The worldwide shortage in the supply of donor organs and tissues is becoming more pronounced. Xenotransplantation may probably give the hope to overcome the problem ultimately. However, it gives rise to a number of social and ethical issues, among them, the pig appears to be a likely source for human transplantation because it entails least social and ethical issues than no-human primates or other animals and the pig is similar to human in many aspects. The ethical and economic aspects must also be taken into consideration. Patient and his family’s privacy may be stripped because the patient has received a new or unusual treatment. Xenograftings will squint towards a kind of commodities which are different from human graftings and it is a challenge to human transplantation. Xenotransplantation brings a risk of creating new human disease and pandemic, so, it is necessary to formulate a policy and provide input to draft guidelines on the regulation of xenotransplantation.
OBJECTIVE: To explore the kidney anatomic structure of banna minipig inbred-lines, and to provide data for kidney xenotransplantation. METHODS: The fresh and infused kidneys of banna minipig (including the vessel and the ureter) were checked by anatomic microscope and vernier caliper in original location and away body. The tissue structure was observed by HE stain. RESULTS: The structure of kidney of banna minipig inbred-lines (including the vessel and the ureter) are similar to that of human being. The fascia propria of kidney is divided into three layers including capsula fibrosa, capsula adipose and fascia renalis. The thickness of cortex renalis is (20.0 +/- 2.4) mm. The average diameter of renal artery is 5.1 mm and is similar to that of human being. All the kidneys of banna minipig inbred-lines have a single branch renal artery. The diameters of left and right ureters are 5.1 mm and 4.7 mm, respectively. CONCLUSION: The kidney of banna minipig inbred-lines is an ideal replacement of human kidney for xenotransplantation.
【Abstract】ObjectiveTo investigate the effect of xenotransplantation of microencapsulated rabbit parathyroid tissue in different sites in rats for the treatment of hypoparathyroidism. MethodsThe parathyroid glands from Wistar rats were removed to make them aparathyroid. Ultimately, sixteen rats were included because their serum calcium values were continuously below 1.6 mmol/L. We also encapsulated the cultured rabbit parathyroid tissue with alginateBaCl2 microcapsule. According to the transplantation sites, rats were randomly divided into two groups: renal adipose microcapsule group and peritoneal microcapsule group, eight in each group. Encapsulated rabbit parathyroid tissues were then transplanted accordingly to different microcapsule groups. The calcium serum contents were examined on 5，15，25，35，45，55 and 65 d respectively after transplantation and the grafts were observed through electron microscope on the 65 d in particular. ResultsThe calcium contents after transplantation in renal adipose microcapsule group restored to normal and the observation outcomes of grafts showed that they survived well. The calcium contents of posttransplantation in peritoneal group also restored to normal with an exception that it dropped to a level lower than 1.6 mmol/L on the 65 d. Electron microscope also showed that there were necrotic tissues in the center and only a few cells survived on the edge of the grafts. Within peritoneal microcapsule group, the values were significantly lower than others taken at different phases. ConclusionMicroencapsulated rabbit parathyroid tissue that was xenotransplanted into rats can survive and function without administration of immunodepressant. There are significant differences of calcium contents at varying phases between two transplantation sites, which demonstrate that renal adipose may be an optimal site for microcapsule xenotransplantation.
Insufficient supply of organ for allotransplantation made the study on finding new organ resources from animal progress. Pig is regarded as one of the optimal donor animals for human. The major obstacle in this field is hyperacute reaction (HAR), which is triggered after the xenogenic natural antibodies preexisting in recipient blood combine to the antigens on the surface of the endothelium and activate the complement system. alpha-Galactose residues (alpha-Gal) on the endothelial cell have been identified as the major xenoantigens. NJZ Pig has been closely breed since 1938, whose family history is clear. Tissue samples from heart, liver, kidney, pancreas, lung, small intestine, skin, spleen, thymus and lymph node were obtained and embedded in paraffin. The sections were performed the immunohistochemical staining with the sera from health volunteers (including all the blood types) as the primary antibodies as well as the biotin labeled bandeirae simplicifolia I isolectin B4 (BS I-B4), which has specific affinity to alpha-galactose. All the staining sections were compared with the tissues digested with alpha-galactosidase. There was no difference between the antigens recognized by sera of different blood types. alpha-Gal was still the major xenoantigen on the endothelial cells. There might exist non-alpha-Gal antigens on the distal convoluted tubules and collecting tubules of the kidney. There was no alpha-Gal distributing on the secreting part of pancreas, either the islet cells or the matrix cells, but surely on pancreatic duct and vessels. All the antigenity was destroyed after the enzyme digestion except that the small intestine gland still positive with the BS I-B4. alpha-Gal is the major xenogenic antigen in NJZ Pigs. There exist some unknown antigens on the distal convoluted tubules and collecting ducts of the kidney. The blood type of recipient is not the first affair to be considered in pig-to-human xenotransplantation. The specificity of BS I-B4 for the alpha-galactose needs more detail research.
