Simultaneous xenotransplantation of human Graves' thyroid tissue and autologous bone marrow cells in severe combined immunodeficient mice: successful reconstitution of human Graves' hyperthyroidism.

Human thyroid xenografts and the autologous bone marrow (BM) cells from five patients with Graves' disease (GD) were simultaneously xenografted into severe combined immunodeficient (SCID) mice to study the role of BM cells for the perpetuation of human GD autoimmunity and hyperthyroidism. All SCID mice engrafted with thyroid tissue (TH) alone, TH + autologous peripheral blood mononuclear cells, and TH + autologous BM cells produced similar amounts of human IgG; however, the production in TH + BM-engrafted mice peaked later than that of mice without BM. Production of thyroperoxidase antibody and thyroglobulin antibody in TH + BM-bearing SCID mice peaked in later weeks after xenografting than in those without BM. Moreover, human Graves' hyperthyroidism was actually reconstituted in TH + BM-transplanted mice; this was confirmed by (A) significantly higher levels and longer periods of secreting thyroid-stimulating antibody than those in mice without BM engraftment. (B) persistent hyperthyroxinemia up to the end of the experiment. (C) extremely high radioidine uptake of the xenografted thyroid tissue, and (D) histological findings of the maintenance of hyperplastic change of the xenografted thyroid epithelial cells. Human BM stem cells (CD34) were identified only in mice with TH + BM xenografts when analyzed by immunohistochemistry. In conclusion, (A) we have developed an animal model for human hyperthyroid GD by simultaneous xenotransplantation of GD thyroid tissue plus autologous BM cells into SCID mice, and (B) BM cells have a crucial role for perpetuating human GD autoimmunity and hyperthyroidism in this system.