Corey K. Goldman

Effect of stromal-cell-derived factor 1 on stem-cell homing and tissue regeneration in ischaemic cardiomyopathy

BACKGROUNDnMyocardial regeneration via stem-cell mobilisation at the time of myocardial infarction is known to occur, although the mechanism for stem-cell homing to infarcted tissue subsequently and whether this approach can be used for treatment of ischaemic cardiomyopathy are unknown. We investigated these issues in a Lewis rat model (ligation of the left anterior descending artery) of ischaemic cardiomyopathy.nnnMETHODSnWe studied the effects of stem-cell mobilisation by use of granulocyte colony-stimulating factor (filgrastim) with or without transplantation of syngeneic cells. Shortening fraction and myocardial strain by tissue doppler imaging were quantified by echocardiography.nnnFINDINGSnStem-cell mobilisation with filgrastim alone did not lead to engraftment of bone-marrow-derived cells. Stromal-cell-derived factor 1 (SDF-1), required for stem-cell homing to bone marrow, was upregulated immediately after myocardial infarction and downregulated within 7 days. 8 weeks after myocardial infarction, transplantation into the peri-infarct zone of syngeneic cardiac fibroblasts stably transfected to express SDF-1 induced homing of CD117-positive stem cells to injured myocardium after filgrastim administration (control vs SDF-1-expressing cardiac fibroblasts mean 7.2 [SD 3.4] vs 33.2 [6.0] cells/mm2, n=4 per group, p<0.02) resulting in greater left-ventricular mass (1.24 [0.29] vs 1.57 [0.27] g) and better cardiac function (shortening fraction 9.2 [4.9] vs 17.2 [4.2]%, n=8 per group, p<0.05).nnnINTERPRETATIONnThese findings show that SDF-1 is sufficient to induce therapeutic stem-cell homing to injured myocardium and suggest a strategy for directed stem-cell engraftment into injured tissues. Our findings also indicate that therapeutic strategies focused on stem-cell mobilisation for regeneration of myocardial tissue must be initiated within days of myocardial infarction unless signalling for stem-cell homing is re-established.

Regional Angiogenesis With Vascular Endothelial Growth Factor in Peripheral Arterial Disease A Phase II Randomized, Double-Blind, Controlled Study of Adenoviral Delivery of Vascular Endothelial Growth Factor 121 in Patients With Disabling Intermittent Claudication

Background—“Therapeutic angiogenesis” seeks to improve perfusion by the growth of new blood vessels. The Regional Angiogenesis with Vascular Endothelial growth factor (RAVE) trial is the first major randomized study of adenoviral vascular endothelial growth factor (VEGF) gene transfer for the treatment of peripheral artery disease (PAD). Methods and Results—This phase 2, double-blind, placebo-controlled study was designed to test the efficacy and safety of intramuscular delivery of AdVEGF121, a replication-deficient adenovirus encoding the 121-amino-acid isoform of vascular endothelial growth factor, to the lower extremities of subjects with unilateral PAD. In all, 105 subjects with unilateral exercise-limiting intermittent claudication during 2 qualifying treadmill tests, with peak walking time (PWT) between 1 to 10 minutes, were stratified on the basis of diabetic status and randomized to low-dose (4×109 PU) AdVEGF121, high-dose (4×1010 PU) AdVEGF121, or placebo, administered as 20 intramuscular injections to the index leg in a single session. The primary efficacy end point, change in PWT (&Dgr;PWT) at 12 weeks, did not differ between the placebo (1.8±3.2 minutes), low-dose (1.6±1.9 minutes), and high-dose (1.5±3.1 minutes) groups. Secondary measures, including &Dgr;PWT, ankle-brachial index, claudication onset time, and quality-of-life measures (SF-36 and Walking Impairment Questionnaire), were also similar among groups at 12 and 26 weeks. AdVEGF121 administration was associated with increased peripheral edema. Conclusions—A single unilateral intramuscular administration of AdVEGF121 was not associated with improved exercise performance or quality of life in this study. This study does not support local delivery of single-dose VEGF121 as a treatment strategy in patients with unilateral PAD.

