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Cardiac xenotransplantation in primates
Abstract:
Successful cardiac xenotransplantation would alleviate the severe shortage of donor organs that presently limits the availability of cardiac transplantation. Early attempts at human xenotransplantation achieved minimal success. However, the effectiveness of cyclosporine in nonhuman xenotransplant models has received little experimental investigation. We have therefore studied the effect of cyclosporine-based immunosuppression in primate cardiac xenograft models using cynomolgus monkey donors and baboon recipients. Donor hearts were transplanted heterotopically into the necks of recipients or in the orthotopic position. Recipients were treated with no immunosuppression (controls), cyclosporine and steroids, or cyclosporine, steroids, azathioprine, and antithymocyte globulin. Statistically significant prolongation of graft survival compared to the control group was observed in the heterotopic groups. Mean survival time of the cyclosporine-treated and steroid-treated heterotopic grafts was 61 days compared to 6 days for grafts in the control group (p = 0.01); the addition of azathioprine and antithymocyte globulin yielded a mean survival of 84 days (p less than 0.01). No significant increase in graft survival was noted in the orthotopic groups treated with either immunosuppressive regimen. Although long-term use of human xenografts as an alternative for heart replacement is not supported by these data, further investigation of the orthotopic model is clearly justified.
Insights
Cyclosporine-based immunosuppression significantly prolonged cardiac xenograft survival in baboons when transplanted heterotopically. Further research into the orthotopic model is warranted for potential cardiac xenotransplantation advancements.
Area of Science:
- Transplantation Immunology
- Xenotransplantation Research
- Cardiovascular Surgery
Background:
- The critical shortage of donor organs for cardiac transplantation necessitates alternative solutions like xenotransplantation.
- Previous xenotransplantation attempts had limited success, with minimal investigation into cyclosporine's efficacy in nonhuman models.
- Primate cardiac xenograft models offer a valuable platform for studying immunosuppressive strategies.
Purpose of the Study:
- To investigate the effectiveness of cyclosporine-based immunosuppression in primate cardiac xenograft models.
- To compare graft survival rates between heterotopic and orthotopic xenotransplantation with varying immunosuppressive regimens.
- To assess the potential of xenotransplantation as a viable alternative for cardiac replacement.
Main Methods:
- Cardiac xenotransplantation was performed using cynomolgus monkey donors and baboon recipients in heterotopic and orthotopic positions.
- Recipients received no immunosuppression (controls), cyclosporine and steroids, or a combination of cyclosporine, steroids, azathioprine, and antithymocyte globulin.
- Graft survival times were meticulously recorded and statistically analyzed to compare different treatment groups.
Main Results:
- Heterotopic cardiac xenografts showed statistically significant prolongation of survival with cyclosporine-based immunosuppression compared to controls.
- Mean graft survival in heterotopic xenografts treated with cyclosporine and steroids was 61 days (p = 0.01), and with additional agents was 84 days (p < 0.01).
- No significant increase in graft survival was observed in orthotopic xenograft models, irrespective of the immunosuppressive regimen used.
Conclusions:
- Cyclosporine-based immunosuppression can significantly enhance cardiac xenograft survival in heterotopic primate models.
- The orthotopic xenotransplantation model requires further investigation despite the lack of significant survival benefit in this study.
- While not yet a definitive solution for cardiac replacement, these findings support continued research into primate cardiac xenotransplantation.