Christopher Springate

Neutrophil activation by plasma opsonized polymeric microspheres: inhibitory effect of Pluronic F127☆

The phagocytosis of drug-loaded polymeric microspheres by white blood cells, such as neutrophils or mononuclear cells, represents the major clearance mechanism by which this foreign material is eliminated from the body. The process of phagocytosis requires the activation of the white blood cells by the microsphere surface, followed by binding and engulfment. Phagocytosis may result in the removal of the microspheres from the blood or the disease site and an inflammatory response. Therefore, we have studied the level of neutrophil activation by microspheres ( +/- opsonization) manufactured from various biomaterials or polymers. Polymer microspheres with equivalent size distributions were made from poly (DL-lactic acid) (PLA), poly(epsilon-caprolactone) (PCL), poly(methyl methacrylate) (PMMA) or a 50 : 50 blend of PLA: poly(ethylene-co-vinyl acetate) (PLA: EVA). Neutrophils were isolated from human blood and activation of these cells by microspheres was measured by chemiluminescence (CL). All four types of microspheres induced only low levels of CL, however these levels were enhanced significantly if the microspheres were pretreated with plasma or IgG suggesting an opsonization effect. The adsorption of IgG or proteins from plasma was confirmed by polyacrylamide gel electrophoresis (SDS-PAGE). The poloxamer Pluronic F127 inhibited the opsonization effect of IgG and plasma on all four types of microspheres and inhibited protein adsorption as measured by SDS-PAGE. Since neutrophil activation is part of the inflammation process in vivo, these in vitro data suggest that all four types of microspheres are likely to be inflammatory if injected into body compartments containing plasma-derived fluids. Pretreatment of the microspheres with Pluronic F127 may reduce the inflammatory potential of the microspheres.

Camptothecin-loaded films for the prevention of postsurgical adhesions

AbstractObjective and design:The purpose of this work was to investigate the local application of camptothecin (CPT), a drug with anti-inflammatory, antiproliferative and antiangiogenic properties, as an inhibitor of surgical adhesion formation in rats. Methods:The anti-adhesion properties of CPT were investigated using the cecal sidewall abrasion model in a total of 92 rats. An adhesion score for each animal was obtained based on the strength and extent of the adhesions. Significance was determined by Students t-test and p values less than 0.05 were considered significant. Treatment:The drug was administered by application of carbodiimide crosslinked hyaluronic acid (HA) films containing CPT at concentrations of 0, 0.6, 2.5 and 7.5% w/w at the site of surgical injury. The HA films were characterized by in vitro measurements of drug release rates. Results:In this model the application of HA films alone, or 0, 0.6, 2.5 or 7.5% w/w CPT-loaded HA films, had a significant effect in reducing the mean strength and area of adhesions (3.8 ± 2.7, 5.6 ± 0.7, 1.3 ± 0.7, 0.9 ± 0.8, 0.7 ± 1.0, respectively) when compared to those animals in which no film was placed (8.4 ± 2.5). In addition, a significant difference was observed in the effect of 0.6, 2.5 and 7.5% w/w CPT-loaded films when compared to the HA or 0% CPT-loaded films (p < 0.05). No toxicity was observed in the rats following administration of these films. Conclusions:CPT loaded films inhibited the formation of adhesions in the rat cecal sidewall abrasion model. HA crosslinked with 2 mM carbodiimide and containing 20% w/w glycerol and 0.6, 2.5 or 7.5% w/w CPT are flexible, mucoadhesive, biocompatible controlled release films that can be used to prevent adhesion formation.

Fucoidan film safely inhibits surgical adhesions in a rat model.

BACKGROUND The purpose of this study was to evaluate the in vivo efficacy of 13 compounds and to further characterize the load limiting and potential toxicity of the most efficacious compound. The cascade of biochemical and molecular events that results in the formation of postsurgical adhesions provides numerous theoretical opportunities for prophylactic intervention. METHODS Candidate agents were loaded into sodium hyaluronate (HA) films and administered to male Sprague-Dawley rats using a cecal-sidewall model of surgical adhesions. An adhesion score was obtained for each rat based on the strength and extent of the adhesions. The most efficacious agent, fucoidan, was further evaluated in a load-limiting study with a concentration range of 0.0033 to 33% w/w per film. The potential toxicity of fucoidan was evaluated in a separate study by comparison of hematology findings, blood chemistry, urinalysis, and incision thickness from rats administered control films or 33% w/w fucoidan films 1 to 4 d prior to sacrifice. RESULTS Fucoidan loaded films reduced adhesion scores by approximately 90% compared with control films (P<0.05). A total of 50% to 100% of animals were adhesion free at fucoidan film loadings of 0.33% to 33% w/w compared with all control film animals having adhesions. No adverse effects were observed from 33% w/w fucoidan films equivalent to approximately 30 mg fucoidan/kg body weight. CONCLUSIONS Local administration of fucoidan film during rat cecal-sidewall surgery safely reduced adhesion scores by approximately 90% and resulted in 50% to 100% of animals being adhesion free.