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J M Isner

Publications and source records attributed to J M Isner.

At least 73 records · Page 4Linked to original sources
PubMed1999

Gene therapy for myocardial angiogenesis.

In patients in whom antianginal medications fail to provide sufficient symptomatic relief, additional interventions such as angioplasty or bypass surgery may be required. Although both types of intervention have been shown to be effective for various types of patients, a certain group of patients may not be candidates for either intervention because of the diffuse nature of their coronary artery disease. Moreover, there are many patients in whom recurrent narrowing and/or occlusion of bypass conduits after initially successful surgery has left the patient again symptomatic with no further angioplasty or surgical option. Ischemic muscle represents a promising target for gene therapy with naked plasmid DNA. Intramuscular transfection of genes encoding angiogenic cytokines, particularly those naturally secreted by intact cells, may constitute an alternative treatment strategy for patients with extensive tissue ischemia in whom contemporary therapies (antianginal medications, angioplasty, bypass surgery) have previously failed or are not feasible. This strategy is designed to promote the development of supplemental collateral blood vessels that will constitute endogenous bypass conduits around occluded native arteries, a strategy termed "therapeutic angiogenesis." Preclinical animal studies from our laboratory have established that intramuscular gene transfer may be used to successfully accomplish therapeutic angiogenesis. More recently, phase 1 clinical studies from our institution have established that intramuscular gene transfer may be used to safely and successfully accomplish therapeutic angiogenesis in patients with critical limb ischemia. The notion that this concept could be extrapolated to the treatment of chronic myocardial ischemia was demonstrated in our laboratory by administering recombinant human vascular endothelial growth factor (VEGF) to a porcine model of chronic myocardial ischemia. Recent experiments performed in this same porcine model of myocardial ischemia have shown that direct intramyocardial gene transfer of naked plasmid DNA encoding VEGF (phVEGF(165), the identical plasmid used in our previous animal and human clinical trials) can be safely and successfully achieved through a minimally invasive chest wall incision. Finally, initial results have supported the concept that intramyocardial injection of naked plasmid DNA encoding VEGF can achieve therapeutic angiogenesis, as demonstrated by clinical improvement in patient symptoms and improved myocardial perfusion shown by single-photon emission computed tomography-sestamibi imaging.

Animals↗
PubMed1999

Rescue of diabetes-related impairment of angiogenesis by intramuscular gene therapy with adeno-VEGF.

Diabetes is a major risk factor for coronary and peripheral artery diseases. Although diabetic patients often present with advanced forms of these diseases, it is not known whether the compensatory mechanisms to vascular ischemia are affected in this condition. Accordingly, we sought to determine whether diabetes could: 1) impair the development of new collateral vessel formation in response to tissue ischemia and 2) inhibit cytokine-induced therapeutic neovascularization. Hindlimb ischemia was created by femoral artery ligation in nonobese diabetic mice (NOD mice, n = 20) and in control C57 mice (n = 20). Hindlimb perfusion was evaluated by serial laser Doppler studies after the surgery. In NOD mice, measurement of the Doppler flow ratio between the ischemic and the normal limb indicated that restoration of perfusion in the ischemic hindlimb was significantly impaired. At day 14 after surgery, Doppler flow ratio in the NOD mice was 0.49+/-0.04 versus 0.73+/-0.06 for the C57 mice (P< or =0.005). This impairment in blood flow recovery persisted throughout the duration of the study with Doppler flow ratio values at day 35 of 0.50+/-0.05 versus 0.90+/-0.07 in the NOD and C57 mice, respectively (P< or =0.001). CD31 immunostaining confirmed the laser Doppler data by showing a significant reduction in capillary density in the NOD mice at 35 days after surgery (302+/-4 capillaries/mm2 versus 782+/-78 in C57 mice (P< or =0.005). The reduction in neovascularization in the NOD mice was the result of a lower level of vascular endothelial growth factor (VEGF) in the ischemic tissues, as assessed by Northern blot, Western blot and immunohistochemistry. The central role of VEGF was confirmed by showing that normal levels of neovascularization (compared with C57) could be achieved in NOD mice that had been supplemented for this growth factor via intramuscular injection of an adenoviral vector encoding for VEGF. We conclude that 1) diabetes impairs endogenous neovascularization of ischemic tissues; 2) the impairment in new blood vessel formation results from reduced expression of VEGF; and 3) cytokine supplementation achieved by intramuscular adeno-VEGF gene transfer restores neovascularization in a mouse model of diabetes.

