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<b>Objective</b> To investigate the differences and the immunocompatibility of wild-type (WT), four-gene modified (TKO/hCD55) and six-gene modified (TKO/hCD55/hCD46/hTBM) pig erythrocytes with human serum. <b>Methods</b> The blood samples were collected from 20 volunteers with different blood groups. WT, TKO/hCD55, TKO/hCD55/hCD46/hTBM pig erythrocytes, ABO-compatible (ABO-C) and ABO-incompatible (ABO-I) human erythrocytes were exposed to human serum of different blood groups, respectively. The blood agglutination and antigen-antibody binding levels (IgG, IgM) and complement-dependent cytotoxicity were detected. The immunocompatibility of two types of genetically modified pig erythrocytes with human serum was evaluated. <b>Results</b> No significant blood agglutination was observed in the ABO-C group. The blood agglutination levels in the WT and ABO-I groups were higher than those in the TKO/hCD55 and TKO/hCD55/hCD46/hTBM groups (all <i>P</i><0.001). The level of erythrocyte lysis in the WT group was higher than those in the ABO-C, TKO/hCD55 and TKO/hCD55/hCD46/hTBM groups. The level of erythrocyte lysis in the ABO-I group was higher than those in the TKO/hCD55 and TKO/hCD55/hCD46/hTBM groups (both <i>P</i><0.01). The pig erythrocyte binding level with IgM and IgG in the TKO/hCD55 group was lower than those in the WT and ABO-I groups. The pig erythrocyte binding level with IgG and IgM in the TKO/hCD55/hCD46/hTBM group was lower than that in the WT group and pig erythrocyte binding level with IgG was lower than that in the ABO-I group (all <i>P</i><0.05). <b>Conclusions</b> The immunocompatibility of genetically modified pig erythrocytes is better than that of wild-type pigs and close to that of ABO-C pigs. Humanized pig erythrocytes may be considered as a blood source when blood sources are extremely scarce.
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Organ transplantation is the optimal treatment for end-stage organ failure. Nevertheless, organ shortage is a global problem, which limits further development of organ transplantation. Recent research shows that genetically modified pig may become a realistic alternative source of clinical organ transplantation donor. Xenotransplantation may serve as one of the effective measures to resolve the problem of organ shortage. Since 2021, 2 cases of living xenotransplantation and 6 cases of xenotransplantation in brain death recipients have been performed worldwide, and phase Ⅰ clinical trial of xenotransplantation has been launched, and the results have exceeded expectations. Therefore, in this article, recent clinical trial results of xenotransplantation in living and brain death recipients were retrospectively analyzed, and scientific, technical and ethical issues related to clinical research of xenotransplantation were illustrated, hoping to provide reference for clinical research of xenotransplantation in China and promote the development of xenotransplantation in clinical practice.
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Objective To summarize the experience and practical value of living donor kidney harvesting in Bama miniature pigs with six gene modified. Methods The left kidney of Bama miniature pigs with six gene modified was obtained by living donor kidney harvesting technique. First, the ureter was occluded, and then the inferior vena cava and abdominal aorta were freed. During the harvesting process, the ureter, renal vein and renal artery were exposed and freed in sequence. The vascular forceps were used at the abdominal aorta and inferior vena cava, and the renal artery and vein were immediately perfused with 4℃ renal preservation solution, and stored in ice normal saline for subsequent transplantation. Simultaneously, the donor abdominal aorta and inferior vena cava gap were sutured. The operation time, blood loss, warm and cold ischemia time, postoperative complications and the survival of donors and recipients were recorded. Results The left kidney of the genetically modified pig was successfully harvested. Intraoperative bleeding was 5 mL, warm ischemia time was 45 s, and cold ischemia time was 2.5 h. Neither donor nor recipient pig received blood transfusion, and urinary function of the kidney transplanted into the recipient was recovered. The donor survived for more than 8 months after the left kidney was resected. Conclusions Living donor kidney harvesting is safe and reliable in genetically modified pigs. Branch blood vessels could be processed during kidney harvesting, which shortens the process of kidney repair and the time of cold ischemia. Living donor kidney harvesting contributes to subsequent survival of donors and other scientific researches.
