title: Platelets can neutralize hydrogen peroxide in an acute toxicity model with cells involved in granulation tissue formation.
abstract: Platelets play a key role in the replacement of the blood clot with granulation tissue during the early steps of bone regeneration. We hypothesized that activated platelets can neutralize locally produced reactive oxygen species, thereby protecting cells involved in granulation tissue formation. The potential of platelet-released supernatant (PRS) to neutralize hydrogen peroxide (H(2)O(2)) was tested in an acute toxicity model with osteogenic, inflammatory, and endothelial cells. In the human fetal osteoblastic cell line 1.19 (hFOB), considerable morphological changes, cell shedding, and dysfunction of the respiratory chain were observed when cells were exposed to 3 mM H(2)O(2). Caspase-3 and poly-(ADP-ribose)-polymerase were not activated, suggesting that cell death occurred by necrosis. Preincubation of osteogenic cells, leukocytes, or endothelial cells with PRS decreased the acute toxicity of H(2)O(2). The capacity of platelets to release H(2)O(2)-detoxifying activity was retained for up to 72 h. Aminotriazole, an inhibitor of catalase, decreased the cytoprotective activity of PRS, whereas blocking of glutathione peroxidase by mercaptosuccinate had no effect. These results suggest that platelet-released catalase can rapidly neutralize cytotoxic amounts of H(2)O(2), a process that may play a role during the early stages of bone regeneration.
authors.affiliation: Department of Oral Surgery, Medical University of Vienna, Austria.
authors.forename: Barbara
authors.initials: B
authors.lastname: Kandler
authors.forename: Philipp
authors.initials: P
authors.lastname: Maitz
authors.forename: Michael B
authors.initials: MB
authors.lastname: Fischer
authors.forename: Georg
authors.initials: G
authors.lastname: Watzek
authors.forename: Reinhard
authors.initials: R
authors.lastname: Gruber
mesh_terms: D001792:Blood Platelets / Q000502:physiology*; D015153:Blotting, Western; D001861:Bone Regeneration; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002374:Catalase / Q000037:antagonists & inhibitors; D002460:Cell Line; D005979:Glutathione Peroxidase / Q000037:antagonists & inhibitors; D006097:Granulation Tissue / Q000473:pathology*; D006801:Humans; D006861:Hydrogen Peroxide / Q000633:toxicity*; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D014945:Wound Healing
chemical_list: D006861:Hydrogen Peroxide; D002374:Catalase; D005979:Glutathione Peroxidase; D011065:Poly(ADP-ribose) Polymerases; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases