Preparation of a Carrier to Achieve In Vivo Delivery of siRNA: The Example of Chitosan-Coated Poly(isobutylcyanoacrylate) Nanoparticles.

This chapter describes the preparation of chitosan-coated poly(isobutylcyanoacrylate) nanoparticles as a suitable carrier to deliver siRNAs to two types of xenograft tumor models of mice. The nanoparticles are prepared by a method of emulsion polymerization that includes steps of polymerization and purification. The polymerization method is carried out in a single pot in an aqueous medium. siRNAs are coupled with the nanoparticles at the end of the preparation by adsorption. The protocol also explains how to determine optimum yield/the titer of association of siRNA with the nanoparticles. It is described for a preparation scale at 4 mL of nanoparticle dispersion at a concentration of 42-46 mg nanoparticles/mL. Optimal loading capacity of the nanoparticles with the siRNA can be achieved by performing an association yield above 90% using a mass ratio of 1 mg siRNA/50 mg of nanoparticles (20 µg siRNA/mg nanoparticles, 1 nmol siRNA (Mw 14 kDa)/mg nanoparticles).

Adjuvant Transjugular Variceal Occlusion at Creation of a Transjugular Intrahepatic Portosystemic Shunt (TIPS): Efficacy and Risks of Bucrylate Embolization.

Adjuvant embolization of varices may reduce rebleeding in patients with a transjugular intrahepatic portosystemic shunt (TIPS). The aim of this study was to investigate the efficacy and the risks of adjuvant variceal embolization at TIPS implantation using bucrylate. PATIENTS AND METHODS: The retrospective study evaluated 104 of 237 cirrhotic patients with TIPS for variceal bleeding who received adjuvant bucrylate embolization. For TIPS creation, bare stents were used in 35 patients (33.7%) and covered stents in 69 patients (66.3%) patients. Isolated gastric varices were seen in 10 patients (9.6%). RESULTS: Six patients (5.8%) rebled during a median follow-up time of 26 months (1-57 months). Rebleeding occurred in 14% (5/35) of patients with a bare stent but only in 1.4% (1/69) of patients with a covered stent. The 1- and 2-year rebleeding rates of all patients were 0.9 and 2.9% and of patients receiving a bare stent were 2.9 and 8.6%, respectively. Bucrylate migration was seen in 13 patients (12.5%). In 9 of these patients (8.7%), asymptomatic lung embolization occurred. This was rare in patients with esophageal varices (3.1%) but frequent (60%) in patients with isolated gastric varices and a spontaneous splenorenal shunt. CONCLUSIONS: Our results suggest that adjuvant embolization using bucrylate is effective and delays variceal rebleeding. The general use of covered stents, however, alleviates the utility of adjuvant bucrylate embolization which may be restricted to patients with a high risk of rebleeding indicated by large varices, active, acute or recent variceal bleeding and advanced cirrhosis. Bucrylate should not be used in isolated gastric varices because it bears a high risk of migration into the lungs.

Functionalized polymer microbubbles as new molecular ultrasound contrast agent to target P-selectin in thrombus.

Thrombotic diseases rarely cause symptoms until advanced stage and sudden death. Thus, early detection of thrombus by a widely spread imaging modality can improve the prognosis and reduce mortality. Here, polymer microbubbles (MBs) made of degradable poly(IsoButylCyanoAcrylate) and functionalized with fucoidan (Fucoidan-MBs) were designed as a new targeted ultrasound contrast agent to image venous thrombus. The physicochemical characterizations demonstrate that the MBs with fucoidan surface exhibit a size of 2-6 µm and stability in suspension at 4 °C up to 2 months. MBs exhibit high echogenicity and could be completely burst under high destructive pulse. Flow chamber experiments on activated human platelets show a higher affinity of Fucoidan-MBs than control anionic MBs (CM-Dextran-MBs) under shear stress conditions. In vivo analysis by ultrasound and histological results demonstrate that Fucoidan-MBs are localized in rat venous thrombotic wall, whereas few CM-Dextran-MBs are present. In addition, the binding of Fucoidan-MBs in healthy vein is not observed. Collectively, Fucoidan-MBs appear as a promising functionalized carrier for ultrasound molecular imaging in thrombotic diseases.