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Organ shortage has become one of the major challenges hindering the development of organ transplantation. Xenotransplantation is one of the most valuable methods to resolve global organ shortage. In recent years, the development of genetic engineering technique and research and development of new immunosuppressant have provided novel theoretical basis for xenotransplantation. International scholars have successively carried out researches on xenotransplantation in genetically modified pigs to non-human primates or brain death recipients, making certain substantial progresses. However, most of the researches are still in the preclinical stage, far from clinical application. Therefore, according to the latest preclinical experimental research progress at home and abroad, the history of xenotransplantation, the development of gene modification technology, xenotransplantation rejection and immunosuppression regimens were reviewed, aiming to provide reference for subsequent research of xenotransplantation, promote clinical application of xenotransplantation and bring benefits to more patients with end-stage diseases.
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CD47 is a transmembrane protein widely expressed on cell surface, which is considered as a key molecule for immune escape. With an increasing number of related studies, the role of CD47 and its ligands in immunomodulatory effects has been gradually understood. Recent studies have investigated the role of CD47 in ischemia-reperfusion injury of allogenetic kidney transplantation, rejection and xenotransplantation. Nevertheless, the specific role and the key mechanism remain elusive. In this article, the structure and function of CD47, common CD47 ligands, the relationship between CD47 and kidney transplantation, and the application of CD47 in kidney transplantation were reviewed, the latest research progress of CD47 in kidney transplantation was summarized, and the limitations of current research and subsequent research direction were analyzed, aiming to provide reference for subsequent application of CD47 in allogeneic and kidney xenotransplantation.
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Human-animal chimera technology is increasingly applied to large animals. It is highly possible to cultivate human organs in pigs for transplantation in the future. Chimeric animals contain more and more human materials and are present in their brains and reproductive systems, which may humanize them and give them a higher moral status and even dignity. It raises an important ethical question: should such chimeric animals be created? If so, how they should be treated. It is not convincing to refute the research of human-animal chimera with the arguments of destroying natural order, unnatural and moral chaos. But the non-identity view holds that scientific research makes the lives of chimeric animals more valuable and that they are not actually harmed because their only other options do not exist. The answers to these ethical questions can resolve the ethical risks arising from the research of human-animal chimera.
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Xenotransplantation is an efficient pathway to solve the problem of transplant organ source deficiency in clinical settings. With the increasing progress of gene editing technique and immune suppression regimen, important development has been achieved on researches regarding pig to non-human primate kidney xenotransplantation, which provides a good condition for the introduction of the technique in the clinical application. In view of the substantial difference between human and non-human primate, and to meet the needs of current ethic requirements, it is necessary to perform subclinical studies for pig to human kidney xenotransplantation. In recent years, such subclinical studies with regard to the genetically modified pig to brain death recipient kidney xenotransplantation had been performed, indicating that kidney xenotransplantation gradually began to transit to the clinical development stage. However, donor/recipient selection and immune suppression regimen has not reached a consensus yet, and has to be clarified in subclinical studies. In this article, the current status and confronted problems of donor/recipient selection, immune suppression regimen and post transplantation management in the subclinical studies of kidney xenotransplantation were reviewed, aiming to promote the clinical transformation of kidney xenotransplantation to the clinical application.
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Objective To explore the public attitude towards kidney xenotransplantation in China by constructing and validating the prediction model based on xenotransplantation questionnaire. Methods A convenient sampling survey was conducted among the public in China with the platform of Wenjuanxing to analyze public acceptance of kidney xenotransplantation and influencing factors. Using random distribution method, all included questionnaires (n=2 280) were divided into the training and validation sets according to a ratio of 7:3. A prediction model was constructed and validated. Results A total of 2 280 questionnaires were included. The public acceptance rate of xenotransplantation was 71.3%. Multivariate analysis showed that gender, marital status, resident area, medical insurance coverage, religious belief, vegetarianism, awareness of kidney xenotransplantation and whether on the waiting list for kidney transplantation were the independent influencing factors for public acceptance of kidney xenotransplantation (all P<0.05). The area under the curve (AUC) of receiver operating characteristic (ROC) of the prediction model in the training set was 0.773, and 0.785 in the validation set. The calibration curves in the training and validation sets indicated that the prediction models yielded good prediction value. Decision curve analysis (DCA) suggested that the prediction efficiency of the model was high. Conclusions In China, public acceptance of kidney xenotransplantation is relatively high, whereas it remains to be significantly enhanced. The prediction model based on questionnaire survey has favorable prediction efficiency, which provides reference for subsequent research.
