Long-term outcome of the fetal adrenal gland transplantation in rats

Three experimental groups have been constructed to evaluate the long-term o utcome of fetal adrenal transplantation in rats. In Group 1 (n = 10), rats underwent bilateral adrenalectomy. In Group 2 (n = 10), rats underwent a sh am procedure which included flank incision and arterial canulization. In Gr oup 3 (n = 20), a left adrenalectomy was performed followed immediately by transplantation of a fetal adrenal graft into the greater omentum and marke d with a prolene suture (Stage 1). One year later, the right adrenal gland of the recipient was removed followed by a determination of the fetal adren al graft function (Stage 2). Craft function was evaluated by measuring ACTH and corticosterone levels; and a histologic examination of the transplante d fetal adrenal gland was obtained at autopsy. In Group 1, all the rats died within first 8 hours, following bilateral adr enalectomy. In Group 2, and Group 3, all rats survived after Stage 1 operat ion. During the Stage 2 operation, it was observed that three rats (15 %) h ad neither fetal adrenal transplant nor prolene suture, seven rats (35 %) h ad a well vascularized and developed fetal adrenal graft and a prolene sutu re. There was no visible fetal adrenal graft but the prolene suture was pre sent in the remaining rats (50 %) in Group 3. After removal of the right ad renal gland (6 and 12 hours later), the mean plasma level of ACTH increased with a decline in mean serum corticosterone level in Group 3 compared to t he sham-operated animals (p < 0.001). In spite of visible, and viable trans plants, all rats died within 48 hours following Stage 2 operation. The mean weight of the fetal adrenal transplant showed a sixteen-fold increase comp ared to the initial weight (p < 0.001) and histologic examination showed al l 3 zones of adrenal cortex, but there were no medullary cells noted. Although the transplanted fetal adrenal grafts survived, their hormonal fun ction was not enough to maintain host viability. Based on these results it is concluded that, insufficiency of the transplanted fetal adrenal gland ma y be secondary to either graft rejection or suppression of the transplanted tissue by the functional recipient adrenal despite the fetal adrenal trans plant survival.