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Background: Patients with dilated cardiomyopathy often have progressive heart failure with systolic dysfunction, ventricular remodeling and clinical decompensation heralded by elevations of filling...

There remains a need for large animal models to evaluate tissue-engineered vascular grafts (TEVGs) under arterial pressure to provide preclinical data for future potential human clinical trials. We present a comprehensive method for the interrogation of TEVGs, using an ovine bilateral arteriovenous (AV) shunt implantation model. Our results demonstrate that this method can be performed safely without complications, specifically acute heart failure, steal syndrome, and hypoxic brain injury, and it is a viable experimental paradigm. Our method allows for a non-invasive evaluation of TEVGs in terms of graft flow, graft diameter, and graft patency, while also allowing for graft needle puncture under ultrasound guidance. In addition, traditional pathological analysis, histology, and immunohistochemistry may be performed with the contralateral side providing paired control data to eliminate inter-subject variability while reducing the total number of animals. Further, we present a review of existing literature of preclinical evaluation of TEVGs in large animal models as AV conduits.

The goal of this study was to confirm the vasopressor and cardiac effects of POTENAY® INJETAVEL (POT), a mephentermine-based product, given to cattle with induced vascular/cardiac depression. Ten healthy Holstein cattle (206 ± 13 kg) followed a randomized-complete-block design (RCBD) utilizing crossover study design. Each animal randomly received (1 ml/25 kg, IM) of either POT (n = 10) or volume-matched placebo control (0.9%NaCl, CP, n = 10). A subset of animals (n = 5) received POT first (day 0) while the remaining (n = 5) received CP; after a six-day washout period, cattle received the opposite compound. Animals were anesthetized and catheterized for systemic/left ventricular hemodynamic monitoring. Myocardial dysfunction/hypotension was induced by increasing the end-tidal isoflurane concentration until arterial blood pressure was 20% lower than at baseline and remained stable. Once the animal was determined to be hypotensive and hemodynamically stable, steady-state hypotensive baseline data (BL2) were acquired, and treatment with either POT or CP was given. Data were acquired post-treatment at every 15 min for 90 min. POT improved cardiac output (+68 L/min, ±14%, p

Introduction: Reduction of myocardial loading and energetic demand while enhancing function are primary needs for the treatment of heart failure (HF). Nitroxyl (HNO) produces cAMP-independent unloading and inotropic/lusitropic support in both laboratory animals and patients with HF. To date, however, the cardiovascular activity of HNO has only been investigated using short-acting parenteral donors. Aim: This study assessed the feasibility of non-parenteral (oral) HNO delivery, by evaluating the cardiovascular responses to a novel slow-release HNO prodrug given to conscious dogs with induced HF. Methods: Dogs were either used for pharmacokinetic assessments or chronically instrumented for arterial pressures and LV pressure-volume (LVPV) recordings; instrumented dogs had HF induced via chronic pacing (e.g., EF: 38 ± 1%, PRSW: 51.2 ± 0.9 mmHg+, EDP: 23 ± 2 mmHg and NT-proBNP > 2500 pM/L). Data were obtained before/after oral (22.5 mg/kg) and/or before/during continuous IV infusion (65 μg/kg/min) treatment with a slow-release HNO prodrug (~30min in vitro t1/2 for release of HNO); load-independent systolic/diastolic function was examined by LVPV relationships obtained for up to 180min after the onset of dosing. Results: The slow-release HNO prodrug was bioavailable orally (%F: 40 ± 4), presenting rapid absortion (Tmax: 0.1 ± 0.5 hr, Cmax: 3.6 ± 1.3 ug/mL) and clearance (t1/2: 0.40 ± 0.01 hr, AUCinf: 4.1±0.8 hr·ug/mL). Oral HNO reduced LV preload (EDV: -7 ± 1%*), filling (EDP: -29 ± 7%*) and end-systolic pressures (ESP: -17 ± 2 %*), without concomitant changes in heart rate (HR: -4 ± 2%). Oral HNO increased stroke volume (SV: 14 ± 3%*) and ejection fraction (EF: 22 ± 3%*), while decreasing arterial elastance (Ea: -27 ± 2 %). Oral HNO enhanced load-independent inotropy (PRSW, +12 ± 2%*) and lusitropy (tau: -15 ± 3 %*, EDPVR: -50 ± 8%*), improved ventriculo-arterial coupling and decreased estimated myocardial demand (PVA: -66 ± 4%*). These effects were comparable to those obtained via IV administration (PRSW: +12 ± 1%*, Ea: -23 ± 3%*, and PVA: -51 ± 8%*). (*: P < 0.05 vs. pre-dosing). Conclusions: These results demonstrate the feasibility of delivering HNO orally to improve myocardial loading and enhance systolic/diastolic function in the setting of HF.

