CD133 is a unique stem cell marker with a molecular weight of 120kDa and five transmembrane regions. It was named AC133. In 2000, the 7th International Working Conference on Human Leukocyte Differentiation Antigens (7th International Workshop on Human Leucocyte) was held in Harrogate, England. Differentiation Antigens (HLDA7) was officially named CD133. CD133 antigen can be recognized by three kinds of CD133 antibodies: clones AC133, 293C3 and AC141. AC133 directly binds to the CD133 / 1 glycosylated antigen epitope and can be used to analyze and sort CD133 + cells from peripheral blood, bone marrow, cord blood, and other tissues. The monoclonal antibodies 293C3 and AC141 recognize the epitope CD133 / 2, which is mainly used for the fluorescence staining of CD133 + cells after MACS sorting. In most cases, CD133 / 1 and CD133 / 2 recognize the same kind of cells, but there is a difference in expression intensity, but in myelodysplastic syndrome (myelodysplastic syndrome, MDS) and certain acute myeloid leukemia (acute myeloid leukemia, AML) It was found that CD133 / 1 and CD133 / 2 were expressed differently, or the normal expression intensity was disordered
In the hematopoietic system, CD133 is expressed on 35-75% of CD34 + cell subsets, mainly found in human fetal liver, bone marrow, cord blood, peripheral blood CD34bright stem cells and precursor cells, including CD34bright, CD38neg / dim, HLA-DRneg / dim, CD90 + and CD117 + cells. In addition, CD133 is also found in a small portion of CD34-cells in these tissues and is not expressed on mature blood cells. Unlike CD34 antigen, CD133 is in late progenitor cells, such as pre-B cells, erythroid colony forming unit (colony forming unit-erythrocyte, CFU-E), and granuloid colony forming unit (colony forming unit-granulocyte, CFU-G) Does not express. It has recently been found that CD133 is also expressed in endothelial precursor cells, fetal neural stem cells and developing epithelial cells.
(1) The application of CD133 sorting in the study of hematopoietic initiating cells The ability of hematopoietic cells (Long term repopulation cells, LTRC) is the most primitive hematopoietic cell, which can be transplanted to the host for a long time. In addition, recent studies have found that LTC-IC is mainly found in the AC133 + CD34 + subgroup. A small group of CD133 + / CD34- cells also have long-term proliferation potential. Therefore, AC133 is considered to be the original hematopoietic cell population (including CD34-cell) markers.
The cord blood CD34 and CD133 sorting studies by Rappold et al. Found that the expansion potential of CD34 + cells in the same specimen was lower than that of CD133 + cells. Therefore, AC133 sorting may be better than CD34 sorting.
Research on stem cell plasticity CD133 is a highly conserved antigen with unclear functions. In order to study the characteristics of CD133 + cells, Handgretinger et al. Used MACS technology to purify CD133 + stem cells from healthy adult volunteers after G-CSF mobilization, with a purity of 94%. Adding Flt3 / Flk2 ligand and IL-6 to culture the purified CD133 + cells in vitro, the adherent cell population will appear after 6 weeks. These cells did not express CD34 or CD133, nor did they express markers of endothelial cells, mesenchymal cells, and dendritic cells. After incubation with stem cell factor (Stem cell factor, SCF), non-adherent cells partially expressed CD133, but CD34 was negative. These non-adherent CD34-cells are highly viable in non-diabetic / severe combined immunodeficiency (Non obese diabetes / Severe combined immunodeficiency disease, NOD / SCID) mice. After transplantation, NOD / SCID mouse bone marrow mononuclear cells or CD133+ stem cells will be transplanted in the second recipient. CD133 + hematopoietic precursor cells can produce CD133-CD34-adherent cell populations, and these cells can form CD133 + CD34-stem cell populations with high planting potential in NOD / SCID mice, indicating that hematopoietic precursor cells have plasticity. Poznansky et al. Used MACS technology to sort out bone marrow AC133 positive cells or CD34 positive CD2 negative cells, and used a three-dimensional spatial structure to reconstruct the thymus environment. The sorted cells were cultured in an artificial matrix. After 14 days, the study found that T cells could be regenerated (equivalent to human fetal thymus cells), and gradually mature and have functions.
(3) Phenotype analysis Buhring and others used MiniMACS to sort bone marrow AC133 and CD34 positive cells, and then performed immunofluorescence detection. It was found that CD34 + AC133 + contained the most primitive precursor cells and myeloid precursor cells; CD34 + AC133- cells were mainly B cells and advanced erythroid precursor cells. 0.2-0.7% AC133 positive cells do not express CD34. Among AC133-positive cells, most of them were AC133 weakly expressed, and 0.1-0.7% AC133 was highly expressed. The phenotype of AC133 weakly expressing cells: CD71low /-, CD38low, CD117 +, CD135 + does not express CD10; the phenotype of AC133 strongly expressing cells: CD71-, CD117-, CD10-, CD38low, CD135 +, HLA-DRhigh, CD45 + (these cells are relatively small, But Hoechst 33342 staining was negative). CD34 + / CD38- bone marrow cells all express AC133. Receptor coexpression analysis: angiopoietin receptors (angiopoietin receptors): TIE (67.6%) and TEK (36.8%); vascular endothelial growth factor receptors (vascular endothelial growth factor receptors): FLT1 (7%), FLT4 (7%), FLT4 3.2%), KDR (10.4%); receptor tyrosine kinase (receptor tyrosine kinase): HEr-2 (15.4%), FLT3 (CD135; 77.6%).
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