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A novel model mimicking the immunoreactivity in pig-to-human xenotransplantation
A Novel Model Mimicking the Immunoreactivity in Pig-to-Human Xenotransplantation J. Cheng, Y. Ma, Y. Li, S. Li, Q. He, and W. Shen
T
HE organ shortage may be solved by xenotransplantation1 and pigs may be the ideal donors for human.2 The models used to study pig-to-human xenogeneic immunoreactivity include perfusion of pig organs with human blood ex vivo,3 mixed cell culture of human and pig immune cells,4 pig-to-no human primates organ transplant,5 and transplant of human and pig cells into severe combined immunodeficient (SCID) mice.6 However, none of these models can mimick the real interaction between humans and pigs in vivo during the course of clinical xenotransplantation. The purpose of this study is to reconstruct the immune system of the pig with human immune cells, so that the transplant immunoreactivity between humans and pigs can be monitored in vivo. MATERIALS AND METHODS Twenty Chinese Neijiang pigs (6 to 12 months, 30 to 50 kg) were divided into four groups: A, control (n ⫽ 5); B, treatment with methotrexate (MTX), CTX, and busulfan (n ⫽ 5); C, intraperitoneal (IP) injection of human bone marrow and spleen cells (HBSC) after B treatment (n ⫽ 5); and D, intravenous (IV) infusion of HBSC after B treatment (n ⫽ 5). Blood and tissue samples were analyzed with routine techniques, flow cytometry, and immunohistochemistry (IHC) to monitor chimerism.
RESULTS
Groups A and B survived definitely. Groups C and D survived 3 to 54 days and 15 hours to 5 months, respectively. Human cells were found in recipient pigs in groups C and D 1 day, 7 days and 5 months after transplantation through IHC and flow cytometry of peripheral blood. However, the proportion of human cells decreased gradually to about 0.6% 5 months after transplantation. The IHC staining on frozen and paraffin sections of organs in groups C and D indicated human cells located in the red pulp and in the region between the red and white pulp of spleens and in the mesenchyma and alveoli of lungs. DISCUSSION
Instead of total body irradiation, IV infusion of immunosuppressive drugs was used in this study. It decreased the white blood cell (WBC) count of treated pigs to 1% to 10% of the normal level reversibly with acceptable side effects. The pig survived for a long time.
Fig 1. WBC were counted in three pigs (A, B, and C) before treatment (Pre), posttreatment with drugs (Pos), and postinjection with spleen cells (Pin).
Our preliminary study suggested that HBSC could survive for a period of time in the immunosuppressed pigs, where they could proliferate and attack the host as human cells in SCID mouse.7,8 The survival time of groups C and D was shorter than that of group B. Therefore, xenogeneic graft-vs-host disease (xGVHD) might occur in groups C and D. Cytotoxicity against natural anti-human serum in the recipient pigs could be avoided by IP injection of human cells, which was superior to group D. After transplantation, the appearance of human cells in the peripheral blood and organs could be due to their migration and homing. Human cells were found in the peripheral blood because of the IV infusion in group D. The ratio of human cells in the recipient was low long after transplantation in both groups C and D. CONCLUSIONS
Chimerism of human cells could be established by transplanting HBSC into immunosuppressed pigs. It is possible to facilitate xGVHD. Pigs offer a novel large animal model for monitoring the immunoreactivity in pig-to-human xenotransplantation. From the Laboratory of Transplant Immunology (J.C., Y.L., S.L., Q.H.) and Department of General Surgery (Y.M., W.S.), First University Hospital, West China University of Medical Sciences, Chengdu, P.R. China. Supported by grant 39993430 from the Natural Science Foundation of China. Address reprint requests to Y. Li, Laboratory of Transplant Immunology, First University Hospital, West China University of Medical Sciences, Chengdu, 610041 P.R. China.
0041-1345/00/$–see front matter PII S0041-1345(00)01117-9
© 2000 by Elsevier Science Inc. 655 Avenue of the Americas, New York, NY 10010
1056
Transplantation Proceedings, 32, 1056–1057 (2000)
PIG-TO-HUMAN XENOTRANSPLANTATION
The proportion of human cells in the peripheral blood of recipient pigs is low but stable long after transplantation both by injection and IV infusion. Therefore, human spleen transplantation initiates xGVHD.