A mechanism for modulation of cellular responses to VEGF: Activation of the integrins

We thank Dr. C. Eng (Ohio State University), Dr. C. Patterson (University of Texas), Dr. E. Pluskota, Dr. Nissam Hat, Dr. W. Kim, and Dr. V. Byers-Ward (CCF) for assistance and reagents.

Gene therapy by adenovirus-mediated vascular endothelial growth factor and angiopoietin-1 promotes perfusion of muscle flaps.

An experimental study was conducted to investigate the potential use of intravascular gene therapy with adenovirus-mediated (Ad) vascular endothelial growth factor (VEGF) or angiopoietin-1 (Ang-1) for the enhancement of muscle flap perfusion and to evaluate the effect of therapy on microcirculatory hemodynamics and microvascular permeability in vivo by using a cremaster muscle flap model in the rat. The cremaster tube flap was left intact after isolation of the pudo-epigastric pedicle. A total of 90 male Sprague-Dawley rats were divided into five groups of 18 each, according to the type of intraarterial treatment. Control flaps received phosphate-buffered saline. Group 2 (the control gene encoding green fluorescent protein, Ad-GFP) served as the adenovirus control. In Groups 3, 4, and 5, flaps were pretreated with Ad-VEGF, Ad-Ang-1, and Ad-Ang-1 + Ad-VEGF, respectively. Flaps were preserved in a subcutaneous pocket in the hindlimb for evaluation of functional capillary density and microvascular permeability indices at 3, 7, and 14 days by intravital microscopy system. At day 7 and 14, Ad-VEGF, Ad-Ang-1, and combined treatment groups showed significantly higher numbers of capillary densities when compared with control and Ad-GFP groups (p < 0.05). At day 14, Ad-VEGF was the superior treatment group compared with Ad-Ang-1 and Ad-VEGF + Ad-Ang-1 (p < 0.05). Overall, there was a linear increase in the number of functional capillaries in all treatment groups (p < 0.05). At day 3 after Ad-Ang-1 therapy, a significantly lower permeability index was found when compared with Ad-VEGF + Ad-Ang-1 and Ad-VEGF alone treatment (p < 0.05). At day 7, the Ad-VEGF group had the highest score of permeability index compared with control, combined, and Ad-Ang-1 groups (p < 0.05). Histologic evaluation of muscle flaps demonstrated mild focal inflammation. There was evidence of mild vasculitis in all flaps except control muscles. Intravascular angiogenic therapy with Ad-VEGF or Ad-Ang-1 was technically feasible, as demonstrated by expression of the control gene, GFP, along the vascular tree. All treatment groups increased perfusion of the muscle flap over a period of 14 days, indicating a long-lasting effect of gene therapy. Ang-1 alone or in combination with VEGF was as effective as VEGF alone in augmenting muscle perfusion with more stable vessels 1 week after gene therapy.

Enhancement of muscle flap hemodynamics by angiopoietin-1.

