In part 5, Prof. Caplan discusses: Mesenchymal stem cells produce huge quantities of bio-molecules, some of which are immunosuppressive; MSCs put up a curtain of molecules around themselves that allows donor (allogeneic) MSCs to be transplanted into a recipient free from immune response; The bio-chemical mechanism of how MSCs shield themselves from host T Cells; Allogeneic hematopoietic stem cell business model; Treatment of graft vs. host disease in children and adults; Treatment of Crohn’s disease with allogeneic mesenchymal stem cells.