title: Activation of platelet-rich plasma using soluble type I collagen.
abstract: OBJECTIVE
  Platelet-rich plasma (PRP) has recently been found to be a useful delivery system for growth factors important to oral tissue healing. But application of PRP in a liquid form to a wound site within the oral cavity can be complicated by significant loss of the PRP into the surrounding oral space unless gelation through the clotting mechanism is accomplished. Gelation is currently accomplished using bovine thrombin; however, rare but serious complications of this method have led to the search for alternative clotting mechanisms, including the use of soluble collagen as a clotting activator. In this work, our hypothesis was that soluble type I collagen would be as effective as bovine thrombin in causing clotting of the PRP and stimulating growth factor release from the platelets and granulocytes.
  
  
  METHODS
  PRP from human donors was clotted using type I collagen or bovine thrombin. Clot retraction was determined by measuring clot diameters over time. The release of platelet-derived growth factor (PDGF)-AB, transforming growth factor (TGF)-beta1, and vascular endothelial growth factor (VEGF) from both types of clots was measured over 10 days using enzyme-linked immunosorbent assasy.
  
  
  RESULTS
  Clots formed using type I collagen exhibited far less retraction than those formed with bovine thrombin. Bovine thrombin and type I collagen stimulated similar release of PDGF-AB and VEGF between 1 and 10 days; however, thrombin activation resulted in a greater release of TGF-beta1 during the first 5 days after activation.
  
  
  CONCLUSIONS
  The use of type I collagen to activate clotting of PRP may be a safe and effective alternative to bovine thrombin. The use of collagen results in less clot retraction and equal release of PDGF-AB and VEGF compared with currently available methods of clot activation.
authors: Department of Orthopaedic Surgery, Harvard Medical School, Children's Hospital of Boston, Boston, MA 02115, USA.
authors: Duretti
authors: D
authors: Fufa
authors: Blake
authors: B
authors: Shealy
authors: May
authors: M
authors: Jacobson
authors: Sherwin
authors: S
authors: Kevy
authors: Martha M
authors: MM
authors: Murray
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D002417:Cattle; D024042:Collagen Type I / Q000494:pharmacology*; D005782:Gels; D006801:Humans; D015539:Platelet Activation / Q000187:drug effects*; D010982:Platelet-Derived Growth Factor / Q000096:biosynthesis*; D053657:Platelet-Rich Plasma / Q000187:drug effects* / Q000378:metabolism; D051381:Rats; D013917:Thrombin / Q000494:pharmacology; D053773:Transforming Growth Factor beta1 / Q000096:biosynthesis*; D042461:Vascular Endothelial Growth Factor A / Q000096:biosynthesis
chemical_list: D024042:Collagen Type I; D005782:Gels; D010982:Platelet-Derived Growth Factor; D053773:Transforming Growth Factor beta1; D042461:Vascular Endothelial Growth Factor A; C095477:platelet-derived growth factor AB; D013917:Thrombin