OBJECTIVE: In the guinea pig-to-rat cardiac xenotransplantation model, the effect of complement depletion by using Chinese Cobra Venom Factor(CVF) on hyperacute rejection was evaluated. METHODS: Cardiac xenograft from guinea pig was transplanted into the abdomen of rat after the recipient being given i.p. a dose of CVF 0.20 microgram/g. the recipients were divided into group A (control group), group B (only given CVF), group C (CVF + Cytoxan + Splenectomy), group D (Cytoxan + Splenectomy) Cytoxan was injected into the abdominal cavity with a dose of 60 mg/Kg. The survival time of xenograft was measured and histologic observation was carried out after the cardiac arrest. RESULTS: The survival time of xenograft ranged from 15 to 3,120 minutes. There were significant difference among group A compared with group B and C (P lt; 0.01), and no difference between group A and group D, as well as group B and C (P gt; 0.05). There were significant difference between group B and D, as well as group C and D(P lt; 0.01). The histologic observation proved that the hyperacute rejection in group A and D was milder than group B and C. CONCLUSION: The study reveals that CVF can prolong the xenograft time by depleting complement activities and restricting hyperacute rejection in this model. Further basic and clinical study of effect of CVF in xenograft transplantation is worthwhile.
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.
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.
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: To evaluate the histological characteristics of xenogeneic graft-versus-host disease (GVHD), and to differentiate it from the allogeneic GVHD. METHODS: The original articles related to the characteristics of xenogeneic GVHD and the relationship between xenogeneic GVHD and allogeneic GVHD were widely reviewed in the past decade. RESULTS: Xenogeneic GVHD was different from allogeneic GVHD in the speed of development, position and features of pathological changes, due to the incompatibility of common simulative signals, adhesive molecules and difference of antigens. Xenogeneic spleen transplantation could induce xenogeneic GVHD. CONCLUSION: Xenogeneic GVHD can be used as a model to mimic rejection in xenotransplantation and to evaluate the compatibility of xenotransplantation.
Objective To review the methods of overcoming immunological rejection in xenotransplantation.Methods The strategies of overcoming immunological rejection in xenotransplantation were analyzed and summaried on the basis of an extensive review of the latest l iterature concerned. Results The research development of immunological rejection mechanism and molecular biological technique provided new approaches for overcoming immunological rejection in xenotransplantation. Conclusion It is only a matter of time for xenotransplantation to be appl ied cl inically.
Objective To improve the Heron’s technique for heterotopic cardiac transplantation in rats by cuff vessel anastomosis in some aspectsand successfully establish the simplified model of cervical cardiac xenotransplantation from guinea pigs donor to SD rats recipients. Methods The donors were 64 male guinea pigs, whose weight ranged from 250 to 350 g； the recipients were 64 male SD rats, whose weight ranged from 300 to 350 g.The guinea pigs donor’s ascending aorta and pulmonary artery were anastomosed to SD rats recipient’s right common carotid artery and external jugular vein respectively with a self-made “sleeve” anastomosis. The modified cuff technique of heterotopic grafting is described in detail. Results 64 consecutive successful transplantations have been performed by single surgeon were done with negligible operative risk. No anastomosis leakage nor vessel obstruction. The total time of surgical procedure were 45 to 60 minutes. The new technique allowed vascular anastomoses to be completed in 2 to 5 minutes. The total cold ischemia time for donor heart was 14 minutes in average. Conclusion This modified Heron’s technique was a simple, economical, practicable,reliable and high reproducible model can be operated by surgeons with minimal training in microvascular surgery, and be applied to various transplantation immunological studies.