Adenoviridae↗
PubMed1999

Gene therapy with vascular endothelial growth factor for inoperable coronary artery disease.

BACKGROUND: Patients presenting with medically intractable angina who have undergone previous coronary bypass (CABG) and/or percutaneous revascularization procedures are frequently deemed "inoperable" based on angiographic findings of diffuse distal disease or a lack of available conduits. We initiated a phase I clinical trial to assess the safety and bioactivity of intramyocardial transfection of plasmid DNA encoding for the angiogenic mitogen vascular endothelial growth factor (ph-VEGF165) in such patients. METHODS: phVEGF165 (125 microg, n = 10; 250 microg, n = 10) was injected directly into the myocardium through a mini left anterior thoracotomy as sole therapy in 20 patients (15 male, 5 female, age 48 to 74 years) with class III or IV angina, reversible ischemia on stress sestamibi scans, and "inoperable" coronary artery disease. RESULTS: All patients tolerated surgery uneventfully and were extubated on the table. No perioperative myocardial infarction, hemodynamic instability, or change in ventricular function occurred. Mean hospital stay was 3.9 days. There was one late death (4 months). Plasma VEGF protein level increased from 30.6+/-4.1 pg/mL pretreatment to 73.7+/-10.1 pg/mL 14 days posttreatment (p = 0.0002) and returned to baseline by day 90. All 16 patients followed to day 90 reported a reduction in angina (nitroglycerin use/week = 60.2+/-4.9 preop vs 3.5+/-1.6 at 90 days; p<0.0001). Seventy percent (7 of 10) patients were completely angina free at 6 months. A reduction in ischemic defects on single photon emission computerized tomography sestamibi scans was observed in 13 of 17 patients at 60 days (7 of 8 in the 250-microg group). Stress perfusion score decreased from 19.4+/-3.7 at baseline to 15.9+/-3.4 at 60 days (p = 0.025). Angiographic evidence of improved collateral filling of at least one occluded vessel was observed in all patients evaluated at day 60. CONCLUSIONS: Direct myocardial gene transfer with phVEGF165 via a mini-thoracotomy can be performed safely and may result in significant symptomatic improvement in patients with "inoperable" coronary artery disease.

Aged↗
PubMed1999

Catheter-based myocardial gene transfer utilizing nonfluoroscopic electromechanical left ventricular mapping.

OBJECTIVES: This study investigated the feasibility and safety of percutaneous, catheter-based myocardial gene transfer. BACKGROUND: Direct myocardial gene transfer has, to date, required direct injection via an open thoracotomy. METHODS: Electroanatomical mapping was performed to establish the site of left ventricular (LV) gene transfer. A steerable, deformable 7F catheter with a 27G needle, which can be advanced 3 to 5 mm beyond its distal tip, was then directed to previously acquired map sites, the needle was advanced, and injections were made into the LV myocardium. RESULTS: In two pigs in which methylene blue dye was injected, discretely stained LV sites were observed at necropsy in each pig, corresponding to the injection sites indicated prospectively by the endocardial map. In six pigs in which the injection catheter was used to deliver plasmid using cytomegalovirus promoter/enhancer, encoding nuclear-specific LacZ gene (pCMV-nlsLacZ) (50 microg/ml) to a single LV myocardial region, peak beta-galactosidase activity after five days (relative light units [RLU], mean 135,333+/-28,239, range = 31,508 to 192,748) was documented in the target area of myocardial injection in each pig. Percutaneous gene transfer of pCMV-nlsLacZ (50 microg/ml) was also performed in two pigs with an ameroid constrictor applied to the left circumflex coronary artery, in each pig, peak beta-galactosidase activity after five days (214,851 and 23,140 RLU) was documented at the injection site. All pigs survived until sacrifice, and no complications were observed with either the mapping or the injection procedures. CONCLUSIONS: Percutaneous myocardial gene transfer can be successfully achieved in normal and ischemic myocardium without significant morbidity or mortality. These findings establish the potential for minimally invasive cardiovascular gene transfer.

