Safety and efficacy of plasmid DNA expressing two isoforms of hepatocyte growth factor in patients with critical limb ischemia.

VM202, a plasmid DNA that expresses two isoforms of hepatocyte growth factor, may elicit angiogenic effects that could benefit patients with critical limb ischemia (CLI). In a phase 2, double-blind trial in 52 CLI patients, we examined the safety and potential efficacy of intramuscular injections of low-dose (n=21) or high-dose (n=20) VM202 or placebo (n=11) in the affected limb (days 0, 14, 28 and 42). Adverse events and serious adverse events were similar among the groups; no malignancy or proliferative retinopathy was seen. In exploratory efficacy analyses, we found no differences in ankle or toe-brachial index, VAS, VascuQuol or amputation rate among the groups. Complete ulcer healing was significantly better in high-dose (8/13 ulcers; P<0.01) versus placebo (1/9) patients. Clinically meaningful reductions (>50%) in ulcer area occurred in high-dose (9/13 ulcers) and low-dose (19/27) groups versus placebo (1/9; P<0.05 and P<0.005, respectively). At 12 months, significant differences were seen in TcPO2 between the high-dose and placebo groups (47.5 ± 17.8 versus 36.6 ± 24.0 mm Hg, respectively; P<0.05) and in the change from baseline among the groups (P<0.05). These data suggest that VM202 is safe and may provide therapeutic bioactivity in CLI patients.

Ischemic tissue repair by autologous bone marrow-derived stem cells: scientific basis and preclinical data.

The success of therapies targeting acute myocardial ischemia and the aging of the population due to improved general medical care has resulted in an increasing population of patients with chronic myocardial ischemia and congestive heart failure who remain symptomatic despite having exhausted the currently available therapeutic options. In this chapter we review the scientific underpinnings of autologous bone marrow-derived cell therapy and the early clinical experience that has fuelled interest in this approach.

Comparative analysis of the in vivo angiogenic properties of stable prostacyclin analogs: a possible role for peroxisome proliferator-activated receptors.

OBJECTIVE: Until recently, prostacyclin (PGI2) biological activities were thought to be exclusively mediated by cell surface receptors named IP. Recent studies have instead identified a novel pathway of PGI2 signaling, occurring through activation of peroxisome proliferator-activated receptors (PPARs) located in the nucleus. The availability of stable PGI2 analogs with different affinity for IP receptors and PPARs provides the possibility to test the importance and function of this dual pathway in vitro and in vivo. In this study, the in vivo angiogenic properties of different PGI2 analogs and the potential relationship between PPAR-mediated pathways, vascular endothelial growth factor (VEGF), and angiogenesis were investigated. METHODS AND RESULTS: By using the murine corneal model of angiogenesis, we found that PGI2 analogs able to act on nuclear PPARs, such as iloprost and carbaprostacyclin (cPGI), induce angiogenesis in vivo. In contrast, cicaprost, a PGI2 analog that only acts on IP receptors, has no in vivo angiogenic activity. Interestingly, angiogenesis induced by iloprost and cPGI does not differ in extent and morphology from that induced by VEGF and is associated with local increment of VEGF mRNA expression and protein levels. Finally, iloprost-induced angiogenesis is significantly decreased by systemic inhibition of VEGF activity, obtained by gene transfer of a soluble form of the VEGF receptor Flt-1. CONCLUSIONS: These data demonstrate that stable PGI2 analogs may have angiogenic properties in vivo, depending on their ability to act on PPARs. The resulting angiogenic process appears to be mediated by VEGF. These findings indicate that important physiological activities in the cardiovascular system, such as angiogenesis and VEGF induction, may be modulated by PGI2 through specific activation of the PPAR signaling pathway in vivo, with potentially important fundamental and clinical implications.

Estrogen receptor-mediated, nitric oxide-dependent modulation of the immunologic barrier function of the endothelium: regulation of fas ligand expression by estradiol.

