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Objective To investigate the isolation and culture of porcine bone marrow mesenchymal stem cell (BMSC) with α-1, 3-galactosyltransferase (GGTA1) gene knockout (GTKO), GTKO/ human CD46 (hCD46) insertion and cytidine monopho-N-acetylneuraminic acid hydroxylase (CMAH)/GGTA1 gene knockout (Neu5GC/Gal), and the protective effect of co-culture with porcine islets on islet cells. Methods Bone marrow was extracted from different transgenic pigs modified with GTKO, GTKO/hCD46 and Neu5GC/Gal. Porcine BMSC were isolated by the whole bone marrow adherent method and then cultured. The morphology of BMSC was observed and the surface markers of BMSC were identified by flow cytometry. Meantime, the multi-directional differentiation induced by BMSC was observed, and the labeling and tracing of BMSC were realized by green fluorescent protein (GFP) transfection. The porcine BMSC transfected with GFP were co-cultured with porcine islet cells. Morphological changes of porcine islet cells were observed, and compared with those in the porcine islet cell alone culture group. Results BMSC derived from pigs were spindle-shaped in vitro, expressing biomarkers of CD29, CD44, CD73, CD90, CD105 and CD166 rather than CD34 and CD45. These cells were able to differentiate into adipocytes, osteoblasts and chondrocytes. Porcine BMSC with GFP transfection could be labeled and traced, which could be stably expressed in the daughter cells after cell division. Porcine BMSC exerted certain protective effect on islet cells. Conclusions GFP-labeled porcine BMSC modified with GTKO, GTKO/hCD46 and Neu5GC/Gal are successfully established, which exert certain protective effect upon islet cells.
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Objective To investigate the establishment of a six-gene-edited pig-to-non-human primate kidney xenotransplantation model. Methods The kidney of humanized genetically-edited pig (GTKO/β4GalNT2KO/CMAHKO/hCD55/hCD46/hTBM) was transplanted into a cynomolgus monkey. The survival of the recipient and kidney condition after blood perfusion were observed. The parenchymal echo, blood flow changes, and size of the kidney were monitored on a regular basis. Routine blood test, kidney function test and electrolyte assessment were carried out. Dynamic changes of urine, feces and body mass were monitored. At the end of life, the transplant kidney, heart, liver, spleen, lung, and cecum were collected for pathological examination. Results The recipient died at postoperative 7 d. After blood flow was restored, the kidney was properly perfused, the organ was soft and the color was normal. At the end of the recipient's life, a slight amount of purulent secretion was attached to the ventral side of the kidney, with evident congestion and swelling, showing the appearance of "red kidney". Postoperatively, the echo of renal parenchyma was increased, blood flow was decreased, the cortex was gradually thickened, and a slight amount of effusion surrounded the kidney and abdominal cavity over time. In the recipient, the amount of peripheral red blood cells, hemoglobin, albumin, and platelets was progressively decreased, and serum creatinine level was increased to 308 μmol/L at postoperative 7 d, whereas the K+ concentration did not significantly change. Light yellow urine was discharged immediately after surgery, diet and drinking water were resumed within postoperative 3 h, and light yellow and normal-shape stool was discharged. The reddish urine was gradually restored to normal color within postoperative 1 d, which were consistent with the results of the routine urine test. A large amount of brown bloody stool was discharged twice in the morning of 2 d after surgery. Omeprazole was given for acid suppression, and the stool returned to normal at postoperative 4 d. The β2-microglobulin level was increased to 0.75 mg/L at postoperative 7 d. The body mass was increased by 1.7 kg. Autopsy pathological examination showed interstitial edema and bleeding of the transplant kidney, a large amount of infiltration of lymphocytes and macrophages, infiltration of lymphocytes in the arteriole wall and arterial cavity, accompanied by arteritis changes, lymphocyte infiltration in the cecal stroma and congestion in the spleen tissues. No significant abnormal changes were observed in other organs. Conclusions The humanized genetically-edited pig-to-non-human primate kidney xenotransplantation model is successfully established, and postoperative survival of the recipient is 1 week.