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The zebrafish xenograft model plays an important role in cancer modelling,especially breast cancer xenografts.This model facilitates the real-time observation of tumor cell growth,metastasis,and interactions with the immune system,thus providing novel insights and experimental foundations for breast cancer treatment.Furthermore,the zebrafish xenograft model offers a valuable tool for high-throughput drug screening.This review provides an overview of the contributions of the zebrafish xenograft model to elucidating the mechanisms underlying breast cancer development,and its use in screening anti-tumor drugs and conducting therapeutic research.
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Objective:To explore the feasibility of a stable pig-to-monkey orthotopic liver transplantation (LT) model and provide a favorable experimental tool for preclinical studies of xenotransplantation.Methods:In this retrospective analysis, the authors reviewed the perioperative conditions and outcomes of 7 pig-to-monkey orthotopic liver transplants performed by a xenotransplantation research team of Second Xiangya Hospital.Gene-edited Banna miniature pigs were selected as donors and rhesus monkeys with similar anatomical characteristics, physiology, biochemistry and immune mechanism to humans were selected as recipients for pig-monkey xenogeneic orthotopic LT.Based upon classic transplantation procedures, whole liver xenogeneic orthotopic transplantation was performed.Surgical processes were modified for minimizing intraoperative hemorrhage and shortening anhepatic period.A bile duct drainage tube was implanted for observing bile secretion.ATG + anti-CD20 + snake venom factor and FK-506 were utilized for immunoinduction pre-operation while tacrolimus, mycophenolate mofetil (MMF) and methyl prednisolone for postoperative immunomaintenance therapy.Antibiotics and antiviral agents were also applied and thrombin complex for improving coagulation functions.Results:All procedures were successfully completed.After the stability and maturity of our model, in case No.7, donor's acquisition operative duration was 42 min without heat ischemic time, donor's trimming time 87 min, donor cold retention time 128 min, recipient's operative duration 123 min and anhepatic phase 27 min.Subhepatic inferior vena cava was occluded for 38 min.Blood loss was around 10 ml.And 4/7 models survived post-operation and the longest survival time was 27 h. Among 3 non-survival cases, the causes were anesthesia accident (n=1) and immaturity of early operation (n=2). Model No.7 had a biliary secretion volume of 86 ml post-operation.Conclusions:Qualified donor acquisition, high-quality vascular anastomosis, intraoperative reduction of blood loss, shortening of anhepatic period, strict fluid replenishing and careful monitoring are essential for boosting the success rate of pig-monkey liver xenotransplantation model.Optimization of donor gene combination and advanced immunosuppression protocol help to further achieve the long-term survival of pig-monkey liver xenotransplantation model.
