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Bernard E Tuch - One of the best experts on this subject based on the ideXlab platform.

  • characterisation of the xenogeneic immune response to microencapsulated Fetal Pig islet like cell clusters transplanted into immunocompetent c57bl 6 mice
    PLOS ONE, 2013
    Co-Authors: Vijayaganapathy Vaithilingam, Cherry Fung, Sabina Ratnapala, Jayne L Foster, Vijesh Vaghjiani, Ursula Manuelpillai, Bernard E Tuch
    Abstract:

    Xenotransplantation of microencapsulated Fetal Pig islet-like cell clusters (FP ICCs) offers a potential cellular therapy for type 1 diabetes. Although microcapsules prevent direct contact of the host immune system with the xenografted tissue, poor graft survival is still an issue. This study aimed to characterise the nature of the host immune cells present on the engrafted microcapsules and effects on encapsulated FP ICCs that were transplanted into immunocompetent mice. Encapsulated FP ICCs were transplanted into the peritoneal cavity of C57BL/6 mice. Grafts retrieved at days 1, 3, 7, 14 and 21 post-transplantation were analysed for pericapsular fibrotic overgrowth (PFO), cell viability, intragraft porcine gene expression, macrophages, myofibroblasts and intraperitoneal murine cytokines. Graft function was assessed ex vivo by insulin secretion studies. Xenogeneic immune response to encapsulated FP ICCs was associated with enhanced intragraft mRNA expression of porcine antigens MIP-1α, IL-8, HMGB1 and HSP90 seen within the first two weeks post-transplantation. This was associated with the recruitment of host macrophages, infiltration of myofibroblasts and collagen deposition leading to PFO which was evident from day 7 post-transplantation. This was accompanied by a decrease in cell viability and loss of FP ICC architecture. The only pro-inflammatory cytokine detected in the murine peritoneal flushing was TNF-α with levels peaking at day 7 post transplantation. This correlated with the onset of PFO at day 7 implying activated macrophages as its source. The anti-inflammatory cytokines detected were IL-5 and IL-4 with levels peaking at days 1 and 7, respectively. Porcine C-peptide was undetectable at all time points post-transplantation. PFO was absent and murine intraperitoneal cytokines were undetectable when empty microcapsules were transplanted. In conclusion, this study demonstrated that the macrophages are direct effectors of the xenogeneic immune response to encapsulated FP ICCs leading to PFO mediated by a combination of both pro- and anti-inflammatory cytokines.

  • expression of fas but not fas ligand on Fetal Pig beta cells
    Xenotransplantation, 2004
    Co-Authors: Lijun Bai, Kathrin Maedler, Marc Y Donath, Bernard E Tuch
    Abstract:

    Background The aim of this study was to determine whether Fetal Pig insulin-producing cells, a potential source of transplantable tissue for the treatment of type 1 diabetes, are affected by the Fas-FasL interaction, one of the cytotoxic pathways involved in T-cell-mediated autoimmune destruction of pancreatic beta cells. Methods Expression of Fas/FasL on Fetal Pig beta cells was assessed by immunohistochemistry, flow cytometry, Western blot, and RT-PCR. Apoptosis of Fetal Pig beta cells induced by soluble FasL (sFasL) or anti-Fas antibody (APO-1) was detected by flow cytometry using PI. Expression of FLIP on Fetal Pig pancreatic tissue was detected by immunofluorescent staining and Western blot. Results Fas was expressed on Fetal Pig pancreatic cells, both beta and non-beta cells, and the level of expression could be upregulated by exposure to human interleukin-1beta (IL1beta) 2000 pg/ml for 24 h. In contrast, FasL was not detected on Fetal Pig pancreatic cells but could be induced on both beta and non-beta cells when the cells were treated with IL1beta. Fas persisted on Fetal Pig beta cells transplanted as islet-like cell clusters into severe combined immunodeficient mice, with expression of this antigen at all times examined, 1 day, 2, 3 and 4 weeks. FasL was absent. Despite the presence of Fas on Fetal Pig beta cells, addition of sFasL or anti-Fas antibody failed to induce apoptosis of the Fetal Pig beta cells. In contrast, Pig lymphocytes, which express Fas, were destroyed by addition of both sFasL and APO-1. A possible reason for this is the expression on the Fetal Pig pancreatic cells of FLIP, an inhibitor of Fas-induced apoptosis. Conclusions Fetal Pig beta cells are resistant to Fas-FasL destruction. Our data imply that Fetal Pig beta cells transplanted into humans with type 1 diabetes may not be destroyed by activated T cells through the Fas-FasL-mediated pathway.

