CONCLUSIONS

Gene therapy using VEGF and G-CSF demonstrated a synergistic effect promoting vessel and tissue repair in mouse hind limb ischemia.

Fragmin/protamine microparticles as cell carriers to enhance viability of adipose-derived stromal cells and their subsequent effect on in vivo neovascularization

We prepared fragmin/protamine microparticles (F/P MPs) as cell carriers to enhance cell viability. Use of material consisting of a low-molecular-weight heparin (fragmin) mixed with protamine resulted in water-insoluble microparticles (about 0.5-1 microm in diameter). In this study, we investigated the capability of F/P MPs to enhance the viabilities of human microvascular endothelial cells (HMVECs), human dermal fibroblasts (fibroblasts), and adipose tissue-derived stromal cells (ATSCs) in suspension culture. F/P MPs were bound to the surfaces of these cells, and the interaction of these cells with F/P MPs induced cells/F/P MPs-aggregate formations in vitro, and maintained viabilities of those cells for at least 3 days. The ATSCs/F/P MPs-aggregates adhered to and grew on suspension culture plates in a fashion similar to those on type I collagen-coated plates. The cultured ATSCs secreted significant amounts of angiogenic heparin-binding growth factors such as FGF-2. When the ATSCs/F/P MPs-aggregates were subcutaneously injected into the back of nude mice, significant neovascularization and fibrous tissue formation were induced near the site of injection from day 3 to week 2. The ATSCs/F/P MPs-aggregates were thus useful and convenient biomaterials for cell-therapy of angiogenesis.

Bone and wound healing augmentation with platelet-rich plasma

Over the past two decades, autologous platelets that have been sequestered, concentrated, and mixed with thrombin to generate growth factor-concentrated platelet-rich plasma for application to bone and wounds to aide healing have been a subject of great interest. This article reviews the literature related to the use of autologous platelet-rich plasma in bone and wound healing, and reviews the processes necessary to secure a high concentration of viable platelets. Although not yet definitive, autologous platelet-rich plasma has been shown to be safe, reproducible, and effective in mimicking the natural process of bone and wound healing.

Intramuscular VEGF repairs the failing heart: role of host-derived growth factors and mobilization of progenitor cells

Skeletal muscle produces a myriad of mitogenic factors possessing cardiovascular regulatory effects that can be explored for cardiac repair. Given the reported findings that VEGF may modulate muscle regeneration, we investigated the therapeutic effects of chronic injections of low doses of human recombinant VEGF-A(165) (0.1-1 microg/kg) into the dystrophic hamstring muscle in a hereditary hamster model of heart failure and muscular dystrophy. In vitro, VEGF stimulated proliferation, migration, and growth factor production of cultured C2C12 skeletal myocytes. VEGF also induced production of HGF, IGF2, and VEGF by skeletal muscle. Analysis of skeletal muscle revealed an increase in myocyte nuclear [531 +/- 12 VEGF 1 microg/kg vs. 364 +/- 19 for saline (number/mm(2)) saline] and capillary [591 +/- 80 VEGF 1 microg/kg vs. 342 +/- 21 for saline (number/mm(2))] densities. Skeletal muscle analysis revealed an increase in Ki67(+) nuclei in the VEGF 1 microg/kg group compared with saline. In addition, VEGF mobilized c-kit(+), CD31(+), and CXCR4(+) progenitor cells. Mobilization of progenitor cells was consistent with higher SDF-1 concentrations found in hamstring, plasma, and heart in the VEGF group. Echocardiogram analysis demonstrated improvement in left ventricular ejection fraction (0.60 +/- 0.02 VEGF 1 microg/kg vs. 0.45 +/- 0.01 mm for saline) and an attenuation in ventricular dilation [5.59 +/- 0.12 VEGF 1 microg/kg vs. 6.03 +/- 0.09 for saline (mm)] 5 wk after initiating therapy. Hearts exhibited higher cardiomyocyte nuclear [845 +/- 22 VEGF 1 microg/kg vs. 519 +/- 40 for saline (number/mm(2))] and capillary [2,159 +/- 119 VEGF 1 microg/kg vs. 1,590 +/- 66 for saline (number/mm(2))] densities. Myocardial analysis revealed approximately 2.5 fold increase in Ki67+ cells and approximately 2.8-fold increase in c-kit(+) cells in the VEGF group, which provides evidence for cardiomyocyte regeneration and progenitor cell expansion. This study provides novel evidence of a salutary effect of VEGF in the cardiomyopathic hamster via induction of myogenic growth factor production by skeletal muscle and mobilization of progenitor cells, which resulted in attenuation of cardiomyopathy and repair of the heart.

Women and heart disease--physiologic regulation of gene delivery and expression: bioreducible polymers and ischemia-inducible gene therapies for the treatment of ischemic heart disease

Ischemic heart disease (IHD) is the leading cause of death in the United States today. This year over 750,000 women will have a new or recurrent myocardial infarction. Currently, the mainstay of therapy for IHD is revascularization. Increasing evidence, however, suggests that revascularization alone is insufficient for the longer-term management of many patients with IHD. To address these issues, innovative therapies that extend beyond revascularization to protection of the myocyte and preservation of ventricular function are required. The emergence of gene therapy and proteomics offers the potential for innovative prophylactic and treatment strategies for IHD. The goal of our research is to develop therapeutic gene constructs for the treatment of myocardial ischemia that are clinically safe and effective. Toward this end, we describe the development of physiologic regulation of gene delivery and expression using bioreducible polymers and ischemia-inducible gene therapies for the potential treatment of ischemic heart disease in women.

