title: Tissue engineering of bladder using vascular  endothelial growth factor gene-modified endothelial progenitor cells.
abstract: OBJECTIVE
  This study assessed the use of vascular endothelial growth factor (VEGF) gene-modified endothelial progenitor cells (EPCs) seeded onto bladder acellular matrix grafts (BAMGs), to enhance the blood supply in tissue-engineered bladders in a porcine model.
  
  
  METHODS
  Autologous porcine peripheral EPCs were isolated, cultured, expanded, characterized, and modified with the VEGF gene using an adenovirus vector. The expression of VEGF was examined using reverse transcriptase polymerase chain reaction (RT-PCR) and an enzyme-linked immunosorbent assay (ELISA). VEGF gene modified EPCs were seeded onto BAMG and cultured for 3 days before implantation into pigs for bladder tissue engineering. A partial bladder cystectomy was performed in 12 pigs. The experimental group (6 pigs) received VEGF gene-modified EPC-seeded BAMG. The control group (6 pigs) received BAMG without seeded EPCs. The resulting tissue-engineered bladders were subject to a general and histological analysis. Microvessel density (MVD) was assessed using immunohistochemistry.
  
  
  RESULTS
  The ex vivo transfection efficiency of EPCs was greater than 60%-70% when concentrated adenovirus was used. The genetically modified cells expressed both VEGF and green fluorescent protein (GFP). Scanning electron microscopy (SEM) and Masson's trichrome staining of cross sections of the cultured cells seeded to BAMG showed cell attachment and proliferation on the surface of the BAMG. Histological examination revealed bladder regeneration in a time-dependent fashion. Significant increases in MVD were observed in the experimental group, in comparison with the control group.
  
  
  CONCLUSIONS
  VEGF-modified EPCs significantly enhanced neovascularization, compared with BAMG alone. These results indicate that EPCs, combined with VEGF gene therapy, may be a suitable approach for increasing blood supply in the tissue engineering of bladders. Thus, a useful strategy to achieve a tissue-engineered bladder is indicated.
authors.affiliation: Department of Urology, Children's Hospital of Shanghai, Children's Hospital affiliated to Shanghai Jiao Tong University, Shanghai - PR China.
authors.forename: Bai-Song
authors.initials: BS
authors.lastname: Chen
authors.forename: Hua
authors.initials: H
authors.lastname: Xie
authors.forename: Sheng-Li
authors.initials: SL
authors.lastname: Zhang
authors.forename: Hong-Quan
authors.initials: HQ
authors.lastname: Geng
authors.forename: Jun-Mei
authors.initials: JM
authors.lastname: Zhou
authors.forename: Jun
authors.initials: J
authors.lastname: Pan
authors.forename: Fang
authors.initials: F
authors.lastname: Chen
mesh_terms: D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D002448:Cell Adhesion; D049109:Cell Proliferation; D002478:Cells, Cultured; D015653:Cystectomy; D042783:Endothelial Cells / Q000378:metabolism / Q000637:transplantation* / Q000648:ultrastructure; D004797:Enzyme-Linked Immunosorbent Assay; D015316:Genetic Therapy; D005822:Genetic Vectors; D006801:Humans; D007150:Immunohistochemistry; D008855:Microscopy, Electron, Scanning; D018919:Neovascularization, Physiologic; D012038:Regeneration; D020133:Reverse Transcriptase Polymerase Chain Reaction; D033581:Stem Cell Transplantation; D013234:Stem Cells / Q000378:metabolism / Q000648:ultrastructure; D013552:Swine; D013997:Time Factors; D023822:Tissue Engineering / Q000379:methods; D054457:Tissue Scaffolds; D014162:Transfection; D001743:Urinary Bladder / Q000098:blood supply / Q000378:metabolism / Q000473:pathology / Q000601:surgery*; D042461:Vascular Endothelial Growth Factor A / Q000096:biosynthesis / Q000235:genetics*
chemical_list: C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A