title: Assessment of sequential combination of 5-fluorouracil-loaded-chitosan-nanoparticles and ALA-photodynamic therapy on HeLa cell line.
abstract: BACKGROUND
  Natural polymers are used as components of nanoparticles (NPs) for drug delivery, as they provide targeted, sustained release and biodegradability. The purpose of this study was to increase the efficacy of the photodynamic therapy (PDT) by the combination of 5-aminolevulinic acid (ALA) with 5-fluorouracil-loaded-chitosan-nanoparticles (5-Fu-CNPs).
  
  
  METHODS
  Nanoparticles based on chitosan (CNPs) were synthesized by the ionic crosslinking method via the TPP addition. 5-Fluorouracil (5-Fu), a first-line anticancer drug, was loaded into these 5Fu-CNPs, and they were assayed as controlled delivery formulation. HeLa cells were incubated in the presence of 5Fu-CNPs for 24h, next ALA was added to the culture medium and 4h later, to complete the PDT, light irradiation took place. Analysis of cell viability, reactive oxygen species (ROS) production, observation of the apoptosis by fluorescence microscopy followed by analysis of caspase-3 activity were carried out.
  
  
  RESULTS
  Spherical 5Fu-CNPs with a mean diameter of 324±43nm, were successfully synthesized and characterized by TEM and DLS. 5-Fu incorporation was achieved successfully (12.3μg 5Fu/mg CNP) and the maximum 5-Fu release took place at 2h. The combined administration of 5Fu-CNPs and PDT mediated by ALA (ALA-PDT) led to an improved efficacy of the antineoplastic treatment by generation of great cytotoxicity inducted through an increased ROS production. HeLa cells were destroyed by apoptosis through activation of caspase pathway.
  
  
  CONCLUSIONS
  This study proves that combination therapy (photodynamic "ALA"+chemical "5-Fu"+immunoadjuvant "chitosan") may be an effective approach for the treatment of cancer.
authors.affiliation: Centro Universitario San Rafael-Nebrija, Madrid, Spain; Departamento de Bioquímica y Biología Molecular III, Facultad de Medicina, UCM, Madrid, Spain.
authors.forename: Marta
authors.initials: M
authors.lastname: Benito-Miguel
authors.affiliation: Departamento de Bioquímica y Biología Molecular III, Facultad de Medicina, UCM, Madrid, Spain.
authors.forename: M Dolores
authors.initials: MD
authors.lastname: Blanco
authors.affiliation: Departamento de Sistemas de Baja Dimensionalidad, Superficies y Materia Condensada, Instituto de Química Física Rocasolano, CSIC, Madrid, Spain. Electronic address: c.gomez@iqfr.csic.es.
authors.forename: Clara
authors.initials: C
authors.lastname: Gómez
mesh_terms: D000622:Aminolevulinic Acid / Q000494:pharmacology*; D000964:Antimetabolites, Antineoplastic / Q000008:administration & dosage / Q000494:pharmacology*; D017209:Apoptosis; D053148:Caspase 3 / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D048271:Chitosan / Q000737:chemistry; D003692:Delayed-Action Preparations; D004337:Drug Carriers; D004359:Drug Therapy, Combination; D005472:Fluorouracil / Q000008:administration & dosage / Q000494:pharmacology*; D006367:HeLa Cells; D006801:Humans; D053758:Nanoparticles / Q000737:chemistry; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000494:pharmacology*; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D000964:Antimetabolites, Antineoplastic; D003692:Delayed-Action Preparations; D004337:Drug Carriers; D017319:Photosensitizing Agents; D017382:Reactive Oxygen Species; D000622:Aminolevulinic Acid; D048271:Chitosan; D053148:Caspase 3; D005472:Fluorouracil
keywords: 5-Fu; ALA; Cell viability; Chitosan; Photodynamic therapy; ROS