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ObjectiveXenotransplantation is an effective way to address the shortage of human organ donors, but it faces serious immune rejection reactions, including hyperacute rejection caused by blood type differences. Establishing a stable, convenient, and reliable method for pig blood type identification can quickly screen suitable donor pigs for xenograft research.MethodsBanna miniature inbred pigs, Diannan small eared pigs, and Bama Xiang pigs were selected as the research objects. DNA was extracted from the blood, oral buccal mucosa, and fetal fibroblasts of the three strains of pigs using DNA extraction kits. The target fragment of the ABO homologous gene EAA intron 7 in pigs was amplified using PCR method. Blood agglutination reaction was used to detect hemolysis in pig anterior vena cava whole blood after adding anti A and B antibodies. Immunohistochemical method was used to detect the expression level of A antigen in pig heart, liver, spleen, lung, and kidney tissues. Immunofluorescence method was used to detect the expression level of A antigen in pig oral mucosa. By comparing the results of different methods for determining pig blood types, the stability and reliability of the PCR method were verified, and a convenient PCR based pigblood type identification method was established.Results Firstly, the blood PCR results of 69 inbred strains of Banna miniature pigs, 7 Diannan small eared pigs, and 34 Bama Xiang pigs showed 20 AO blood types, 66 AA blood types, and 24 O blood types. The PCR results of fetal fibroblasts from 47 Diannan small eared pigs showed that all 47 fetuses were O blood type. Among them, the oral mucosal PCR results of 8 gene edited cloned pigs were consistent with those of donor fetal fibroblasts, all of which were O blood type. The oral mucosal PCR results of 8 wild-type pigs (2 inbred lines of Banna miniature pigs, 4 Diannan small eared pigs, and 2 Bama Xiang pigs) were consistent with the blood PCR identification results. Then, 11 inbred lines of Banna miniature pigs, 4 Diannan small eared pigs, and 2 Bama Xiang pigs were randomly selected for blood agglutination reaction validation, and the results were consistent with the PCR identification results of both blood samples and oral mucosa samples. Moreover, immuno-histochemical analysis was performed on the heart, liver, lung, kidney, and spleen tissues of one Banna miniature pig inbred line and two Bama Xiang pigs, and the results were consistent with blood PCR identification and blood agglutination reaction results. Finally, oral mucosal samples were collected from 2 inbred strains of Banna miniature pigs and 1 Bama Xiang pig for immunofluorescence detection, and the results were consistent with the blood PCR identification results.ConclusionBy collecting fetal cells and oral mucosal samples from live pigs for PCR detection, the blood type of pigs can be accurately and efficiently identified, providing a convenient method for blood type screening of xenograft donor pigs.
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After continuous efforts from generations of transplant surgeons, kidney transplantation (KT) has become an optimal treatment for end-stage renal disease.However, an imbalance between supply and demand of organs has always restricted the development of KT.For this clinical dilemma, xenotransplantation is expected to become one practical alternative for alleviating organ shortage.This review summarized recent literature reports of kidney xenotransplantation and the latest cases of pig-to-human kidney and heart transplantations.Also clinical transformations and applications of kidney xenotransplantation were discussed.
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Islet transplantation has developed rapidly over the last 20 years and is becoming one of the ideal clinical treatment options for type 1 diabetes mellitus (T1DM). There is growing clinical evidence that islet transplantation has significant efficacy in insulin independence or reduction, preventing hypoglycemic episodes and preventing diabetic complications.However, clinical islet transplantation still faces challenges, such as a shortage of donor resources, difficulties in early implantation and survival of islet grafts, and immune rejection.In the future, donor pancreatic donation and its effective utilization should be promoted, and clinical exploration of xenogeneic islet transplantation and stem cell-derived islet transplantation should be encouraged to effectively solve the problem of insufficient islet source.At the same time, through continuous research and development of new materials and technologies, optimize the location of islet transplantation to improve the implantation and survival of islet grafts, and gradually eliminate the need for immunosuppression.In addition, we should actively promote the development and application of post-islet transplantation graft monitoring tools to further ensure the long-term survival of post-islet transplantation grafts, so that more diabetic patients can benefit from it.
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Organ shortage is a critical factor limiting the development of organ transplantation. Xenotransplantation is expected to resolve the problem of organ shortage, which has become a new research hotspot. Study of costimulatory signaling pathway related to T cell regulation is a hot topic in terms of immunity of xenotransplantation. Since the discovery of costimulatory molecule CD28, multiple costimulatory molecules have been identified, including costimulatory and coinhibitory receptors and their related ligands. Specific T cell activation of donors is the key factor leading to acute immune rejection. The expression and induction of costimulatory molecules on T cells differ during different immune stages, and these costimulatory molecules play a key role in maintaining T cell tolerance and the balance of T cell immune response. At present, increasing attention has been diverted to the role of costimulatory signaling pathway in organ transplantation. In this article, the latest research progress in costimulatory signaling pathway related to xenotransplantation immunity was reviewed, aiming to provide reference for the optimization of xenotransplantation immunosuppression regimen.
