DNA Aß42 immunization via needle-less Jet injection in mice and rabbits as potential immunotherapy for Alzheimer's disease.

Alzheimer's disease (AD) is the most common form of dementia found in the elderly and disease progression is associated with accumulation of Amyloid beta 1-42 (Aß42) in brain. An immune-mediated approach as a preventive intervention to reduce amyloid plaques without causing brain inflammation is highly desirable for future clinical use. Genetic immunization, in which the immunizing agent is DNA encoding Aß42, has great potential because the immune response to DNA delivered into the skin is generally non-inflammatory, and thus differs quantitatively and qualitatively from immune responses elicited by peptides, which are inflammatory with production of IFNγ and IL-17 cytokines by activated T cells. DNA immunization has historically been proven difficult to apply to larger mammals. A potential barrier to use DNA immunization in large mammals is the method for delivery of the DNA antigen. We tested jet injection in mice and rabbits and found good antibody production and safe immune responses (no inflammatory cytokines). We found significant reduction of amyloid plaques and Aß peptides in brains of the DNA Aß42 immunized 3xTg-AD mouse model. This study was designed to optimize DNA delivery for possible testing of the DNA Aß42 vaccine for AD prevention in a clinical trial.

The feasibility of ultrasound-assisted endovascular laser thrombolysis in an acute rabbit thrombosis model.

PURPOSE: This study aimed to test the feasibility of combined ultrasound and laser technique, namely, ultrasound-assisted endovascular laser thrombolysis (USELT), for thrombolysis by conducting in vivo tests in a rabbit thrombosis model. MATERIALS AND METHODS: An acute thrombus was created in the right jugular vein of rabbit and then was treated with ultrasound only, laser only, and USELT to dissolve the blood clot. A total of 20 rabbits were used. Out of which, the first three rabbits were used to titrate the laser and ultrasound parameters. Then, five rabbits were treated with ultrasound only, five rabbits were treated with laser only, and seven rabbits were treated with USELT. During USELT, 532-nm laser pulses were delivered endovascularly directly to the clot through a fiber optic, and 0.5 MHz ultrasound pulses were applied noninvasively to the same region. A laser fluence of 4 to 12 mJ/cm2 and ultrasound amplitude of 1 to 2 MPa were used. Recanalization of the jugular vein was assessed by performing ultrasound Doppler imaging immediately after the treatment. The maximum blood flow speed after the treatment as compared to its value before the treatment was used to calculate the blood flow recovery in vessel. RESULTS: The blood flow was fully recovered (100%) in three rabbits, partially recovered in two rabbits (more than 50% and less than 100%) with mean percentage recovery of 69.73% and poorly recovered in two rabbits (<50%) with mean percentage recovery of 6.2% in the USELT group. In contrast, the treatment group with ultrasound or laser alone did not show recanalization of vein in any case, all the five rabbits were poorly/not recovered with a mean percentage recovery of 0%. CONCLUSIONS: The USELT technology was shown to effectively dissolve the blood clots in an acute rabbit jugular vein thrombosis model.

Evaluation of a DNA Aß42 Vaccine in Aged NZW Rabbits: Antibody Kinetics and Immune Profile after Intradermal Immunization with Full-Length DNA Aß42 Trimer.

A pathological hallmark of Alzheimer's disease (AD) are amyloid plaques in the brain consisting of aggregated amyloid-ß 42 peptide (Aß42) derived from cellular amyloid-ß protein precursor (AßPP). Based on successful experiments in mouse AD models, active immunization with Aß42 peptide and passive immunizations with anti-Aß42 antibodies were started in clinical trials. Active Aß42 peptide immunization in humans had led to an inflammatory autoimmune response, and the trial was stopped. Passive immunizations had shown some effects in slowing AD pathology. Active DNA Aß42 immunizations administered with the gene gun into the skin elicits a different immune response and is non-inflammatory. While in rodents, good responses had been found for this type of immunization, positive results in larger mammals are missing. We present here results from sixteen New Zealand White Rabbits, which underwent intradermal DNA Aß42 immunization via gene gun. The humoral immune response was analyzed from blood throughout the study, and cellular immune responses were determined from spleens at the end of the study. A good anti-Aß antibody response was found in the rabbit model. The T cell response after re-stimulation in cell culture showed no IFNγ producing cells when ELISPOT assays were analyzed from PBMC, but low numbers of IFNγ and IL-17 producing cells were found in ELISPOTS from spleens (both 5 immunizations). Brains from immunized rabbits showed no signs of encephalitis. Based on these results, DNA Aß42 immunization is highly likely to be safe and effective to test in a possible clinical AD prevention trial in patients.

