A comparison of three methods of decellularization of pig corneas to reduce immunogenicity

·AIM: To investigate whether decellularization using different techniques can reduce immunogenicity of the cornea, and to explore the decellularized cornea as a scaffold for cultured corneal endothelial cells(CECs).Transplantation of decellularized porcine corneas increases graft transparency and survival for longer periods compared with fresh grafts.·METHODS: Six-month-old wild-type pig corneas were cut into 100-200 μm thickness, and then decellularized by three different methods: 1) 0.1% sodium dodecyl sulfate(SDS); 2) hypoxic nitrogen(N2); and 3) hypertonic NaCl. Thickness and transparency were assessed visually. Fresh and decellularized corneas were stained with hematoxylin/eosin(H&E), and for the presence of galactose-α1,3-galactose(Gal) and N-glycolylneuraminic acid(NeuGc, a nonGal antigen). Also, a human IgM/IgG binding assay was performed. Cultured porcine CECs were seeded on the surface of the decellularized cornea and examined after H&E staining.· RESULTS: All three methods of decellularization reduced the number of keratocytes in the stromal tissue by 】80% while the collagen structure remained preserved. No remaining nuclei stained positive for Gal or NeuGc, and expression of these oligosaccharides on collagen was also greatly decreased compared to expression on fresh corneas. Human IgM/IgG binding to decellularized corneal tissue was considerably reduced compared to fresh corneal tissue. The cultured CECs formed a confluent monolayer on the surface of decellularized tissue.· CONCLUSION: Though incomplete, the significant reduction in the cellular component of the decellularized cornea should be associated with a significantly reduced in vivo immune response compared to fresh corneas.

Influence of the invasion of peripheral blood mononuclear cells by hepatitis B virus on immune response of the patients with chronic hepatitis B

Objective:To exploretheinfluenceof HBVinvasionintoperipheralbloodmononuclearcells(PBMC)on theimmuneresponseof patientswithchronichepatitisB.Method s:Thecytokinelevelsintheculturesupernatantof PBMCfrom56patientswithchronichepatitisB weredeterminedby ELISA,andPCRwasemployedto amplifythe HBVDNA.Results:Thelevelsof IFN-γinpatientswithhepatitisB waslowerthanthosetof thecontrol,butthe differencewasnotstatisticallysignificant,whilethelevelsof IL-4weresignificantlyhigherthanthoseof thecontrol(P<0.01).Theserumlevelsof HBVDNAwerenegativelycorrelatedwiththatof IFN-γin culturesupernatantsof PBMC.Thirty-fivepatientspositiveof HBVDNA inthePBMCswereidentifiedfrom56patientswithhepatitisB,andtheirIFN-γlevelprovedto be significantlydifferent.Conclusions:Th2cell-mediatedimmuneresponseis predo-minantin chronichepatitisB whichis associatedwiththechronicityof HBVinfection.HBVinvasionintothe PBMCsmayaffectTh1andTh2cell-mediatedimmuneresponseof thepatientswithchronichepatitisB.