Animals↗
PubMed1999

Ischemia- and cytokine-induced mobilization of bone marrow-derived endothelial progenitor cells for neovascularization.

Endothelial progenitor cells (EPCs) have been isolated from circulating mononuclear cells in human peripheral blood and shown to be incorporated into foci of neovascularization, consistent with postnatal vasculogenesis. We determined whether endogenous stimuli (tissue ischemia) and exogenous cytokine therapy (granulocyte macrophage-colony stimulating factor, GM-CSF) mobilize EPCs and thereby contribute to neovascularization of ischemic tissues. The development of regional ischemia in both mice and rabbits increased the frequency of circulating EPCs. In mice, the effect of ischemia-induced EPC mobilization was demonstrated by enhanced ocular neovascularization after cornea micropocket surgery in mice with hindlimb ischemia compared with that in non-ischemic control mice. In rabbits with hindlimb ischemia, circulating EPCs were further augmented after pretreatment with GM-CSF, with a corresponding improvement in hindlimb neovascularization. There was direct evidence that EPCs that contributed to enhanced corneal neovascularization were specifically mobilized from the bone marrow in response to ischemia and GM-CSF in mice transplanted with bone marrow from transgenic donors expressing beta-galactosidase transcriptionally regulated by the endothelial cell-specific Tie-2 promoter. These findings indicate that circulating EPCs are mobilized endogenously in response to tissue ischemia or exogenously by cytokine therapy and thereby augment neovascularization of ischemic tissues.

Animals↗
PubMed1999

Vascular smooth muscle cell growth arrest on blockade of thrombospondin-1 requires p21(Cip1/WAF1).

Abnormal proliferation of vascular smooth muscle cells (VSMCs) is thought to play an important role in the pathogenesis of atherosclerosis and restenosis. Previous studies have implicated the extracellular matrix protein thrombospondin-1 (TSP1) in mitogen-dependent proliferation of VSMCs. In this study, we investigated the molecular mechanisms involved in TSP1-mediated regulation of VSMC growth. Neutralizing A4.1 anti-TSP1 antibody inhibited the activity of the G(1)/S cyclin-dependent kinase 2 (cdk2) and blocked the induction of S-phase entry, which normally occurs in serum-stimulated VSMCs. This growth-inhibitory effect was associated with a marked induction of p21(Cip1/WAF1) (p21) expression in A4.1-treated VSMCs. Moreover, addition of A4.1 antibody to VSMCs markedly increased the level of p21 bound to cdk2. Thus growth arrest on antibody blockade of TSP1 may be mediated by the cdk inhibitory protein p21. Consistent with this notion, anti-TSP1 antibody inhibited [(3)H]-thymidine incorporation in wild-type but not in p21-deficient mouse embryonic fibroblasts (MEFs). Together, these data suggest that p21 plays an important role in TSP1-mediated control of cellular proliferation.

Animals↗
PubMed1999

Role of endothelial nitric oxide synthase in endothelial cell migration.