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Objective To validate whether the expression of human cluster of differentiation 55 (hCD55) protein in porcine islet cells could inhibit the activation of complement components in human serum. Methods Four adult pigs with WT (wild type), GTKO [α-1, 3-galactosyltransferase (GGTA1) knockout], GTKO/hCD55 and hCD55 genotypes were selected. Islet cells were isolated from WT, GTKO and GTKO/hCD55 pigs, and the purity and insulin secretion function were detected. The expression of hCD55 at the DNA, RNA and protein levels was analyzed by agarose gel electrophoresis, reverse transcription polymerase chain reaction (RT-PCR) and flow cytometry, respectively. Complement-dependent cytotoxicity assay and complement deposition assay were performed under the incubation conditions with fresh human serum. Results The purity of isolated porcine islet cells from three genotype pigs was > 75%, and the glycemic index was > 1. The expression of hCD55 messenger RNA(mRNA) and protein in GTKO/hCD55 porcine islet cells decreased the deposition of human complement component C3c and membrane-attacking complex C5b-9, and reduced the cytotoxicity. Conclusions The expression of hCD55 protein in porcine islet cells could inhibit the activation of human complement and reduce complement-mediated killing effect, indicating that hCD55 protein could exert complement protection effect on porcine islet cells. These findings provide theoretical basis for the application of hCD55 in islet xenotransplantation.
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Objective To investigate the effect of human CD47 (hCD47) in inducing the immune tolerance of human macrophages to porcine endothelial cells. Methods The porcine iliac endothelial cell (PIEC) transfected with pCDH-hCD47-FLAG plasmid was assigned into the pCDH-hCD47 group, PIEC transfected with pCDH-FLAG empty vector plasmid was assigned into the pCDH group, PIEC transfected with hCD47-dN was assigned into the pCDH-hCD47-dN group and human umbilical vein endothelial cell (HUVEC) was assigned into the positive control group. The cells were co-cultured with human macrophages to detect and analyze the phosphorylation of signal regulatory protein α (SIRPα) and the killing effect of human macrophages on PIEC. Furthermore, porcine arteriae endothelial cell (PAEC) was isolated from GT－/－ and GT－/－/ hCD 47 gene editing pigs to analyze the phosphorylation of SIRPα and the killing effect of human macrophages on PAEC. Results The pCDH group cells could not induce the phosphorylation of SIRPα, whereas the pCDH-hCD47 group cells could activate the phosphorylation of SIRPα after 10 min co-culture with human macrophages, and the degree of phosphorylation of SIRPα was increased with the prolongation of the co-culture time. The pCDH-hCD47-dN group cells failed to activate the phosphorylation of SIRPα. Human macrophages exerted significant effect on killing the pCDH group cells. The pCDH-hCD47 group cells could evidently inhibit the killing effect of human macrophages (P < 0.05), whereas the pCDH-hCD47-dN cells failed to suppress the killing effect of human macrophages. GT－/－-PAEC could not activate the phosphorylation of SIRPα after co-culture with human macrophages. However, GT－/－/hCD47-PAEC significantly activated the phosphorylation of SIRPα after co-culture with human macrophages. Human macrophages exerted significant killing effect on GT－/－-PAEC, and GT－/－/hCD47-PAEC could obviously inhibit the killing effect of human macrophages (P < 0.05). Conclusions The expression of hCD47 in the porcine endothelial cells can inhibit the killing effect of human macrophages on endothelial cells by activating the phosphorylation of SIRPα.