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Organ transplantation is the most effective treatment for all categories of end-stage organ diseases. To resolve the shortage of donors in organ transplantation, widespread attention has been diverted to xenotransplantation. At present, clinicians mainly highlight the problems related to xenotransplantation rejection and viral infection. The physiology of xenotransplantation has been rarely studied. Kidney performs endocrine function by producing erythropoietin (EPO), renin and activating vitamin D. Although these pathways are usually well preserved in allogeneic transplantation, species-specific differences, especially those between pigs and non-human primates, may still affect the physiological function of transplant organs. In this article, the changes of EPO, renin-angiotensin-aldosterone system (RAAS) and active vitamin D3 of pig and human after xenotransplantation were illustrated, aiming to provide reference for subclinical research of xenotransplantation.
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Objective To evaluate the role and potential mechanism of interleukin (IL)-18/IL-18 binding protein (BP) in mediating the killing effect of natural killer (NK)-92MI cells upon endothelial cells from α-1, 3- galactosyltransferase gene-knockout (GTKO) porcine models. Methods NK-92MI cells were divided into the NK, NK+IL-18, NK+GTKO, IL-18+NK+GTKO and IL-18+IL-18BP+NK+GTKO groups. The messenger ribonucleic acid (mRNA) levels of inflammation-related genes in NK-92MI cells were detected by quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR). The killing effect of NK-92MI cells on endothelial cells from GTKO porcine models was evaluated by lactate dehydrogenase (LDH) assay. The apoptosis of endothelial cells from GTKO porcine models was assessed by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) assay. The expression levels of proteins with killing effect and apoptosis-related proteins were determined by Western blot. Results Compared with the NK, NK+IL-18 and NK+GTKO groups, the expression levels of interferon (IFN)-γ, tumor necrosis factor (TNF)-α, IL-8, IL-3, IL-6 and granulocyte-macrophage colony stimulating factor (GM-CSF) mRNA were up-regulated in NK-92MI cells in the IL-18+NK+GTKO group, and the differences were statistically significant (all P < 0.05). Compared with the IL-18+NK+GTKO group, the expression levels of IFN-γ, TNF-α, IL-8, IL-3, IL-6 and GM-CSF mRNA were down-regulated in NK-92MI cells in the IL-18+IL-18BP+NK+GTKO group, and the differences were statistically significant (all P < 0.05). Compared with the NK+GTKO group, the expression levels of perforin, granzyme B and IFN-γ proteins in NK-92MI cells were up-regulated, the killing rate of NK-92MI cells against endothelial cells from GTKO porcine models was enhanced, the apoptosis rate of endothelial cells from GTKO porcine models was increased, and the ratios of B cell lymphoma-2 (Bcl-2)-associated X protein (Bax)/Bcl-2 and cleaved Caspase-3/Caspase-3 in endothelial cells from GTKO porcine models were elevated in the IL-18+NK+GTKO group, and the differences were statistically significant (all P < 0.05). Compared with the IL-18+NK+GTKO group, the expression levels of perforin, granzyme B and IFN-γ proteins were down-regulated, the killing rate of NK-92MI cells against endothelial cells from GTKO porcine models was decreased, the apoptosis rate of endothelial cells from GTKO porcine models was decreased, and the ratios of Bax/Bcl-2 and cleaved Caspase-3/Caspase-3 in endothelial cells from GTKO porcine models were declined in the IL-18+IL-18BP+NK+GTKO group, and the differences were statistically significant (all P < 0.05). Conclusions IL-18BP may block the expression of inflammation-related genes in NK-92MI cells induced by IL-18 and the killing effect of NK-92MI cells on endothelial cells from GTKO porcine models.
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Heart transplantation is one of the most effective strategies to treat end-stage heart failure. Multiple challenges, such as difficulty in preservation of heart allograft, rejection and postoperative complications, emerge in heart allotransplantation. After decades of research and practice, most problems have been resolved. Nevertheless, the shortage of donor organs has become increasingly prominent. To alleviate the shortage of donor organs, artificial heart and heart xenotransplantation have captivated attention, and obtained significant progress in recent years. The application of artificial heart in clinical practice has significantly enhanced the survival rate of patients with end-stage heart failure, which is expected to become the standard treatment for end-stage heart failure. Heart xenotransplantation still faces many challenges, which is still far from clinical application. In this article, the history of heart transplantation, development of heart allotransplantation, use of artificial heart and research progress on heart xenotransplantation were reviewed, and the future development direction of heart transplantation was predicted.
