Hematopoietic Stem Cell Markers

Hematopoietic stem cells (HSCs) have long been thought to originate from hemangioblasts, the mesoderm derived cells formed during early embryonic development, which also give rise to endothelial stem cells. However, the hemogenic endothelium (a specialized endothelial cell population) has more recently been proposed to generate hematopoietic stem cells via an endothelial to hematopoietic transition. In adult mammals, hematopoietic stem cells reside mainly in the bone marrow, where they represent approximately 0.01% of the total cell population. Hematopoietic stem cells are also found in low numbers (around 1 in 100,000 cells) in the peripheral blood and are enriched in umbilical cord blood and the placenta. The role of hematopoietic stem cells is to generate all of the cells of the blood, a process termed hematopoiesis. To achieve this, hematopoietic stem cells initially differentiate into either common lymphoid progenitor (CLP) cells or common myeloid progenitor (CMP) cells, which then follow different developmental pathways in response to specific stimuli. Cells with a lymphoid lineage include T lymphocytes, B lymphocytes, and natural killer (NK) cells, while cells with a myeloid lineage include eosinophils, basophils, neutrophils, and erythrocytes (red blood cells), as well as monocytes, dendritic cells, macrophages, and megakaryocytes (which give rise to platelets). The cluster of differentiation antigen CD34 is one of the best known markers of human hematopoietic stem cells. It is measured in combination with other cell surface proteins to identify hematopoietic stem cells and early progenitor subsets, but is lacking from mature blood cells, which instead express lineage (Lin) specific markers. Human hematopoietic stem cells are commonly defined as CD34⁺ CD38^- CD45RA^- CD90⁺ Lin^-, while CLP cells are identified as CD34⁺ CD38^- CD45RA⁺ CD90^- Lin^- and CMP cells as CD34⁺ CD38⁺ CD45RA^- Lin^-. Mouse hematopoietic stem cells may be defined as CD34^- CD48^– CD117⁺ CD150⁺ Sca-1⁺ Lin^–. Hematopoietic stem cells have broad clinical utility. Bone marrow transplantation has been used for decades to replenish healthy blood cells following chemotherapy or radiotherapy to treat cancer, as well as to correct deficiencies in the hematopoietic system due to conditions such as aplastic anaemia, sickle cell anaemia, or severe combined immunodeficiency (SCID). Within the transplantation setting, umbilical cord blood offers the advantages of easier collection and decreased risk of graft-versus-host disease following allogeneic transplants. In addition, hematopoietic stem cells are being investigated as a means of treating conditions such as multiple sclerosis, Alzheimer’s disease, and diabetes. We offer a large range of hematopoietic stem cell markers including CD34 antibodies, CD38 antibodies, and c-Kit antibodies, covering various host species, formulations, and conjugates.