title: Efficacy of autologous leukocyte-reduced platelet-rich plasma therapy for patellar tendinopathy in a rat treadmill model.
abstract: BACKGROUND
  An autologous platelet-rich plasma (PRP) therapy has currently been applied for the tendinopathy; however, its efficacy and an optimal platelets concentration in PRP were uncertain. We analyzed them in an animal model prepared using a repetitive running exercise.
  
  
  METHODS
  We made the tendinopathy rat model of patellar tendon using a rodent treadmill machine. Rats with tendinopathy were injected with leukocyte-reduced PRP at the platelets concentration of 1.0×106/μL (P10 group), PRP at the platelets concentration of 5.0×105/μL (P5 group) or normal saline (control group) into the space between the patellar tendon and the fat pad bilaterally or were multiply dry-needled at the tibial insertion site (MN group) at once. To assess the pain-reliving effect, the spontaneous locomotor activities at night (12 h) were measured every day. Histological sections of the patellar tendon stained with hematoxylineosin or prepared by TdT-mediated dUTP nick end labeling were microscopically analyzed.
  
  
  RESULTS
  The numbers of spontaneous locomotor activities in the P10 group were significantly larger than those in the P5, MN or control groups and they recovered up to a healthy level. On histologic examinations, the numbers of microtears, laminations, or apoptotic cells in the patellar tendons in the P10 or P5 groups were significantly lower than those in the MN or control groups, although no significant differences were observed between the P10 and P5 groups.
  
  
  CONCLUSIONS
  The injections of an autologous leukocyte-reduced PRP were effective for pain relief and for partial restoration of the patellar tendon in the tendinopathy rat model. The injections of a PRP at the platelets concentration of 1.0×106/μL completely relieved the pain and were more effective than those at the platelets concentration of 5.0×105/μL whereas there was no difference for the effect of histological restoration or apoptosis inhibition between them.
authors.affiliation: Department of Orthopaedic Surgery, The Jikei University School of Medicine, Tokyo, Japan.
authors.forename: Mamoru
authors.initials: M
authors.lastname: Yoshida
authors.affiliation: Department of Orthopaedic Surgery, The Jikei University School of Medicine, Tokyo, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Funasaki
authors.affiliation: Department of Orthopaedic Surgery, The Jikei University School of Medicine, Tokyo, Japan.
authors.forename: Keishi
authors.initials: K
authors.lastname: Marumo
keywords: platelet-rich plasma; rat; tendinopathy