Endoscopic Cyanoacrylate Injection with Post-injection Audible Doppler Assessment of Gastric Varices: A Single-Institution Experience.

BACKGROUND AND AIMS: Gastric varices (GV) have higher rates of morbidity and mortality from hemorrhage than esophageal varices. Several studies have shown the safety and efficacy of cyanoacrylate (CA) injection for acute gastric variceal hemorrhage. We report data from our experience with CA injection for GV before and after routine use of post-injection audible Doppler assessment (ADA) for GV obturation and describe long-term outcomes after this therapy. METHODS: We retrospectively identified patients who had documented GV, underwent CA injection, and had at least 2 weeks of follow-up. We recorded and analyzed the survival and rebleeding rates with patient demographics, clinical data, and endoscopy findings between two groups of patients who were categorized by CA injection prior to and after inception of the ADA technique. RESULTS: Seventy-one patients were identified with 16 patients analyzed in a group where ADA was not used (Pre-ADA) and 55 analyzed where ADA was used (Post-ADA). No rebleeding events were observed within 1 week of initial CA injection. No embolic events were reported after any initial CA injection within 4 weeks. The rate of bleed-free survival at 1 year was 69.6% in the Pre-ADA group and 85.8% in the Post-ADA without statistical significance. The all-cause 1-year mortality was 13.8% in the Pre-ADA group and 10.7% in the Post-ADA group without statistical significance. CONCLUSIONS: ADA of CA-injected GV does not appear to significantly affect adverse events or clinical outcomes; however, our findings are limited by small sample size and cohort proportions allowing for significant type II statistical error. Further prospective investigation is required to determine the impact of ADA on clinical outcomes after GV obturation.

[COMPLICATIONS OF VIDEOTHORACOSCOPIC BIOPSY OF INTRATHORACIC LYMPH NODES AND METHODS OF THEIR PROPHYLAXIS].

Videothoracoscopy constitute a secure miniinvasive method of diagnosis of intrathoracic lymphadenopathy syndrome. Pulmonary hemorrhage and injury constitute intraoperative videothoracoscopic complications, and pulmonary collapse, hemorrhage, purulent complications ­ postoperative complications. Satisfactory intraoperative visualization, guaranteeing optimal position of the patient's body on operative table and sufficient pulmonary collapse on the intervention side, application of medical аlpha­cyanacrylate adhesive with hemostatic sponge for hemostasis in a biopsy zone, systemic application of antibiotics constitute the main prophylactic methods for videothoracoscopic complications and optimization of conditions for videothoracoscopic biopsy of intrathoracic lymphatic nodes. Application of the methods proposed have permitted to reduce the intraoperative complications rate from 19.2 tо 2.8%, and a postoperative one ­ from 23 tо 2.8%.

Critical analysis of cyanoacrylate in intestinal and colorectal anastomosis.

BACKGROUND: Although cyanoacrylate glue (CA) has been widely used in various kinds of medical applications, its application in gastrointestinal anastomosis remains limited, and outcomes of experimental studies have not been satisfactory. This systematic review summarizes research regarding CA application in intestinal and colorectal anastomosis, and correlates methodological aspects to experimental outcomes. METHODS: A systematic literature search was performed using Medline, Embase, Cochrane, and Web-of-Science libraries. Articles were selected if CA was applied to intestinal or colorectal anastomoses. Included articles were categorized according to CA molecular structure; the method details in each study were extracted and analyzed. RESULTS: Twenty-two articles were included. More than half of the inclusions reported positive outcomes (seven articles) or neutral outcomes (eight articles). Analysis of the methods revealed that methodological details such as CA dosage, time of polymerization were not consistently reported. Porcine studies, inverted anastomosis, and n-butyl-cyanoacrylate studies showed more positive outcomes; everted anastomosis, and oversized sutures might negatively influence the outcomes. CONCLUSIONS: Owing to the positive outcome from the porcine studies, application of CA in gastrointestinal (GI) anastomosis still seems promising. To achieve a better consistency, more methodological details need to be provided in future studies. Optimizing the dosage of CA, choice of animal model, inverted anastomosis construction, and other method details may improve intestinal and colorectal anastomoses with CA application in future studies.