REFERENCES 1. Barker CF, Markmann JF: Surgery 112:3, 1992 2. Steele DTR, Auchincloss H: Annu Rev Med 46:351, 1995
1057 3. Fiane AE, Viden V, Scolz T, et al: Transplant Proc 27:3560, 1995 4. Sato T, Tsuchida F, Shimura T, et al: Transplant Proc 27:693, 1995 5. Sablinski T, Giarello P, Ballin M, et al: Surgery 121:381, 1997 6. Sawada T, Dellapelle PA, Seebach JD, et al: Transplantation 63:1331, 1997 7. Hoffman-Fezer G, Gall C, Zngerle U, et al: Blood 8:3440, 1993 8. Maziruddin B, Shiroki R, Shishido S, et al: J Clin Invest 97:1267, 1996
T
HE organ shortage may be solved by xenotransplantation1 and pigs may be the ideal donors for human.2 The models used to study pig-to-human xenogeneic immunoreactivity include perfusion of pig organs with human blood ex vivo,3 mixed cell culture of human and pig immune cells,4 pig-to-no human primates organ transplant,5 and transplant of human and pig cells into severe combined immunodeficient (SCID) mice.6 However, none of these models can mimick the real interaction between humans and pigs in vivo during the course of clinical xenotransplantation. The purpose of this study is to reconstruct the immune system of the pig with human immune cells, so that the transplant immunoreactivity between humans and pigs can be monitored in vivo. MATERIALS AND METHODS Twenty Chinese Neijiang pigs (6 to 12 months, 30 to 50 kg) were divided into four groups: A, control (n ⫽ 5); B, treatment with methotrexate (MTX), CTX, and busulfan (n ⫽ 5); C, intraperitoneal (IP) injection of human bone marrow and spleen cells (HBSC) after B treatment (n ⫽ 5); and D, intravenous (IV) infusion of HBSC after B treatment (n ⫽ 5). Blood and tissue samples were analyzed with routine techniques, flow cytometry, and immunohistochemistry (IHC) to monitor chimerism.
RESULTS
Groups A and B survived definitely. Groups C and D survived 3 to 54 days and 15 hours to 5 months, respectively. Human cells were found in recipient pigs in groups C and D 1 day, 7 days and 5 months after transplantation through IHC and flow cytometry of peripheral blood. However, the proportion of human cells decreased gradually to about 0.6% 5 months after transplantation. The IHC staining on frozen and paraffin sections of organs in groups C and D indicated human cells located in the red pulp and in the region between the red and white pulp of spleens and in the mesenchyma and alveoli of lungs. DISCUSSION
Instead of total body irradiation, IV infusion of immunosuppressive drugs was used in this study. It decreased the white blood cell (WBC) count of treated pigs to 1% to 10% of the normal level reversibly with acceptable side effects. The pig survived for a long time.
Fig 1. WBC were counted in three pigs (A, B, and C) before treatment (Pre), posttreatment with drugs (Pos), and postinjection with spleen cells (Pin).
Our preliminary study suggested that HBSC could survive for a period of time in the immunosuppressed pigs, where they could proliferate and attack the host as human cells in SCID mouse.7,8 The survival time of groups C and D was shorter than that of group B. Therefore, xenogeneic graft-vs-host disease (xGVHD) might occur in groups C and D. Cytotoxicity against natural anti-human serum in the recipient pigs could be avoided by IP injection of human cells, which was superior to group D. After transplantation, the appearance of human cells in the peripheral blood and organs could be due to their migration and homing. Human cells were found in the peripheral blood because of the IV infusion in group D. The ratio of human cells in the recipient was low long after transplantation in both groups C and D. CONCLUSIONS
Chimerism of human cells could be established by transplanting HBSC into immunosuppressed pigs. It is possible to facilitate xGVHD. Pigs offer a novel large animal model for monitoring the immunoreactivity in pig-to-human xenotransplantation. From the Laboratory of Transplant Immunology (J.C., Y.L., S.L., Q.H.) and Department of General Surgery (Y.M., W.S.), First University Hospital, West China University of Medical Sciences, Chengdu, P.R. China. Supported by grant 39993430 from the Natural Science Foundation of China. Address reprint requests to Y. Li, Laboratory of Transplant Immunology, First University Hospital, West China University of Medical Sciences, Chengdu, 610041 P.R. China.
0041-1345/00/$–see front matter PII S0041-1345(00)01117-9
© 2000 by Elsevier Science Inc. 655 Avenue of the Americas, New York, NY 10010
1056
Transplantation Proceedings, 32, 1056–1057 (2000)
PIG-TO-HUMAN XENOTRANSPLANTATION
The proportion of human cells in the peripheral blood of recipient pigs is low but stable long after transplantation both by injection and IV infusion. Therefore, human spleen transplantation initiates xGVHD.
REFERENCES 1. Barker CF, Markmann JF: Surgery 112:3, 1992 2. Steele DTR, Auchincloss H: Annu Rev Med 46:351, 1995
1057 3. Fiane AE, Viden V, Scolz T, et al: Transplant Proc 27:3560, 1995 4. Sato T, Tsuchida F, Shimura T, et al: Transplant Proc 27:693, 1995 5. Sablinski T, Giarello P, Ballin M, et al: Surgery 121:381, 1997 6. Sawada T, Dellapelle PA, Seebach JD, et al: Transplantation 63:1331, 1997 7. Hoffman-Fezer G, Gall C, Zngerle U, et al: Blood 8:3440, 1993 8. Maziruddin B, Shiroki R, Shishido S, et al: J Clin Invest 97:1267, 1996