  • Fetal Pig beta cells are resistant to the toxic effects of human cytokines
    Transplantation, 2002
    Co-Authors: Lijun Bai, Bernard E Tuch, Bernhard J Hering, Ann M Simpson
    Abstract:

    BACKGROUND The cytokine tumour necrosis factor-alpha (TNF-alpha) is thought to be responsible for primary nonfunction of islets when transplanted. This, and two other cytokines, interleukin-1beta (IL-1beta) and interferon-gamma (IFN-gamma) are also implicated in the autoimmune destruction of beta cells. It is unknown if the Fetal Pig beta cell, which is being transplanted as a treatment for type 1 diabetes, is affected by these cytokines. METHODS We compared the effects of the cytokines on the function and viability of adult and Fetal Pig beta cells. The cells were cultured for up to 3 days in the presence of 2000 pg/ml of human IL-1beta, 1000 U/ml of TNF-alpha, and 1000 U/ml of IFN-gamma, as well as 1000 U/ml of porcine IFN-gamma. Cumulative insulin levels, insulin content, metabolic activity, and viability of these cells were examined. Additionally, nitric oxide production and the activity of antioxidant enzymes in these cells were also determined. RESULTS TNF-alpha and the combination of the three human cytokines caused a transient increase in cumulative insulin levels. TNF-alpha alone enhanced insulin content on day 3. There was no effect of these human cytokines on mitochondrial function and viability. In contrast, porcine IFN-gamma inhibited Fetal Pig beta cell function and also caused their death. Adult Pig islets are sensitive to the toxic effects of human TNF-alpha, IL-1beta, the combination of the three cytokines, and porcine IFN-gamma. The activity of the antioxidant enzymes catalase, glutathione peroxidase, and superoxide dismutase were significantly higher in Fetal Pig beta cells than in adult islets, implying that this may be the reason for the lack of adverse effects of the cytokines on the Fetal beta cell. CONCLUSION Fetal Pig beta cells are resistant to the toxic effect of the human cytokines, TNF-alpha and IL-1beta, in vitro. This resistance suggests that Fetal, but not adult beta cells, when transplanted into humans with type 1 diabetes may be protected from primary nonfunction and will be partially protected from autoimmune destruction.

  • comparison of size viability and function of Fetal Pig islet like cell clusters after digestion using collagenase or liberase
    Cell Transplantation, 2002
    Co-Authors: Pauline Georges, Roslyn P Muirhead, Lindy Williams, Sara Holman, Muhammad T Tabiin, Sophia K Dean, Bernard E Tuch
    Abstract:

    Liberase is a highly purified blend of collagenases that has been specifically developed to eliminate the numerous problems associated with the conventional use of crude collagenase when isolating islet-like cell clusters (ICCs) from pancreases of different species. The influence of Liberase on yield, size, viability, and function of ICCs has been documented when this enzyme was used to digest adult but not Fetal pancreases. In this study, we compared the effects of collagenase and Liberase on Fetal Pig ICCs. A total of eight Fetal Pig pancreas digestions were analyzed. Fetuses were obtained from Large White Landrace Pigs of gestational age 80 ± 2.1 days. The pancreases were digested with either 3 mg/ml collagenase P or 1.2 mg/ml Liberase HI. The time taken to digest the pancreas was shorter for collagenase when compared with Liberase (22 ± 2 vs. 31 ± 2 min). The size of ICCs was similar for both collagenase (83 ± 0.5 µm) and Liberase (79 ± 0.4 µm) as was the number of ICCs produced per pancreas (7653 ± 1297 vs. 8101 ± 1177). Viability, as assessed using fluorescent markers, was slightly greater for Liberase (79 ± 1% vs. 76 ± 1%, p < 0.05). Responsiveness to β-cell stimulus (20 mM KCl) was similar for both methods of isolation, as was the insulin content of the ICCs, both in vitro and at 1 month after transplantation of 1500 ICCs beneath the renal capsule of immunoincompetent mice. Despite the high content of endotoxins in collagenase, the above results show that this enzyme was equally as efficient as Liberase in isolating functional ICCs from Fetal Pig pancreas.

  • comparison of size viability and function of Fetal Pig islet like cell clusters after digestion using collagenase or liberase
    Cell Transplantation, 2002
    Co-Authors: Pauline Georges, Roslyn P Muirhead, Lindy Williams, Sara Holman, Muhammad T Tabiin, Sophia K Dean, Bernard E Tuch
    Abstract:

    Liberase is a highly purified blend of collagenases that has been specifically developed to eliminate the numerous problems associated with the conventional use of crude collagenase when isolating islet-like cell clusters (ICCs) from pancreases of different species. The influence of Liberase on yield, size, viability, and function of ICCs has been documented when this enzyme was used to digest adult but not Fetal pancreases. In this study, we compared the effects of collagenase and Liberase on Fetal Pig ICCs. A total of eight Fetal Pig pancreas digestions were analyzed. Fetuses were obtained from Large White Landrace Pigs of gestational age 80 +/- 2.1 days. The pancreases were digested with either 3 mg/ml collagenase P or 1.2 mg/ml Liberase HI. The time taken to digest the pancreas was shorter for collagenase when compared with Liberase (22 +/- 2 vs. 31 +/- 2 min). The size of ICCs was similar for both collagenase (83 +/- 0.5 microm) and Liberase (79 +/- 0.4 microm) as was the number of ICCs produced per pancreas (7,653 +/- 1,297 vs. 8,101 +/- 1,177). Viability, as assessed using fluorescent markers, was slightly greater for Liberase (79 +/- 1% vs. 76 +/- 1%, p < 0.05). Responsiveness to beta-cell stimulus (20 mM KCl) was similar for both methods of isolation, as was the insulin content of the ICCs, both in vitro and at I month after transplantation of 1,500 ICCs beneath the renal capsule of immunoincompetent mice. Despite the high content of endotoxins in collagenase, the above results show that this enzyme was equally as efficient as Liberase in isolating functional ICCs from Fetal Pig pancreas.

E Krysin - One of the best experts on this subject based on the ideXlab platform.

  • amniotic and allantoic fluid concentrations of thyroxine 3 3 5 tri iodothyronine 3 3 di iodothyronine and 3 5 di iodothyronine in the Pig during the period of gestation
    Journal of Endocrinology, 1995
    Co-Authors: E Brzezinskaslebodzinska, A B Slebodzinski, E Krysin
    Abstract:

    Thyroxine (T 4 ), 3,3',5'-tri-iodothyronine (reverse T 3 ; rT 3 ) and di-iodothyronines (3,3'-T 2 and 3',5'-T 2 ) were measured in Pig amniotic fluid (AF) and allantoic fluid (Al) between 32 and 113 days of normal pregnancy. Low but measurable quantities of T 4 in AF and Al (2.1±0.3 and 3.2±0.5 nmol/l respectively) were found before the onset of Fetal thyroid gland function, which indicates the maternal source of T 4 . The presence of rT 3 (55.8±4.1 pmol/l in AF and 49.8±5.3 pmol/l in Al), 3,3'-T 2 (45.5± 0.6 pmol/l in AF and 49.2±9.2 pmol/l in Al) and 3',5'-T 2 (20.8±2.6 pmol/l in AF and 24.0±2.2 pmol/l in Al) may be attributed to the monodeiodinase system already active in Fetal Pig tissues in early pregnancy, as demonstrated previously. T 3 concentration was undetectable in both AF and Al. An approximately twofold increase in the levels of T 4 , rT 3 and T 2 s in AF and Al at mid-gestation was observed. T 4 and rT 3 in AF showed a positive correlation with protein concentrations. AF rT 3 concentration (but not T 4 ) correlated with rT 3 in the cord and maternal serum. The 3,3'-T 2 and 3',5'-T 2 in AF and Al showed parallel changes to rT 3 , while the rT 3 /3,3'-T 2 and rT 3 /3',5'-T 2 molar ratios remained constant. T 4 concentrations in AF and Al were markedly lower than in corresponding maternal and Fetal serum ; the rT 3 concentration in Al was equal to that in AF and two to four times lower than in Fetal serum. In spite of differences between serum hormone patterns in the Pig and human near term, iodothyronine concentrations in AF showed some similarities, mainly the following: undetectable T 3 , a strong correlation between rT 3 , T 4 and AF total protein and the presence of 3,3'-T 2 and 3',5'-T 2 in measurable levels. Comparative data for Al, except the ones in the present study in the Pig, are not available.

  • differences in the thyroxine triiodothyronine and reverse triiodothyronine contents of Fetal Pig tissues relative to gestational age
    Acta Veterinaria Hungarica, 1995
    Co-Authors: E Krysin
    Abstract:

    : The concentrations of thyroxine (T4), 3,5,3'-triiodothyronine (T3) and 3,3',5'-triiodothyronine (reverse T3) were measured in the liver, kidney and skeletal muscles of Pig fetuses from day 32 to 113 of age. The iodothyronines were found to be present already between days 32 and 39, that is before the onset of Fetal thyroid function. In the liver, kidneys and skeletal muscles T4 reached maximal concentrations at midgestation (days 56 and 93). The T3 level increased with gestational age in all tissues examined but, as opposed to T4, its maximal value was reached shortly before birth. The rT3 level was the highest between days 85 and 100 in the liver and kidney; however, in the skeletal muscles it did not change with gestation. The presented profiles of change of T4 and rT3 in the examined tissues did not correspond to the blood hormone pattern already observed in Pig, whereas changes in tissue T3 concentrations were similar to those in the serum.

M Sykes - One of the best experts on this subject based on the ideXlab platform.

  • highly disparate xenogeneic skin graft tolerance induction by Fetal Pig thymus in thymectomized mice conditioning requirements and the role of coimplantation of Fetal Pig liver
    Transplantation, 2001
    Co-Authors: Yong Zhao, J. S. Arn, Joseignacio Rodriguezbarbosa, Kirsten G Swenson, Gaoping Zhao, M Sykes
    Abstract:

    Background. Highly disparate xenogeneic Pig skin graft tolerance and efficient repopulation of mouse CD4 + T cells are achieved in thymectomized (ATX) B6 mice that receive T cell and natural killer (NK) cell depletion by injection of a mixture of monoclonal antibodies (mAbs) (GK1.5, 2.43, 30-H12, and PK136) on days -6, -1, +7, and +14 and 3 Gy total body irradiation (TBI) followed by implantation of Fetal Pig thymus/liver (FP THY/LIV) grafts on day 0. The requirements for each treatment in this model to achieve Pig skin graft tolerance have not previously been defined. Therefore, we performed a series of experiments to address the role of each treatment in achieving maximal skin graft tolerance. Methods. Peripheral mouse CD4 + T-cell repopulation and Pig skin graft survival were followed in this Pig-to-mouse model in which recipient B6 mice were treated with modified regimens that omitted thymectomy, 3 Gy TBI, anti-Thyl.2, and anti-NK1.1 mAbs, injection of a mixture of mAbs on day +14, or coimplantation of FP LIV, respectively. Results. Prolongation but not permanent survival of donor MHC-matched Pig skin grafts was observed in euthymic B6 mice that received T and NK cell depletion, 3 Gy TBI, and 7 Gy thymic irradiation and FP THY/LIV in the mediastinum, suggesting that full xenogeneic tolerance was not achieved in euthymic mice. However, after grafting FP THY alone to ATX B6 mice treated either with the standard regimen, or with a conditioning regimen that omitted all components of the conditioning regimen except treatment with anti-CD4 and anti-CD8 mAbs, efficient peripheral repopulation of mouse CD4 + T cells and long-term donor MHC-matched Pig skin graft acceptance were observed. Conclusions. Highly disparate xenogeneic Pig skin graft tolerance can be achieved by grafting FP THY alone in anti-CD4 and anti-CD8 mAb-treated ATX B6 mice, but not in euthymic B6 mice. Additional treatment of ATX recipient mice with anti-Thy1.2 and NK1.1 mAbs and 3 Gy TBI is not essential for donor Pig skin graft tolerance induction.

  • the induction of specific Pig skin graft tolerance by grafting with neonatal Pig thymus in thymectomized mice
    Transplantation, 2000
    Co-Authors: Yong Zhao, J. S. Arn, David H. Sachs, Joseignacio Rodriguezbarbosa, Kirsten G Swenson, Rolf N Barth, Akira Shimizu, M Sykes
    Abstract:

    Background. Xenogeneic donor-specific tolerance can be induced by transplanting Fetal Pig thymus and liver tissue (FP THY/LIV) to thymectomized (ATX), T/NK cell-depleted mice. By using neonatal Pig tissue, we hoped to overcome two obstacles that arise with the use of Fetal Pig tissue: (1) the inability to keep Fetal Pigs alive after harvesting their thymic tissue, resulting in unavailability of their skin or other organs for grafting; and (2) the limited Fetal thymic tissue yield, making application to large animals and humans more difficult. Methods. Neonatal Pig thymus tissue (NP THY) was grafted into ATX, T/NK cell-depleted, 3Gy whole body-irradiated, originally immunocompetent B6 mice to evaluate the ability of NP THY to reconstitute mouse CD4 + T cells and to induce xenogeneic tolerance to donor Pig skin grafts. Results. Repopulation of mouse CD4 + T cells in the peripheral tissues was observed in T/NK cell-depleted, ATX B6 mice that received NP THY with or without neonatal Pig spleen (NP SPL), but not in those receiving NP SPL alone, indicating that Pig thymus grafting was necessary and sufficient for mouse T cell recovery. Seven of nine NP THY/SPL-grafted ATX mice and two of six NP THY-grafted ATX mice that reconstituted >5% CD4 + cells in PBL accepted donor Pig skin long-term without lymphocyte infiltration, whereas they rejected allogeneic BALB/c skin and third party Pig skin grafts as rapidly as euthymic mice. Conclusions. NP THY can support the development of mouse CD4 + T cells that are functional and specifically tolerant to donor Pig antigens in ATX, T/NK cell-depleted, 3 Gy whole body-irradiated, originally immunocompetent B6 mice. Additional grafting of NP SPL with NP THY improves the efficiency of tolerance induction in this model.

Yong Zhao - One of the best experts on this subject based on the ideXlab platform.

