title: Characterization of age-related changes of tendon stem cells from adult human tendons.
abstract: OBJECTIVE
  The present study evaluated the presence of stem cells in hamstring tendons from adult subjects of different ages. The aim was to isolate, characterize and expand these cells in vitro, and to evaluate whether cell activities are influenced by age.
  
  
  METHODS
  Tendon stem cells (TSCs) were isolated through magnetic sorting from the hamstring tendons of six patients. TSC percentage, morphology and clonogenic potential were evaluated, as well as the expression of specific surface markers. TSC multi-potency was also investigated as a function of age, and quantitative polimerase chain reaction was used to evaluate gene expression of TSCs cultured in suitable differentiating media.
  
  
  RESULTS
  The presence of easily harvestable stem cell population within adult human hamstring tendons was demonstrated. These cells exhibit features such as clonogenicity, multi-potency and mesenchymal stem cells markers expression. The age-related variations in human TSCs affect the number of isolated cells and their self-renewal potential, while multi-potency assays are not influenced by tendon ageing, even though cells from younger individuals expressed higher levels of osteogenic and adipogenic genes, while chondrogenic genes were highly expressed in cells from older individuals.
  
  
  CONCLUSIONS
  These results may open new opportunities to study TSCs to better understand tendon physiology, healing and pathological processes such as tendinopathy and degenerative age-related changes opening new frontiers in the management of tendinopathy and tendon ruptures.
authors.affiliation: Unit of Orthopedics and Trauma Surgery, Center for Integrated Research, Università Campus Bio-Medico di Roma, via Alvaro del Portillo 200, 00128, Rome, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Ruzzini
authors.forename: Franca
authors.initials: F
authors.lastname: Abbruzzese
authors.forename: Alberto
authors.initials: A
authors.lastname: Rainer
authors.forename: Umile Giuseppe
authors.initials: UG
authors.lastname: Longo
authors.forename: Marcella
authors.initials: M
authors.lastname: Trombetta
authors.forename: Nicola
authors.initials: N
authors.lastname: Maffulli
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Denaro
mesh_terms: D000328:Adult; D002478:Cells, Cultured; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D013234:Stem Cells / Q000166:cytology* / Q000502:physiology; D013710:Tendons / Q000166:cytology* / Q000502:physiology; D055815:Young Adult