Intraarterial polidocanol injection for the treatment of peripheral arteriovenous malformations.

PURPOSE: The purpose of this study was to investigate the efficacy and safety of intraarterial transcatheter administration of polidocanol as an alternative treatment for peripheral arteriovenous malformations (AVMs). METHODS: The study comprised 10 patients (six males and four females) with a mean age of 28.8 years (range 8-52 years). All patients had trunk or extremity AVMs. Following the administration of general anesthesia or intravenous (IV) sedation, the patients underwent staged intraarterial polidocanol sclerotherapy with or without additional embolizations for their AVMs. The administration of polidocanol was executed by intraarterial infusion through a microcatheter or by direct percutaneous entry into the nidus under ultrasound guidance. RESULTS: A total of 19 sessions were accomplished in 10 patients. Polidocanol was used alone in six of the 19 sessions. In 13 sessions, polidocanol was used in combination with another agent (including n-butyl cyanoacrylate (NBCA), lipiodol, and ethanol) and/or coils. In two sessions, polidocanol was administered percutaneously under ultrasound guidance directly into the nidus documented by arteriography. No major complications occurred. CONCLUSION: Intraarterial transcatheter administration of polidocanol alone or in combination with other agents is a safe and effective alternative treatment for peripheral AVMs.

An unusual cause of pulmonary artery pseudoaneurysm: acrylate embolism.

Sclerotherapy is commonly used to manage bleeding from oesophageal varices. In a patient with cirrhosis of the liver, sclerotherapy with bucrylate was followed by a pulmonary embolism and then by a decline in general health. A chest radiograph taken 5 months later disclosed a left perihilar opacity, surrounding and invading the pulmonary artery. Despite moderate fixation by positron emission tomography and inconclusive bronchoscopy findings, an upper left lobectomy was deemed in order. A left pulmonary artery pseudoaneurysm was found during the surgery. The pseudoaneurysm ruptured during dissection, requiring a left pneumonectomy. The pathological examination showed shredding of the left pulmonary artery, which contained foreign material. At points of contact with this material, destruction and severe polymorphic inflammation of the pulmonary parenchyma were noted. There was no evidence of tumour or infection. These findings strongly suggested an iatrogenic pulmonary artery pseudoaneurysm related to a bucrylate embolism through porto-systemic vascular shunts. We are not aware of previously reported cases.

The counterbalanced effect of size and surface properties of chitosan-coated poly(isobutylcyanoacrylate) nanoparticles on mucoadhesion due to pluronic F68 addition.

PURPOSE: To evaluate of the effect of size and surface characteristics of poly(isobutylcyanoacrylate) nanoparticles coated with pluronic F68 and thiolated chitosan on mucoadhesion. METHODS: Nanoparticles were obtained by radical emulsion polymerization in presence of different amounts of F68 (0-4%w/v). Mucoadhesion was ex vivo evaluated by applying nanoparticle suspension on rat intestinal mucosa and quantifying the amount of attached nanoparticles after incubation. RESULTS: F68 unimers added in the polymerization medium allowed decreasing nanoparticle size from 251 to 83 nm, but resulted in nanoparticle surface modification. The amount of thiolated chitosan onto nanoparticle surface was decreased resulting in lower thiol groups and zeta potential. Consequently, the decrease of nanoparticle hydrodynamic diameter resulted in eight-fold-increase of the number of nanoparticles attached to the mucosa but a significant decrease of the weight of attached nanoparticles was observed. This unexpected result was due to a decrease of the amount of chitosan and thiolated chitosan available to interact with mucus upon addition of F68 in the polymerization medium. CONCLUSIONS: Addition of F68 should not be recommended to improve the amount of mucoadherent nanoparticles. Further studies could allow understanding if the low amount of small size nanoparticles could be able to improve oral bioavailability.

[Case of repeated hemoptysis successfully treated with bronchial artery embolization with N-butyl cyanoacrylate].