  • highly disparate xenogeneic skin graft tolerance induction by Fetal Pig thymus in thymectomized mice conditioning requirements and the role of coimplantation of Fetal Pig liver
    Transplantation, 2001
    Co-Authors: Yong Zhao, J. S. Arn, Joseignacio Rodriguezbarbosa, Kirsten G Swenson, Gaoping Zhao, M Sykes
    Abstract:

    Background. Highly disparate xenogeneic Pig skin graft tolerance and efficient repopulation of mouse CD4 + T cells are achieved in thymectomized (ATX) B6 mice that receive T cell and natural killer (NK) cell depletion by injection of a mixture of monoclonal antibodies (mAbs) (GK1.5, 2.43, 30-H12, and PK136) on days -6, -1, +7, and +14 and 3 Gy total body irradiation (TBI) followed by implantation of Fetal Pig thymus/liver (FP THY/LIV) grafts on day 0. The requirements for each treatment in this model to achieve Pig skin graft tolerance have not previously been defined. Therefore, we performed a series of experiments to address the role of each treatment in achieving maximal skin graft tolerance. Methods. Peripheral mouse CD4 + T-cell repopulation and Pig skin graft survival were followed in this Pig-to-mouse model in which recipient B6 mice were treated with modified regimens that omitted thymectomy, 3 Gy TBI, anti-Thyl.2, and anti-NK1.1 mAbs, injection of a mixture of mAbs on day +14, or coimplantation of FP LIV, respectively. Results. Prolongation but not permanent survival of donor MHC-matched Pig skin grafts was observed in euthymic B6 mice that received T and NK cell depletion, 3 Gy TBI, and 7 Gy thymic irradiation and FP THY/LIV in the mediastinum, suggesting that full xenogeneic tolerance was not achieved in euthymic mice. However, after grafting FP THY alone to ATX B6 mice treated either with the standard regimen, or with a conditioning regimen that omitted all components of the conditioning regimen except treatment with anti-CD4 and anti-CD8 mAbs, efficient peripheral repopulation of mouse CD4 + T cells and long-term donor MHC-matched Pig skin graft acceptance were observed. Conclusions. Highly disparate xenogeneic Pig skin graft tolerance can be achieved by grafting FP THY alone in anti-CD4 and anti-CD8 mAb-treated ATX B6 mice, but not in euthymic B6 mice. Additional treatment of ATX recipient mice with anti-Thy1.2 and NK1.1 mAbs and 3 Gy TBI is not essential for donor Pig skin graft tolerance induction.

  • the induction of specific Pig skin graft tolerance by grafting with neonatal Pig thymus in thymectomized mice
    Transplantation, 2000
    Co-Authors: Yong Zhao, J. S. Arn, David H. Sachs, Joseignacio Rodriguezbarbosa, Kirsten G Swenson, Rolf N Barth, Akira Shimizu, M Sykes
    Abstract:

    Background. Xenogeneic donor-specific tolerance can be induced by transplanting Fetal Pig thymus and liver tissue (FP THY/LIV) to thymectomized (ATX), T/NK cell-depleted mice. By using neonatal Pig tissue, we hoped to overcome two obstacles that arise with the use of Fetal Pig tissue: (1) the inability to keep Fetal Pigs alive after harvesting their thymic tissue, resulting in unavailability of their skin or other organs for grafting; and (2) the limited Fetal thymic tissue yield, making application to large animals and humans more difficult. Methods. Neonatal Pig thymus tissue (NP THY) was grafted into ATX, T/NK cell-depleted, 3Gy whole body-irradiated, originally immunocompetent B6 mice to evaluate the ability of NP THY to reconstitute mouse CD4 + T cells and to induce xenogeneic tolerance to donor Pig skin grafts. Results. Repopulation of mouse CD4 + T cells in the peripheral tissues was observed in T/NK cell-depleted, ATX B6 mice that received NP THY with or without neonatal Pig spleen (NP SPL), but not in those receiving NP SPL alone, indicating that Pig thymus grafting was necessary and sufficient for mouse T cell recovery. Seven of nine NP THY/SPL-grafted ATX mice and two of six NP THY-grafted ATX mice that reconstituted >5% CD4 + cells in PBL accepted donor Pig skin long-term without lymphocyte infiltration, whereas they rejected allogeneic BALB/c skin and third party Pig skin grafts as rapidly as euthymic mice. Conclusions. NP THY can support the development of mouse CD4 + T cells that are functional and specifically tolerant to donor Pig antigens in ATX, T/NK cell-depleted, 3 Gy whole body-irradiated, originally immunocompetent B6 mice. Additional grafting of NP SPL with NP THY improves the efficiency of tolerance induction in this model.

