title: Intestinal absorption of insulin nanoparticles: contribution of M cells.
abstract: Nanodelivery systems have been extensively studied as a strategy for the effective treatment of type 1 diabetes in animal models. Nanoparticle formulations have been shown to contribute to increased intestinal absorption of insulin according to established pathways. It is important to determine whether intestinal absorption of the hormone, specifically occurs through a privileged pathway that is favored because of particular properties of the nanoparticles. Confocal fluorescence microscopy has revealed that nanoparticles-based oral insulin delivery in intestinal tissues causes their accumulation in Peyer's patches. To quantify the preponderance of M cells involved in the overall absorption of insulin in the intestine, in vitro and in vivo results of insulin-loaded nanoparticles were analyzed and criticized based on the utilized method and whether it has translational impact for the treatment of diabetes in humans. The degree of insulin nanoparticles uptake will be interpreted for its effectiveness in the prevention/treatment of other pathologies.
  
  
  BACKGROUND
  This study investigates nano-formulation based insulin delivery through the oral route, with particular attention to their accumulation in Peyer patches and the role of M-cells in their absorption. While oral delivery of insulin would be an important step from the standpoint of convenience, accurate dosing and issues of potential toxicity need to be considered before clinical translation of this method.
authors.affiliation: Centre for Pharmaceutical Sciences, Faculty of Pharmacy, University of Coimbra, Azinhaga de Santa Comba, Coimbra, Portugal.
authors.forename: Marlene Almeida
authors.initials: MA
authors.lastname: Lopes
authors.affiliation: Centre for Pharmaceutical Sciences, Faculty of Pharmacy, University of Coimbra, Azinhaga de Santa Comba, Coimbra, Portugal; Department of Pharmaceutics, Faculty of Pharmacy, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Bárbara Azevedo
authors.initials: BA
authors.lastname: Abrahim
authors.affiliation: Department of Pharmaceutics, Faculty of Pharmacy, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Lucio Mendes
authors.initials: LM
authors.lastname: Cabral
authors.affiliation: Department of Pharmaceutics, Faculty of Pharmacy, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Carlos Rangel
authors.initials: CR
authors.lastname: Rodrigues
authors.affiliation: Institute of Biomedical Research in Light and Image (IBILI), Faculty of Medicine, University of Coimbra, Coimbra, Portugal.
authors.forename: Raquel Maria Fino
authors.initials: RM
authors.lastname: Seiça
authors.affiliation: Centre for Pharmaceutical Sciences, Faculty of Pharmacy, University of Coimbra, Azinhaga de Santa Comba, Coimbra, Portugal.
authors.forename: Francisco José
authors.initials: FJ
authors.lastname: de Baptista Veiga
authors.affiliation: Centre for Pharmaceutical Sciences, Faculty of Pharmacy, University of Coimbra, Azinhaga de Santa Comba, Coimbra, Portugal. Electronic address: aribeiro@ff.uc.pt.
authors.forename: António José
authors.initials: AJ
authors.lastname: Ribeiro
mesh_terms: D000284:Administration, Oral; D000818:Animals; D004337:Drug Carriers / Q000378:metabolism; D006801:Humans; D007004:Hypoglycemic Agents / Q000008:administration & dosage* / Q000493:pharmacokinetics* / Q000627:therapeutic use; D007328:Insulin / Q000008:administration & dosage* / Q000493:pharmacokinetics* / Q000627:therapeutic use; D007408:Intestinal Absorption; D007413:Intestinal Mucosa / Q000166:cytology* / Q000378:metabolism; D053758:Nanoparticles / Q000378:metabolism*; D010581:Peyer's Patches / Q000166:cytology / Q000378:metabolism
chemical_list: D004337:Drug Carriers; D007004:Hypoglycemic Agents; D007328:Insulin
keywords: Insulin nanoparticle; Intestinal absorption; M cell; Mesenteric pathway; Oral delivery