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Objective To investigate the optimal condition for the detection of anti-non-galactose (Gal) xenoantigen and antibody in human serum.Mehtods Peripheral blood mononuclear cell (PBMC) obtained from Wuzhishan miniature pig models with α-1,3-galactosyltransferase gene knockout (GTKO) were used as target cells,mixed and incubated with healthy human serum of different concentrations (4.8％,16.7％ and 100％) for 0.5,1.0,2.0,3.0 and 6.0 h,respectively.The abilities of PBMC to bind with IgM and IgG were detected by flow cytometry.Results At the serum concentration of 16.7％,the ability ofnon-Gal IgM to bind with PBMC was significantly enhanced from 0.5 h to 3.0 h incubation (P＜0.01),whereas no statistical significance was noted in terms of IgG (P＞0.05).Increasing serum concentration could also enhance the ability of non-Gal IgM to bind with PBMC.At the serum concentration of 100％ and incubation for 3 h,the ability of IgM to bind with PBMC was the highest among all groups (P＜0.01).At the serum concentration of 100％ and incubation for 6 h,the ability of IgG to bind with PBMC was significantly enhanced (P＜0.05).Prolonging incubation time and increasing serum concentration did not affect the activity of PBMC.Conclusions The optimal condition for detection of anti-non-Gal xenoantigen and antibody is determined.A quantity of 1×105 PBMC from pig should be incubated with 100％ human serum for 3 h for detection of IgM level,or incubated with 100％ human serum for 6 h for measurement of IgG level.This optimized condition contributes to screening the donor pigs which lowly express non-Gal antigen.
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To summarize the breeding and identification of Wuzhishan miniature pig models with α-l,3-galactosyltransferase (GGTA1) gene-knockout (GTKO).Methods The breeding and reproduction perform of GTKO Wuzhishan miniature pigs were assessed and the quantity of piglets was counted.The GTKO Wuzhishan miniature pig models with GGTA1gene knockout were validated by polymerase chain reaction(PCR).The αGal phenotype of peripheral blood mononuclear cells (PBMC) in human,wild-type Wuzhishan miniature pigs and GTKO Wuzhishan miniature pigs was detected by fluorescent microscope and flow cytometry.Routine blood test parameters were statistically compared between the GTKO and wild-type Wuzhishan miniature pigs.Results The inheritance of GGTA1 genotype complied with Mendel's law.Flow cytometry detected no fluorescent expression of PBMC in GGTA1-/-pig models,which were consistent with the genotype identification results.The mean piglets of the primiparous GTKO Wuzhishan miniature pigs were (6.8±1.8) and (8.3±2.2) for the multiparous Wuzhishan miniature pigs.No statistical significance was noted in routine blood test parameters between the GTKO and wild-type Wuzhishan miniature pigs (all P＞0.05).Conclusions Stable inheritance and normal reproductive capacity are observed in two generations of Wuzhishan miniature pigs continuously.GTKO Wuzhishan miniature pig is a reliable donor for heterogeneous organ transplantation.
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To investigate the changes in the expression levels of scavenger receptor class B member 1 (SCARB 1) in the liver tissues before and after liver xenotransplantation and analyze the relationship between the variations in the SCARB1 expression and coagulation regulating dysfunction in the recipients.Methods The Wuzhishan miniature pig with α-1,3-galactosyltransferase gene-knockout(GTKO) was utilized as the donor and Macaca thibetana was chosen as the recipient.Heterotopic auxiliary liver xenotransplantation models were established.The liver tissue specimen was collected before and after liver xenotransplantation.Primary hepatocytes were extracted from the pig using collagenase digestion method.Human peripheral blood mononuclear cells were obtained by immunomagnetic bead sorting.These two types of cells were co-cultured and supplemented with human plasma to establish cell models with coagulation regulating dysfunction following liver xenotransplantation.Quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) and Western blot were performed to quantitatively measure and statistically compared the expression levels of messenger ribonucleic acid (mRNA) and protein of SCARB1 in the tissue and cell samples.At the cellular level,the expression of SCARB 1 was interfered by lentiviral vector.The coagulation time was detected to validate the effect upon coagulation function.Results The expression levels of SCARB1 mRNA and protein were significantly down-regulated after liver xenotransplantation (both P＜0.05).In the cell models,the expression levels of SCARB1 mRNA and protein in the porcine hepatocytes co-cultured with human monocytes were significantly down-regulated compared with those in porcine hepatocytes without intervention (both P＜0.05).Compared with the non-intervention group,the coagulation time was significantly prolonged after the expression of SCARB1 was interfered by lentiviral vector (P＜0.05).Conclusions The down-regulated expression of SCARB1 in the liver graft is one of the main causes of mediating coagulation regulating dysfunction.Intervention of SCARB1 expression contributes to resolve the coagulation regulating dysfunction in the recipients after liver xenotransplantation.
