title: Quantitative analysis of collagen network structure and fibril dimensions in cartilage repair with autologous chondrocyte transplantation.
abstract: OBJECTIVE
  The aim of this study was to undertake a stereological analysis to quantify the dimensions of the collagen network in the repair tissue of porcine joints after they had been subjected to autologous chondrocyte transplantation (ACT).
  
  
  METHODS
  ACT was used to repair cartilage lesions in knee joints of pigs. Electron-microscopic stereology, immunostaining for type II collagen, and quantitative polarized-light microscopy were utilized to study the collagen fibrils in the repair tissue 3 and 12 months after the operation.
  
  
  RESULTS
  The collagen volume density (V(V)) was lower in the repair tissue than in normal cartilage at 3 months (20.4 vs. 23.7%) after the operation. The collagen surface density (S(V), 1.5·10(-2) vs. 3.1·10(-2) nm(2)/nm(3)) and V(V) increased with time in the repair tissue (20.4 vs. 44.7%). Quantitative polarized-light microscopy detected a higher degree of collagen parallelism in the repair tissue at 3 months after the operation (55.7 vs. 49.7%). In contrast, 1 year after the operation, fibril parallelism was lower in the repair tissue than in the control cartilage (47.5 vs. 69.8%).
  
  
  CONCLUSIONS
  Following ACT, V(V) and S(V) increased in the repair tissue with time, reflecting maturation of the tissue. One year after the operation, there was a lower level of fibril organization in the repair tissue than in the control cartilage. Thus, the newly synthesized collagen fibrils in the repair tissue appeared to form a denser network than in the control cartilage, but the fibrils remained more randomly oriented.
authors.affiliation: Department of Anatomy, Institute of Biomedicine, University of Kuopio, Kuopio, Finland. teemu.langsjo@fimnet.fi
authors.forename: Teemu K
authors.initials: TK
authors.lastname: Långsjö
authors.forename: Anna I
authors.initials: AI
authors.lastname: Vasara
authors.forename: Mika M
authors.initials: MM
authors.lastname: Hyttinen
authors.forename: Mikko J
authors.initials: MJ
authors.lastname: Lammi
authors.forename: Antti
authors.initials: A
authors.lastname: Kaukinen
authors.forename: Heikki J
authors.initials: HJ
authors.lastname: Helminen
authors.forename: Ilkka
authors.initials: I
authors.lastname: Kiviranta
mesh_terms: D000818:Animals; D002358:Cartilage, Articular / Q000166:cytology* / Q000378:metabolism* / Q000648:ultrastructure; D002478:Cells, Cultured; D019902:Chondrocytes / Q000166:cytology*; D024043:Collagen Type II / Q000378:metabolism*; D007719:Knee Joint / Q000166:cytology* / Q000378:metabolism* / Q000648:ultrastructure; D046529:Microscopy, Electron, Transmission; D013552:Swine; D014182:Transplantation, Autologous / Q000379:methods*
chemical_list: D024043:Collagen Type II