title: Animal model of implant capsular contracture: effects of chitosan.
abstract: BACKGROUND
  The mechanism(s) responsible for breast capsular contracture (CC) remain unknown, but inflammatory pathways play a role. Various molecules have been attached to implant shells in the hope of modifying or preventing CC. The intrinsic antibacterial and antifungal activities of chitosan and related oligochitosan molecules lend themselves well to the study of the infectious hypothesis; chitosan's ability to bind to growth factors, its hemostatic action, and its ability to activate macrophages, cause cytokine stimulation, and increase the production of transforming growth factor (TGF)-β1 allow study of the hypertrophic scar hypothesis.
  
  
  OBJECTIVE
  The authors perform a comprehensive evaluation, in a rabbit model, of the relationship between CC and histological, microbiological, and immunological characteristics in the presence of a chitooligosaccharide (COS) mixture and a low molecular weight chitosan (LMWC).
  
  
  METHODS
  Eleven adult New Zealand rabbits were each implanted with three silicone implants: a control implant, one impregnated with COS, and one impregnated with LMWC. At four-week sacrifice, microdialysates were obtained in the capsule-implant interfaces for tumor necrosis factor alpha (TNF-α) and interleukin-8 (IL-8) level assessment. Histological and microbiological analyses were performed.
  
  
  RESULTS
  Baker grade III/IV contractures were observed in the LMWC group, with thick capsules, dense connective tissue, and decreased IL-8 levels (p < .05) compared to control and COS groups. Capsule tissue bacterial types and microdialysate TNF-α levels were similar among all groups.
  
  
  CONCLUSIONS
  Chitosan-associated silicone implantation in a rabbit model resulted in Baker grade III/IV CC. This preclinical study may provide a model to test various mechanistic hypotheses of breast capsule formation and subsequent CC.
authors: Faculty of Medicine, University of Porto, Hospital de São João, Serviço de Cirurgia Plástica, 4202-451 Porto, Portugal. marisamarquesmd@gmail.com
authors: Marisa
authors: M
authors: Marques
authors: Spencer A
authors: SA
authors: Brown
authors: Pedro
authors: P
authors: Rodrigues-Pereira
authors: M
authors: M
authors: Natália
authors: D S
authors: DS
authors: Cordeiro
authors: Aliuska
authors: A
authors: Morales-Helguera
authors: Luís
authors: L
authors: Cobrado
authors: Lara
authors: L
authors: Queirós
authors: Rui
authors: R
authors: Freitas
authors: João
authors: J
authors: Fernandes
authors: Inês
authors: I
authors: Correia-Sá
authors: Acácio Gonçalves
authors: AG
authors: Rodrigues
authors: José
authors: J
authors: Amarante
mesh_terms: D000818:Animals; D018427:Breast Implants / Q000009:adverse effects*; D048271:Chitosan / Q000494:pharmacology*; D004195:Disease Models, Animal; D005260:Female; D057910:Implant Capsular Contracture / Q000209:etiology* / Q000382:microbiology / Q000473:pathology; D016209:Interleukin-8 / Q000378:metabolism; D017551:Microdialysis; D009844:Oligosaccharides / Q000737:chemistry; D011817:Rabbits; D020034:Silicone Gels; D053773:Transforming Growth Factor beta1 / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D016209:Interleukin-8; D009844:Oligosaccharides; D020034:Silicone Gels; D053773:Transforming Growth Factor beta1; D014409:Tumor Necrosis Factor-alpha; D048271:Chitosan