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Objective This study was aimed to characterize the swine leukocyte antigen( SLA) class I genes of GGTA1 -/ - Wuzhishan minipigs and compare their similarity to human leukocyte antigen( HLA) . It has important implica?tions for understanding the cellular rejection in xenotransplantation. Methods Specimens of ear tissue from six founding GGTA1 -/ - Wuzhishan minipigs were collected, and the SLA class I genes (SLA?1, SLA?3, SLA?2) were amplified by RT?PCR. Purified products were cloned into pEASY?T1 vectors and sequenced, followed by BLAST alignment and using bioin? formatc analysis to characterize the SLA class I genes and compare with the similarity to HLA. Results A total of six al?leles were detected, among them alleles were previously reported (SLA?1?0703,SLA?2?1102, SLA?3?0401, SLA?3?0403), and the other were novel (SLA?1?0401wz01, SLA?2?11wz01). The homology between alleles of SLA class I genes in Wuzhishan minipigs and HLA was from 70?5% to 72?1%. The homology analysis of critical amino acid residues on HLA binding with human CD8 + molecules showed that SLA?1?0401wz01, SLA?1?0703, SLA?2?11wz01, SLA?2?1102 and SLA?3?0401 occurred mutant at amino acid positions 225 and 228 ( T→S,T→M) , whereas the other loci were highly conserved. There was a high homology at amino acid level between SLA?2?11wz01, SLA?2?1102 and HLA class I genes which are NK cell KIRs binding sites. Conclusions The amino acid sequences of SLA class I genes of GGTA1 -/ -Wuzhishan minipigs have a high homology to HLA. From the point of view of cell?mediated xenograft rejection, the amino acid sequences of SLA class I genes of GGTA1 -/ - Wuzhishan minipigs have a high homology to HLA, therefore, Wzhishan minipigs may become a good potential donor for pig?human xenotransplantation.
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Objective Getting the robust exogenous gene expression vector under the control of porcine insulin promoter, and to lay the foundation for pancreaticβ-cells specific transgene expressing pigs.Method Using porcine insu-lin promoter ( PIP, 1500 bp of the 5′UTR from the porcine INS gene including the first exon and the first intron) to con-struct expression vector, the HindIII restriction site which connected the sequences of PIP and EGFP was designed before ATG, named PIP-HindIII-EGFP.Considering that the different location of restriction site may affect the expression efficien-cy of the transgene, we optimized the expression vector.Firstly the HindIII restriction site was deleted to realize the seam-less connection of PIP and EGFP,the vector was named PIP-EGFP.Also we mutated the 3′intron splicing acceptor site( SA) of the first intron into HindIII restriction site, named as PIP-SA( M)-EGFP.Three different EGFP expression vectors were respectively transfected MIN-6 mouse pancreatic β-cells, pig ear fibroblasts and kidney cells.The transfected cells were cultured for 48 h and harvested for RT-PCR, flow cytometry and Western blot analysis, to analyze and compare the expres-sion efficiency of vectors.Results After transfection,green fluorescence was observed only in MIN-6 mouse pancreaticβ-cells.RT-PCR analysis and product sequencing showed that the three expression vectors did have different stability with in-tron splicing.The PIP-HindIII-EGFP construct and PIP-EGFP vector produced two kinds of mRNA with the first intron spliced and no spliced, indicating the instability of intron splicing.Mutation of the PIP splice site would cause the first in-tron not spliced, while flow cytometry and Western blot displayed that the mutation induced a most efficient expression of the downstream gene.Conclusions A robust and specific β-cells expression vector has been successfully generated by mutating the intron splicing acceptor site of the porcine insulin promoter.It provides the foundation for preparation of pigs with pancreaticβ-cells specifically expressing the transgene.