GTKO rabbit: A novel animal model for preclinical assessment of decellularized xenogeneic grafts via in situ implantation.

Wild type (WT) animals cannot be used to objectively assess the immunogenicity of animal tissue-derived biomaterials when used as recipients due to difference with human in α-Gal expression. The purpose of this study is to compare the differences of immunological responses between the GGTA1 gene-knockout (GTKO) rabbits and WT rabbits after implantation with animal tissue-derived biomaterials. The porcine-derived decellularized bone matrix (natural bone material, NBM) and fresh porcine cancellous bone (PCB) were implanted in GTKO rabbits and WT rabbits, respectively, and sham operation was used as control (Con). At 2- and 6-week post-implantation, the related immunological items including antibody levels, serum-mediated cell lysis, cytokines, lymphocyte subtypes, and histopathological changes were assessed. GTKO rabbits exhibited more sensitive immune responses than WT rabbits after PCB implantation, resulted from a significant increase of antibodies (except total antibodies) and cytokines levels, cell lysis ratios, CD4/CD8 proportions, and inflammatory cells infiltration. Immunological factors and inflammatory cells infiltrate in GTKO rabbits after NBM implantation were significantly lower than those in the PCB group. Among the three groups, the NBM group showed the highest contents of new bone formation elements. In conclusion, the GTKO rabbit is a more sensitive alternative model than WT rabbit for preclinical study of xenografts via in situ implantation. Studies on multiple gene-edited animals are also necessary for more comprehensively evaluating xenoimmunologen risks of animal tissue-derived biomaterials in the future. Additionally, the immunogenicity of NBM was remarkably decreased compared to PCB.

Immunological Risk Assessment of Xenogeneic Dural Patch by Comparing with Raw Material via GTKO Mice.

OBJECTIVE: In this study, α-Gal epitope-deficient (GGTA1 knockout (GTKO)) mice were used to assess the immunological risks of xenogeneic dural patch by comparing with raw material. METHODS: The xenogeneic dural patch (T2) was prepared from bovine pericardium (T1, raw material) through decellularization and carboxymethyl chitosan (CMCS) coating. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were used to characterize the collagen fibers and surface microstructural changes in the T1 and T2 samples. The remnant α-Gal epitopes and DNA of implants were detected by standardized method. T1 and T2 were implanted subcutaneously into GTKO mice for 4 and 12 weeks, respectively, and the negative control group (Con) was only performed sham operation. The total serum antibody, anti-Gal antibody, and splenic lymphocyte subtypes were analyzed by ELISA or flow cytometry, and histological analysis of implant-tissue was performed by H&E and Masson stain. RESULTS: TEM and Sirius red staining showed that the collagen fibers in the dural patch were closely arranged, and SEM showed that a loose three-dimensional structure was successfully constructed on the surface of the dural patch after CMCS coating. The remnant DNA in T2 was 24.64 ± 8.73 ng/mg (dry weight), and clearance of α-Gal epitope was up to 99.83% compared to T1. The significant increases in serum total IgM, anti-Gal IgG, and anti-Gal IgM at 4 weeks and the significant changes in anti-Gal IgG and spleen lymphocyte at 12 weeks were observed in the T1 group, but no significant change was observed in the T2 group, compared to the control group. Histological semiquantitative analysis showed severe cell and tissue responses at 4 weeks and a moderate response at 12 weeks in the T1 group, while a moderate response at 4 weeks and a slight response at 12 weeks in the T2 group. CONCLUSIONS: The results demonstrated that the xenogeneic dural patch has a lower and acceptable immunological risk compared to the raw material and control, respectively. On the other hand, it was suggested that GTKO mice are useful experimental model for immunological risk assessment of animal tissue-derived biomaterials.

[Evaluation of the acute toxicity of pharmaceutical wastewater to luminescent bacteria].

Acute toxicity of wastewater from 5 nodes of technological process in the pharmaceutical factory sewage treatment station was studied by luminescent bacteria tests. The EC50, TUa and LID of the wastewater in underground regulating tanks was 3.44%, 29 and 625, respectively, indicating the water was extremely/highly toxic; for the wastewater in surface regulating tanks, the EC50, TUa and LID was 2.46%, 41 and 244, respectively, also extremely/highly toxic; for the wastewater in middle sediment tanks, the EC50 > 100% and LID was 10, which was moderately toxic; for the wastewater in secondary sediment tanks and the final effluents, the EC50 was above 100% and LID was 1, with no observed toxicity. The results indicated that the existing treatment process effectively reduced the acute toxicity of the pharmaceutical wastewater to luminescent bacteria, the effluents showed no observed toxicity to luminescent bacteria, which was lower than the relative effluent limits of pharmaceutical wastewater. The wastewater in lower concentration did not inhibit the luminosity, but enhanced the luminosity.