Engraftment potential into NOD/SCID mice of CD34+ cells derived from human fetal liver as compared to fetal bone marrow.

BACKGROUND AND OBJECTIVES We hypothesized that qualitative or quantitative differences in hematopoietic stem cells from fetal liver (FL) and fetal bone marrow (FBM) may be the cause of their organ specificity. DESIGN AND METHODS To analyze possible differences in vivo, we compared the engraftment potential of equal numbers of CD34+ cells isolated from human FL or FBM into immunodeficient NOD/SCID mice. RESULTS Mice showing engraftment following transplantation of CD34+ cells from FL demonstrated 14% (range 2-76%) CD45+ cells of human origin in the bone marrow compared to significantly lower levels of engraftment (4%, range 2-20%, p < 0.04) of FBM CD34+ cells. Likewise, the percentage of CD34+ CD38- cells in FBM was 4 times lower than the percentage in FL (1.4+/-0.9% and 5.6+/-0.7%, respectively). Similar organ distribution of engrafted human cells was found. Subset analysis of human cells in bone marrow of engrafted mice revealed identical distribution of the lymphoid, myeloid and erythroid lineages after transplantation of CD34+ cells from FL or FBM. INTERPRETATION AND CONCLUSIONS The FL CD34+ cells showed a four-fold higher content of the CD34+ CD38- subset coinciding with a four-fold higher engraftment of CD34+ cells into NOD/SCID mice. Since the organ distribution and differentiation potential of the cells engrafted were similar, we concluded that CD34+ hematopoietic cells derived from FL and FBM have quantitatively different, but qualitatively the same potential for engraftment into NOD/SCID mice.