Objective To summarize the research progress of xenotransplantation.Methods Domestic and international publications about xenotransplantation were summarized and reviewed. Results Hyperacute xenograft rejection was a huge problem for xenotransplantation， but it could be alleviated if the organs or tissues of donor were genetically modified. So far the graft survival time differed greatly due to characteristics of different organ. Conclusions By reviewing the studies of relevant papers about xenotransplantation， a comprehensive understanding of research background and a suitable research direction of xenotransplantation can be supplied. The graft organs or tissues from genetically modified donors are expected to avoid or alleviate hyperacute xenograft rejection.
Objective To observe the dynamic histopathologic changes of acute rejection in rat orthotopic liver transplantation (OLT) model after tacrolimus discontinued and provide some prediction and evaluation data for clinical acute rejection after liver transplantation. Methods Kamada two-cuff technique was used to establish 60 rat OLT model， and male DA rats, male Lewis rats were used as donors and recipients respectively. Therapeutic amount of tacrolimus (0.05 mg/kg, twice per day, continued for 8 d, 1 d before operation and 7 d after operation, intragastric administrated) was administrated to recipients, then continuously half dose was decreased every day beginning from day 8 after operation and tacrolimus administration was stopped on day 13. Liver tissues were collected on day 7, 14, 21, and 28 after liver transplantation. Histopathologic changes and rejection activity index (RAI) of liver tissues were observed, survival time of recipients was calculated. Results Owing to protection effects of tacrolimus, liver tissues displayed no significant histopathologic changes of acute rejection in 7 d after OLT, while typical acute rejection histopathologic changes began to be observed on day 14 after OLT due to tacrolimus discontinuation. On day 14, 21, and 28, RAI were 3.7±0.9, 6.3±0.9, and 8.1±0.7 respectively. Survival time of recipients was (20.85±0.71) d with a median of 21 d. Conclusion Acute rejection could be induced in rat OLT model after tacrolimus discontinuation, and data collected from this model shows some extent of predictive value and assessment value for clinical liver acute rejection.
ObjectiveTo introduce transforming growth factor β(TGFβ) and the relationship between TGFβ and graft rejection. Methods Relevent articles in recent years were reviewed.ResultsThe immunodepressive function of TGFβ could resist transplant organ rejection injury in early postoperative period ; meanwhile TGFβ also caused fibroblast migration and promoted matrix deposition by increasing collagen production and decreasing collagen breakdown via inhibition of collagenases,which resulted in transplant organ fibrosis and arteriosclerosis, gene polymorphisms of the TGFβ were associated with it. Moreover,ischemia reperfusion injury and immunodepressive drug also affected production of TGFβ.ConclusionTGFβ as a pleiotropic and multifunctional cytokine contributes to the development of acute and chronic rejection.
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.
ObjectiveTo explore apoptosis of acinar cells during pancreatic allograft rejection in rats.MethodsGroups of Wistar rats underwent heterotopic pancreaticoduodenal transplantation from syngenic Wistar of allogenic SD rats. The grafts were harvested on postoperative day 3, 5 and 7. All graft samples were subjected to histological examination and apoptotic cells of graft acinar cells using in situ terminal deoxynucleotidy1 transferasemediated dUTP nickend labeling (TUNEL). Histopathological rejection score and apoptotic index (AI) were analyzed. ResultsThe incidence of apoptotic cells was increased steadily over time in allografts, in contrast with syngenic grafts. The apoptotic cells in allografts were mainly acinar cells and few infiltrating lymphocytes. A significant correlation between apoptotic index and histopathological rejection score was noted.ConclusionTUNEL can display apoptosis of single cell in situ. Apoptosis is an important mechanism of tissue injury in acute pancreatic allograft rejection in rats. Acinar cell apoptosis can be used as a valuble index to estimate the injury of grafts and to monitor the acute rejection.
Objective To investigate the mechanism of hyperacute rejection (HAR) in pig to rhesus monkey vein xenograft. Methods Porcine femoral vein was transplanted into rhesus monkey. Deposits of IgM, IgG, C3 and C4 on the grafts were observed by immunoflurescence. Results Great deal of IgM, C3 and C4 were seen along the endothelium of donor vein, but IgG was not seen. ConclusionIn pig to monkey xenograft model, HAR is intiated by the binding of xenoreactive IgM to donor xenoantigens and followed by the activation of complement via the classical pathway.
