Figure 2.

Experimental setup. The design of the mouse study follows the well established, sex-mismatched diallelic (CD45.2/Ly5.2 into CD45.1/Ly5.1) serial bone marrow transplantation model.^7,8,21 This model had enabled us to discover serious side effects of γ-retroviral gene transfer before their occurrence in clinical gene therapy studies, in particular the phenomenon of induced clonal dominance. Shortly, Lin– bone marrow cells from male donors were transduced with the promoter-deprived γ-retroviral self-inactivating vector and transplanted into female mice after TBI (10 Gy). Seven months later, hematopoietic organs of these mice were thoroughly investigated before secondary transplantation into irradiated mice took place. After a further observation period of 5 months, final analysis of hematopoietic organs, including molecular analysis of vector insertion sites, was performed.