Vectors and target cells for gene therapy of blood diseases

Gene therapy is the introduction of genetic material into somatic cells in order to correct a genetic defect or provide a new therapeutic function. Since the advent of gene transfer technologies, hematopoietic stem cells and hematologic diseases have been the focus of intensive efforts: blood cells can be removed from the body easily and reintroduced following ex vivo manipulation. The major applications of gene therapy for hematologic diseases fall into four major categories: genetic marking of hematopoietic progenitor cells, replacement of a missing or defective gene in an inherited deficiency, gene therapy of neoplastic disorders, intracellular immunization against human immunodeficiency virus (HIV) infection or other viral disorders. This review summarizes the different methods used for gene delivery and focuses on target cells for hematologic diseases amenable to gene therapy.