title: siRNA-loaded liposomes: Inhibition of encystment of Acanthamoeba and toxicity on the eye surface.
abstract: Current treatments for Acanthamoeba keratitis are unspecific. Because of the presence of the resilient cyst form of the parasite, the infection is persistent. Silencing the key protein of cyst formation, glycogen phosphorylase, has shown potential for reducing encystment processes of the Acanthamoeba trophozoite. However, a suitable carrier to protect and deliver siRNA sequences is still needed.
  DOPE:DSPE-PEG liposomes were prepared by three different techniques and used to associate a therapeutic siRNA sequence. Liposomes prepared by film hydration followed by membrane extrusion were considered the most adequate ones with average size of 250 nm and zeta potential of +45 mV, being able to associate siRNA for at least 24 hr in culture medium. siRNA-liposomes could inhibit up to 66% of the encystment process. Cell viability studies demonstrated MTT reduction capacity higher than 80% after 3 hr incubation with this formulation. After 24 hr of incubation, LDH activity ranged for both the formulations from around 4% to 40%. In vivo tolerance studies in mice showed no macroscopic alteration in the eye structures up to 24 hr after eight administrations during 1 day. Histological studies showed regular tissue architecture without any morphological alteration. Overall, these results suggest that the formulations developed are a promising new strategy for the treatment of ocular keratitis caused by Acanthamoeba spp.
authors.affiliation: Graduate Program in Pharmaceutical Sciences, School of Pharmacy, Federal University of Rio Grande do Sul, Porto Alegre, Brazil.|Institute of Pharmacology and Toxicology, Universitätsmedizin Berlin, Berlin, Germany.
authors.forename: Kathrin
authors.initials: K
authors.lastname: Faber
authors.affiliation: Graduate Program in Pharmaceutical Sciences, School of Pharmacy, Federal University of Rio Grande do Sul, Porto Alegre, Brazil.
authors.forename: Giovanni K
authors.initials: GK
authors.lastname: Zorzi
authors.affiliation: Graduate Program in Pharmaceutical Sciences, School of Pharmacy, Federal University of Rio Grande do Sul, Porto Alegre, Brazil.
authors.forename: Nathalya T
authors.initials: NT
authors.lastname: Brazil
authors.affiliation: Graduate Program of Agricultural and Environmental Microbiology, Institute of Basic Health Sciences, Porto Alegre, Brazil.
authors.forename: Marilise B
authors.identifier: http://orcid.org/0000-0002-5227-4594
authors.initials: MB
authors.lastname: Rott
authors.affiliation: Graduate Program in Pharmaceutical Sciences, School of Pharmacy, Federal University of Rio Grande do Sul, Porto Alegre, Brazil.
authors.forename: Helder F
authors.identifier: http://orcid.org/0000-0002-5808-3043
authors.initials: HF
authors.lastname: Teixeira
mesh_terms: D000048:Acanthamoeba / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D000818:Animals; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D003315:Cornea / Q000187:drug effects* / Q000378:metabolism / Q000469:parasitology / Q000473:pathology; D005123:Eye / Q000187:drug effects / Q000378:metabolism / Q000469:parasitology / Q000473:pathology; D024981:Glycogen Phosphorylase / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008081:Liposomes / Q000737:chemistry* / Q000633:toxicity; D008297:Male; D051379:Mice; D010316:Particle Size; D015800:Protozoan Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology*
chemical_list: D008081:Liposomes; D015800:Protozoan Proteins; D034741:RNA, Small Interfering; D024981:Glycogen Phosphorylase
keywords: 
  Acanthamoeba
  ; encystment; liposome; ocular drug delivery; siRNA