title: Rapidly dissociated autologous meniscus tissue enhances meniscus healing: An in vitro study.
abstract: OBJECTIVE
  Treatment of meniscus tears is a persistent challenge in orthopedics. Although cell therapies have shown promise in promoting fibrocartilage formation in in vitro and preclinical studies, clinical application has been limited by the paucity of autologous tissue and the need for ex vivo cell expansion. Rapid dissociation of the free edges of the anterior and posterior meniscus with subsequent implantation in a meniscus lesion may overcome these limitations. The purpose of this study was to explore the effect of rapidly dissociated meniscus tissue in enhancing neotissue formation in a radial meniscus tear, as simulated in an in vitro explant model.
  
  
  METHODS
  All experiments in this study, performed at minimum with biological triplicates, utilized meniscal tissues from hind limbs of young cows. The effect of varying collagenase concentration (0.1%, 0.2% and 0.5% w/v) and treatment duration (overnight and 30 minutes) on meniscus cell viability, organization of the extracellular matrix (ECM), and gene expression was assessed through a cell metabolism assay, microscopic examination, and quantitative real-time reverse transcription polymerase chain reaction analysis, respectively. Thereafter, an explant model of a radial meniscus tear was used to evaluate the effect of a fibrin gel seeded with one of the following: (1) fibrin alone, (2) isolated and passaged (P2) meniscus cells, (3) overnight digested tissue, and (4) rapidly dissociated tissue. The quality of in vitro healing was determined through histological analysis and derivation of an adhesion index.
  
  
  RESULTS
  Rapid dissociation in 0.2% collagenase yielded cells with higher levels of metabolism than either 0.1% or 0.5% collagenase. When seeded in a three-dimensional fibrin hydrogel, both overnight digested and rapidly dissociated cells expressed greater levels of collagens type I and II than P2 meniscal cells at 1 week. At 4 and 8 weeks, collagen type II expression remained elevated only in the rapid dissociation group. Histological examination revealed enhanced healing in all cell-seeded treatment groups over cell-free fibrin controls at weeks 1, 4, and 8, but there were no significant differences across the treatment groups.
  
  
  CONCLUSIONS
  Rapid dissociation of meniscus tissue may provide a single-step approach to augment regenerative healing of meniscus repairs.
authors.affiliation: a Center for Cellular and Molecular Engineering, Department of Orthopaedic Surgery , University of Pittsburgh School of Medicine , Pittsburgh , PA , USA.|b Department of Anatomy and Cell Biology , College of Medicine, National Taiwan University , Taipei , Taiwan.|c Institute of Medicine, Suranaree University of Technology , Nakhon Ratchasima , Thailand.
authors.forename: Piya-On
authors.initials: PO
authors.lastname: Numpaisal
authors.affiliation: a Center for Cellular and Molecular Engineering, Department of Orthopaedic Surgery , University of Pittsburgh School of Medicine , Pittsburgh , PA , USA.|d McGowan Institute for Regenerative Medicine, University of Pittsburgh , Pittsburgh , PA , USA.
authors.forename: Benjamin B
authors.initials: BB
authors.lastname: Rothrauff
authors.affiliation: a Center for Cellular and Molecular Engineering, Department of Orthopaedic Surgery , University of Pittsburgh School of Medicine , Pittsburgh , PA , USA.|e Ri.MED Foundation , Palermo , Italy.
authors.forename: Riccardo
authors.initials: R
authors.lastname: Gottardi
authors.affiliation: b Department of Anatomy and Cell Biology , College of Medicine, National Taiwan University , Taipei , Taiwan.
authors.forename: Chung-Liang
authors.initials: CL
authors.lastname: Chien
authors.affiliation: a Center for Cellular and Molecular Engineering, Department of Orthopaedic Surgery , University of Pittsburgh School of Medicine , Pittsburgh , PA , USA.|d McGowan Institute for Regenerative Medicine, University of Pittsburgh , Pittsburgh , PA , USA.
authors.forename: Rocky S
authors.initials: RS
authors.lastname: Tuan
mesh_terms: D000268:Adhesiveness; D000818:Animals; D002417:Cattle; D017364:Collagenases / Q000378:metabolism; D005109:Extracellular Matrix / Q000187:drug effects / Q000378:metabolism; D005337:Fibrin / Q000494:pharmacology; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D020100:Hydrogels / Q000494:pharmacology; D000072600:Meniscus / Q000187:drug effects / Q000473:pathology*; D014182:Transplantation, Autologous; D014945:Wound Healing / Q000187:drug effects
chemical_list: D020100:Hydrogels; D005337:Fibrin; D017364:Collagenases
keywords: Cell therapy; meniscus; single-step procedure