We report a case of repeated hemoptysis successfully treated with bronchial artery embolization (BAE) with N-butyl cyanoacrylate (NBCA). A 75-year-old woman with non-tuberculous mycobacteriosis and pulmonary aspergillosis was admitted with recurrent hemoptysis despite repeated BAE. Considering the ineffectiveness of BAE with Spongel or polyvinyl alcohol, BAE with NBCA was selected. Immediate cessation of hemoptysis was obtained and it has not been seen for 2 years. Although NBCA is the most widely used liquid embolic material to treat brain aneurysm, arteriovenous malformations or gastric varices, there are only a few cases are reported in the treatment of hemoptysis. It seems to be a possible useful treatment for patients with repeated hemoptysis.

Reducing laparoscopic radical prostatectomy false-positive margin rates using cyanoacrylate tissue glue.

BACKGROUND: Trauma to the prostate surface from laparoscopic instruments may have a role in creating false-positive margins during laparoscopic radical prostatectomy (LRP). OBJECTIVE: To determine the feasibility of using cyanoacrylate glue to repair iatrogenic lacerations and to evaluate the glue's effect on the positive surgical margin rates of LRP specimens. DESIGN, SETTING, AND PARTICIPANTS: We used porcine kidneys as a surrogate experimental tissue to help determine the quality, robustness, and adequacy of glued repairs in experimentally created lacerations. A matched control group of unrepaired kidney specimens and kidney specimens repaired with glue were subjected to full histopathologic processing. Exposure of a nephron to surface marker ink was considered to be a "positive margin." The efficacy and impact of glue repairs on LRP specimens that had sustained iatrogenic intraoperative surface trauma were also assessed. MEASUREMENTS: We evaluated the success of glue repair in preventing subcapsular renal parenchymal staining. We also compared the rate of positive margins in LRP specimens with and without routine glue repair of the surface of the prostate. RESULTS AND LIMITATIONS: The glue remained effective throughout the entire laboratory process and did not interfere with histopathologic assessment. As hypothesised, cyanoacrylate glue repair of the renal lacerations prevented staining of subcapsular tissues with marker dye and therefore prevented what might otherwise be considered false-positive staining. The rate of positive margins of the 40 LRP specimens without glue repair was 35%, compared with a rate of 10% for 40 glue-repaired specimens. The limitations of the study are that follow-up was short and that the prostatectomy specimens were compared with consecutive controls rather than with matched randomised controls. CONCLUSIONS: Cyanoacrylate glue is a novel, inexpensive, and very effective prostate repair agent that does not interfere with histologic processing. It is possible to accurately repair iatrogenic prostate lacerations with cyanoacrylate glue and, in doing so, to considerably reduce the rate of spurious false-positive surgical margins.

Percutaneous injection of hemostatic agents for severe blunt hepatic trauma: an experimental study.

This study was designed to evaluate whether percutaneous injection of hemostatic agents under the guidance of contrast-enhanced ultrasound (CEUS) can stop hemorrhage from severe hepatic trauma. Eighteen dogs were impacted by a miniature impactor to create blunt hepatic trauma. Fourteen with appropriate liver lesions were divided into two groups: the treatment group (n = 7) and the control group (n = 7). In the treatment group, hemocoagulase atrox and alpha-cyanoacrylate were respectively injected into the injury sites and transected micro-vessels under the guidance of CEUS. In the control group, normal saline was injected into the injury sites. CEUS and CT were performed at 3, 7, 14, and 21 days after the focal injection. Surviving animals were killed on the 21st day for pathologic examination. All animals of the treatment group survived. Three dogs of the control group died in the first 24 h. In the treatment group, CEUS and CT demonstrated that hepatic lesions became smaller gradually from the 3rd to the 21st day after injection. The focal injection of hemostatic agents under the guidance of CEUS can stop hemorrhage from hepatic trauma of grade III~IV or IV. During the period of 3 weeks, no side effect was found.

siRNA nanoformulation against the ret/PTC1 junction oncogene is efficient in an in vivo model of papillary thyroid carcinoma.

