Somatic gene therapy into hematopoietic cells. Current status and future implications

Retroviral-mediated gene transfer is a powerful tool for introducing and expressing single genes into hematopoietic cells. There has clearly been a tremendous amount of progress in the development of retroviral gene transfer technology over the past 7 years. This is evidenced by improvements in transduction efficiency and expression in animals and its selected use currently in human trials. Critical experiments that must yet be performed relate to the in vitro identification, transduction, and expansion of pluripotent hematopoietic stem cells in vitro as well as the development of retroviral vectors that maximize in vivo expression in the desired target cells.