title: Osteochondral Biopsy Analysis Demonstrates That BST-CarGel Treatment Improves Structural and Cellular Characteristics of Cartilage Repair Tissue Compared With Microfracture.
abstract: OBJECTIVE
  The efficacy and safety of BST-CarGel, a chitosan-based medical device for cartilage repair, was compared with microfracture alone at 1 year during a multicenter randomized controlled trial (RCT) in the knee. The quality of repair tissue of osteochondral biopsies collected from a subset of patients was compared using blinded histological assessments.
  
  
  METHODS
  The international RCT evaluated repair tissue quantity and quality by 3-dimensional quantitative magnetic resonance imaging as co-primary endpoints at 12 months. At an average of 13 months posttreatment, 21/41 BST-CarGel and 17/39 microfracture patients underwent elective second look arthroscopies as a tertiary endpoint, during which ICRS (International Cartilage Repair Society) macroscopic scoring was carried out, and osteochondral biopsies were collected. Stained histological sections were evaluated by blinded readers using ICRS I and II histological scoring systems. Collagen organization was evaluated using a polarized light microscopy score.
  
  
  RESULTS
  BST-CarGel treatment resulted in significantly better ICRS macroscopic scores (P = 0.0002) compared with microfracture alone, indicating better filling, integration, and tissue appearance. Histologically, BST-CarGel resulted in a significant improvement of structural parameters-Surface Architecture (P = 0.007) and Surface/Superficial Assessment (P = 0.042)-as well as cellular parameters-Cell Viability (P = 0.006) and Cell Distribution (P = 0.032). No histological parameters were significantly better for the microfracture group. BST-CarGel treatment also resulted in a more organized repair tissue with collagen stratification more similar to native hyaline cartilage, as measured by polarized light microscopy scoring (P = 0.0003).
  
  
  CONCLUSIONS
  Multiple and independent analyses in this biopsy substudy demonstrated that BST-CarGel treatment results in improved structural and cellular characteristics of repair tissue at 1 year posttreatment compared with microfracture alone, supporting previously reported results by quantitative magnetic resonance imaging.
authors.affiliation: Bio-Orthopaedics Division, Piramal Life Sciences, Laval, Quebec, Canada.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Méthot
authors.affiliation: Institute of Biomedical Engineering, École Polytechnique de Montréal, Montreal, Quebec, Canada.
authors.forename: Adele
authors.initials: A
authors.lastname: Changoor
authors.affiliation: Department of Chemical Engineering, École Polytechnique de Montréal, Montreal, Quebec, Canada.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Tran-Khanh
authors.affiliation: Institute of Biomedical Engineering, École Polytechnique de Montréal, Montreal, Quebec, Canada; Department of Chemical Engineering, École Polytechnique de Montréal, Montreal, Quebec, Canada.
authors.forename: Caroline D
authors.initials: CD
authors.lastname: Hoemann
authors.affiliation: Department of Surgery, Dalhousie University, Halifax, Nova Scotia, Canada.
authors.forename: William D
authors.initials: WD
authors.lastname: Stanish
authors.affiliation: Bio-Orthopaedics Division, Piramal Life Sciences, Laval, Quebec, Canada.
authors.forename: Alberto
authors.initials: A
authors.lastname: Restrepo
authors.affiliation: Bio-Orthopaedics Division, Piramal Life Sciences, Laval, Quebec, Canada.
authors.forename: Matthew S
authors.initials: MS
authors.lastname: Shive
authors.affiliation: Institute of Biomedical Engineering, École Polytechnique de Montréal, Montreal, Quebec, Canada; Department of Chemical Engineering, École Polytechnique de Montréal, Montreal, Quebec, Canada.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Buschmann
keywords: biopsy; cartilage repair; collagen organization; histology: scoring systems; polarized light microscopy