title: Improved antithrombotic activity and diminished bleeding side effect of a PEGylated αIIbβ3 antagonist, disintegrin.
abstract: BACKGROUND
  The applicability of protein drugs is confined by protein degradation and rapid elimination. PEGylation of polypeptides improves protein stability by sterically obstructing the degradation by serum proteases and reduces renal clearance by the increased mass.
  
  
  METHODS
  We compared the antithrombotic activities of intact rhodostomin (Rn) and PEGylated rhodostomin (PRn) both in vitro and in vivo systems. In addition, the functional half-life in inhibiting platelet aggregation and the tendency in causing bleeding side effect were investigated.
  
  
  RESULTS
  Rn and PRn both potently inhibited human and mouse platelet aggregation induced by collagen, thrombin or ADP in vitro with a similar IC50 around 60-100nM. Rotational thromboelastometry assay indicated that PRn was more effective than Rn in preventing clot formation in human whole blood. In platelet-rich plasma from mice injected with Rn or PRn, the inhibitory effects on collagen-induced platelet aggregation were also comparable, but Rn caused higher bleeding tendency. In ferric chloride-induced arterial thrombosis, Rn and PRn significantly prolonged occlusion time at high dosage (0.2μg/g). However, PRn obviously prolonged the occlusion time even given at a lower dosage (0.06μg/g). The functional half-life assay revealed that PEGylation prolonged the in vivo half-life of Rn.
  
  
  CONCLUSIONS
  PRn exhibits higher antithrombotic potency and longer half-life in vivo as compared with native Rn on a molar basis. In addition, PRn exhibits a better safety profile at an efficacious antithrombotic dose in vivo. Therefore, PEGylation may be one of the ideal options in modifying disintegrin derivatives as the safe therapeutic agents for integrin-related diseases.
authors.affiliation: Graduate Institute of Pharmacology, College of Medicine, National Taiwan University, Taipei, Taiwan.
authors.forename: Chun-Chieh
authors.initials: CC
authors.lastname: Hsu
authors.affiliation: Department of Biochemistry, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
authors.forename: Woei-Jer
authors.initials: WJ
authors.lastname: Chuang
authors.affiliation: Department of Medicine, Mackay Medical College, New Taipei City, Taiwan.
authors.forename: Ching-Hu
authors.initials: CH
authors.lastname: Chung
authors.affiliation: Graduate Institute of Pharmacology, College of Medicine, National Taiwan University, Taipei, Taiwan.
authors.forename: Chien-Hsin
authors.initials: CH
authors.lastname: Chang
authors.affiliation: Graduate Institute of Pharmacology, College of Medicine, National Taiwan University, Taipei, Taiwan.
authors.forename: Hui-Chin
authors.initials: HC
authors.lastname: Peng
authors.affiliation: Graduate Institute of Pharmacology, College of Medicine, National Taiwan University, Taipei, Taiwan. Electronic address: turfu@ntu.edu.tw.
authors.forename: Tur-Fu
authors.initials: TF
authors.lastname: Huang
mesh_terms: D000818:Animals; D001792:Blood Platelets / Q000187:drug effects; D019483:Disintegrins / Q000009:adverse effects / Q000737:chemistry / Q000493:pharmacokinetics / Q000627:therapeutic use; D004355:Drug Stability; D006207:Half-Life; D006470:Hemorrhage / Q000097:blood / Q000139:chemically induced*; D006801:Humans; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D010455:Peptides / Q000009:adverse effects* / Q000737:chemistry / Q000493:pharmacokinetics / Q000627:therapeutic use*; D010974:Platelet Aggregation / Q000187:drug effects; D010975:Platelet Aggregation Inhibitors / Q000009:adverse effects* / Q000737:chemistry / Q000493:pharmacokinetics / Q000627:therapeutic use*; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000037:antagonists & inhibitors* / Q000378:metabolism; D011092:Polyethylene Glycols / Q000737:chemistry; D055550:Protein Stability; D013927:Thrombosis / Q000097:blood / Q000188:drug therapy*
chemical_list: D019483:Disintegrins; D010455:Peptides; D010975:Platelet Aggregation Inhibitors; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; C072026:rhodostomin; D011092:Polyethylene Glycols
keywords: Disintegrin; Integrin αIIbβ3; PEGylation; Platelet; anti-thrombosis