Polyglycolic Acid Fibrous Scaffold Improving Endothelial Cell Coating and Vascularization of Islet

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.

Allograft rejection-related gene expression in the endothelial cells of renal transplantation recipients after cytomegalovirus infection

Objective： To explore the effects of cytomegalovirus （CMV） infection on rejection-related gene expression in the endothelial cells of renal transplantation recipients. Methods： Endothelial cells （ECs） were cultured and stimulated by a variety of factors： A, normal control group; B, inactivated human cytomegalovirus （HCMV） infection group; C, HCMV infection group; D, HCMV supematant infection group; and E, ganciclovir HCMV group. Expression of intercellular adhesion molecule-1 （ICAM-1） and major histocompability complex （MHC） class I and class II antigens was detected by flow cytometry （FCM） and immuno- histochemistry. Results： We found characteristic CMV-infected ECs in this study. There were no significant differences among groups A, B and D （P〉0.05）. Although the expression levels of ICAM-1 were not significantly different between groups C and E （P〉0.05）, the ICAM-1 expression in these two groups was significantly higher than that in group A （P〈0.05）. ICAM-1 expression was detected in groups C and E, while there was no expression in groups A, B and D. Furthermore, there was no significant difference of ICAM-1 mRNA expression between groups C and E （P〉0.05）. Human leucocyte antigen （HLA）-ABC expression was detected in all the groups, while HLA-DR expression was only detected in groups C and E. There were no significant dif- ferences of HLA-ABC and HLA-DR expression among groups A, B and D （P〉0.05）. However, the HLA-ABC and HLA-DR expression levels in groups C and D were higher than those of the remaining groups previously reported （P〈0.05）. Meanwhile, the HLA-ABC and HLA-DR expression levels in group E were lower than those of group C （P〈0.05）. Conclusion： CMV could up-regulate the expression levels of ICAM-1 and MHC antigens, which was closely related to allograft rejection.