BACKGROUND: Premenopausal women have a lower incidence of coronary artery disease than postmenopausal women or same-age men. Although the mechanisms of this apparent relative protection against atherosclerosis remain ill defined, estradiol, which is present in higher concentrations before menopause, is considered to play a central role. Recently, Fas ligand (FasL) expression by the vascular endothelium has been shown to inhibit the migration of inflammatory cells into the vessel wall, an event that is considered crucial for the development of atherosclerosis. METHODS AND RESULTS: The regulation of endothelial FasL expression by estradiol was investigated in vivo and in vitro. In an ovariectomized, cholesterol-clamped rabbit model, FasL expression was shown to be downregulated by elevations in serum cholesterol, which also resulted in invasion of the arterial wall by macrophages. Estradiol replacement resulted in restoration of FasL expression, with resultant inhibition of leukocyte traffic across the endothelium. Inhibition of NO production by addition of L-NAME to the drinking water of the estradiol-treated rabbits abrogated these effects. In vitro, estradiol is shown to regulate FasL expression at the transcriptional level via an estrogen receptor-mediated, NO-dependent mechanism. CONCLUSIONS: Estradiol transcriptionally regulates endothelial FasL expression by a mechanism involving at least one of the estrogen receptors. In an animal model of atherosclerosis, estradiol restores FasL expression, which is suppressed by atherogenic levels of serum cholesterol. The maintenance of endothelial FasL expression by estradiol may represent a mechanism of estrogen's apparent antiatherogenic effect.

In vivo blockade of tumor necrosis factor-alpha accelerates functional endothelial recovery after balloon angioplasty.

BACKGROUND: Tumor necrosis factor-alpha (TNF) is expressed locally in arteries at sites of balloon injury. In vitro studies have shown that TNF inhibits cell cycle progression and induces apoptosis in endothelial cells. Accordingly, we performed a series of experiments to test the hypothesis that inhibiting TNF could accelerate endothelial recovery after angioplasty. METHODS AND RESULTS: TNF soluble receptor (TNFsr) has been shown to neutralize the actions of TNF in vitro and in vivo. Sprague-Dawley rats received TNFsr versus control IgG through an intraperitoneal injection. De-endothelializing balloon injury was then performed, and animals were killed after 1 week to evaluate re-endothelialization (Evans blue dye staining) and after 2 weeks to evaluate re-endothelialization and endothelial function. At both time points, blockade of TNF using TNFsr resulted in an increase in re-endothelialization, as measured as absolute area and percent area re-endothelialized. TNFsr also accelerated functional endothelial recovery, which manifest as an increase in nitric oxide production. Neointimal thickening was also shown inhibited. CONCLUSIONS: In vivo blockade of TNF accelerates functional endothelial recovery after barotraumatic de-endothelializing injury. These findings suggest that locally expressed TNF acts to inhibit functional endothelial recovery after angioplasty and that transient blockade of TNF may improve the long-term success of angioplasty.

Intracoronary administration of recombinant human vascular endothelial growth factor to patients with coronary artery disease.

BACKGROUND: Patients with severe myocardial ischemia who are not candidates for percutaneous or surgical revascularization have few therapeutic options. Therapeutic angiogenesis in animal models with use of recombinant human vascular endothelial growth factor (rhVEGF) has resulted in successful revascularization of ischemic myocardium. This was a dose escalation trial designed to determine the safety and tolerability of intracoronary rhVEGF infusions. METHODS AND RESULTS: Patients were eligible if they had stable exertional angina, a significant reversible perfusion defect by stress myocardial perfusion study, and coronary anatomy that was suboptimal for percutaneous coronary intervention or coronary artery bypass grafting. rhVEGF was administered to a total of 15 patients by 2 sequential (eg, right and left) intracoronary infusions, each for 10 minutes, at rates of 0.005 (n = 4), 0.017 (n = 4), 0.050 (n = 4), and 0.167 mg/kg/min (n = 3). Pharmacokinetic sampling and hemodynamic monitoring were performed for 24 hours. Radionuclide myocardial perfusion imaging was performed before treatment and at 30 and 60 days after treatment. Follow-up angiograms were performed on selected patients at 60 days. The maximally tolerated intracardiac dose of rhVEGF was 0.050 mg/kg/min. Minimal hemodynamic changes were seen at 0.0050 mg/kg/min (2% +/- 7% [SD] mean decrease in systolic blood pressure from baseline to nadir systolic blood pressure), whereas at 0.167 mg/kg/min there was a 28% +/- 7% mean decrease from baseline to nadir (136 to 95 mm Hg systolic). Myocardial perfusion imaging was improved in 7 of 14 patients at 60 days. All 7 patients with follow-up angiograms had improvements in the collateral density score. CONCLUSION: rhVEGF appears well tolerated by coronary infusion at rates up to 0.050 mg/kg/min. This study provides the basis for future clinical trials to assess the clinical benefit of therapeutic angiogenesis with rhVEGF.

