Comparative study of hemopoietic precursors from fetal and adult bone marrow: utilization of stem cells derived from miscarriages

A quantitative assessment of the content of hematopoietic stem cells in mouse and human endosteal-bone marrow: a simple and rapid method for the isolation of mouse central bone marrow

BACKGROUND

Isolation of bone marrow cells, including hematopoietic stem cells, is a commonly used technique in both the research and clinical settings. A quantitative and qualitative assessment of cell populations isolated from mouse and human bone marrow was undertaken with a focus on the distribution of hematopoietic cells between the central bone marrow (cBM) and endosteal bone marrow (eBM).

METHODS

Two approaches to cBM isolation from the hind legs were compared using the C57BL/6J and BALB/cJ strains of laboratory mice. The content of hematopoietic stem cells in eBM was compared to cBM from mice and human fetal bone marrow using flow cytometry. Enzymatic digestion was used to isolate eBM and its effects on antigen expression was evaluated using flow cytometry. Humanized immunodeficient mice were used to evaluate the engraftment of human precursors in the cBM and eBM and the effects of in vivo maturation on the fetal stem cell phenotype were determined.

RESULTS

The two methods of mouse cBM isolation yielded similar numbers of cells from the femur, but the faster single-cut method recovered more cells from the tibia. Isolation of eBM increased the yield of mouse and human stem cells. Enzymatic digestion used to isolate eBM did, however, have a detrimental effect on detecting the expression of the human HSC-antigens CD4, CD90 and CD93, whereas CD34, CD38, CD133 and HLA-DR were unaffected. Human fetal HSCs were capable of engrafting the eBM of immunodeficient mice and their pattern of CD13, CD33 and HLA-DR expression partially changed to an adult pattern of expression about 1 year after transplantation.

CONCLUSIONS

A simple, rapid and efficient method for the isolation of cBM from the femora and tibiae of mice is detailed. Harvest of tibial cBM yielded about half as many cells as from the femora, representing 6.4 % and 13 %, respectively, of the total cBM of a mouse based on our analysis and a review of the literature. HSC populations were enriched within the eBM and the yield of HSCs from the mouse and human long bones was increased notably by harvest of eBM.

Analysis and characterization of hematopoietic progenitor cells from fetal bone marrow, adult bone marrow, peripheral blood, and cord blood

Hematopoietic stem cell transplantation has been increasingly used to replace a defective hematopoietic system and to treat various genetic defects as well as malignant diseases. However, the limitations of conventional bone marrow transplantation have stimulated an intense interest in exploring the use of alternative sources of hematopoietic stem cells, including peripheral blood mononuclear cells (PBMC) and cord blood (CB). A major investigative effort of our laboratory has been focused on evaluating fetal bone marrow (FBM) for transplantation. The current study compares and characterizes the functional and phenotypic characteristics of FBM, CB, adult bone marrow (ABM), and PBMC by clonogenicity assays, immunogenicity, and the quantification of progenitor cells. There was a striking difference in the proportion of CD34+ cells in FBM, ABM, PBMC, and CB (24.6%, 2.1%, 0.5%, and 2.0%, respectively). The clonogenic potential, as measured by colony forming unit in culture (CFU-C) assay, was significantly higher in FBM when compared with ABM, PBMC, and CB (202.5, 73.5, 40.8, and 65.5 colonies/10(5) cells, respectively). There was a significant decrease in proliferative responsiveness in mixed lymphocyte reaction (MLR) assay of FBM and CB compared with ABM and PBMC. These observations indicate that each source of hematopoietic stem cells has different intrinsic properties closely correlated with ontogenetic age that is a vital determinant for phenotypic characteristics, lineage commitments, immunogenicity, and proliferative potentials.

Gestational age changes in circulating CD34+ hematopoietic stem/progenitor cells in fetal cord blood

OBJECTIVE

We sought to evaluate the frequency of CD34+ hematopoietic progenitor/stem cells across gestation and the proliferative response of early versus late gestational age fetal blood to growth factor stimulation.

STUDY DESIGN

Fetal blood samples were obtained at 17 to 41 weeks' gestational age. The mononuclear cell population was separated by red blood cell lysis. The frequency of CD34+ cells within the lymphocyte-monocyte light scatter gate and the expression of CD34 by colony-forming cells of different types were determined by fluorescence-activated cell sorting. The growth response of colony-forming cells to varying concentrations of defined growth factors (interleukin-3, interleukin-6, granulocyte-macrophage colony-stimulating factor, stem cell factor, and erythropoietin) was determined, as well as the frequency of burst-forming units erythroid, colony-forming units granulocyte-macrophage, and total colony-forming cells. Samples from 17 to 24 weeks' gestation (early) were compared with those of 39 to 41 weeks' gestation (late).

RESULTS

The frequency of CD34+ cells in early fetal blood (17 to 24 weeks' gestation) was 4.9-fold higher (6.4% vs 1.3%, p < 0.002) than term gestation (37 to 41 weeks' gestation) and declined linearly with gestational age (p < 0.0001). When gestational ages were grouped into 4-week blocks (17 to 20, 21 to 24, 25 to 28, 29 to 32, 33 to 36, and >37 weeks), statistically significant changes in the frequency of CD34+ cells did not occur until after 28 weeks' gestation. By cell sorting, >99% of all colony-forming cells were contained within the CD34+ population at all gestational ages tested. Compared with term, the frequency of colony-forming cells was significantly greater in early fetal blood (burst-forming units erythroid [18.1-fold, p < 0.0001], colony-forming units granulocyte-macrophage [2.9-fold, p <0.001], and total colony-forming cells [9.4-fold, p < 0.0001]). However, when the frequency of colony-forming cells was corrected for the frequency of CD34+ cells, only the number of burst-forming units erythroid remained significantly greater in early fetal blood. The relative size of the colonies formed by individual progenitors from early fetal blood was greater than those from term samples.

CONCLUSIONS

From 17 to 41 weeks' gestation the frequency of CD34+ cells in fetal blood, which includes hematopoietic progenitors and stem cells, decreases. This decline occurs during the transition from hepatic to bone marrow hematopoiesis. Early fetal blood, with a higher circulating frequency of progenitor/stem cells and proliferative capacity, may be a preferable target for gene therapy.