Endothelium-derived nitric oxide (NO) and its precursor L-arginine have been implied to promote angiogenesis, but little is known about the precise mechanism. The inhibition of endogenous NO formation by Nomega-nitro-L-arginine methyl ester (L-NAME) (1 mmol/L) but not its inactive enantiomer D-NAME (1 mmol/L) inhibited endothelial cell sprouting from the scratched edge of the cultured bovine aortic endothelial cell monolayer. Inhibition of endogenous NO release by L-NAME was confirmed by amperometric measurement using an NO-specific electrode. In the modified Boyden chamber, L-NAME (1 mmol/L) significantly inhibited endothelial cell migration, whereas L-NAME did not affect endothelial DNA synthesis as assessed by analysis of [3H]thymidine incorporation. We then examined alteration of endothelial cell adhesion molecule expression after the inhibition of NO by L-NAME in cultured human umbilical vein endothelial cells. In both normoxic and hypoxic conditions, L-NAME (1 mmol/L) inhibited surface expression of integrin alphavbeta3, which is an important integrin facilitating endothelial cell survival and angiogenesis. However, L-NAME did not affect the expression of platelet endothelial cell adhesion molecule-1, intercellular adhesion molecule-1, vascular endothelial adhesion molecule-1, gap junction protein connexin 43, and VE-cadherin, which have been reported to potentially affect angiogenesis. In summary, inhibition of endothelial NO synthase by L-NAME attenuated endothelial cell migration but not proliferation in vitro. Furthermore, endogenous endothelium-derived NO maintains the functional expression of integrin alphavbeta3, a mediator for endothelial migration, survival, and angiogenesis. Endothelium-derived NO, thus, may play an important role in mediating angiogenesis by supporting endothelial cell migration, at least partly, via an integrin-dependent mechanism.

Animals↗
PubMed1998

Direct intramuscular injection of plasmid DNA encoding angiopoietin-1 but not angiopoietin-2 augments revascularization in the rabbit ischemic hindlimb.

BACKGROUND: Angiopoietin-1 (Ang1) and angiopoietin-2 (Ang2) have recently been identified as ligands for the endothelial cell-specific Tie2 receptor. Little is known regarding the impact of these Tie2 ligands on postnatal neovascularization. Accordingly, we tested the hypothesis that gene transfer of plasmid DNA encoding Ang1 and Ang2 could modulate collateral vessel development in a rabbit model of hindlimb ischemia. METHODS AND RESULTS: pAng1* (n=15), pJFE control (no Ang1* insert) (n=9), pAng2 (n=9), pcDNA3 control (no Ang2 insert) (n=10), or saline (n=5) was injected intramuscularly into the rabbit ischemic hindlimb. Collateral vessel development and limb perfusion were assessed before and 30 days after treatment. Calf blood pressure ratio (ischemic to normal hindlimb) was increased 30 days after Ang1* gene transfer versus controls (Ang1*, 0.90+/-0.02; pJFE, 0.76+/-0.05; saline, 0.77+/-0. 03; P<0.05). Angiographic score was higher (P<0.05) in the pAng1* group (0.63+/-0.02) than in the pJFE (0.51+/-0.03) or saline (0. 52+/-0.02) group. Maximal (postpapaverine) blood flow in the ischemic limb was higher (P<0.05) after pAng1* (67.8+/-4.9 mL/min) than pJFE (51.2+/-4.4 mL/min) or saline (52.9+/-4.9 mL/min). Capillary density and capillary/muscle fiber ratio (242+/-12/mm2 and 0.89+/-0.06, respectively) were higher (P<0.01) with pAng1* than pJFE (172+/-11/mm2 and 0.64+/-0.05) or saline (166+/-10/mm2 and 0. 67+/-0.05). Neovascularization was not enhanced with pAng2. CONCLUSIONS: Ang1 but not Ang2 gene transfer produces anatomic and physiological evidence of enhanced collateral vessel formation. Ang1 may modulate neovascularization in adult animals and thus represents a feasible therapeutic strategy for patients with tissue ischemia. The role of Ang2 in postnatal neovascularization remains to be clarified.

Angiography↗
PubMed1998

Tie2 receptor ligands, angiopoietin-1 and angiopoietin-2, modulate VEGF-induced postnatal neovascularization.

