AUTOIMMUNE-DISEASES AS STEM-CELL DISORDERS

Using an animal model for insulin-dependent diabetes mellitus (IDDM), the NOD mouse, we have demonstrated that allogeneic bone marrow transp lantation (BMT) has a preventative effect on IDDM, and that a combined transplantation of pancreas and bone marrow can be used to treat IDDM . We have also shown that BMT has a curative effect on systemic autoim mune diseases in (NZB x NZW) F-1, BXSB, and (NZW x BXSB) F-1 mice but not in MRL/lpr mice. Since MRL/lpr mice possess abnormal radioresistan t hemopoietic stem cells (HSCs), they suffer a relapse 5 months after BMT. Recently, me have found that major histocompatibility complex (MH C)-matched stromal cells in the bone marrow are essential to the suppo rt of HXCs in the Co phase. We therefore attempted to treat autoimmune diseases in MRL/lpr mice by the transplantation of stromal cells with HSCs. Transplantation of HSCs with bone to recruit stromal cells was indeed found to have a curative effect on autoimmune diseases in the m ice. These results indicate that BMT with bone graft will become a val uable strategy for the treatment of patients with both systemic and or gan-specific autoimmune diseases. To prove that autoimmune diseases or iginate from defects in HSCs, we transferred the HSCs of autoimmune-pr one mice to normal mice. BMT or transplantation of stem-cell concentra tes induced organ-specific and/or systemic autoimmune diseases in [NOD -->C3H/HeN] and [(NZW x BXSB)F-1-->C3H/HeN or C57BL/6J] chimeric mice. These results provide direct evidence that the etiopathogenesis of au toimmune diseases, including both organ-specific and systemic autoimmu ne diseases, is attributable to defects in the HSCs themselves. We fur ther provide that various intractable diseases such as non-insulin-dep endent diabetes mellitus and chronic nephritis (focal glomeruloscleros is) are also organ-specific autoimmune diseases, and that BMT can be u sed to treat them.