Initial Experience With the Pediatric Impella Device: A Feasibility Study in a Porcine Model.

OBJECTIVE: This study's objective was to evaluate insertion techniques and device fit of the pediatric version of the Impella ventricular assist device in swine which had similar sized carotids and left ventricles (LVs) as children weighing 10-20 kg. BACKGROUND: Options for minimally invasive circulatory support in children are limited. A modified device based on the current Impella 2.5 platform was created in an effort to provide minimally invasive circulatory support for children. METHODS: Animal studies (n = 10) were performed to determine technical feasibility of device implant via the right common carotid artery (RCCA) in swine with a carotid and LV size similar to children with a BSA < 1 m2 and weight 10-20 kg. The RCCA diameter was measured on pre-implant ultrasound and the LV length was measured at necropsy. The animals were supported for 4 hr and the device explanted. Blood samples and post-explant necropsy was performed to evaluate for device related complications. RESULTS: All animals underwent successful device insertion. Mean carotid artery diameter by ultrasound was 3.5 ± 0.3 mm. There was no LV or aortic/mitral valve damage with a minimum LV length of 5.4 cm. CONCLUSIONS: Minimally invasive circulatory support is needed in small children. Limitations are primarily related to vessel and chamber size. The Impella Pediatric catheter was safely and successfully implanted in carotid arteries similar in size to children weighing 10-20 kg with minimal complications. © 2016 Wiley Periodicals, Inc.

Comparative Evaluation of Two Venous Sampling Techniques for the Assessment of Pancreatic Insulin and Zinc Release upon Glucose Challenge.

Advances in noninvasive imaging modalities have provided opportunities to study ß cell function through imaging zinc release from insulin secreting ß cells. Understanding the temporal secretory pattern of insulin and zinc corelease after a glucose challenge is essential for proper timing of administration of zinc sensing probes. Portal venous sampling is an essential part of pharmacological and nutritional studies in animal models. The purpose of this study was to compare two different percutaneous image-guided techniques: transhepatic ultrasound guided portal vein access and transsplenic fluoroscopy guided splenic vein access for ease of access, safety, and evaluation of temporal kinetics of insulin and zinc release into the venous effluent from the pancreas. Both techniques were safe, reproducible, and easy to perform. The mean time required to obtain desired catheter position for venous sampling was 15 minutes shorter using the transsplenic technique. A clear biphasic insulin release profile was observed in both techniques. Statistically higher insulin concentration but similar zinc release after a glucose challenge was observed from splenic vein samples, as compared to the ones from the portal vein. To our knowledge, this is the first report of percutaneous methods to assess zinc release kinetics from the porcine pancreas.

Novel bioresorbable stent coating for drug release in congenital heart disease applications.

A novel double opposed helical poly-l-lactic acid (PLLA) bioresorbable stent has been designed for use in pediatrics. The aim was to test the PLLA stent biocompatibility. The PLLA stent was immersed into whole pig's blood in a closed loop circuit then fibrin and platelet association was assessed via enzyme-linked immunosorbent assay. D-Dimer was valued at 0.2 ± 0.002 ng/mL and P-selectin 0.43 ± 00.01 ng/mL indicating limited association of fibrin and platelets on the stent. To improve biocompatibility by targeting inflammatory cells, dexamethasone was incorporated on PLLA fibers with two coating methods. Both coatings were poly(l-lactide-co-glycolide) acid (PLGA) but one was made porous with sucrose while the other remained nonporous. There was no change in mechanical properties of the fiber with either coating of PLGA polymer. The total amount of dexamethasone released was then determined for each coating. The cumulative drug release for the porous fiber was significantly higher (∼100%) over 8 weeks than the nonporous fiber (40%). Surface examination of the fiber with scanning electron microscopy showed more surface microfracturing in coatings that contain pores. The biocompatibility of this novel stent was demonstrated. Mechanical properties of the fiber were not altered by coating with PLGA polymer. Anti-inflammatory drug release was optimized using a porous PLGA polymer.

A novel design biodegradable stent for use in congenital heart disease: mid-term results in rabbit descending aorta.