OBJECTIVE The major obstacle in pig to human transplantation is acute and hyperacute rejection (HAR) triggered mainly by alpha-galactosyl residues(alpha-Gal) in donor. Since the inbred-line Banna pig(IBNP) and Wuzhishan pig (IWZSP) are highly inbred and may be the potential donor for xenotransplantation, it is important to investigate the reaction between human serum and inbred-line pig tissues as well as the distribution of alpha-Gal in these tissues. METHODS Samples from heart, liver, spleen, lung, kidney, pancreas, small intestine, thymus, skin, lymph node and blood vessels at all levels were collected from four 8 to 11-month-old male IBNPs and one IWZSP. Affinity-immunohistochemistry assays were conducted following routine procedures on paraffin sections with normal human sera of blood type A, B, O, AB and BSI-B4(alpha-Gal specific binding lectin) as the primary antibodies or affinity reagents. Sections digested by alpha-galactosidase were also examined as control. RESULTS Parallel results were obtained from these pig tissues stained against human sera and BSI-B4. There was no significant difference both in the antigens recognized by sera of different blood types or BSI-B4 and in the distribution of alpha-Gal. The best alpha-Gal positive staining was appeared in vascular endothelial cells at all levels and partial parenchyma cells. However, tissues of cartilage, peripheral nerve and muscle were negative. After digested by alpha-Galactosidase, all samples were negative against BSI-B4 and human sera except few positions that showed different staining. CONCLUSION The distribution of target antigen is similar in various tissues of the two kinds of pigs. Though alpha-Gal is the major xenoantigen in IBNP and IWZSP, there may be some unknown antigens related to pig to human transplantation. Possibly the level and distribution of antigen expression in pig tissues are not the first affair to be considered, and these pigs should be genetically modified in order to eliminate rejection in pig to human xenotransplantation.
After escaping from the hyperacute rejection (HAR), the xenograft has to be faced the challenge of acute vascular, acute cellular and even chronic rejection. Endothelial cells have been confirmed as a kind of antigen processing cell (APC) in allo-rejection. The porcine aortic endothelial cell (PAEC) expressed SLA-II and B7 which are the characteristics of professional APC. PAEC also has plenty of alpha-Gal residues, whether the antigen play any role in the post-HAR is still unknown. Human and porcine peripheral blood lymphocyte (PBLC) were isolated and divided into two parts, one for the effectors and the another were incubated with mitomycin C (MMC) as stimulators. The two kinds of PBLC were mixed-cultured within five days. Cultured PAEC from NJZ Pig was incubated with MMC and divided into two: One digested with alpha-galactosidase. The two kinds of PAEC were taken as stimulators to mixed-culture with human PBLC for five days. All the proliferation was detected with 3H-TdR intermingled in the system. The results showed that allo-MLR was ber than xeno-MLR in the cases. The proliferation was much ber when PAEC was used as the stimulator than that of porcine PBLC. However, the response was remarkably decreased after the digestion of alpha-Gal with alpha-galactosidase. The conclusion was that the low response of porcine-to-human MLR in vitro might be related to the predominant indirect pathway of antigen recognition in this system. While PAEC was used as the stimulator the proliferation in MLR was ber which might be concerned that PAEC itself was an APC as well as xeno-antigen sources, thus the direct pathway was predominant and worked more efficiently. The alpha-Gal might induce T cell proliferation through the linkage with the biological big molecules working as a complete antigen. The other post-HAR antigen might also exist in PAEC such as SLA-II, etc.
