Vectors with the potential for stable transgene integration are
widely used in basic hematology and clinical trials of gene medicine.
In basic research, both gain-of-function and loss-of-function
situations of individual genes can be created by gene transfer,
leading to a wide range of applications in developmental biology,
stem cell biology, immunology, leukemia research, and human
genetics. With the first evidence of successful modification of
murine hematopoietic cells using retroviral gene vectors (1, 2),
researchers have also explored the therapeutic potential of this
approach. To date, the emerging discipline of gene therapy is a
highly diversified field that offers entirely novel approaches to
treat a great variety of human diseases (3). All hematopoietic cell
types are of major interest in this context, since the modification
of the hematopoietic stem cell population may potentially give
rise to a completely transgenic hematopoiesis with the potential
to cure genetic disorders or fight severe chronic infections, and
the targeting of mature cells such as lymphocytes or antigen-presenting
dendritic cells offers all types of transient and semipermanent
modifications of the immune system