Human CD34+ hematopoietic stem cells capable of multilineage engrafting NOD/SCID mice express flt3 : Distinct flt3 and c-kit expression and response patterns on mouse and candidate human hematopoietic stem cells

• The cytokine tyrosine kinase receptors c-kit and flt3 are expressed and function in early mouse and human hematopoiesis. Through its ability to promote ex vivo expansion and oncoretroviral transduction of primitive human hematopoietic progenitors, the flt3 ligand (FL) has emerged as a key stimulator of candidate human hematopoietic stem cells (HSCs). However, recent studies in the mouse suggest that though it is present on short-term repopulating cells, flt3 is not expressed on bone marrow long-term reconstituting HSCs, the ultimate target for the development of cell replacement and gene therapy. Herein we demonstrate that though only a fraction of human adult bone marrow and cord blood CD34+long-term culture-initiating cells (LTC-ICs) express flt3, most cord blood lymphomyeloid HSCs capable of in vivo reconstituting nonobese diabetic/severe combined immunodeficiency (NOD/SCID) mice are flt3+. The striking difference in flt3 and c-kit expression on mouse and candidate human HSCs translated into a corresponding difference in flt3 and c-kit function because FL was more efficient than SCF at supporting the survival of candidate human HSCs. In contrast, SCF is far superior to FL as a viability factor for mouse HSCs. Thus, the present data provide compelling evidence for a contrasting expression and response pattern of flt3 and c-kit on mouse and human HSCs.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Hematologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Hematology (hsv//eng)

Nyckelord

Animals

Antigens

CD34

Bone Marrow

Cell Survival

Fetal Blood

fms-Like Tyrosine Kinase 3

Graft Survival

Hematopoietic Stem Cell Transplantation

Hematopoietic Stem Cells

Humans

Lymphopoiesis

Membrane Proteins

Mice

SCID

Myelopoiesis

Proto-Oncogene Proteins

Proto-Oncogene Proteins c-kit

Receptor Protein-Tyrosine Kinases

Stem Cell Factor

Transplantation

Heterologous

MEDICINE

MEDICIN

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