title: Polyglycolic Acid Fibrous Scaffold Improving Endothelial Cell Coating and Vascularization of Islet.
abstract: BACKGROUND
  Improving islet graft revascularization has become a crucial task for prolonging islet graft survival. Endothelial cells (ECs) are the basis of new microvessels in an isolated islet, and EC coating has been demonstrated to improve the vascularization and survival of an islet. However, the traditional method of EC coating of islets has low efficiency in vitro. This study was conducted to evaluate the effect of a polyglycolic acid (PGA) scaffold on the efficiency of islet coating by ECs and the angiogenesis in the coated islet graft.
  
  
  METHODS
  A PGA fibrous scaffold was used for EC coating of islet culture and was evaluated for its efficiency of EC coating on islets and islet graft angiogenesis.
  
  
  RESULTS
  In in vitro experiments, we found that apoptosis index of ECs-coating islet in PGA group (27% ± 8%) was significantly lower than that in control group (83% ± 20%, P < 0.05) after 7 days culture. Stimulation index was significantly greater in the PGA group than in the control group at day 7 after ECs-coating (2.07 ± 0.31 vs. 1.80 ± 0.23, P < 0.05). vascular endothelial growth factor (VEGF) level in the PGA group was significantly higher than the coating in the control group after 7 days culture (52.10 ± 13.50 ng/ml vs. 16.30 ± 8.10 ng/ml, P < 0.05). Because of a tight, circumvallated, adhesive and three-dimensional growth microenvironment, islet cultured in a PGA scaffold had higher coating efficiency showing stronger staining intensity of enzyme than those in the control group after 14 days of culture following ECs-coating. For in vivo study, PGA scaffold significantly prolonged the average survival time of EC-coated islet graft after transplantation compared with control group (15.30 ± 5.60 days vs. 8.30 ± 2.45 days, P < 0.05). The angiogenesis and area of survived grafts were more in the PGA group compared with the control group by measuring the mean microvessel density (8.60 ± 1.21/mm2 vs. 5.20 ± 0.87/mm2, P < 0.05). In addition, expression of VEGF and tyrosin-protein kinase receptor (Tie-2) gene increased in PGA scaffold group than that in control group by real-time reverse transcription-polymerase chain reaction analysis.
  
  
  CONCLUSIONS
  These results demonstrate that the efficiency of EC coating of islets was successfully increased by culturing ECs on a PGA scaffold. This method enhances the function, survival, and vascularization of isolated islets in vitro and in vivo.
authors.affiliation: Department of Renal Transplantation, Center of Nephrology, The First Affiliated Hospital of Xi'an Jiaotong University School of Medicine, Xi'an, Shaanxi 710061, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Li
authors.affiliation: Department of Rheumatism and Immunology, The First Affiliated Hospital of Xi'an Jiaotong University School of Medicine, Xi'an, Shaanxi 710061, China.
authors.forename: Ping
authors.initials: P
authors.lastname: Fan
authors.affiliation: Department of Renal Transplantation, Center of Nephrology, The First Affiliated Hospital of Xi'an Jiaotong University School of Medicine, Xi'an, Shaanxi 710061, China.
authors.forename: Xiao-Ming
authors.initials: XM
authors.lastname: Ding
authors.affiliation: Department of Renal Transplantation, Center of Nephrology, The First Affiliated Hospital of Xi'an Jiaotong University School of Medicine, Xi'an, Shaanxi 710061, China.
authors.forename: Xiao-Hui
authors.initials: XH
authors.lastname: Tian
authors.affiliation: Department of Renal Transplantation, Center of Nephrology, The First Affiliated Hospital of Xi'an Jiaotong University School of Medicine, Xi'an, Shaanxi 710061, China.
authors.forename: Xin-Shun
authors.initials: XS
authors.lastname: Feng
authors.affiliation: Department of Renal Transplantation, Center of Nephrology, The First Affiliated Hospital of Xi'an Jiaotong University School of Medicine, Xi'an, Shaanxi 710061, China.
authors.forename: Hang
authors.initials: H
authors.lastname: Yan
authors.affiliation: Department of Renal Transplantation, Center of Nephrology, The First Affiliated Hospital of Xi'an Jiaotong University School of Medicine, Xi'an, Shaanxi 710061, China.
authors.forename: Xiao-Ming
authors.initials: XM
authors.lastname: Pan
authors.affiliation: Department of Renal Transplantation, Center of Nephrology, The First Affiliated Hospital of Xi'an Jiaotong University School of Medicine, Xi'an, Shaanxi 710061, China.
authors.forename: Pu-Xun
authors.initials: PX
authors.lastname: Tian
authors.affiliation: Department of Renal Transplantation, Center of Nephrology, The First Affiliated Hospital of Xi'an Jiaotong University School of Medicine, Xi'an, Shaanxi 710061, China.
authors.forename: Jin
authors.initials: J
authors.lastname: Zheng
authors.affiliation: Department of Renal Transplantation, Center of Nephrology, The First Affiliated Hospital of Xi'an Jiaotong University School of Medicine, Xi'an, Shaanxi 710061, China.
authors.forename: Chen-Guang
authors.initials: CG
authors.lastname: Ding
authors.affiliation: Department of Renal Transplantation, Center of Nephrology, The First Affiliated Hospital of Xi'an Jiaotong University School of Medicine, Xi'an, Shaanxi 710061, China.
authors.forename: Wu-Jun
authors.initials: WJ
authors.lastname: Xue
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D042783:Endothelial Cells / Q000187:drug effects; D004797:Enzyme-Linked Immunosorbent Assay; D006085:Graft Survival / Q000187:drug effects; D007328:Insulin / Q000378:metabolism; D007515:Islets of Langerhans / Q000187:drug effects; D016381:Islets of Langerhans Transplantation / Q000379:methods*; D018919:Neovascularization, Physiologic / Q000187:drug effects; D011100:Polyglycolic Acid / Q000737:chemistry / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017208:Rats, Wistar; D054457:Tissue Scaffolds / Q000737:chemistry*
chemical_list: D007328:Insulin; D011100:Polyglycolic Acid