title: No evidence for the use of stem cell therapy for tendon disorders: a systematic review.
abstract: BACKGROUND
  Stem cells have emerged as a new treatment option for tendon disorders. We systematically reviewed the current evidence for stem cell therapy in tendon disorders.
  
  
  METHODS
  Randomised and non-randomised controlled trials, cohort studies and case series with a minimum of 5 cases were searched in MEDLINE, CENTRAL, EMBASE, CINAHL, PEDro and SPORTDiscus. In addition, we searched grey literature databases and trial registers. Only human studies were included and no time or language restrictions were applied to our search. All references of included trials were checked for possibly eligible trials. Risk of bias assessment was performed using the Cochrane risk of bias tool for controlled trials and the Newcastle-Ottawa scale for case series. Levels of evidence were assigned according to the Oxford levels of evidence.
  
  
  RESULTS
  4 published and three unpublished/pending trials were found with a total of 79 patients. No unpublished data were available. Two trials evaluated bone marrow-derived stem cells in rotator cuff repair surgery and found lower retear rates compared with historical controls or the literature. One trial used allogenic adipose-derived stem cells to treat lateral epicondylar tendinopathy. Improved Mayo Elbow Performance Index, Visual Analogue Pain scale and ultrasound findings after 1-year follow-up compared with baseline were found. Bone marrow-derived stem cell-treated patellar tendinopathy showed improved International Knee Documentation Committee, Knee injury and Osteoarthritis Outcome Score subscales and Tegner scores after 5-year follow-up. One trial reported adverse events and found them to be mild (eg, swelling, effusion). All trials were at high risk of bias and only level 4 evidence was available.
  
  
  CONCLUSIONS
  No evidence (level 4) was found for the therapeutic use of stem cells for tendon disorders. The use of stem cell therapy for tendon disorders in clinical practice is currently not advised.
authors.affiliation: The Sports Physician Group, Department of Sports Medicine, OLVG West, Amsterdam, The Netherlands.|Department of Orthopaedic Surgery, Academic Medical Centre, Amsterdam, The Netherlands.
authors.forename: Haiko I M F L
authors.identifier: http://orcid.org/0000-0001-7857-4694
authors.initials: HIMFL
authors.lastname: Pas
authors.affiliation: The Sports Physician Group, Department of Sports Medicine, OLVG West, Amsterdam, The Netherlands.|Bergman Clinics, Naarden, The Netherlands.|Department of Elite Sports, NOC*NSF, Medical Staff, Arnhem, The Netherlands.
authors.forename: Maarten H
authors.initials: MH
authors.lastname: Moen
authors.affiliation: Department of Chemical and Pharmaceutical Biology, Groningen Research Institute of Pharmacy, Groningen University, Groningen, The Netherlands.
authors.forename: Hidde J
authors.initials: HJ
authors.lastname: Haisma
authors.affiliation: Rehabilitation, Nursing Science and Sports Department, University Medical Centre Utrecht, Utrecht, The Netherlands.
authors.forename: Marinus
authors.identifier: http://orcid.org/0000-0001-5742-7441
authors.initials: M
authors.lastname: Winters
mesh_terms: D064987:Cell- and Tissue-Based Therapy; D006801:Humans; D007719:Knee Joint / Q000503:physiopathology; D016032:Randomized Controlled Trials as Topic; D000070636:Rotator Cuff Injuries / Q000628:therapy; D013234:Stem Cells / Q000166:cytology*; D052256:Tendinopathy / Q000628:therapy*
keywords: Cellular; Review; Tendon