Angiopoietin-1 (Ang1) has been recently identified as the major physiological ligand for the tyrosine kinase receptor Tie2 and assigned responsibility for recruiting and sustaining periendothelial support cells. Angiopoietin-2 (Ang2) was found to disrupt blood vessel formation in the developing embryo by antagonizing the effects of Ang1 and Tie2 and was thus considered to represent a natural Ang1/Tie2 inhibitor. In vivo effects of either angiopoietin on postnatal neovascularization, however, have not been previously described. Accordingly, we used the cornea micropocket assay of neovascularization to investigate the impact of angiopoietins on neovascularization in vivo. Neither Ang1 nor Ang2 alone promoted neovascularization. Pellets containing vascular endothelial growth factor (VEGF) alone induced corneal neovascularity extending from the limbus across the cornea. Addition of Ang 1 to VEGF (Ang1+VEGF) produced an increase in macroscopically evident perfusion of the corneal neovasculature without affecting macroscopic measurements of length (0.58+/-0.03 mm) or circumferential neovascularity (136+/-10 degrees). In contrast, pellets containing Ang2+VEGF promoted significantly longer (0.67+/-0.05 mm) and more circumferential (160+/-15degrees) neovascularity than VEGF alone or Ang1+VEGF (P<0.05). Excess soluble Tie2 receptor (sTie2-Fc) precluded modulation of VEGF-induced neovascularization by both Ang2 and Ang1. Fluorescent microscopic findings demonstrated enhanced capillary density (fluorescence intensity, 2.55+/-0.23 e+9 versus 1.23+/-0.17 e+9, P<0.01) and increased luminal diameter of the basal limbus artery (39.0+/-2.8 versus 27.9+/-1.3 microm, P<0.01) for Ang1+VEGF compared with VEGF alone. In contrast to Ang1+VEGF, Ang2+VEGF produced longer vessels and, at the tip of the developing capillaries, frequent isolated sprouting cells. In the case of Ang2+VEGF, however, luminal diameter of the basal limbus artery was not increased (26.7+/-1.9 versus 27.9+/-1.3, P=NS). These findings constitute what is to our knowledge the first direct demonstration of postnatal bioactivity associated with either angiopoietin. In particular, these results indicate that angiopoietins may potentiate the effects of other angiogenic cytokines. Moreover, these findings provide in vivo evidence that Ang1 promotes vascular network maturation, whereas Ang2 works to initiate neovascularization.

Angiopoietin-1↗
PubMed1998

Chemotactic properties of angiopoietin-1 and -2, ligands for the endothelial-specific receptor tyrosine kinase Tie2.

Angiopoietin-1 and its putative natural antagonist, angiopoietin-2, were recently isolated, and the critical role of angiopoietin-1 in embryogenic angiogenesis was demonstrated by targeted gene disruption. Specific biological effects of angiopoietin-1, however, have yet to be defined. In this study we demonstrate that angiopoietin-1, but not angiopoietin-2, is chemotactic for endothelial cells. In contrast, angiopoietin-1 as well as angiopoietin-2 exhibit no proliferative effect on endothelial cells. Excess soluble Tie2, but not Tie1 receptor, abolish the chemotactic response of endothelial cells toward angiopoietin-1. Angiopoietin-2 dose-dependently blocks directed migration toward angiopoietin-1, consistent with the role of angiopoietin-2 as a naturally occurring inhibitor of angiopoietin-1. Fibroblasts stably transfected with Tie2 receptor exhibit chemotactic responses for both angiopoietin-1 and angiopoietin-2. Fibroblasts stably expressing a transfected chimeric receptor consisting of the ectodomain of TrkC fused to the cytoplasmic domain of Tie2 also exhibit a chemotactic response to neurotrophin 3 (NT-3), a specific ligand for TrkC. Endothelial cells are shown to express angiopoietin-2 mRNA and protein, indicating the potential for autocrine activation of angiopoietin/Tie2. Finally, the demonstration that Tie2 as well as angiopoietin-1 are expressed in normal human arteries and veins suggests that the role of angiopoietin/Tie2 may extend beyond embryonic angiogenesis to maintaining integrity of the adult vasculature.

Adult↗
PubMed1998

Nitric oxide synthase modulates angiogenesis in response to tissue ischemia.

