Stem cells are primal cells common to all multi-cellular organisms that retain the ability to renew themselves through cell division and can differentiate into a wide range of specialized cell types. The three broad categories of mammalian stem cells exist: embryonic stem cells, derived from blastocytes, adult stem cells, which are found in adult tissues, and cord blood stem cells, which are found in the umbilical cord. In a developing embryo, stem cells are able to differentiate into all of the specialized embryonic tissues. In adult organisms, stem cells and progenitor cells act as a repair system for the body, replenishing specialized cells.

4G10.3

• a biochemical and immunological marker of limbal basal cells, hypothesized to be corneal epithelial stem cells. PMID: 1730535

AA4

• the fetal stem cell marker, is expressed in three major cell types: vascular endothelial cells, aorta-associated hematopoietic clusters, and primitive fetal liver hematopoietic progenitors. PMID: 10403644

AC133

• a novel marker for human hematopoietic stem and progenitor cells. PMID: 9389720

Bcrp/ABCG2

• stem cell marker. PMID: 15044468
• a marker for side population stem cells, is expressed in human heart. PMID: 16116030

c-Mpl

• thrombopoietin receptor, c-Mpl, is a selective surface marker for human hematopoietic stem cells. PMID: 16480521

CD9

• a surface marker on mouse and rat male germline stem cells. PMID: 12954725

CD34

• the main marker of the hematopoietic stem cell population. PMID: 10494177, PMID: 7519070
• a marker for pluripotent stem cells also present on lineage-committed hematopoietic progenitors from bone marrow and a subpopulation of immature thymocytes. PMID: 7505122

CD133 (Prominin-1)

• a neural stem cell surface marker. PMID: 16302851, PMID: 15976444
• a plasma membrane marker found in several types of somatic stem cells, including hematopoietic and neural stem cells. PMID: 15917475
• a neural and hematopoietic stem cell marker, is expressed in adult human differentiated cells and certain types of kidney cancer. PMID: 15558321
• a novel marker for human prostatic epithelial stem cells. PMID: 15226377
• the surrogate stem cell marker. PMID: 17332245
• a plasma membrane marker found in several types of somatic stem cells, including hematopoietic and neural stem cells. PMID: 15917475

CDCP1

• a novel stem cell marker, is expressed in hematopoietic cell line K562 but not in Jurkat. PMID: 16926850, PMID: 16823897
• a novel marker for hematopoietic stem cells. PMID: 12799299

Connexin 43

• a negative cell surface marker for the stem cell-containing population of human limbal epithelial cells. PMID: 16424398

Endoglin

• a functional marker that defines long-term repopulating hematopoietic stem cells. PMID: 12438646

ER-MP12

• a positive marker for the isolation of murine long-term in vitro repopulating stem cells. PMID: 7635179

Fibroblast growth factor receptor-3

• a marker for precartilaginous stem cells. PMID: 10546645

Flk-2

• a marker in hematopoietic stem cell differentiation. PMID: 11724967

gpt

• as a positive and negative selectable marker in embryonal stem cells. PMID: 8018715

Human Rex-1 (hRex-1)

• also referred to as zinc-finger protein-42, Zfp42, encodes a zinc finger protein expression of which is believed to be characteristic of pluripotent stem cells. PMID: 16865673
• highly expressed in mouse and human embryonic stem cells and one of several gene markers used to identify human stem cells. PMID: 16344273

Interleukin-2 receptors

• a differentiation marker on intrathymic stem cells. PMID: 3919312

Interleukin-3 receptor alpha chain

• a unique marker for human acute myelogenous leukemia stem cells. PMID: 11021753

KDR

• a positive functional marker defining stem cells and distinguishing them from progenitors. PMID: 10477517

Keratin 19

• a stem cell marker in vivo and in vitro. PMID: 15502175
• a biochemical marker of skin stem cells in vivo and in vitro. PMID: 8743949

Lamin A/C

• a marker of mouse and human embryonic stem cell differentiation. PMID: 16179429

Macromolecular insoluble cold globulin (MICG)

• a marker for pluripotential hemopoietic stem cells. PMID: 6600469

Musashi-1

• in human normal colon crypt cells: a possible stem cell marker of human colon epithelium. PMID: 12924647
• a marker of stem and early lineage progenitor cells in murine intestinal tissue. PMID: 12558601
• an evolutionally conserved marker for CNS progenitor cells including neural stem cells.PMID: 10657706

Nestin

• a putative neural stem cell marker that is expressed in different areas of the adult mammalian brain that are known to support mitotic activity. PMID: 16343784
• a neuroectodermal stem cell marker molecule, is expressed in Leydig cells of the human testis and in some specific cell types from human testicular tumours. PMID: 15127288

Nucleostemin

• present in bone marrow and neuronal stem cells. PMID: 17000083

Oct4 (Oct-4)

• a pluripotent stem cell marker, has been shown to present a stem cell marker that is expressed in embryonic cells and in germ cell tumors. PMID: 16809941, PMID: 15955835
• a marker for undifferentiated (early-stage) embryonic stem (ES) cells. PMID: 13678453, PMID: 16730572

p63

• a reliable myoepithelial and stem cell marker. PMID: 12195217

Podocalyxin

• a marker of embryonic hematopoietic stem cells (HSCs) and erythroid cells and of adult HSCs and that it may be a valuable marker for the purification of these cells for transplantation. PMID: 15701716

R2/60

• present on a subset of bone marrow (BM) hematopoietic stem cells. PMID: 7860091

PSCA (Prostate stem cell antigen)

• a homologue of the Ly-6/Thy-1 family of cell surface antigens. PMID: 12771726

Sox1

• a transcription factor from the SoxB1 subgroup and widely used marker of neural stem cells. PMID: 16797497

SOX2

• a persistent marker for multipotential neural stem cells derived from embryonic stem cells, the embryo or the adult. PMID: 15711057

Stem cell Antigen 1 and 2 (Sca-1 and Sca-2)

• expressed by mouse bone marrow stem cells. PMID: 2460547

Telomerase

• a promising marker of biological immortality of germ, stem, and cancer cells. PMID: 9467857

Thy-1

• a cell surface marker used in conjunction with CD34 and lineage-specific markers to identify hematopoietic stem cells. PMID: 9462642
• Thy-1-specific antibody 5E10 is an attractive tool for further studies on the biology and purification of human stem cells. PMID: 7683034

Transcription factor Stat5

• an early marker of differentiation of murine embryonic stem cells. PMID: 9566306

W7C5

• defines a novel molecule that is expressed on CD34+ as well as on CD34- stem cell subsets. PMID: 11458505

In recent years, scientists have discovered a wide array of stem cells that have unique capabilities to self-renew, grow indefinitely, and differentiate or develop into multiple types of cells and tissues. Researchers now know that many different types of stem cells exist but they all are found in very small populations in the human body, in some cases 1 stem cell in 100,000 cells in circulating blood. And, when scientists examine these cells under a microscope, they look just like any other cell in the tissue where they are found. So, how do scientists identify these rare type of cells found in many different cells and tissues—a process that is much akin to finding a needle in a haystack? The answer is rather simple thanks to stem cell "markers." This feature describes stem cell marker technology and how it is used in the research laboratory.