[Growth factors for therapeutic angiogenesis in cardiovascular diseases]. / Factores de crecimiento para la angiogénesis terapéutica en las enfermedades cardiovasculares.

Therapeutic angiogenesis based on the administration of growth factors with angiogenic activity allows enhancement of collateral vessels able to palliate insufficient tissue perfusion secondary to obstruction of native arteries. At present, this type of therapy is addressed to patients that fail to respond to conventional treatment (surgical or percutaneous revascularization). The most extensively investigated angiogenic growth factors are vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF). These cytokines can be administered either as recombinant proteins or as the genes encoding for these proteins. Both approaches have pros and cons that are under investigation in animal models and in clinical studies. Although clinical trials consist so far of small, often non-randomized series, preliminary results are promising. For example, administration of VEGF or FGF has been associated to objective evidence of increased tissue perfusion in patients with myocardial ischemia, and to a significant improvement of pain and ischemia in patients with peripheral arterial disease. Contrarily to expected, these interventions have been associated to scant adverse side effects, although larger clinical trials will be necessary in order to prove the safety and effectiveness of these interventions. Nevertheless, it seems clear that it is feasible to induce effective therapeutic angiogenesis in selected patients without significant associated toxicity.

Assessment of risks associated with cardiovascular gene therapy in human subjects.

Clinical trials of cardiovascular gene therapy, whether using viral (53%) or nonviral (47%) vectors, have thus far disclosed no evidence indicative of inflammatory or other complications, including death, directly attributable to the vector used. Indeed, despite the fact that initial trials of cardiovascular gene therapy targeted patients with end-stage vascular disease, including critical limb ischemia and refractory myocardial ischemia, the mortality for patients enrolled in clinical trials of cardiovascular gene therapy reported to date compares favorably with mortality for similar groups of patients in contemporary controlled studies of medical or interventional therapies. The most common morbidity reported after cardiovascular gene transfer is lower extremity edema; in contrast to data involving genetically engineered mice, however, evidence of life- or limb-threatening edema has not been described in any patients, including patients after gene transfer for myocardial ischemia. Concerns regarding the potential for angiogenic cytokines to promote the progression of atherosclerosis are not supported by angiographic follow-up of patients with coronary or peripheral vascular disease. The levels and duration of gene expression investigated for therapeutic angiogenesis transfer have been unassociated with hemangioma formation. Likewise, there is little evidence from either preclinical or clinical studies to support the notion that the administration of angiogenic growth factors, per se, is sufficient to stimulate the growth of neoplasms. Patients enrolled in clinical studies of angiogenic cytokines, including patients with diabetes and a previous history of retinopathy, have disclosed no evidence to suggest that ocular pathology is a risk of angiogenic growth factor gene transfer.

Randomized, single-blind, placebo-controlled pilot study of catheter-based myocardial gene transfer for therapeutic angiogenesis using left ventricular electromechanical mapping in patients with chronic myocardial ischemia.