Delivery is a very important concern for therapeutic applications of siRNA. In this study, we have used chitosan-coated poly(isobutylcyanoacrylate) nanoparticles to deliver siRNA with a complementary sequence to the fusion oncogene ret/PTC1. By screening the mRNA junction we have selected a potent siRNA sequence able to inhibit this oncogene in a model of Papillary Thyroid Carcinoma cells. This siRNA sequence has then been validated by a shRNA approach using the same sequence. Furthermore, the high ret/PTC1 inhibition has triggered a phenotypic reversion of the transformed cells. We have designed well-defined chitosan decorated nanoparticles and succeeded to reduce their size. They have allowed to protect ret/PTC1 siRNA from in vivo degradation and leading to significant tumour growth inhibition after intratumoral administration.

In vitro evaluation of calcium binding capacity of chitosan and thiolated chitosan poly(isobutyl cyanoacrylate) core-shell nanoparticles.

The ability of chitosan and its derivatives to bind cations is well known. Chitosan and thiolated chitosan were recently associated with poly(isobutyl cyanoacrylate) (PIBCA) nanoparticles leading to very promising results in terms of bioadhesion and permeation enhancement properties. Taking into account the influence that cations concentration have in the maintenance of both the permeation and the enzymatic barrier of the oral route, the possible cation binding capacity of these colloidal systems might be interesting in the use of these nanocarriers for the oral administration of pharmacologically active peptides. The aim of the present work was to in vitro evaluate the capacity of these colloidal systems to bind calcium, a model cation of physiological interest in the intestinal tract. The presence of chitosan on the nanoparticle surface importantly increased the calcium binding ability, in comparison to non-coated PIBCA nanoparticles. In addition, its presentation in the gel layer surrounding the nanoparticles, also beneficiated its binding capacity, obtaining 2-3 folds higher values when the polymer coated the nanoparticles than when it was in solution. The cross-linked structure observed for thiolated chitosan, due to the formation of inter- and intra-chain disulphide bonds, diminished the accessibility of cation to active sites of the polymer, decreasing the binding capacity of the calcium ion. However, when the amount of free thiol groups on the nanoparticle surface was high enough, the binding behaviour observed was higher than for nanoparticles elaborated with non-modified polymer.

Tuning of shell and core characteristics of chitosan-decorated acrylic nanoparticles.

The aim of the work was to develop a new family of chitosan-coated acrylic nanoparticles to increase the specificity of absorption of drugs associated given by the mucosal route. To achieve this goal, techniques of radical and anionic emulsion polymerisation of isobutylcyanoacrylate (IBCA) were used. Changes in the shell composition were made by using chitosan of different molecular weight and thiolated chitosan to modify the particle surface properties in order to vary the mucosae-nanoparticle interactions. The core was also modified by the inclusion of methyl methacrylate (MMA) as second monomer potentially able to improve the control of drug release. Finally, the labelling of nanoparticles core with a fluorophore, methacryloxyethyl thiocarbamoyl rhodamine B (Polyfluor), was successfully achieved, necessary for the in vitro and in vivo evaluation of the systems created. Results showed that nanoparticle size varied from 200 to 500 nm, depending on the molecular weight of chitosan used. Positive surface charge values were obtained in all cases. In addition, evidences of the presence of thiol groups were obtained (0.03-0.16 x 10(-3)micromol/cm(2) of nanoparticle).

Percutaneous protective coil occlusion of the proximal inferior mesenteric artery before N-butyl cyanoacrylate embolization of type II endoleaks after endovascular repair of abdominal aortic aneurysms.

Bowel ischemia can complicate treatment of type II endoleak with liquid or semiliquid agents such as n-butyl cyanoacrylate (NBCA) if nontarget embolization of the inferior mesenteric artery (IMA) occurs. The current report describes four cases of type II endoleak in which the IMA was the main outflow vessel and was prophylactically occluded with embolization coils before NBCA injection into the endoleak nidus. The purpose was to prevent unintentional embolization of the NBCA into IMA branches. If feasible, protective IMA coil occlusion should be considered in type II endoleaks with IMA outflow in cases of NBCA embolization.

Embolization of an aortic arch pseudoaneurysm with coils and N-butyl-cyanoacrylate.

Endovascular treatment strategies are evolving as viable alternatives for the treatment of aortic pseudoaneurysms. The present report describes an enlarging aortic arch pseudoaneurysm that was successfully treated with a combination of embolization with detachable coils and N-butyl-cyanoacrylate.