title: FGF-2 Stimulates the Growth of Tenogenic Progenitor Cells to Facilitate the Generation of Tenomodulin-Positive Tenocytes in a Rat Rotator Cuff Healing Model.
abstract: BACKGROUND
  Fibroblast growth factor (FGF)-2 has the potential to enhance tendon-to-bone healing after rotator cuff (RC) injury.
  
  
  OBJECTIVE
  FGF-2 stimulates tenogenic differentiation of progenitors to improve the biomechanical strength and histological appearance of repaired RCs in rats.
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  Adult male Sprague-Dawley rats (N = 156) underwent unilateral surgery to repair the supraspinatus tendon to insertion sites. The FGF-2-treated group (gelatin hydrogel containing 5 μg of FGF-2) and a control group (gelatin hydrogel only) were compared to investigate the effects of FGF-2 at 2, 4, 6, 8, and 12 weeks postoperatively. Biomechanical testing was performed at 6 and 12 weeks. Semiquantitative histological analysis and immunohistochemical analysis for the proliferating cell nuclear antigen (PCNA) were performed, and the expression of tendon-related markers, including Scleraxis (Scx) and Tenomodulin (Tnmd), was monitored by real-time reverse transcription polymerase chain reaction (RT-PCR) and in situ hybridization. SRY-box containing gene 9 (Sox9) expression was monitored by RT-PCR and immunohistochemical analysis. At 2 and 4 weeks, immunohistochemical analysis for mesenchymal stem cell (MSC) markers was also performed.
  
  
  RESULTS
  The FGF-2-treated group demonstrated a significant improvement in mechanical strength at 6 and 12 weeks and significantly higher histological scores than the control group at ≥4 weeks. The average incidence of PCNA-positive cells was significantly higher at 2 and 4 weeks, and more cells expressing MSC markers were detected at the insertion site in the FGF-2-treated group. The expression level of Scx increased significantly in the FGF-2-treated group from 4 to 8 weeks, while the Tnmd level increased significantly from 4 to 12 weeks postoperatively. The localization of Tnmd overlapped with the locations of reparative tissues accompanying collagen fibers with an aligned orientation. Sox9 expression was significantly upregulated at 4 weeks in the FGF-2-treated group.
  
  
  CONCLUSIONS
  FGF-2 promotes growth of the tenogenic progenitor cells, which participate in tendon-to-bone healing, resulting in biomechanical and histological improvement of the repaired RC.
  
  
  CONCLUSIONS
  These findings provide clues regarding the clinical development of regenerative repair strategies for RC injury.
authors: Department of Orthopaedic Surgery, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan.
authors: Takuya
authors: T
authors: Tokunaga
authors: Department of Molecular Biology and Biochemistry, Division of Basic Life Sciences, Institute of Biomedical & Health Sciences, Hiroshima University, Hiroshima, Japan.
authors: Chisa
authors: C
authors: Shukunami
authors: Department of Orthopaedic Surgery, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan.
authors: Nobukazu
authors: N
authors: Okamoto
authors: Department of Orthopaedic Surgery, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan.
authors: Takuya
authors: T
authors: Taniwaki
authors: Department of Orthopaedic Surgery, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan.
authors: Kiyoshi
authors: K
authors: Oka
authors: Department of Mechanical System Engineering, Graduate School of Science and Technology, Kumamoto University, Kumamoto, Japan.
authors: Hidetoshi
authors: H
authors: Sakamoto
authors: Department of Advanced Joint Reconstructive Surgery, Kumamoto University Hospital, Kumamoto University, Kumamoto, Japan.
authors: Junji
authors: J
authors: Ide
authors: Department of Orthopaedic Surgery, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan.
authors: Hiroshi
authors: H
authors: Mizuta
authors: Department of Cellular Differentiation, Institute for Frontier Medical Sciences, Kyoto University, Kyoto, Japan hiraki@frontier.kyoto-u.ac.jp.
authors: Yuji
authors: Y
authors: Hiraki
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology*; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism*; D019637:Orthopedic Procedures / Q000379:methods*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017006:Rotator Cuff / Q000473:pathology; D000070636:Rotator Cuff Injuries; D013234:Stem Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D013708:Tendon Injuries / Q000378:metabolism / Q000473:pathology / Q000601:surgery*; D014945:Wound Healing / Q000187:drug effects*
chemical_list: D008565:Membrane Proteins; C486027:Tnmd protein, rat; D016222:Fibroblast Growth Factor 2
keywords: FGF-2; Scleraxis; Sox9; Tenomodulin; cell proliferation; rotator cuff healing; tenogenic progenitors