Mesenchymal stem cells are known to possess a variety of immune modulatory activities such as suppression of allogeneic responses, as well as induction of T regulatory cells. Mechanisms include expression of IDO and HLA-G. Mesenchymal stem cells have been demonstrated effective in patients with heart failure and are clinically in trials for graft versus host disease.
The current patent teaches the use of mesenchymal stem cells as antigen presenting cells. This means that the mesenchymal stem cells can be used not only for blocking immune response but also for activating it, when the cells are properly stimulated.
In the claims, restriction is not made to T effector or T regulatory, but only on the interaction between the mesenchymal stromal cell (another way of saying mesenchymal stem cell). The first claim states:
"An isolated interferon.gamma. (IFN.gamma.) stimulated stromal antigen-presenting cell wherein said isolated stromal antigen-presenting cell expresses MHC II and presents antigen in association with said MHC II, wherein said antigen is recognizable by T cells."
Given Dendreon's success using autologous antigen pulsed dendritic cells as cancer vaccines, it will be interesting to see if the current patent also finds similar uses.