A population analysis of VEGF transgene expression and secretion

The induction of therapeutic angiogenesis with gene therapy approaches has received considerable interest and some limited clinical success. A major drawback to this approach is a lack of understanding of the pharmacokinetics of therapeutic protein delivery. This has become increasingly more relevant as recent studies have illustrated a defined therapeutic window for angiogenic protein secretion into the local microenvironment. For cell based gene therapies, with cells widely distributed throughout the tissue, this implies that any individual cell must attain a specific secretion rate to produce a local angiogenic response. Here we report a reproducible technique enabling the study of growth factor secretion from individual cells following transient plasmid transfection. We demonstrate significant variability in single cell vascular endothelial growth factor (VEGF) secretion with the majority of total protein secretion arising from a small subpopulation of transfected cells. We demonstrate that VEGF secretion is linearly correlated to intracellular plasmid copy number and protein secretion does not appear to reach saturation within the cell population. The selection of gene therapy approaches that optimize individual cell secretion profiles may be essential for the development of effective gene therapies.

Therapeutic angiogenesis: a new treatment approach for ischemic heart disease--Part II

Angiogenesis is the biologic process of forming new blood vessels and is being investigated as an innovative therapeutic approach to help manage ischemic heart disease and peripheral vascular disease. Research studies have identified various angiogenic growth factors and progenitor cells that can enhance new blood vessel formation. This is Part II of an article that began publication in the July/August issue of Cardiology in Review. Preclinical investigations in animal models have explored the potential use of growth factors with and without progenitor cells to treat myocardial ischemia. The results of clinical trials with growth factor infusions and gene therapy techniques to enhance growth factor production have shown some promise, but therapeutic angiogenesis remains at an early stage of development.

Heparin modification of calcium phosphate bone cements for VEGF functionalization

A promising strategy to promote angiogenesis within an engineered tissue is the local and sustained delivery of an angiogenic factor by the substitute itself. Recently, we reported on functionalization of Biocement D (BioD) and several modifications of this calcium phosphate bone cement with vascular endothelial growth factor (VEGF). Maintenance of biological activity of VEGF after release from the cement was improved by modification of BioD with mineralized collagen type I (BioD/coll). However, BioD/coll composites showed a higher initial burst of VEGF release than do the unmodified BioD. In the present study, VEGF release from BioD/coll composites modified with different amounts of heparin was investigated. We found a distinct reduction of the initial burst of release by adding heparin in a concentration-dependent manner. Moreover, the heparin modification had a positive impact on the biological activity of released VEGF. An advancement of biological properties of BioD/coll by addition of heparin was further shown by improved adhesion of endothelial cells on the cement surface. Characterization of material properties of the heparin-modified BioD/coll composites revealed a finer microstructure with smaller HA-particles and a higher specific surface area than heparin-free BioD/coll. However, higher amounts of heparin resulted in a reduced compressive strength. The rheological properties of these cement pastes have been found to be favorable for good handling particularly with regard to their clinical application.

Gene and stem cell therapy in peripheral arterial occlusive disease

Abstract

Peripheral arterial occlusive disease (PAOD) is a manifestation of systemic atherosclerosis strongly associated with a high risk of cardiovascular morbidity and mortality. In a considerable proportion of patients with PAOD, revascularization either by endovascular means or by open surgery combined with best possible risk factor modification does not achieve limb salvage or relief of ischaemic rest pain. As a consequence, novel therapeutic strategies have been developed over the last two decades aiming to promote neovascularization and remodelling of collaterals. Gene and stem cell therapy are the main directions for clinical investigation concepts. For both, preclinical studies have shown promising results using a wide variety of genes encoding for growth factors and populations of adult stem cells, respectively. As a consequence, clinical trials have been performed applying gene and stem cell-based concepts. However, it has become apparent that a straightforward translation into humans is not possible. While several trials reported relief of symptoms and functional improvement, other trials did not confirm this early promise of efficacy. Ongoing clinical trials with an improved study design are needed to confirm the potential that gene and cell therapy may have and to prevent the gaps in our scientific knowledge that will jeopardize the establishment of angiogenic therapy as an additional medical treatment of PAOD. This review summarizes the experimental background and presents the current status of clinical applications and future perspectives of the therapeutic use of gene and cell therapy strategies for PAOD.

A novel angiographic methodology for the quantification of angiogenesis

The objective is to develop a method to quantify the dynamic information of contrast transport using angiography for investigating angiogenic treatments. In the rabbit hindlimb ischemia model, contrast media transport was examined for both arteries and the microvasculature. Time histories of image intensity were constructed and modeled. The differences in contrast transport quantified by the parameters of the mathematical model were statistically compared between animals treated with an adenoviral vector that expressed vascular endothelial growth factor and untreated animals. The data reveal that after one week of ischemia, treated animals have a statistical increase in the number of large vessels that convect blood more efficiently. This analysis further shows a statistically significant increase in the angiographic blush in the treated animals. A methodology is described that offers the capability of examining the number and geometry of large arteries, the dynamics of contrast transport, and the amount of angiographic blush that is related to microvascular density. In therapeutic angiogenesis, numerous techniques are used to measure variables such as the angiographic score, capillary density, and regional blood flow. The analysis presented herein can offer information of these variables, and is transferable from the laboratory to the clinical arena.