title: The effect of platelet-rich plasma on normal soft tissues in the rabbit.
abstract: BACKGROUND
  Platelet-rich plasma is reported to contain multiple growth factors, and has been utilized in orthopaedic surgery to aid healing in multiple tissues. To date, the use of autologous platelet-rich plasma has not been studied for its effects on normal soft tissue.
  
  
  METHODS
  Eighteen adult New Zealand White rabbits were injected with 0.5 mL of autologous platelet-rich plasma in the right or left quadriceps muscle, Achilles tendon, medial collateral ligament, subcutaneous tissue, tibial periosteum, and ankle joint. Saline solution was injected on the contralateral side as a control. The soft tissues were examined histologically at two weeks (six rabbits) and six weeks (six rabbits), and soft tissues from six rabbits that had been reinjected at six weeks were examined at twelve weeks.
  
  
  RESULTS
  Inflammatory skin lesions were visible at forty-eight hours at superficial platelet-rich plasma sites. All lesions resolved by six days. Compared with findings in control specimens, histological analysis of platelet-rich plasma injection sites at two weeks showed a marked inflammatory infiltrate with lymphocytic and monocytic predominance. Intra-articular injection showed villous synovial hyperplasia and chronic synovitis. Tendon and ligament sites showed new collagen deposition. Intramuscular injection sites showed thrombosis, necrosis, and calcium deposition. Subcutaneous sites also showed calcium deposition without necrosis as well as collagen nodules representing early scar tissue. Histological examination of platelet-rich plasma injection sites at six and twelve weeks demonstrated a persistent but diminished inflammatory infiltrate. Focal areas of scar tissue were seen with fibroblasts, collagen formation, and neovascularity. All saline solution sites at all times were nonreactive.
  
  
  CONCLUSIONS
  Platelet-rich plasma can initiate an inflammatory response in the absence of an inciting injury in normal soft tissue in rabbits.
authors.affiliation: Aspen Orthopaedic Associates, 100 East Main Street, Suite 101, Aspen, CO 81611, USA.
authors.forename: N Lindsay
authors.initials: NL
authors.lastname: Harris
authors.forename: William E
authors.initials: WE
authors.lastname: Huffer
authors.forename: Eleanor
authors.initials: E
authors.lastname: von Stade
authors.forename: Andrew I
authors.initials: AI
authors.lastname: Larson
authors.forename: Shawn
authors.initials: S
authors.lastname: Phinney
authors.forename: Mark L
authors.initials: ML
authors.lastname: Purnell
mesh_terms: D000125:Achilles Tendon / Q000187:drug effects* / Q000473:pathology; D000818:Animals; D000843:Ankle Joint; D001688:Biological Products / Q000494:pharmacology; D003238:Connective Tissue / Q000187:drug effects* / Q000473:pathology; D007267:Injections; D017746:Joint Capsule / Q000187:drug effects* / Q000473:pathology; D008297:Male; D017888:Medial Collateral Ligament, Knee / Q000187:drug effects* / Q000473:pathology; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000473:pathology; D053657:Platelet-Rich Plasma; D011817:Rabbits; D013977:Tibia
chemical_list: D001688:Biological Products