We determined the dose-dependent effects of OC99, a novel, stabilized hemoglobin-based oxygen-carrier, on hemodynamics, systemic and pulmonary artery pressures, surrogates of tissue oxygen debt (arterial lactate7.2±0.1 mM/L and arterial base excess−17.9±0.5 mM/L), and tissue oxygen tension (tPO2) in a dog model of controlled severe oxygen-debt from hemorrhagic shock. The dose/rate for OC99 was established from a pilot study conducted in six bled dogs. Subsequently twenty-four dogs were randomly assigned to one of four groups (n=6per group) and administered: 0.0, 0.065, 0.325, or 0.65 g/kg of OC99 combined with 10 mL/kg lactated Ringers solution administered in conjunction with 20 mL/kg Hextend IV over 60 minutes. The administration of 0.325 g/kg and 0.65 g/kg OC99 produced plasma hemoglobin concentrations of0.63±0.01and1.11±0.02 g/dL, respectively, improved systemic hemodynamics, enhanced tPO2, and restored lactate and base excess values compared to 0.0 and 0.065 g/kg OC99. The administration of 0.65 g/kg OC99 significantly elevated pulmonary artery pressure. Plasma hemoglobin concentrations of OC99 ranging from 0.3 to 1.1 g/dL, in conjunction with colloid based fluid resuscitation, normalized clinical surrogates of tissue oxygen debt, improved tPO2, and avoided clinically relevant increases in pulmonary artery pressure.

The natural vasoactive intestinal peptide (VIP) triggers potent pulmonary vasodilatation by activating the G-protein-coupled VAPC receptors, and has been suggested as a therapeutic target in pulmonary artery hypertension (PAH); however, VIP’s clinical utility is limited due to its short half-life. A novel ELP fusion technology (PhaseBio’s) permits the creation of long-acting protein-fusion biopolymer-based VPAC-receptor agonists. Here, the pulmonary/systemic hemodynamic effects of two novel ELP-enhanced VIP analogues (ELP-VIP) were evaluated in anesthetized rats with hypoxia-induced PAH. Sprague-Dawley rats (259 ± 5 g, n = 25) were anesthetized (propofol), intubated, mechanically-ventilated (95% FiO2), and instrumented for systemic (arterial) and mean pulmonary-artery pressure monitoring. Following instrumentation PAH was induced by acutely decreasing the inspired FiO2 (to ∼10-11%). Subsequently, the animals were assigned to receive either a novel VPAC agonist (VIP-ELP, n = 18: 3-6 mg/kg) or placebo (VEH, n = 11: 0.9% NaCl). Treatments were delivered as acute single-dose boluses given either intravenously (IV) or intratracheally (IT) at a fixed volume. Reductions in the inspired FiO2 resulted in sustained pulmonary artery pressure increases (+45 ± 3%, 28 ± 1 to 41 ± 1 mmHg; P < 0.05), consistent with hypoxic PAH. Induced-PAH was preserved in the absence of active treatment, as pulmonary pressures remained elevated following placebo administration (VEH: -1 ± 2%, from 40 ± 2 to 40 ± 2 mmHg; n = 11, N.S.). Acute administration of the VIP-ELP analogues resulted in rapid pulmonary artery pressure reductions (-24 ± 3%, from 41 ± 1 to 31 ± 1 mmHg, P < 0.05) with moderate/negligible changes in systemic pressures (MAP: -12 ± 6%) and heart rate (-4 ± 3%). Notably, the pulmonary vaso-relaxation triggered by VIP-ELP agonists was sustained and independent of the route of administration (IV: -17 ± 4%, n = 8; IT: -28 ± 4%, n = 10). The novel ELP-enhanced VIP analogues triggered rapid and sustained reductions in pulmonary-artery pressures in the setting of induced (hypoxic) pulmonary hypertension (PAH). These effects were independent of the route of administration, as both intravenous/intra-tracheal administrations were efficacious.