OBJECTIVES: This study evaluates the feasibility of delivery and deployment of low and medium molecular weight (LMW and MMW, respectively) double-opposing helical (DH) poly-l-lactic acid biodegradable stent (BDS) in rabbit descending aorta (DAO). Secondary objectives were to assess patency and inflammation of stented vessels at 9 months and to investigate safety following intentional embolization of stent fragments in DAO. BACKGROUND: A BDS that will relieve aortic obstruction and disappears as the child grows older allowing for preservation of aortic wall elasticity and natural growth of aorta will be ideal to treat Coarctation (CoA). BDS have never been evaluated in the DAO. METHODS: Seven New Zealand white rabbits underwent implantation of DH-LMW (n = 7), DH-MMW (n = 3), and metal stents (n = 7) in DAO. BDS fragments were intentionally embolized into DAO in two rabbits. RESULTS: All stents were deployed via a 6-French sheath. Five BDS covered the origin of major DAO side branches. Angiography and intravascular ultrasound showed good stent apposition to the wall of DAO with minimal luminal loss at 9 months follow-up. All stents had minimal neointimal hyperplasia on histopathology. Adverse events included 1 death, 1 aortic aneurysm, and lower extremity ulceration due to self-mutilation in an embolization rabbit. CONCLUSIONS: Pilot study confirms the feasibility of delivery and deployment of up to 6-millimeter diameter DH BDS in rabbit DAO. Stent integrity with DH design was maintained at 9 months with minimal vessel inflammation. Potential morbidity due to embolized BD fragments cannot be ruled out and needs further evaluation.

Estrogen alters remodeling of the vaginal wall after surgical injury in guinea pigs.

Loss of pelvic organ support (i.e., pelvic organ prolapse) is common in menopausal women. Surgical reconstruction of pelvic organ prolapse is plagued with high failure rates. The objective of this study was to determine the effects of estrogen on biomechanical properties, lysyl oxidase (LOX), collagen content, and histomorphology of the vagina with or without surgical injury. Nulliparous ovariectomized guinea pigs were treated systemically with either 50 µg/kg/day estradiol (E2,) or vehicle. After 2 wk, vaginal surgery was performed, and animals were treated with either beta-aminopropionitrile (BAPN, an irreversible LOX inhibitor), or vehicle to determine the role of LOX in recovery of the vaginal wall from injury with or without E2. Estradiol resulted in (i) significant growth, increased smooth muscle, and increased thickness of the vagina, (ii) increased distensibility without compromise of maximal force at failure, and (iii) increased total and cross-linked collagen. In the absence of E2, BAPN resulted in decreased collagen and vaginal wall strength in the area of the injury. In contrast, in E2-treated animals, increased distensibility, maximal forces, and total collagen were maintained despite BAPN. Interestingly, LOX mRNA was induced dramatically (9.5-fold) in the injured vagina with or without E2 at 4 days. By 21 days, however, LOX levels declined to near baseline in E2-deprived animals. LOX mRNA levels remained strikingly elevated (12-fold) at 21 days in the estrogenized vagina. The results suggest that prolonged E2 induced increases in LOX, and collagen cross-links may act to sustain a matrix environment that optimizes long-term surgical wound healing in the vagina.

The impact of temperature and pump flow rate during selective cerebral perfusion on regional blood flow in piglets.

OBJECTIVE: Ideal temperature and flow rate for selective cerebral perfusion (SCP) are not known. We examined regional organ perfusion in a piglet SCP model. METHODS: Three groups underwent SCP at 30 mL/kg/min at different temperatures (15°C, 25°C, and 32°C) and 4 groups remained at 25°C for SCP at different flow rates (10, 30, 50 and 75 mL/kg/min). Fluorescent microspheres were injected at 5 minutes of normothermic cardiopulmonary bypass (CPB), immediately before SCP, SCP 45 minutes, SCP 90 minutes, and 2 hours after CPB. Brain and lower body organs were collected to examine regional blood flow (RBF, mL/min/g). RESULTS: At 2 hours after CPB, RBF of the 32°C group was higher than that of the 15°C group (P < .05) at the caudate nucleus and hippocampus; RBF of the 32°C group was higher than that of the 25°C and 15°C groups (P < .05) at the neocortex. No significant difference in RBF was observed among any of the 25°C groups at different flow rates. Also, there was no significant difference between the RBF to the left and right sides of brain in either the temperature or flow rate groups. RBF did significantly increase with temperature in the liver and quadriceps during SCP (P < .05). At the kidney, RBF at SCP 90 minutes was significantly higher than that at SCP 45 minutes when all temperature groups were combined (P < .05). CONCLUSIONS: SCP at 32°C provides higher brain RBF 2 hours after CPB. Increasing SCP flow rate does not increase RBF significantly at 25°C. Higher temperature during SCP results in improved RBF to the liver and quadriceps.