title: Organ Pretreatment With Cytotopic Endothelial Localizing Peptides to Ameliorate Microvascular Thrombosis and Perfusion Deficits in Ex Vivo Renal Hemoreperfusion Models.
abstract: BACKGROUND
  Hypothermic machine organ perfusion (HMP) offers opportunity to manipulate grafts with pharmacological agents prior to transplantation. Pretreating organs with novel cytotopic anticoagulant peptides that localize to endothelial cell membranes could ameliorate microvascular thrombotic sequelae posttransplantation. We describe experiments testing thrombalexin (TLN), a novel cell binding thrombin inhibitor, using porcine and unused human kidneys in a series of ex vivo normothermic hemoreperfusion models.
  
  
  METHODS
  Thirty-eight porcine kidneys were used. Control kidneys underwent pretreatment via HMP with either unmodified perfusion solution (n = 15) or solution with inactive-TLN (absent anticoagulant effect, n = 4). Test kidneys were perfused with TLN-treated solution (n = 19). All kidneys then underwent hemoreperfusion. Two unused human kidneys underwent a similar protocol.
  
  
  RESULTS
  Hypothermic machine perfusion pretreatment facilitated delivery and tethering of TLN in the organ microvasculature. Hemoreperfusion challenge demonstrated improved perfusion in TLN-treated kidneys compared with controls: 26.4% superior flow (30.6 vs. 23.1 mL/min per 100 g, P = 0.019) and 28.9% higher perfusion flow indices (0.43 vs. 0.32 mL/min per 100 g mm Hg, P = 0.049). Orthogonal polarization spectral imaging demonstrated superior microvascular capillary perfusion in TLN-treated organs versus controls (9.1 vs 2.8 pl/s per mm, P = 0.021). Rapid-sampling microdialysis for cortical [lactate] as a marker of tissue ischemia/metabolism detected lower levels in TLN-treated kidneys. Perfusate analysis demonstrated reduced fibrin generation in TLN-treated kidneys correlating with perfusion data.
  
  
  CONCLUSIONS
  Our data suggest that HMP graft pretreatment with cytotopic anticoagulants is feasible and ameliorates perfusion deficits seen in ex vivo hemoreperfusion models. There is potential for further development and application of this translational strategy to deliver locally active anticoagulants directly within grafts and decrease microvascular thrombotic sequelae, while avoiding systemic anticoagulation and its associated risks.
authors.affiliation: 1 Department of Surgery, Imperial College, London, United Kingdom. 2 Department of Bioengineering, Imperial College, London, United Kingdom. 3 Imperial College Renal and Transplant Centre, Hammersmith Hospital, Imperial College Healthcare NHS Trust, London, United Kingdom. 4 MRC Centre for Transplantation, King's College London, United Kingdom.
authors.forename: Karim
authors.initials: K
authors.lastname: Hamaoui
authors.forename: Sally
authors.initials: S
authors.lastname: Gowers
authors.forename: Martyn
authors.initials: M
authors.lastname: Boutelle
authors.forename: Terry H
authors.initials: TH
authors.lastname: Cook
authors.forename: George
authors.initials: G
authors.lastname: Hanna
authors.forename: Ara
authors.initials: A
authors.lastname: Darzi
authors.forename: Richard
authors.initials: R
authors.lastname: Smith
authors.forename: Anthony
authors.initials: A
authors.lastname: Dorling
authors.forename: Vassilios
authors.initials: V
authors.lastname: Papalois
mesh_terms: D000818:Animals; D000925:Anticoagulants / Q000494:pharmacology*; D050377:Cold Ischemia; D004730:Endothelium, Vascular / Q000473:pathology*; D006801:Humans; D007668:Kidney / Q000473:pathology; D016030:Kidney Transplantation; D008833:Microcirculation; D009926:Organ Preservation / Q000379:methods*; D019188:Organ Preservation Solutions; D010455:Peptides / Q000494:pharmacology*; D015424:Reperfusion; D013552:Swine; D013917:Thrombin / Q000037:antagonists & inhibitors; D013927:Thrombosis / Q000473:pathology*
chemical_list: D000925:Anticoagulants; D019188:Organ Preservation Solutions; D010455:Peptides; C000619912:thrombalexin; D013917:Thrombin