To investigate the immunoreaction, histological reaction and turnover by comparing the xenotransplantation of fresh human amniotic membrane (HAM) with that of preserved HAM, and to analyze the cl inical appl ication value of different kinds of HAM preparations. Methods Subcutaneous implant models were establ ished in 150 BALB/C mice, which were randomized into 5 groups of 30 mice each, based on different implants: fresh amniotic membrane (FAM), double fresh amniotic membrane (DFAM), glycerin preserved amniotic membrane (GPAM), chorion (positive control) or merely operation (negative control). The tissue samples from grafted area were observed with SABC and HE staining, and the inflammatory cells were calculated with l ight microscopy. 1, 2, 4, 8 and 12 weeks after surgery. Results The mice in all of groups were normal in eating and moving, and the wound surface healed well. In all of AM groups, the expression of MHC Ⅱ and the calculation of inflammatory cells were much less than those in chorion groups, showing significant differences (P lt; 0.01). At 1, 8 and 12 weeks after surgery, there were no significant differences in the expression of MHC Ⅱ and the calculation of inflammatory cells in all of AM groups, compared with other groups (P gt; 0.05). From 2 weeks to 4 weeks after surgery, there were no significant differences in the expression of MHC Ⅱ and the calculation of inflammatory cells between FAM and DFAM groups (P gt; 0.05), but they were both more than those in GPAM groups, showing significant differences (P lt; 0.05). At the 4th week after surgery, in all of AM groups, the expression of MHC Ⅱ and the calculation of inflammatory cells were less than those at the 2nd week, showing significant difference (P lt; 0.01).The amniotic epithel ium was still al ive in fresh AM groups until 4 weeks after transplantation. Early after surgery, fibroblasts infiltrated AM from the substantia basilaris layer while made fibrous capsule around the epithel ium. After 12 weeks, the amnion absorbed. Conclusion As a kind of heterologous biomaterial, whether fresh or preserved, HAM can be seemedof ideal immunocompatibil ity and histocompatibil ity. Fresh HAM with al ive epithel ium may be more successful in area ofrepair and reconstruction.
Objective
To evaluate tissue regeneration, body reaction, and biological safety of xenogeneous bladder acellular matrix (BAM) that can be used to repair rabbit bladder.
Methods
Porcine BAM was prepared through physical, chemical, and enzymatic methods, and the effects of acellularization and the structure were observed with HE staining and scanning electron microscope (SEM). Eighteen New Zealand white rabbits (weighing, 2.5-3.0 kg) undergoing partial cystectomy were randomly divided into 2 groups. After partial (about 30%) cystectomy, the porcine BAM was used to replace partial rabbit bladder in the experimental group (n=12), and the incision was directly sutured as control group (n=6). The survival condition of animals was observed after operation. At 15 days, 1, 2, 3, and 6 months after operation, the blood routine, renal function, and electrolyte were tested by collecting the blood samples. At 1, 2, 3, and 6 months after operation, maximum bladder capacity, bladder leak point pressure, and bladder compliance were measured through urodynamic studies. Then gross observation was performed for regeneration of bladder, and the specimens of the bladder were harvested for HE staining and immunohistochemical staining. The surrounding organs and local lymphoid tissues were harvested for gross observation and HE staining.
Results
Cell components were completely removed in the porcine BAM, showing three-dimensional porous structure under SEM. All the animals survived during the experiment. At 15 days after operation, white blood cell count increased, and then returned to normal level in 2 groups, showing no significant difference between 2 groups (P gt; 0.05). The tests of renal function and electrolyte suggested no significant difference between 2 groups (P gt; 0.05). The level of serum creatinine showed a tendency of increase, but it remained within normal range at 6 months after operation. The maximum bladder capacity and compliance in experimental group were significantly higher than those in control group at 3 and 6 months after operation (P lt; 0.05), but no significant difference in bladder leak point pressure at each time point between 2 groups (P gt; 0.05). The urothelial regeneration, smooth muscle regeneration, and blood vessel regeneration were seen by histological observation in 2 groups. In the 2 groups, chronic inflammatory cells infiltration could be observed at 1 month postoperatively, and then chronic inflammatory cells decreased significantly (P lt; 0.05), until complete disappearance. There was no significant difference in score of chronic inflammatory cell infiltration between 2 groups at 3 and 6 months after operation (P gt; 0.05). The α-smooth muscle actin expression was significantly increased with time passing in 2 groups (P lt; 0.05), and it was significantly higher in control group than in experimental group at each time point (P lt; 0.05). In addition, gross and HE staining observations showed no abnormalities in surrounding organs and local lymphoid tissues.
Conclusion
No immune rejection response occurs when porcine BAM is used for xenotransplantation. It is indicated that porcine BAM is relative safety for xenotransplantation.
OBJECTIVE The pathogenesis, mechanism, manifestation and diagnosis of graft-versus-host disease(GVHD) are reviewed in this article. METHODS The relevant articles in recent public magazines were reviewed and summarized. RESULTS It was indicated that GVHD occurred in the conditioned recipients in animal experiments and clinical transplantations. Humoral and cellular factors were involved in GVHD, which could be diagnosed and classified according to their characteristics. CONCLUSION As a kind of interactions between the host and donor, GVHD are severely harmful to the host. It may also occur in xenotransplantation, where GVHD can be utilized in the studies on transplant immunology, oncology etc. Xenogeneic GVHD is receiving more and more attentions.