Abstract: Objective To study the antiacute rejection effect of Pachymic acid (PA) in heart transplantation rats, in order to select a new antirejection medicine with low side effect from traditional Chinese medicine. Methods We established the model by transplanting Wistar rats (32,donor) heart allografts into the abdomen of SD rats (32,receptor). The homologous hearttransplanted rats were then randomly divided into 4 groups with 16 rats in each group. Olive oil solution with PA 1 mg/(kg·d), PA 10 mg/(kg·d), Cyclosporine (CsA) 5 mg/(kg·d) and olive oil solution 0.5 ml/(kg·d) were respectively given intragastrically to lowdosage PA group, highdosage PA group, CsA group and the control group till the end of observation. Survival time of heart allografts, heart beating and the histological changes of allografts were examined and serum level of interleukin2 (IL-2) and interferon-γ (IFN-γ) were determined by enzymelinked immunosorbent assay (ELISA). Results Survival time in the highdosage PA group, the lowdosage PA group and the CsA group were 24.90±0.99 d, 15.50±1.60 d and 26.80±0.88 d respectively, which is much better than the control group (6.10±1.10 d, q=22.363, P=0.000; q=44.793, P=0.000; q=49.272,P=0.000). IL-2 serum level in the highdosage PA group, the lowdosage PA group and the CsA group were all lower than that in the control group (q=14.483, P=0.000; q=3.705, P=0.000; =21.418,P=0.000), whileIL-2 serum level in the highdosage group was lower than that in the lowdosage group (q=10.778,P=0.000). Similarly, IFN-γ serum level in the first three groups were all lower than that in the control group (q=16.508,P=0000; q=4.281, P=0.000;q=19.621, P=0.000) and IFNγ serum level in the highdosage group was also lower than that in the lowdosage group (q=14.975, P=0.000). Pathological examination 7 days after the surgery showed that pathologic lesion was much more relieved in the two PA groups and the CsA group than the control group. Conclusion Acute rejection of heart transplantation can be effectively suppressed by PA.
Abstract: Objective To assess the feasibility of transferring major histocompatibility complex (MHC) gene into the thymus to mitigate xenograft rejection. Methods By molecular cloning technique, we extracted and proliferated the-H-2K d gene from donor mice (MHC class Ⅰ gene of Balb/c mice) and constructed the expression vector plasmid of pCI-H-2K d. Twenty SD rats were selected as receptors, and by using random number table, they were divided into the experimental group and the control group with equal number of rats in each group. By ultrasoundguided puncture and lipofection method, the pCI-H-2Kd was injected into thymus of SD rats in the experimental group and meanwhile, empty vector plasmid of pCIneo was injected into thymus of SD rats in the control group. Subsequently, we transplanted the donor mice myocardium xenografts into the receptor rats, and observed the xenograft rejection in both the two groups. Results The survival time of the xenotransplanted myocardium in the experimental group was significantly longer than that in the control group (14.61±2.98 d vs. 6.40±1.58 d, t=-7.619,Plt;0.05). Microtome section of transplanted myocardium in the control group showed a relatively large amount of lymphocyte infiltration and necrosis occurred to most part of the transplanted myocardium, while microtome section of experiment group showed no lymphocyte infiltration and most of the cells of the transplanted myocardium were still alive. After mixed lymphocyte culture, the reaction of receptors to donor cells in the experiment group was obviously lower than that in the control group (t=4.758, P=0.000).After the count by flow cytometer, the xenoMHC molecules were expressed in the receptors’ thymus with a transfection efficiency of 60.7%. Conclusion Our findings suggest that xenograft rejection can be mitigated substantially by donor’s MHC gene transferring into receptor’s thymus. This may provide theoretical and experimental evidence for inducing xenotransplantation tolerance.