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Xenotransplantation holds the promise of being used to address the imbalance between organ supply and demand for clinical transplantation. Pigs have natural features that make them more suitable donors for transplant organs than non-human primates. A series of biological barriers that arise after pig organ transplantation have been overcome by genetic engineering and pharmacological suppression. Mean- while, the gradual maturity of the genetic engineering technology has been significantly optimized for suit- able pigs for xenotransplantation, and promoted the development of pig organ transplantation research. Although it will take time for pig organ xenotransplantation to enter the clinical trial stage, recent studies conducted in a few brain-dead or critically ill patients have exhibited the great potential of porcine xeno- transplantation in solving the imbalance between supply and demand of organs for clinical transplantation.
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Objective To investigate the attitudes and influencing factors of transplantation-related populations towards kidney xenotransplantation. Methods From June 2022 to January 2023, stratified random sampling was performed from patients awaiting kidney transplantation, patients after kidney transplantation, patients' relatives and medical students. Four hundred subjects were collected from each population and 1600 subjects were investigated using a self-designed questionnaire. Baseline data of the respondents, their attitudes towards kidney xenotransplantation and the reasons of rejecting kidney xenotransplantation were analyzed. The influencing factors of attitudes towards kidney xenotransplantation were also identified. Results A total of 1 493 valid questionnaires were collected, and the questionnaire retrieval rate was 93.31%. About 93.10% of the respondents accepted allogeneic kidney transplantation, and 66.78% had heard of kidney xenotransplantation. Seven hundred and ninety-five respondents suggested that they could accept kidney xenotransplantation "when kidney xenotransplantation and allogeneic kidney transplantation yielded the same results and risks". Six hundred and ninety-eight respondents indicated that they were "unable" or "uncertain" whether they could accept kidney xenotransplantation (χ2=16.409，P=0.001). Among these 698 respondents, the proportion of them who were willing to accept kidney xenotransplantation when they did not meet the conditions of allogeneic kidney transplantation was 10.9%. About 35.8% of respondents were willing to accept kidney xenotransplantation if it yielded less risk and better prognosis compared with allogeneic kidney transplantation. If the time of awaiting kidney xenotransplantation was shorter than that of allogeneic kidney transplantation, 21.2% were willing to accept kidney xenotransplantation. If the cost of kidney xenotransplantation was less than that of allogeneic kidney transplantation, 24.5% of them were willing to accept kidney xenotransplantation. The main reasons of rejecting kidney xenotransplantation included surgical risk and other unknown risks. Multivariate analysis showed that respondents residing in cities and towns for a long period of time, those who accept allogeneic kidney transplantation and those who have heard of kidney xenotransplantation showed more positive attitudes towards kidney xenotransplantation. Conclusions Different transplantation-related populations have different attitudes towards kidney xenotransplantation, and the overall attitudes are positive. Active promotion of kidney xenotransplantation research and carrying out relevant popular science education contribute to improving public attitudes towards the acceptance of kidney xenotransplantation.
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Organ transplantation is the most effective treatment for various types of end-stage diseases. To resolve the problem of donor shortage in organ transplantation, the possibility of xenotransplantation has been gradually explored by surgeons. Pig is one of the common donor sources for xenotransplantation. As a bridge between two species, the viruses carried by pig organs may be transmitted between species and cause the risk of zoonosis. Porcine endogenous retrovirus (PERV) is integrated into the genome, which is a category of retrovirus featuring cross-species transmission. In this article, the influencing factors of transmission characteristics of PERV, the transmission risk of PERV and its recombinant virus, and the detection and transmission risk assessment of PERV in xenotransplantation test were reviewed, aiming to provide reference for alleviating severe shortage of donor organs and driving the advancement of xenotransplantation technologies.