BACKGROUND: Catheter-based myocardial gene transfer (GTx) has not been previously tested in human subjects. Accordingly, we performed a pilot study to investigate the feasibility and safety of catheter-based myocardial GTx of naked plasmid DNA encoding vascular endothelial growth factor-2 (phVEGF-2) in patients with chronic myocardial ischemia. METHODS AND RESULTS: A steerable, deflectable 8F catheter incorporating a 27-guage needle was advanced percutaneously to the left ventricular myocardium of 6 patients with chronic myocardial ischemia. Patients were randomized (1:1) to receive phVEGF-2 (total dose, 200 microgram), which was administered as 6 injections into ischemic myocardium (total, 6.0 mL), or placebo (mock procedure). Injections were guided by NOGA left ventricular electromechanical mapping. Patients initially randomized to placebo became eligible for phVEGF-2 GTx if they had no clinical improvement 90 days after their initial procedure. Catheter injections (n=36) caused no changes in heart rate or blood pressure. No sustained ventricular arrhythmias, ECG evidence of infarction, or ventricular perforations were observed. phVEGF-2-transfected patients experienced reduced angina (before versus after GTx, 36.2+/-2.3 versus 3.5+/-1.2 episodes/week) and reduced nitroglycerin consumption (33.8+/-2.3 versus 4.1+/-1.5 tablets/week) for up to 360 days after GTx; reduced ischemia by electromechanical mapping (mean area of ischemia, 10.2+/-3.5 versus 2.8+/-1.6 cm(2), P=0.04); and improved myocardial perfusion by SPECT-sestamibi scanning for up to 90 days after GTx when compared with images obtained after control procedure. Conclusions-This randomized trial of catheter-based phVEGF-2 myocardial GTx provides preliminary indications regarding the feasibility, safety, and potential efficacy of percutaneous myocardial GTx to human left ventricular myocardium.

Gene therapy with vascular endothelial growth factor for inoperable coronary artery disease: anesthetic management and results.

UNLABELLED: Gene transfer for therapeutic angiogenesis represents a novel treatment for medically intractable angina in patients judged not amenable to further conventional revascularization. We describe the anesthetic management of 30 patients with class 3 or 4 angina, enrolled in a Phase 1 clinical trial to assess the safety and bioactivity of direct myocardial gene transfer of naked DNA-encoding vascular endothelial growth factor (phVEGF(165)), as sole therapy for refractory angina. The phVEGF(165) was injected directly into the myocardium through a mini-thoracotomy. All patients had major clinical predictors for adverse perioperative cardiac complications. Fast-track anesthetic management with remifentanil and desflurane, multimodal analgesia, and aggressive hemodynamic control with nitroglycerin and esmolol were used. All patients tolerated anesthesia and surgery without problems. No perioperative myocardial infarction, hemodynamic instability, or ventricular failure occurred. VEGF injections caused no clinically significant changes in cardiovascular function. Mean hospital stay was 3.8 days. There was one late death (5 months postoperative). Twenty-nine of 30 patients experienced reduced angina (56.2 +/- 4.1 episodes/week preoperatively versus 3.8 +/- 1.6 postoperatively, P < 0.0001) and reduced sublingual nitroglycerin consumption (60.1 +/- 4.4 tablets/week preoperatively versus 2.9 +/- 1.1 postoperatively, P < 0.0001). IMPLICATIONS: Previously revascularized patients now judged "inoperable," continue to present with chronic, recurrent angina. Our study describes the anesthetic considerations and management of such patients treated with a novel approach by using gene therapy to stimulate angiogenesis and improve perfusion to ischemic myocardium.

Estrogen and angiogenesis: A review.

Multiple lines of evidence suggest that estrogen directly modulates angiogenesis via effects on endothelial cells. Under physiological conditions, angiogenesis is routinely observed in the uterus in association with fluctuations in the levels of circulating estradiol and other sex steroids. In pathological circumstances, such as breast cancer, a clear association between estrogen, estrogen receptor expression by endothelial cells, angiogenic activity, and/or tumor invasiveness has been made. Studies performed in our laboratory have revealed that estradiol accelerates functional endothelial recovery after arterial injury. Despite these consistent observations, the mechanisms by which estrogen regulates angiogenesis under physiological and pathological circumstances have not been defined.

Genetic targeting for cardiovascular therapeutics: are we near the summit or just beginning the climb?

This article is based on an Experimental Biology symposium held in April 2001 and presents the current status of gene therapy for cardiovascular diseases in experimental studies and clinical trials. Evidence for the use of gene therapy to limit neointimal hyperplasia and confer myocardial protection was presented, and it was found that augmenting local nitric oxide (NO) production using gene transfer (GT) of NO synthase or interruption of cell cycle progression through a genetic transfer of cell cycle regulatory genes limited vascular smooth muscle hyperplasia in animal models and infra-inguinal bypass patients. The results of application of vascular endothelial growth factor (VEGF) GT strategies for therapeutic angiogenesis in critical limb and myocardial ischemia in pilot clinical trials was reviewed. In addition, experimental evidence was presented that genetic manipulation of peptide systems (i.e., the renin-angiotensin II system and the kallikrein-kinin system) was effective in the treatment of systemic cardiovascular diseases such as hypertension, heart failure, and renal failure. Although, as of yet, there are no well controlled human trials proving the clinical benefits of gene therapy for cardiovascular diseases, the data presented here in animal models and in human subjects show that genetic targeting is a promising and encouraging modality, not only for the treatment and long-term control of cardiovascular diseases, but for their prevention as well.

