title: Bone marrow-derived cells from the footprint infiltrate into the repaired rotator cuff.
abstract: BACKGROUND
  Cells from the bone marrow are considered important during the rotator cuff repair process, but the kinetics of bone marrow-derived cells in this process is unknown.
  
  
  OBJECTIVE
  To analyze the kinetics of bone marrow cells during the rotator cuff repair process, to review whether or not they are histologically involved in rotator cuff healing, and to analyze the biomechanics of the repaired tissues.
  
  
  METHODS
  Bone marrow chimeric rats that express green fluorescent protein (GFP) only in bone marrow- and circulation-derived cells were created. Bilateral supraspinatus tendons were separated from the greater tuberosity of the humeral head to produce a rotator cuff transection model. Drilling into the bone marrow was performed in the greater tuberosity of the right humerus and the supraspinatus tendon was repaired (drilling group), while the supraspinatus tendon was repaired on the left shoulder without drilling (control group). We examined the histology of the rotator cuff, the ultimate force-to-failure, and the proportion of GFP-positive cells in the repaired rotator cuff at 2, 4 and 8 weeks after surgery.
  
  
  RESULTS
  Mesenchymal cells were observed in the repaired rotator cuff at 2 weeks in both groups. There were more GFP-positive cells in the drilling group than the control group at 2, 4 and 8 weeks. The ultimate force-to-failure was significantly higher in the drilling group than the control group at 4 and 8 weeks.
  
  
  CONCLUSIONS
  Bone marrow-derived cells passed through holes drilled in the humerus footprint, infiltrated the repaired rotator cuff and contributed to postsurgical rotator cuff healing.
authors.affiliation: Department of Orthopaedics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan.
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Kida
authors.forename: Toru
authors.initials: T
authors.lastname: Morihara
authors.forename: Ken-Ichi
authors.initials: K
authors.lastname: Matsuda
authors.forename: Yoshiteru
authors.initials: Y
authors.lastname: Kajikawa
authors.forename: Hisakazu
authors.initials: H
authors.lastname: Tachiiri
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Iwata
authors.forename: Kazuhide
authors.initials: K
authors.lastname: Sawamura
authors.forename: Atsuhiko
authors.initials: A
authors.lastname: Yoshida
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Oshima
authors.forename: Takumi
authors.initials: T
authors.lastname: Ikeda
authors.forename: Hiroyoshi
authors.initials: H
authors.lastname: Fujiwara
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Kawata
authors.forename: Toshikazu
authors.initials: T
authors.lastname: Kubo
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D001854:Bone Marrow Cells / Q000502:physiology*; D002465:Cell Movement; D004195:Disease Models, Animal; D006811:Humerus / Q000601:surgery; D059630:Mesenchymal Stem Cells / Q000502:physiology*; D051381:Rats; D017006:Rotator Cuff / Q000503:physiopathology* / Q000601:surgery*; D000070636:Rotator Cuff Injuries; D014945:Wound Healing / Q000502:physiology*