We tested the hypothesis that endothelial nitric oxide synthase (eNOS) modulates angiogenesis in two animal models in which therapeutic angiogenesis has been characterized as a compensatory response to tissue ischemia. We first administered L-arginine, previously shown to augment endogenous production of NO, to normal rabbits with operatively induced hindlimb ischemia. Angiogenesis in the ischemic hindlimb was significantly improved by dietary supplementation with L-arginine, compared to placebo-treated controls; angiographically evident vascularity in the ischemic limb, hemodynamic indices of limb perfusion, capillary density, and vasomotor reactivity in the collateral vessel-dependent ischemic limb were all improved by oral L-arginine supplementation. A murine model of operatively induced hindlimb ischemia was used to investigate the impact of targeted disruption of the gene encoding for ENOS on angiogenesis. Angiogenesis in the ischemic hindlimb was significantly impaired in eNOS-/- mice versus wild-type controls evaluated by either laser Doppler flow analysis or capillary density measurement. Impaired angiogenesis in eNOS-/- mice was not improved by administration of vascular endothelial growth factor (VEGF), suggesting that eNOS acts downstream from VEGF. Thus, (a) eNOS is a downstream mediator for in vivo angiogenesis, and (b) promoting eNOS activity by L-arginine supplementation accelerates in vivo angiogenesis. These findings suggest that defective endothelial NO synthesis may limit angiogenesis in patients with endothelial dysfunction related to atherosclerosis, and that oral L-arginine supplementation constitutes a potential therapeutic strategy for accelerating angiogenesis in patients with advanced vascular obstruction.

Animals↗
PubMed1998

Therapeutic angiogenesis.

Therapeutic angiogenesis constitutes a fundamental survival mechanism that acts to preserve the integrity of tissues subjected to ischemia. Supplemental administration of angiogenic cytokines--as recombinant protein or plasmid DNA--have been shown to augment collateral development when endogenous angiogenesis is suboptimal for organ function, and thus constitute a novel therapeutic option for the treatment of cardiovascular disease. These angiogenic cytokines, all of which share in common the ability to act as mitogens for endothelial cells, do not promote angiogenesis in an indiscriminate fashion; thus angiogenic cytokines selectively produce neovascularization in the ischemic tissues. The purpose of this review is to consider the mechanisms responsible for therapeutic angiogenesis which develops endogenously as well as strategies which have been devised to augment this response. The development of blood vessels is considered from the context of the embryonic paradigm; certain principles which have emerged from studies of pathologic neovascularization; and, principally, the development of collateral blood vessels supplying ischemic tissues, either endogenously or in response to administered growth factors.

Angiogenic Proteins↗
PubMed1998

Effects of poloxamer 407 on transfection time and percutaneous adenovirus-mediated gene transfer in native and stented vessels.

UNLABELLED: Reduction in transfection time and the ability to perform gene transfer in conjunction with endovascular stent implantation constitute two important challenges for percutaneous adenovirus-mediated gene transfer to vessel walls. Studies have suggested that the use of biocompatible polyol poloxamer 407 could be useful. We first evaluated the use of poloxamer 407 for percutaneous gene transfer in nonstented rabbit iliac arteries. A 200-microl mixture of Ad-RSVbetagal or Ad-CMVLuc in either phosphate-buffered saline (PBS) or 20% poloxamer was delivered. After 3 days, gene transfection was evaluated by X-Gal staining or measurement of luciferase activity. Poloxamer use resulted in a 3- to 15-fold increase in the percentage of transfected cells (X-Gal, p = 0.001) and a 16-fold increase in protein product (luciferase activity, p = 0.03), and allowed a decrease in transfection time from 30 to 5 min with minimal reduction in transfection efficiency. We then evaluated the feasibility of percutaneous gene transfer, using Ad-RSVbetagal diluted in pure PBS or 20% poloxamer, in conjunction with stent implantation. Gene delivery was performed either immediately before (pre-) or after (post-) stent implantation. When adenoviruses were diluted in PBS, gene transfer had a low efficiency (prestent, 0.3%; poststent, 0.2%; NS). With poloxamer, the efficacy was much higher (p = 0.0001) and similar "pre" (2.2%) or "post" (1.7%) stent delivery (NS). CONCLUSIONS: (1) The use of poloxamer, rather than PBS, as a vehicle increases the efficacy of percutaneous adenovirus-mediated gene transfer and reduces transfection time; (2) gene transfer performed during stent implantation with poloxamer is feasible and achieves a significant level of gene expression. Thus percutaneous gene delivery is applicable to conventional stents and could present an attractive method by which to achieve local biological effects in a stent environment.