ObjectiveTo investigate the aim antigen coursing the hyperacute rejection of xenotransplantation. MethodsDocuments about hyperacute rejection in xenotransplantation were reviewed and summarized in detail. ResultsPig is thought to be one of the ideal donors of xenotransplantation, but the major obstacle is hyperacute rejection mediated by complement that is activated though human serum. αGal is recognized as the major antigen and its expression is controlled by α1,3 galactosyltransferase. Immunoabsorption of preexsisted antibody, enzymatic digestion of αGal, knockout αGT gene and transgenic technology have been used to solve this problem. Even so, there remain other antigens which can combine with natural antibodies in human serum, such as, 40×103 molecule in erythrocyte, 210×103, 105×103 and 50×103 antigen in pig embryo brain cell, etc. Conclusion αGal is the major antigen which course the hyperacute rejection. Besides αGal, many nonalphagal need further investigation.
OBJECTIVE To evaluate the general situation of the native pig breeds and the relative present study conditions for better development of xenotransplantation in China. METHODS By comparing the profits between the pigs and the non-human primates as the potential donors for xenotransplantation and emphasizing the source of the pigs as the organ donors from the transplantation studies, we analyzed the possible values of the native pig breeds as the donors. RESULTS As one of the richest resources in the world, the species variation and relative genetic stability of Chinese native pig breeds could be the very valuable resources for xenotransplantation study and utilization. As a reverse, the xenotransplantation could provide opportunity for more economically and environmentally utilization of the pigs besides as the meat supply. CONCLUSION As a very valuable and potential resource of organ donor, the native pig breeds of China might be noticed by the xenotransplantation colleagues in the world. It is necessary, to keep the balance among the risk vs. benefit and the protection vs. utilization of this valuable resource.
Objective To investigate the immunological rejection after hepatocyte transplantation for acute liver failure （ALF） in mice．Methods The hepatocytes were isolated from pig，BALB/c and C57BL/6 mice livers were conducted and then transplanted into C57BL/6 mice．CCl4 was used to make ALF mice model．The experimental animals were randomly divided into three groups， including syngenic group，allogeneic group，and xenogenic group．The survival statuses of all the mice were recorded. The alteration of T lymphocyte subsets，immune globulin，and cytokine were determined．Results ①The survival ratio was 8/10，6/10， and 3/10 in the syngenic group， allogeneic group， and xenogenic group， respectively．The survival ratio in the syngenic group was significantly higher than that in the other two groups （P＜0.05）．②The CD4+ and CD8+ T cells of the peripheral blood in the syngenic group did not change significantly on week one after transplantation．The CD4+ T cells in the allogeneic group reached the peak on day 3 after hepatocyte transplantation （P＜0.05）， while CD8+ T cells did not change much in one week．The CD4+ and CD8+ T cells in the xenogenic group increased and reached the peak on day 3 after transplantation （P＜0.05）．③There were no significantly differences of IgM and IgG in the syngenic group among 0.5， 1， and 3 d after transplantation. IgM of the allogeneic group and xenogenic group reached the peak on day 1 （P＜0.05） and IgG reached the peak on day 3 （P＜0.05） after transplantation．④The concentrations of IFN-γ， TNF-ɑ， and IL-2 in the allogeneic group and xenogenic group were significantly higher than those in the syngenic group （P＜0.05）．The concentration of IL-6 of the xenogenic group was higher than that of the other two groups （P＜0.05）. Conclusions CD4+ and CD8+ T cells play an important role in immune response to both allogeneic and xenogenic hepatocyte transplantation， as well as induce humoral immune response early after hepatocyte transplantation．
Objective To summarize the current advance of xenotransplantation. Methods Relevant literatures about current advance of xenotransplantation published recently domestic and abroad were collected and reviewed. Results Major progress of xenotransplantation had been made in the understanding of xenoimmunobiology in the last two decades and in the threshold of clinical application. However, many problems of immunological rejection were still needed to be explored and resolved. Conclusion Xenotransplantation as a transplantation source has an extensive potential to resolve the shortage of transplanted organs for end-stage organ failure, how to suppress rejection and prolong survival of grafts more effectively is a focal point of search in the future.