title: Gene silencing of CD47 and antibody ligation of thrombospondin-1 enhance ischemic tissue survival in a porcine model: implications for human disease.
abstract: BACKGROUND
  Insufficient tissue perfusion underlies many acute and chronic diseases. Tissue perfusion in turn requires adequate blood flow, determined in large part by the relative state of relaxation or constriction of arterial vessels. Nitric oxide (NO) produced by vascular cells modulates blood flow and tissue perfusion by relaxing and dilating arteries. Recently, we reported that the secreted protein thrombospondin-1 (TSP1), through its cell surface receptor CD47, limits the ability of NO to relax and dilate blood vessels and thus decreases tissue perfusion. In the present study, we tested the hypothesis that blocking TSP1-CD47 signaling increases ischemic tissue survival in random cutaneous porcine flaps.
  
  
  METHODS
  Random cutaneous flaps 2 x 10 cm2 were raised in white hairless Yucatan miniature pigs and were treated with a monoclonal antibody to TSP1, an antisense morpholino oligonucleotide to CD47 or control agents and tissue survival assessed. Primary vascular smooth muscle cell cultured from Yucatan pigs were also treated with the same agents +/- and an NO donor (DEA/NO) and cGMP quantified.
  
  
  RESULTS
  Antibody blockade of TSP1 or morpholino suppression of CD47 dramatically enhanced survival of random tissue flaps. These responses correlated with increased blood vessel patency and tissue blood flow on vessel injection studies. NO-stimulated cGMP flux in Yucatan vascular smooth muscle cell was abrogated after antibody or morpholino treatment.
  
  
  CONCLUSIONS
  Antibody ligation of TSP1 or antisense morpholino knock down of CD47 greatly increased tissue survival to ischemia. Given the similarity between porcine and human soft tissues these results suggest significant therapeutic potential for people.
authors.affiliation: Laboratory of Pathology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892-1500, USA. isenberj@mail.nih.gov
authors.forename: Jeff S
authors.initials: JS
authors.lastname: Isenberg
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Romeo
authors.forename: Justin B
authors.initials: JB
authors.lastname: Maxhimer
authors.forename: Jeremy
authors.initials: J
authors.lastname: Smedley
authors.forename: William A
authors.initials: WA
authors.lastname: Frazier
authors.forename: David D
authors.initials: DD
authors.lastname: Roberts
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology*; D051928:CD47 Antigen / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D020868:Gene Silencing; D007511:Ischemia; D020319:Oligodeoxyribonucleotides, Antisense / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013524:Surgical Flaps / Q000098:blood supply*; D013552:Swine; D013556:Swine, Miniature; D019700:Thrombospondin 1 / Q000037:antagonists & inhibitors*; D046509:Tissue Culture Techniques; D014022:Tissue Survival / Q000187:drug effects* / Q000502:physiology
chemical_list: D000911:Antibodies, Monoclonal; D051928:CD47 Antigen; D020319:Oligodeoxyribonucleotides, Antisense; D019700:Thrombospondin 1