In vivo effect of magnetic microspheres loaded with E2-a in the treatment of alveolar echinococcosis

Abstract

The alveolar echinococcosis of human is a severe helminthic disease caused by the larva of Echinococcus multilocularis tapeworms. Novel compounds or therapy strategies for the treatment of alveolar echinococcosis are urgently needed due to the limitation of the widely used albendazole. Magnetic microspheres as drug carriers in magnetically targeted therapy of tumor have gained growing interests advantaged by delivering the drug to the aimed site, achieving localized therapeutic effect effectively under the influence of an external magnetic field. In this study, we formulated magnetic microspheres loaded with E2-a (PLGA-Fe-E2-a) and identified the activity in E. multilocularis-infected mice which infected with 3,000 protoscoleces intraperitoneally. Compared with the untreated control, with the help of a magnet, there was a significant reduction in parasite burden with PLGA-Fe-E2-a treatment and similar reduction observed with albendazole. PLGA-Fe-E2-a treatment group also showed a significant increase in the IFN-γ level and impaired morphological and ultrastructural alterations. Most importantly, one-third concentrations of E2-a from PLGA-Fe-E2 based on the release profile of E2-a was equally effective in inhibiting metacestode growth as E2-a treated group, supporting efficacy and bioavailability of a drug. It will be an alternative treatment for alveolar echinococcosis using magnetic microspheres as drug carriers.

Figure 1

Physicochemical characteristics of magnetic microspheres loaded with E2-a (PLGA-Fe-E2-a). Representative SEM micrographs of the surface morphology of PLGA-Fe-E2-a. The bar of the panel was 1 μm (left) or 5 μm (right). The particle size (C) and zeta potential (D) of PLGA-Fe-E2-a were assessed by dynamic light scattering. The particle size and polydispersity index of PLGA-Fe-E2-a were 2,315 nm and 0.312, respectively. The zeta potential of PLGA-Fe-E2-a was − 3.50 mV. PLGA-Fe-E2-a dispersed in the water (left) and in the presence of an external magnet (right) (D). In vitro cumulative release profile of PLGA-Fe-E2-a at 37 °C and Higuchi analysis of E2-a from PLGA-Fe-E2-a (E,F). Notes: Higuchi analysis was carried out by plotting square root time against percent drug release. E2-a concentrations were measured by a UV–visible spectrophotometer at 210 nm.

Figure 2

In vivo treatment of E. multilocularis infected mice with PLGA-Fe-E2-a. BALB/c mice were intraperitoneally infected with E. multilocularis metacestodes. At the 14th week after infection, mice with secondary alveolar echinococcosis were treated with PBS, albendazole (100 mg/kg/day), E2-a (50 mg/kg/day) or PLGA-Fe-E2-a (50 mg/kg/3 day). After six weeks of treatment, mice were sacrificed. The parasite cysts were resected and weighted. Macroscopic (A), the representative pathological characteristics (H&E stain, magnification 100 ×). Samples of parasite vesicles were processed for haematoxylin and eosin (H&E) staining (B). Samples of cysts were used to scanning electron microscopy (SEM) examination (C,D). Note the distorted morphology of the germinal layer (GL) in those specimens treated with PLGA-Fe-E2-a. GC germinal layer, LL laminated layer. Bar = 10 μm (C) or 50 μm (D).