title: A novel in vitro model of ischaemic preconditioning: its effect on cell viability in human skeletal muscle and a possible explanation for the 'second window of protection'.
abstract: BACKGROUND
  The ischaemia-reperfusion (IR) injury causes significant morbidity. Ischaemic preconditioning (IPC) is a technique for limiting the effects of the IR injury. Its potential has not yet been harnessed in orthopaedics.
  
  
  OBJECTIVE
  To establish a novel in vitro IR model using a human skeletal muscle cell line. Secondly, to introduce simulated IPC to the model and examine the effect of this on cell viability.
  
  
  METHODS
  A human skeletal muscle cell line was cultured in vitro. Placing the cells in a hypoxic buffer and a closed hypoxic environment simulated ischaemia. Reversing this process simulated reperfusion. IPC was simulated by alternate cycles of ischaemia and reperfusion. Cell viability comparisons were made between control and experimental groups of cells.
  
  
  RESULTS
  A reproducible in vitro IR model was established. The addition of simulated IPC is associated with increased cell death at 12 and 24 h of reperfusion. Significantly greater cell survival is seen in the IPC group when measured at 72 h reperfusion.
  
  
  CONCLUSIONS
  We hypothesise that IPC initially decreases cell number. The remaining cells are more robust. This selected cell line then expands over the course of 72 h and displays greater resistance to the IR injury. This theory can help explain delayed preconditioning.
authors.affiliation: pmagill8@gmail.com
authors.forename: Paul
authors.initials: P
authors.lastname: Magill
authors.forename: Pauline
authors.initials: P
authors.lastname: Walsh
authors.forename: Terence
authors.initials: T
authors.lastname: Murphy
authors.forename: Kevin J
authors.initials: KJ
authors.lastname: Mulhall
mesh_terms: D018929:Cell Culture Techniques; D015687:Cell Hypoxia; D002470:Cell Survival; D006801:Humans; D019194:Ischemic Preconditioning; D008955:Models, Cardiovascular; D018482:Muscle, Skeletal / Q000098:blood supply / Q000473:pathology* / Q000502:physiology; D015427:Reperfusion Injury / Q000473:pathology / Q000517:prevention & control*