Abstract:Objective To investigate immunoinh.ibitory effects of paclitaxel on acute rejection of allogeneic heart transplantation in rats. Methods Heterotopic abdominal cardiac transplantation was performed from Wistar rats to SD rats. Seventy recipients were randomly divided into five groups,14 rats in each group. Control group： rats didn＇t receive any immunoinhibitory drug; group Ⅰ ： low-dose paclitaxel （0.75 mg/kg · d） was injected intraperitoneally; group Ⅱ ： high-dose paclitaxel （1.5 mg/kg ·d） was injected intraperitoneally; group Ⅲ ： cyclosporin A（CsA, 5 mg/ kg·d） was administered orally; group Ⅳ ： low-dose paclitaxel （0. 75 mg/kg · d） was injected intraperitoneally in combination with CsA （5 mg/kg · d administered orally）. General conditions of recipient, allograft survival and pathologic lesion at 7th day posttransplantation were observed. Results Allograft survival in treating groups were significantly prolonged compared with control group （P〈 0. 05）. Moreover, allograft survival in group IV was significantly prolonged compared with those in group Ⅰ and group Ⅲ （P〈0.05）. On 7th day posttransplantation, cardiac allograft looked swollen and International Society for Heart and Lung Transplantation （ISHLT） score was 3 or 4 in control group; cardiac allograft beat vigorously, showed pink in color and felt tender in group Ⅰ and group Ⅱ , ISHLT-score was 2 or 3. Compared to control group, pathologic lesion of grafts in group Ⅰ and group Ⅱ were significantly relieved （P〈0.05）. Cardiac allograft beat well and ISHLT-score was 2 in group Ⅲ. Cardiac allograft looked as normal and beat vigorously, ISHLT-score was less than 2 in group IV ; the protective effects on cardiac allograft was better than those in group Ⅰ and group Ⅱ （P〈0. 05）. Conclusion Paclitaxel could obviously suppress acute rejection and prolong survival of rat cardiac allograft. Paclitaxel and CsA has synergistic effect on prevention acute rejection.
Objective To investigate the effect of human placental-derived mesenchymal stem cells (PMSCs) on immunological rejection in mouse allogeneic skin transplantation. Methods The placenta fetal tissues from voluntary donors were used to isolate and culture the PMSCs, and the 3rd passage PMSCs were used in the experiment. Thirty Vr ∶ CD1 (ICR) mice at age of 1-2 days were used as skin donors for allogeneic skin transplantation. Thirty C57BL/6 mice at age of 6-8 weeks as recipients were made back skin defect of 12 mm in diameter and were randomly divided into 3 groups (n=10): group A, autograft; group B, allogeneic graft + PBS tail vein injection; and group C, allogeneic graft + human PMSCs (1 × 105 cells/mouse) tail vein injection. The flap survival was observed. At 7 days after skin transplantation, blood leukocyte counting, abdominal fluid macrophage activation, and the expression levels of interleukin 4 (IL-4), interleukin 17 (IL-17), and interferon γ (INF-γ) in blood and spleen were detected by ELISA and RT-PCR, respectively. Results The flap survival time was significantly longer in group A [(58.33 ± 4.04) days] than in groups B and C [(3.80 ± 0.92) days and (6.80 ± 0.82) days] (P lt; 0.05), and in group C than in group B (P lt; 0.05). At 7 days after transplantation, the blood leukocyte number was (6.32 ± 0.45) × 109/L in group A, (7.45 ± 0.52) × 109/L in group B, and (6.35 ± 0.39)× 109/ L in group C, and it was significantly more in group B than in groups A and C (P lt; 0.05). The macrophage activation rate of the abdominal fluid was 6.87% ± 2.40% in group A, 7.84% ± 0.44% in group B, and 15.98% ± 2.87% in group C; group C was significantly higher than groups A and B (P lt; 0.01). ELISA results showed that there was no significant difference in the concentrations of IL-4 among 3 groups (P gt; 0.05). Compared with group B, the concentrations of IL-17 and IFN-γ were significantly reduced in group C (P lt; 0.05), while the concentration of IFN-γ was significantly increased in group B when compared with group A (P lt; 0.05). RT-PCR results showed that there were significant differences in the expressions of IL-4, IL-17, and IFN-γ mRNA between groups B, C and group A (P lt; 0.05); the expressions of IL-4 and IFN-γ mRNA were significantly lower in group C than in group B (P lt; 0.05). Conclusion Human PMSCs transplantation can suppress the acute immunological rejection in allogeneic skin transplantation. The possible mechanism may be partially related to the inhibitory effect on the secretion of IL-17 and IFN-γ.