title: The long-term behavior of lightweight and heavyweight meshes used to repair abdominal wall defects is determined by the host tissue repair process provoked by the mesh.
abstract: BACKGROUND
  Although heavyweight (HW) or lightweight (LW) polypropylene (PP) meshes are widely used for hernia repair, other alternatives have recently appeared. They have the same large-pore structure yet are composed of polytetrafluoroethylene (PTFE). This study compares the long-term (3 and 6 months) behavior of meshes of different pore size (HW compared with LW) and composition (PP compared with PTFE).
  
  
  METHODS
  Partial defects were created in the lateral wall of the abdomen in New Zealand White rabbits and then repaired by the use of a HW or LW PP mesh or a new monofilament, large-pore PTFE mesh (Infinit). At 90 and 180 days after implantation, tissue incorporation, gene and protein expression of neocollagens (reverse transcription-polymerase chain reaction/immunofluorescence), macrophage response (immunohistochemistry), and biomechanical strength were determined. Shrinkage was measured at 90 days.
  
  
  RESULTS
  All three meshes induced good host tissue ingrowth, yet the macrophage response was significantly greater in the PTFE implants (P < .05). Collagen 1/3 mRNA levels failed to vary at 90 days yet in the longer term, the LW meshes showed the reduced genetic expression of both collagens (P < .05) accompanied by increased neocollagen deposition, indicating more efficient mRNA translation. After 90-180 days of implant, tensile strengths and elastic modulus values were similar for all 3 implants (P > .05).
  
  
  CONCLUSIONS
  Host collagen deposition is mesh pore size dependent whereas the macrophage response induced is composition dependent with a greater response shown by PTFE. In the long term, macroporous meshes show comparable biomechanical behavior regardless of their pore size or composition.
authors.affiliation: Department of Surgery and Medical Specialities, University of Alcalá, Alcalá de Henares, Madrid, Spain.
authors.forename: Gemma
authors.initials: G
authors.lastname: Pascual
authors.forename: Belén
authors.initials: B
authors.lastname: Hernández-Gascón
authors.forename: Marta
authors.initials: M
authors.lastname: Rodríguez
authors.forename: Sandra
authors.initials: S
authors.lastname: Sotomayor
authors.forename: Estefania
authors.initials: E
authors.lastname: Peña
authors.forename: Begoña
authors.initials: B
authors.lastname: Calvo
authors.forename: Juan M
authors.initials: JM
authors.lastname: Bellón
mesh_terms: D034861:Abdominal Wall / Q000601:surgery*; D000818:Animals; D001696:Biomechanical Phenomena; D003094:Collagen / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D015870:Gene Expression; D059685:Herniorrhaphy; D008264:Macrophages / Q000502:physiology; D008297:Male; D008853:Microscopy; D011126:Polypropylenes; D011138:Polytetrafluoroethylene; D011817:Rabbits; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013526:Surgical Mesh; D014945:Wound Healing / Q000276:immunology
chemical_list: D011126:Polypropylenes; D011138:Polytetrafluoroethylene; D003094:Collagen