Adenoviruses, Human↗
PubMed1998

Constitutive expression of phVEGF165 after intramuscular gene transfer promotes collateral vessel development in patients with critical limb ischemia.

BACKGROUND: Preclinical studies have indicated that angiogenic growth factors can stimulate the development of collateral arteries, a concept called "therapeutic angiogenesis." The objectives of this phase 1 clinical trial were (1) to document the safety and feasibility of intramuscular gene transfer by use of naked plasmid DNA encoding an endothelial cell mitogen and (2) to analyze potential therapeutic benefits in patients with critical limb ischemia. METHODS AND RESULTS: Gene transfer was performed in 10 limbs of 9 patients with nonhealing ischemic ulcers (n=7/10) and/or rest pain (n=10/10) due to peripheral arterial disease. A total dose of 4000 microg of naked plasmid DNA encoding the 165-amino-acid isoform of human vascular endothelial growth factor (phVEGF165) was injected directly into the muscles of the ischemic limb. Gene expression was documented by a transient increase in serum levels of VEGF monitored by ELISA. The ankle-brachial index improved significantly (0.33+/-0.05 to 0.48+/-0.03, P=.02); newly visible collateral blood vessels were directly documented by contrast angiography in 7 limbs; and magnetic resonance angiography showed qualitative evidence of improved distal flow in 8 limbs. Ischemic ulcers healed or markedly improved in 4 of 7 limbs, including successful limb salvage in 3 patients recommended for below-knee amputation. Tissue specimens obtained from an amputee 10 weeks after gene therapy showed foci of proliferating endothelial cells by immunohistochemistry. PCR and Southern blot analyses indicated persistence of small amounts of plasmid DNA. Complications were limited to transient lower-extremity edema in 6 patients, consistent with VEGF enhancement of vascular permeability. CONCLUSIONS: These findings may be cautiously interpreted to indicate that intramuscular injection of naked plasmid DNA achieves constitutive overexpression of VEGF sufficient to induce therapeutic angiogenesis in selected patients with critical limb ischemia.

Adult↗
PubMed1998

Potentiated angiogenic effect of scatter factor/hepatocyte growth factor via induction of vascular endothelial growth factor: the case for paracrine amplification of angiogenesis.

BACKGROUND: Scatter factor/hepatocyte growth factor (SF/HGF) is a pleiotropic growth factor that stimulates proliferation and migration of endothelial cells (ECs) via the c-Met receptor, present on ECs as well as other cell types, including smooth muscle cells (SMCs). We studied the effects of recombinant human (rh) SF/HGF in vitro and in vivo in a rabbit model of hindlimb ischemia. We further compared these effects with those of recombinant human vascular endothelial growth factor (rhVEGF165), an EC-specific mitogen. METHODS AND RESULTS: In vitro, rhSF/HGF and rhVEGF165 exhibited similar effects on proliferation and migration of ECs. When both cytokines were administered together, the result was an additive effect on EC proliferation and a synergistic effect on EC migration. Application of rhSF/HGF to cultures of human SMCs resulted in the induction of VEGF mRNA and protein. In vivo, administration of rhSF/HGF (500 microg x 3) was associated with significant improvements in collateral formation (P<.001) and regional blood flow (P<.0005) and with a significant reduction in muscle atrophy (P<.0001). These effects were significantly more pronounced than those of rhVEGF165 administered according to the same protocol (P<.05). Neither remote angiogenesis nor other pathological sequelae were observed with either rhSF/HGF or rhVEGF165. CONCLUSIONS: The pleiotropic effects of certain growth factors may potentiate angiogenesis via a combination of direct effects on EC proliferation and migration and indirect effects that result in the generation of other potent EC mitogens from non-EC populations. The synergistic effects demonstrated when SF/HGF and VEGF are administered together in vitro may be reproduced in vivo by SF/HGF-induced upregulation of VEGF in vascular SMCs.

Animals↗