title: Guanylate-binding protein 1 expression from embryonal endothelial progenitor cells reduces blood vessel density and cellular apoptosis in an axially vascularised tissue-engineered construct.
abstract: BACKGROUND
  Guanylate binding protein-1 (GBP-1) is a large GTPase which is actively secreted by endothelial cells. It is a marker and intracellular inhibitor of endothelial cell proliferation, migration, and invasion. We previously demonstrated that stable expression of GBP-1 in murine endothelial progenitor cells (EPC) induces their premature differentiation and decreases their migration capacity in vitro and in vivo. The goal of the present study was to assess the antiangiogenic capacity of EPC expressing GBP-1 (GBP-1-EPC) and their impact on blood vessel formation in an axially vascularized 3-D bioartificial construct in vivo.
  
  
  RESULTS
  Functional in vitro testing demonstrated a significant increase in VEGF secretion by GBP-1-EPC after induction of cell differentiation. Undifferentiated GBP-1-EPC, however, did not secrete increased levels of VEGF compared to undifferentiated control EPC expressing an empty vector (EV-EPC). In our In vivo experiments, we generated axially vascularized tissue-engineered 3-D constructs. The new vascular network arises from an arterio-venous loop (AVL) embedded in a fibrin matrix inside a separation chamber. Total surface area of the construct as calculated from cross sections was larger after transplantation of GBP-1-EPC compared to control EV-EPC. This indicated reduced formation of fibrovascular tissue and less resorption of fibrin matrix compared to constructs containing EV-EPC. Most notably, the ratio of blood vessel surface area over total construct surface area in construct cross sections was significantly reduced in the presence of GBP-1-EPC. This indicates a significant reduction of blood vessel density and thereby inhibition of blood vessel formation from the AVL constructs caused by GBP-1. In addition, GBP-1 expressed from EPC significantly reduced cell apoptosis compared to GBP-1-negative controls.
  
  
  CONCLUSIONS
  Transgenic EPC expressing the proinflammatory antiangiogenic GTPase GBP-1 can reduce blood vessel density and inhibit apoptosis in a developing bioartificial vascular network and may become a new powerful tool to manipulate angiogenetic processes in tissue engineering and other pathological conditions such as tumour angiogenesis.
authors.affiliation: Department of Plastic and Hand Surgery, University of Erlangen-Nuremberg, Krankenhausstr 12 91054, Erlangen, Germany. oliver.bleiziffer@uk-erlangen.de
authors.forename: Oliver
authors.initials: O
authors.lastname: Bleiziffer
authors.forename: Matthias
authors.initials: M
authors.lastname: Hammon
authors.forename: Andreas
authors.initials: A
authors.lastname: Arkudas
authors.forename: Christian D
authors.initials: CD
authors.lastname: Taeger
authors.forename: Justus P
authors.initials: JP
authors.lastname: Beier
authors.forename: Kerstin
authors.initials: K
authors.lastname: Amann
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Naschberger
authors.forename: Michael
authors.initials: M
authors.lastname: Stürzl
authors.forename: Raymund E
authors.initials: RE
authors.lastname: Horch
authors.forename: Ulrich
authors.initials: U
authors.lastname: Kneser
mesh_terms: D000818:Animals; D017209:Apoptosis; D002460:Cell Line; D003470:Culture Media; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000378:metabolism*; D008297:Male; D051379:Mice; D018919:Neovascularization, Physiologic / Q000502:physiology*; D051381:Rats; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism*; D023822:Tissue Engineering; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism
chemical_list: D003470:Culture Media; C490288:Gbp2b protein, mouse; D042461:Vascular Endothelial Growth Factor A; C467480:vascular endothelial growth factor A, mouse; D019204:GTP-Binding Proteins