  • Immune restoration by Fetal Pig thymus grafts in T cell-depleted, thymectomized mice.
    Journal of immunology (Baltimore Md. : 1950), 1997
    Co-Authors: Yong Zhao, Jay A. Fishman, Justin J. Sergio, J L Oliveros, Denise A. Pearson, Gregory L. Szot, Robert A. Wilkinson, J. S. Arn, David H. Sachs, Megan Sykes
    Abstract:

    Donor-specific tolerance can be induced across a discordant xenogeneic barrier in T/NK cell-depleted, thymectomized (ATX) B10 mice by grafting of Fetal Pig thymic and liver tissue (FP THY/LIV) under the kidney capsule. We have now examined the phenotype and function of murine T cells that develop in FP THY/LIV grafts in these mice. Mouse CD4+ T cells reached normal levels in PBL by 14 wk, and were maintained up to 30 wk. Similar proportions of splenic CD4+ cells expressed the naive phenotype (CD45RBhighMEL-14+CD44low) in FP THY/LIV graft recipients and euthymic control mice. These CD4 cells were functional, demonstrating normal proliferative responses and up-regulation of CD25 and CD69 after activation by mitogens or alloantigens. They proliferated in response to the protein Ag KLH presented by host MHC following in vivo immunization. ATX B10 mice grafted with FP THY/LIV also cleared Pneumocystis carinii infections, whereas simultaneously-treated ATX B10 mice not receiving FP THY were unable to do so. Discordant xenogeneic thymus grafting can therefore restore immune competence. Thus, in addition to tolerance induction, xenogeneic thymic replacement might have a potential role in the reconstitution of immunity in patients afflicted with immunodeficiencies affecting the thymus.

  • skin graft tolerance across a discordant xenogeneic barrier
    Nature Medicine, 1996
    Co-Authors: Yong Zhao, Justin J. Sergio, David H. Sachs, Kirsten Swenson, Scott J Arn, Megan Sykes
    Abstract:

    Specific T–cell tolerance may be essential for successful xenotransplantation in humans. Grafting of thymectomized, T cell–depleted normal mice with xenogeneic Fetal Pig thymus and liver (FP THY/LIV) tissue results in the recovery of functional CD4 antigen–positive cells. We have tested T–cell tolerance by skin grafting. Donor–matched Pig skin survived permanently (>200 days), whereas allogeneic mouse skin was rapidly rejected. Nontolerant control mice rejected Pig skin within 26 days. Both porcine and murine histocompatibility class IIhigh cells were detected in long–term thymus grafts, and T–cell repertoire analyses suggested that tolerance to both donors and recipients developed, at least in part, by intragraft clonal deletion. This study demonstrates the principle that tolerance, measured by the stringent criterion of skin grafting, can be induced across a widely disparate species barrier.

Ann M Simpson - One of the best experts on this subject based on the ideXlab platform.

  • Fetal Pig beta cells are resistant to the toxic effects of human cytokines
    Transplantation, 2002
    Co-Authors: Lijun Bai, Bernard E Tuch, Bernhard J Hering, Ann M Simpson
    Abstract:

