title: Anterior cruciate ligament constructs fabricated from human mesenchymal stem cells in a collagen type I hydrogel.
abstract: BACKGROUND
  Disruptions of the anterior cruciate ligament (ACL) of the knee joint are common and are currently treated using ligament or tendon grafts. In this study, we tested the hypothesis that it is possible to fabricate an ACL construct in vitro using mesenchymal stem cells (MSC) in combination with an optimized collagen type I hydrogel, which is in clinical use for autologous chondrocyte transplantation (ACT).
  
  
  METHODS
  ACL constructs were molded using a collagen type I hydrogel containing 5 x 10(5) MSC/mL and non-demineralized bone cylinders at each end of the constructs. The constructs were kept in a horizontal position for 10 days to allow the cells and the gel to remodel and attach to the bone cylinders. Thereafter, cyclic stretching with 1 Hz was performed for 14 days (continuously for 8 h/day) in a specially designed bioreactor.
  
  
  RESULTS
  Histochemical analysis for H and E, Masson-Goldner and Azan and immunohistochemical analysis for collagen types I and III, fibronectin and elastin showed elongated fibroblast-like cells embedded in a wavy orientated collagenous tissue, together with a ligament-like extracellular matrix in the cyclic stretched constructs. No orientation of collagen fibers and cells, and no formation of a ligament-like matrix, could be seen in the non-stretched control group cultured in a horizontal position without tension. RT-PCR analysis revealed an increased gene expression of collagen types I and III, fibronectin and elastin in the stretched constructs compared with the non-stretched controls.
  
  
  CONCLUSIONS
  In conclusion, ACL-like constructs from a collagen type I hydrogel, optimized for the reconstruction of ligaments, and MSC have been fabricated. As shown by other investigators, who analyzed the influence of cyclic stretching on the differentiation of MSC, our results indicate a ligament-specific increased protein and gene expression and the formation of a ligament-like extracellular matrix. The fabricated constructs are still too weak for animal experiments or clinical application and current investigations are focusing on the development of a construct with an internal augmentation using biodegradable fibers.
authors.affiliation: Division of Tissue Engineering, Orthopaedic Center for Musculoskeletal Research, König-Ludwig-Haus, Julius-Maximilians-University, Würzburg, Germany.
authors.forename: U
authors.initials: U
authors.lastname: Nöth
authors.forename: K
authors.initials: K
authors.lastname: Schupp
authors.forename: A
authors.initials: A
authors.lastname: Heymer
authors.forename: S
authors.initials: S
authors.lastname: Kall
authors.forename: F
authors.initials: F
authors.lastname: Jakob
authors.forename: N
authors.initials: N
authors.lastname: Schütze
authors.forename: B
authors.initials: B
authors.lastname: Baumann
authors.forename: T
authors.initials: T
authors.lastname: Barthel
authors.forename: J
authors.initials: J
authors.lastname: Eulert
authors.forename: C
authors.initials: C
authors.lastname: Hendrich
mesh_terms: D000818:Animals; D016118:Anterior Cruciate Ligament / Q000166:cytology*; D001672:Biocompatible Materials / Q000737:chemistry / Q000378:metabolism*; D019149:Bioreactors; D001854:Bone Marrow Cells / Q000166:cytology; D002417:Cattle; D018929:Cell Culture Techniques; D002478:Cells, Cultured; D024042:Collagen Type I / Q000737:chemistry / Q000378:metabolism*; D024061:Collagen Type III / Q000378:metabolism; D004549:Elastin / Q000378:metabolism; D005109:Extracellular Matrix / Q000378:metabolism; D005353:Fibronectins / Q000378:metabolism; D006651:Histocytochemistry; D006801:Humans; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000737:chemistry / Q000378:metabolism*; D007150:Immunohistochemistry; D007719:Knee Joint / Q000166:cytology; D008422:Materials Testing; D059630:Mesenchymal Stem Cells / Q000166:cytology*; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D023822:Tissue Engineering
chemical_list: D001672:Biocompatible Materials; D024042:Collagen Type I; D024061:Collagen Type III; D005353:Fibronectins; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D004549:Elastin