Angiopoietin-1 (Ang-1) constitutes a novel family of endothelial cell-specific angiogenic factors. Ang-1 functions mainly in remodeling, maturation, and stabilization of blood vessels. Its direct role in the process of angiogenesis remains unknown. The authors designed an experimental study to investigate the angiogenic potential of Ang-1 and to determine its hemodynamic effects on the cremaster muscle flap model in the rat. Adenovirus-mediated gene therapy was used for delivery of Ang-1. The study sample included 45 male Sprague–Dawley rats weighing 200 to 250 g. After the cremaster muscle tube flaps were prepared, rats were randomized into three different groups of 15 animals. In group I (the control), the flaps received phosphate-buffered saline (PBS). In group II, flaps were treated with adenovirus vector encoding Ang-1 (Ad-Ang-1). In group III, flaps received a control gene encoding green fluorescein protein (Ad-GFP). All treatments were administered via intra-arterial injections of either viral particles (108 placque-forming units) or PBS. The external iliac artery was used for this purpose. The cremaster tube flap was then preserved in a subcutaneous pocket in the lower limb. The tube flap was withdrawn from the limb on days 3, 7, and 14 after intra-arterial injection to evaluate microcirculatory measurements such as red blood cell velocity, vessel diameter, capillary density, and microvascular permeability by intravital microscopy. Evaluations were performed by an investigator who was blinded to treatment groups. In aseries of control experiments performed with Ad-GFP, adenoviral gene expression was evidenced by the observation of shiny GFP deposits along the vessel walls under fluorescence microscopy throughout the whole cremaster flap 2 days after transfection. At day 3 there was no evidence of any differences in capillary density and permeability index (PI). At day 7, the functional capillary density was significantly higher in the Ad-Ang-1-treated group compared with the control and the Ad-GFP groups (10/hpf ± 2 vs. 7/hpf ± 0.5, p =0.006; 5/hpf ± 1.6, p =0.0001). The PI in the Ad-Ang-1-treated group was significantly lower compared with the Ad-GFP-treated group (1.1/hpf ± 0.1% vs. 1.4/hpf ± 0.1%, p =0.0005). At 14 days, the number of the flowing capillaries was significantly higher in the Ad-Ang-1-treated group compared with the control and the Ad-GFP-treated groups (13/hpf ± 1.7 vs. 9/hpf ± 2 and 6/hpf ± 1.3, p =0.0001). The microvascular PI was significantly lower in the Ad-Ang-1-treated group compared with the Ad-GFP-treated group (1.3/hpf ± 0.2% vs. 1.8/hpf ± 0.5%, p =0.004). Histologically, the cremaster flaps revealed focal and mild inflammation regardless of the treatment and time point of evaluation. There was evidence of vasculitis in muscles pretreated with Ad-GFP and Ad-Ang-1. In summary, in the Ad-Ang-1-treated cremaster flaps, functional capillary density increased from 46% at day 7 to 98% at day 14 when compared with the control group (p < 0.0001). In conclusion, in this experimental muscle flap model, Ad-Ang-1 treatment proved to be a successful method of angiogenic therapy, providing a long-lasting angiogenic effect over a period of 14 days. The increased capillary perfusion accompanied by the formation of more stable and mature vessels resistant to fluorescein isothiocyanate-conjugated albumin leakage may serve as in vivo evidence that Ang-1 therapy improves skeletal muscle flap hemodynamics. These exciting findings raise the possibility that Ang-1 may have implications for therapeutic angiogenesis. To the authors” knowledge, their study demonstrates for the first time the feasibility of intravascular gene therapy using a virus vector in an attempt to enhance muscle flap hemodynamics.

Intra-arterial adenoviral mediated tumor transfection in a novel model of cancer gene therapy

BackgroundThe aim of the present study was to develop and characterize a novel in vivo cancer gene therapy model in which intra-arterial adenoviral gene delivery can be characterized. In this model, the rat cremaster muscle serves as the site for tumor growth and provides convenient and isolated access to the tumor parenchyma with discrete control of arterial and venous access for delivery of agents.ResultsUtilizing adenovirus encoding the green fluorescent protein we demonstrated broad tumor transfection. We also observed a dose dependant increment in luciferase activity at the tumor site using an adenovirus encoding the luciferase reporter gene. Finally, we tested the intra-arterial adenovirus dwelling time required to achieve optimal tumor transfection and observed a minimum time of 30 minutes.ConclusionWe conclude that adenovirus mediated tumor transfection grown in the cremaster muscle of athymic nude rats via an intra-arterial route could be achieved. This model allows definition of the variables that affect intra-arterial tumor transfection. This particular study suggests that allowing a defined intra-tumor dwelling time by controlling the blood flow of the affected organ during vector infusion can optimize intra-arterial adenoviral delivery.