title: A chondrocyte infiltrated collagen type I/III membrane (MACI® implant) improves cartilage healing in the equine patellofemoral joint model.
abstract: Autologous chondrocyte implantation (ACI) has improved outcome in long-term studies of joint repair in man. However, ACI requires sutured periosteal flaps to secure the cells, which precludes minimally-invasive implantation, and introduces complications with arthrofibrosis and graft hypertrophy. This study evaluated ACI on a collagen type I/III scaffold (matrix-induced autologous chondrocyte implantation; MACI(®)) in critical sized defects in the equine model.
  
  
  METHODS
  Chondrocytes were isolated from horses, expanded and seeded onto a collagen I/III membrane (ACI-Maix™) and implanted into one of two 15-mm defects in the femoral trochlear ridge of six horses. Control defects remained empty as ungrafted debrided defects. The animals were examined daily, scored by second look arthroscopy at 12 weeks, and necropsy examination 6 months after implantation. Reaction to the implant was determined by lameness, and synovial fluid constituents and synovial membrane histology. Cartilage healing was assessed by arthroscopic scores, gross assessment, repair tissue histology and immunohistochemistry, cartilage glycosaminoglycan (GAG) and DNA assay, and mechanical testing.
  
  
  RESULTS
  MACI(®) implanted defects had improved arthroscopic second-look, gross healing, and composite histologic scores, compared to spontaneously healing empty defects. Cartilage GAG and DNA content in the defects repaired by MACI implant were significantly improved compared to controls. Mechanical properties were improved but remained inferior to normal cartilage. There was minimal evidence of reaction to the implant in the synovial fluid, synovial membrane, subchondral bone, or cartilage.
  
  
  CONCLUSIONS
  The MACI(®) implant appeared to improve cartilage healing in a critical sized defect in the equine model evaluated over 6 months.
authors.affiliation: Comparative Orthopedics Laboratory, Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA. Electronic address: AJN1@cornell.edu.
authors.forename: A J
authors.initials: AJ
authors.lastname: Nixon
authors.affiliation: Comparative Orthopedics Laboratory, Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
authors.forename: E
authors.initials: E
authors.lastname: Rickey
authors.affiliation: Genzyme-Sanofi, 500 Kendall St, Cambridge, MA, USA.
authors.forename: T J
authors.initials: TJ
authors.lastname: Butler
authors.affiliation: Comparative Orthopedics Laboratory, Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
authors.forename: M S
authors.initials: MS
authors.lastname: Scimeca
authors.affiliation: Genzyme-Sanofi, 500 Kendall St, Cambridge, MA, USA.
authors.forename: N
authors.initials: N
authors.lastname: Moran
authors.affiliation: Genzyme-Sanofi, 500 Kendall St, Cambridge, MA, USA.
authors.forename: G L
authors.initials: GL
authors.lastname: Matthews
mesh_terms: D000818:Animals; D001182:Arthroscopy; D001696:Biomechanical Phenomena / Q000502:physiology; D001706:Biopsy; D002358:Cartilage, Articular / Q000187:drug effects / Q000502:physiology*; D002470:Cell Survival; D017690:Cell Transplantation / Q000379:methods*; D002478:Cells, Cultured; D019902:Chondrocytes / Q000473:pathology / Q000637:transplantation*; D024042:Collagen Type I / Q000008:administration & dosage / Q000494:pharmacology*; D024061:Collagen Type III / Q000008:administration & dosage / Q000494:pharmacology*; D004195:Disease Models, Animal; D006025:Glycosaminoglycans / Q000502:physiology; D006736:Horses; D006801:Humans; D066298:In Vitro Techniques; D057071:Patellofemoral Joint / Q000293:injuries* / Q000503:physiopathology; D016896:Treatment Outcome; D014945:Wound Healing / Q000187:drug effects* / Q000502:physiology
chemical_list: D024042:Collagen Type I; D024061:Collagen Type III; D006025:Glycosaminoglycans
keywords: Autologous chondrocyte implantation; Cartilage repair; Collagen type I/III membrane; Equine; Joint; MACI