USE OF HUMAN MESENTERIC ARTERIES TO STUDY CHRONIC VASCULAR REJECTION IN SCID/BEIGE MICE RECONSTITUTED WITH HUMAN SPLEEN CELLS.

Abstract

P1182 Aims: We wanted to establish a preclinical model of chronic vascular rejection (CVR) by transplanting small arteries from the mesentery of cadaveric organ donors by the rapid “sleeve” technique into SCID/beige mice reconstituted with human allogeneic spleen cells. Methods: We have previously developed the rapid “sleeve” technique to study CVR in mice after orthotopic aortic allografts. In the present study we use SCID/beige mice which have no functional adaptive or innate immune system and accept allogeneic or xenogeneic grafts. After institutional authorisation and with informed consent from relatives, we obtain tissues and cells from cadaveric organ donors. A piece of mesentery is recovered from the donor and kept in buffered solution at 4°C until use. Dissection of the mesentery reveals a multitude of small arteries of the same size as the mouse aorta. These arteries can then be transplanted in place of the infrarenal aorta of the mice. Cells for the immunological reconstitution of the mice are obtained from the spleen or bone-marrow of the organ donor. After separation, the cells are frozen for later use. Reconstitution of mice is monitored by the presence of human T cells in blood samples obtained from retroorbital puncture (flow cytometry) and by detection of human IgG (ELISA). Mice were considered humanized when we detected more than 0.5% human CD3+ cells in the blood. Results: In a previous work, 13 arterial segments from 13 different donors undergoing various surgical procedures were grafted successfully into 13 SCID/beige mice. The arteries were of very variable quality and were difficult to match in size with the infrarenal aorta. In the present series, 23 suitable arterial segments have been obtained from the mesentery of 3 cadaveric donors. The quality of the arteries was excellent and there has been no problem in applying the sleeve technique at the proximal and distal anastomosis. One mouse died on the operating table, 3 during the first 24 hours (thrombosis). One mouse died day 7 (thrombosis). Ten of the mice received 3x107 human spleen cells i.p. one week after the arterial graft, in four of them the spleen cells were from the same donor as the artery (autologous). One of these mice died 5 days after from bowel obstruction. All mice receiving spleen cells showed circulating human CD3+ cells 2 weeks after injection. The mice were sacrificed 5 weeks after the arterial graft. SCID/beige mice reconstituted with allogeneic spleen cells showed infiltration of human T lymphocytes in the arterial wall with a considerable intimal thickening and proliferation of smooth muscle cells. In mice that received either autologous spleen cells or no cells, a normal vascular anatomy was observed without any lymphocyte infiltration or intimal thickening. No lymphomas were observed. Conclusion: Human mesenteric arteries transplanted into SCID/Beige mice humanized by human allogeneic spleen cells constitute an excellent preclinical model for the study of treatment of CVR under human allograft conditions.