Left ventricular electromechanical mapping to assess efficacy of phVEGF(165) gene transfer for therapeutic angiogenesis in chronic myocardial ischemia.

BACKGROUND: NOGA left ventricular (LV) electromechanical mapping (EMM) can be used to distinguish among infarcted, ischemic, and normal myocardium. We investigated the use of percutaneous LV EMM to assess the efficacy of myocardial gene transfer (GTx) of naked plasmid DNA encoding for vascular endothelial growth factor (phVEGF(165)), administered during surgery by direct myocardial injection in patients with chronic myocardial ischemia. METHODS AND RESULTS: A total of 13 consecutive patients (8 men, mean age 60.1+/-2. 3 years) with chronic stable angina due to angiographically documented coronary artery disease, all of whom had failed conventional therapy (drugs, PTCA, and/or CABG), were treated with direct myocardial injection of phVEGF(165) via a minithoracotomy. Foci of ischemic myocardium were identified on LV EMM by preserved viability associated with an impairment in linear local shortening. Myocardial viability, defined by mean unipolar and bipolar voltage recordings >/=5 and >/=2 mV, respectively, did not change significantly after GTx. Analysis of linear local shortening in areas of myocardial ischemia, however, disclosed significant improvement after (15.26+/-0.98%) versus before (9.94+/-1.53%, P:=0. 004) phVEGF(165) GTx. The area of ischemic myocardium was consequently reduced from 6.45+/-1.37 cm(2) before GTx to 0.95+/-0. 41 cm(2) after GTx (P:=0.001). These findings corresponded to improved perfusion scores calculated from single-photon emission CT-sestamibi myocardial perfusion scans recorded at rest (7.4+/-2.1 before GTx versus 4.5+/-1.4 after GTx, P:=0.009) and after pharmacological stress (12.8+/-2.7 before GTx versus 8.5+/-1.7 after GTx, P:=0.047). CONCLUSIONS: The results of EMM constitute objective evidence that phVEGF(165) GTx augments perfusion of ischemic myocardium. These findings, together with reduction in the size of the defects documented at rest by serial single-photon emission CT-sestamibi imaging, suggest that phVEGF(165) GTx may successfully rescue foci of hibernating myocardium.

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.

Intraoperative multiplane transesophageal echocardiography for guiding direct myocardial gene transfer of vascular endothelial growth factor in patients with refractory angina pectoris.

Gene transfer for therapeutic angiogenesis represents a novel treatment for patients with chronic angina refractory to standard medical therapy and not amenable to conventional revascularization. We sought to assess the role of intraoperative multiplane transesophageal echocardiography (MPTEE) in guiding injection of naked DNA encoding vascular endothelial growth factor (VEGF) into the left ventricular (LV) myocardium of patients with refractory angina. After exposing the LV myocardium via a limited lateral thoracotomy, each of 17 patients in this series received 4 separate injections of VEGF DNA into different myocardial sites. Initial injections in the first patient produced intracavitary microbubbles, indicating injection of DNA into the LV chamber. Subsequently, each injection was preceded by a test injection of agitated saline. The absence of microbubbles while visualizing the LV cavity during the test injection verified that the ensuing injection of DNA would not be inadvertently squandered in the LV chamber itself. Intracavitary LV microbubbles were observed by MPTEE in 13 of 64 (20.3%) saline test injections and in 8 of 16 (50.0%) patients in which saline test injection was used, leading to adjustments in needle position. MPTEE imaging detected a previously unknown large, apical left ventricular thrombus in one patient, thereby preventing inadvertent injection of VEGF DNA through the myocardium into the thrombus. Imaging during and after injection verified no deleterious impact on LV function. We conclude that MPTEE is a useful tool for ensuring that myocardial gene therapy performed by direct needle injection results in gene transfer to the LV myocardium.

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.

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.