In adults, the bone marrow compartment contains hematopoietic stem cells (HSCs) which can differentiate into progenitors with more restricted lineage potential and generate all cellular elements of the blood. HSCs for
stem cell transplantation can be obtained by bone marrow collection, mobilization into peripheral blood followed by
apheresis, or use of stem cells from cord blood. Currently,
hematopoietic stem cell transplantation (SCT) is used to treat patients with various
hematological diseases. Although substantial progress has been made, a number of challenges can limit the efficacy of HSC
transplantation, including the occurrence of
graft-versus-host disease (GvHD) in allogeneic
stem cell transplantation (ASCT), the susceptibility of patients to
opportunistic infections and relapse of
malignancies after SCT. Recent studies indicate that small interfering RNAs (siRNAs) can specifically and efficiently interfere with the expression of oncogenic genes. Therefore, the possibility of interfering with the expression of these
proteins in hematopoietic cells may offer a new option to correct cell differentiation and function. In addition to the generation of T cells restricted by nonself MHC as reviewed by Stauss and colleagues in 1999, the modulation of
NK cell receptor expression and T-cell activation is a new strategy that could limit GvHD. This chapter reviews the recent advances in ASCT and discusses the potential application of RNAi in hematopoietic cells.