Hematopoietic stem cells are capable of self-renewal or differentiation when they divide. Three types of cell divisions exist. A dividing stem cell may generate 2 new stem cells (symmetrical renewal division), or 2 differentiating cells (symmetrical differentiation division), or 1 cell of each type (asymmetrical division). This study was aimed to explore an efficient and stable method to distinguish the way of cell division in hematopoietic stem cells. Previous studies showed that the distribution of Numb in a cell could be used to distinguish the type of cell division in various kinds of cells. Therefore, the distribution of Numb protein was detected by immunofluorescence in mitotic CD48(-)CD150(+)LSK cells of mice exploring the relationship between Numb protein and centrosomes. Since CD48 positive marks the HSC that have lost the ability to reconstitute the blood system in mice, CD48 marker could be used to distinguish cell fate decision between self-renewal and differentiation as a living marker. In this study, the CD48(-)CD150(+)LSK cells were sorted from bone marrow cells of mice and the cells were directly labeled with Alexa Fluor (AF) 488-conjugated anti-CD48 antibody in living cultures. After 3 days, the percentage of AF488(+) cells was evaluated under microscope and by FACS. Then colony forming cell assay (CFC) was performed and the ability of cell proliferation were compared between AF488(+) and AF488(-) cells. The results showed that Numb could be used to distinguish different cell division types of hematopoietic stem cells, which was symmetrically or asymmetrically segregated in mitotic CD48(-)CD150(+)LSK cells. The self-labeled fluorochrome could be detected both by FACS as well as microscope. There were about 40% AF488(+) cells after 3 day-cultures in medium titrated with self-labeled AF 488-conjugated anti-CD48 antibody, and the results were consistent between confocal fluorescence microscopy and flow cytometry analysis. The colony forming ability of AF488(+) cells was significantly higher than that of AF488(-) cells (P < 0.05). The proliferation ability of AF488(-) cells was also significantly higher than AF488(+) cells (P < 0.05). It is concluded that the expression of CD48 can distinguish cell division of hematopoietic stem cells and can be used as a live marker for the loss of stemness. In comparison with the Numb protein staining, this method can be used in living cells, thus provides greater convenience for subsequent cell culture studies and cell transplantation experiments.
Animals ; Antigens, CD ; metabolism ; Biomarkers ; metabolism ; CD48 Antigen ; Cell Division ; Cells, Cultured ; Hematopoietic Stem Cells ; cytology ; metabolism ; Mice ; Mice, Inbred C57BL

BACKGROUNDThe SLAM family recently has been reported to show an important biological role in lymphocyte development and immunological function, and it is efficient to highly purify hematopoietic stem cells using a simple combination of SLAM family members. To elucidate the presence of this family on acute lymphoblastic leukemia (ALL), as well as its relationship with the leukemia-initiating potential, we analyzed the expression pattern of this family members on human ALL progenitor cells, combined with serial xenotransplantation assay.

METHODSExpression analysis was carried out by flow cytometry. We combined the expression pattern of human CD(150), CD(244) and CD(48) with serial xenotransplantation of B-ALL progenitor cells to indicate their relationship.

RESULTSCD(48) and CD(244) were expressed on most B-ALL progenitor cells, the percentage being (93.08 ± 6.46)% and (63.37 ± 29.31)%, respectively. Interestingly, the proportion of CD(150)(+) cells declined obviously in engrafted cases ((24.94 ± 7.32)%) compared with non-engrafted cases ((77.54 ± 5.93)%, P < 0.01), which indicated that only blast cells with low percentage of CD(150)(+) population were able to reconstitute leukemia into primary, secondary and tertiary NOD/SCID mice.

CONCLUSIONSSLAM family members are present on B-ALL progenitor cells and the leukemia-initiating potential of leukemic blasts is correlated negatively with the proportion of CD(150)(+) cells, the percentage of which can serve as a useful predictor for engraftment success of B-ALL to immune deficient mice.

Adolescent ; Adult ; Aged ; Animals ; Antigens, CD ; analysis ; CD48 Antigen ; Child, Preschool ; Female ; Flow Cytometry ; Humans ; Infant ; Male ; Mice ; Mice, Inbred NOD ; Mice, SCID ; Middle Aged ; Precursor Cell Lymphoblastic Leukemia-Lymphoma ; blood ; Receptors, Cell Surface ; analysis ; Receptors, Immunologic ; analysis ; Signaling Lymphocytic Activation Molecule Family ; Signaling Lymphocytic Activation Molecule Family Member 1 ; Transplantation, Heterologous

OBJECTIVETo detect the expression profile of NK ligands in acute leukemia cell lines and investigate the differential expression pattern between acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML).

METHODSUsing quantitative real-time PCR, 23 NK ligands (MICA, MICB, ULBP-1, ULBP-2, ULBP-3, ULBP-4, HLA-E, HLA-G, CD48, NBTA, HLA-F, LLT-1, PVR, Nectin2, CD72, CD80, ICAM-1, LFA-3, CRACC, Fas, DR4, DR5, TNFR1) were detected in 6 acute leukemia cell lines, including 3 ALL cell lines (CEM, Jurkat T, Reh) and 3 AML cell lines (HL-60, KG-1a, NB4), respectively. Independent-samples t test analysis was performed to determine statistical significance.

RESULTSUsing β-actin as reference gene, the relative expression results showed that the expression of 4 NK ligands between ALL and AML is significantly different. Specifically, the level of ULBP-2 is higher in ALL (CEM: 1, Jurkat T: 0.617, Reh: 0.246) than that in AML (HL-60: 0.000, KG-1a: 0.003, NB4: 0.000)(P = 0.047). However, the expressions of CD48, PVR(PVR-1, PVR-2) and DR4 is higher in AML (HL-60: 13.987, 4.403, 10.334, 8.711; KG-1a: 5.387, 2.900, 7.315, 4.512; NB4: 7.763, 3.248, 7.049, 6.127) than that in ALL (CEM: 1, 1, 1, 1; Jurkat T: 2.035, 1.553, 3.888, 0.449; Reh: 1.559, 0.000, 0.000, 1.304) (P = 0.044, 0.014, 0.014, 0.011). And there're no significant differences between the rest 19 NK ligands.

CONCLUSIONSULBP-2, CD48, PVR and DR4 might play an important role in the distinct mechanisms in leukemogenesis between ALL and AML and could be potential targets for diagnosis and treatment.

Acute Disease ; Antigens, CD ; genetics ; metabolism ; CD48 Antigen ; Cell Line, Tumor ; GPI-Linked Proteins ; genetics ; metabolism ; HL-60 Cells ; Humans ; Intercellular Signaling Peptides and Proteins ; genetics ; metabolism ; Leukemia ; genetics ; metabolism ; Leukemia, Myeloid, Acute ; genetics ; metabolism ; Ligands ; Membrane Proteins ; genetics ; metabolism ; Precursor Cell Lymphoblastic Leukemia-Lymphoma ; genetics ; metabolism ; Real-Time Polymerase Chain Reaction ; Receptors, TNF-Related Apoptosis-Inducing Ligand ; genetics ; metabolism ; Receptors, Virus ; genetics ; metabolism