    BACKGROUND The cytokine tumour necrosis factor-alpha (TNF-alpha) is thought to be responsible for primary nonfunction of islets when transplanted. This, and two other cytokines, interleukin-1beta (IL-1beta) and interferon-gamma (IFN-gamma) are also implicated in the autoimmune destruction of beta cells. It is unknown if the Fetal Pig beta cell, which is being transplanted as a treatment for type 1 diabetes, is affected by these cytokines. METHODS We compared the effects of the cytokines on the function and viability of adult and Fetal Pig beta cells. The cells were cultured for up to 3 days in the presence of 2000 pg/ml of human IL-1beta, 1000 U/ml of TNF-alpha, and 1000 U/ml of IFN-gamma, as well as 1000 U/ml of porcine IFN-gamma. Cumulative insulin levels, insulin content, metabolic activity, and viability of these cells were examined. Additionally, nitric oxide production and the activity of antioxidant enzymes in these cells were also determined. RESULTS TNF-alpha and the combination of the three human cytokines caused a transient increase in cumulative insulin levels. TNF-alpha alone enhanced insulin content on day 3. There was no effect of these human cytokines on mitochondrial function and viability. In contrast, porcine IFN-gamma inhibited Fetal Pig beta cell function and also caused their death. Adult Pig islets are sensitive to the toxic effects of human TNF-alpha, IL-1beta, the combination of the three cytokines, and porcine IFN-gamma. The activity of the antioxidant enzymes catalase, glutathione peroxidase, and superoxide dismutase were significantly higher in Fetal Pig beta cells than in adult islets, implying that this may be the reason for the lack of adverse effects of the cytokines on the Fetal beta cell. CONCLUSION Fetal Pig beta cells are resistant to the toxic effect of the human cytokines, TNF-alpha and IL-1beta, in vitro. This resistance suggests that Fetal, but not adult beta cells, when transplanted into humans with type 1 diabetes may be protected from primary nonfunction and will be partially protected from autoimmune destruction.

  • lowering of blood glucose to nondiabetic levels in a hyperglycemic Pig by allografting of Fetal Pig isletlike cell clusters
    Transplantation, 2001
    Co-Authors: Bernard E Tuch, Ann M Simpson, Muhammad T Tabiin, Danielle C Wright, Gregory W Keogh, Simon Roberts, Mu Yao, Sophia K Valencia, Hayley Scott
    Abstract:

    Background. Fetal Pig isletlike cell clusters (ICCs) will differentiate when grafted into the thymus gland of outbred immunosuppressed nondiabetic Pigs for up to 3 months. Whether these cells will survive for a similar period in a diabetic recipient and will mature with secretion of insulin to ameliorate the hyperglycemia is unknown. Methods. Between 40,000 and 125,000 ICCs (7,000 to 11,400 ICCs/kg) were injected into the thymus gland of five juvenile Pigs immunosuppressed with cyclosporine and deoxyspergualin, and the animals were subsequently made diabetic by the injection of streptozotocin. Insulin was administered subcutaneously, with one Pig dying from hypoglycemia. The animal with the least number of ICCs transplanted was killed 81 days later, and the graft was analyzed histologically. Blood glucose levels and porcine C-peptide in the remaining animals were monitored for a median of 101 days. Results. Histological analysis of the graft showed numerous epithelial cell clusters; the percentage of cells that contained insulin, glucagon, somatostatin, and pancreatic polypeptide were 61%, 64%, 25%, and 18%, respectively. Some cells contained more than one hormone. Porcine C-peptide was detected from 21 days after induction of diabetes but not before. In the Pig receiving the most ICCs, blood glucose levels were lowered to nondiabetic levels 109 days after transplantation. Plasma C-peptide levels in response to glucagon in this Pig steadily increased after grafting; peak levels were 0, 0.21, 0.45, and 0.52 ng/ml at 4, 21, 49, and 80 days after induction of diabetes compared to 0.09 ng/ml in control diabetic Pigs. The secretion of C-peptide in response to oral and intravenous glucose and arginine also was greater than in untransplanted diabetic Pigs, the pattern of secretion being consistent with developing Fetal β cells as the source of the C-peptide. Pancreatic insulin content was 0.1 mU/mg, 4% of that in nondiabetic Pigs, and the number of β cells per islet was 3 to 6 compared to 90 in nondiabetic controls. Conclusions. ICCs will differentiate and function for up to 111 days when transplanted into outbred immunosuppressed Pigs rendered diabetic. Blood glucose levels can be lowered to nondiabetic levels when sufficient numbers of ICCs are grafted.