Download stem cells – glossary

STEM CELLS – GLOSSARY
Acute Lymphoblastic Leukemia (ALL): A type of leukemia in which people have an excess of
lymphoblasts which crowd out healthy adult white blood cells.
Allogeneic stem cell transplant: A type of stem cell transplant is which the stem cells from a compatible donor
are transplanted into a patient.
Apheresis: A procedure in which blood is collected from one arm of a donor, the stem cells are removed from
the blood and the blood is returned via the other arm of the donor.
Autologous stem cell transplant: A type of stem cell transplant is which the patient’s own stem cells are
removed, stored and returned to him or her.
Blastocyst: A spherical structure formed in early embryonic development that is made up of an outer layer of
cells (trophoectoderm), a fluid-filled cavity (the blastocoel) and a cluster of cells on the interior (the inner cell
mass).
Bone Marrow Transplant (BMT): This procedure, also called a hematopoietic stem cell (HSC) transplant, involves
the transfer of healthy HSCs obtained from a donor’s bone marrow to a patient with a disease such as leukemia.
Cell Lineage Tree: A hierarchal representation of the various committed specialized cell types that are derived
from unspecialized stem cells and progenitor cells.
Cell-based Therapies: Therapeutic interventions that use specialized cell types that have been differentiated
from stem cells to repair or replace damaged or destroyed cells or tissues.
Cellular Receptors: Receptors found on the plasma membrane or in the cytoplasm of a cell, to which one or
more specific signaling molecules may attach. Binding of signaling molecules to the cellular receptors initiates a
cascade of molecular events that determine cellular functions.
Chemotherapy: The treatment of cancer using a combination of drugs. Originally the word chemotherapy
referred to any treatment using chemicals, but today only refers to the treatment of cancer. Chemotherapy
drugs primarily work by slowing down mitosis (cell division) of fast-dividing cells such as cancerous cells.
Clonally Derived: All cells in a population that are derived from a single cell.
Cord Blood Bank: A facility which stores umbilical cord blood for future use. Cord blood banks may be public
(anyone can use the blood) or private (blood reserved for the family of the donor).
Cord Blood Transplant: This procedure involves the transfer of healthy hematopoietic stem cells (HSC) obtained
from a donor’s umbilical cord to a patient with a disease such as leukemia.
Cure: Refers to disease-free survival. A person who is cured does not have his/her disease come back over time.
Copyright Let’s Talk Science ©2011.
Developed in collaboration with Stem Cell Network.
STEM CELLS – GLOSSARY
Differentiated Cells: Cells originally derived from stem cells that have acquired new
characteristics, allowing them to perform specialized functions.
Differentiation: A developmental process through which unspecialized cells (or undifferentiated to stem cells)
acquire new characteristics allowing them to perform specialized functions while loosing their potency.
Ectoderm: A germ layer found during embryonic development. Ectoderm tissue gives rise to tissue of the
nervous system, including the spine, brain, peripheral nerves and the skin.
Embryonic Stem Cells (ESCs): Pluripotent stem cells derived from the inner cell mass of a blastocyst stage
embryo.
Endoderm: A germ layer found during embryonic development. Endoderm tissue gives rise to the lining of the
gastrointestinal tract and its associated organs, including the lungs, liver and intestine.
Endogenous Stem Cell Stimulation: A treatment procedure that activates tissue-resident stem cells within the
damaged tissue (endo = inside, genous = generated) to divide and differentiate into specialized cells of the tissue.
Endogenous stem cells can be stimulated using drugs with small molecules.
Exogenous Stem Cell Replacement Therapy: Treatment procedures that use stem cells that have been
differentiated into specialized cell types outside of the body (exo = outside, genous = generated) to repair or
replace damaged or destroyed cells or tissues through transplantation.
Extraembryonic Tissues: Supportive tissues of the embryo proper comprised of cells derived from a fertilized
egg (zygote). These tissues are required for normal embryonic development, but they do not become part of
the fetus. Cells of the trophoblast are examples of extraembryonic cells that eventually develop into the
placenta, and extraembryonic endoderm cells, which eventually develop into the yolk sac.
Feeder Layer: A layer of supportive cells that other cell types are cultured on top of. The feeder layer functions
to support the viability, growth and general function of the other cells in co-culture environments. Embryonic
stem cells (ESCs) are routinely co-cultured on a layer of mouse embryonic fibroblasts (MEFs). MEFs function as
a feeder layer to supply the ESCs with factors that maintain ESCs in an undifferentiated state.
Fibroblast: A specialized somatic cell type that is commonly found in loose connective tissue. Fibroblasts
function to maintain the organization of cells in the body by secreting protein components of the extracellular
matrix.
Germ layer (also called the germinal epithelium): A group of cells formed during embryonic development. In
humans there are three distinct germ layers: the endoderm, mesoderm and ectoderm.
Graft-Versus-Host Disease (GVHD): occurs when the donor stem cells (the graft) attacks the patient’s cells (the
host).
Graft-Versus-Tumor (GVT): occurs when white blood cells from the donor identify the cancer cells that remain
in the patient’s body after the chemotherapy and/or radiation (the tumor) as foreign and attack them.
Copyright Let’s Talk Science ©2011.
Developed in collaboration with Stem Cell Network.
STEM CELLS – GLOSSARY
Haplotype: A group of genes which are inherited together from a single parent. The origin of the
word comes from the words haploid (cells with only one set of chromosomes) and genotype (genetic
makeup of an organism).
Hematopoietic stem cells (HSCs): Multipotent stem cells which give rise to all the blood cell types.
Hematopoietic Stem Cells: Stem cells found within the bone marrow that give rise to all blood cells including red
blood cells, white blood cells and platelets.
Host-Versus-Graft effect: occurs when the patient’s immune system *the host] fights and rejects the donor stem
cells [the graft]).
Human Leukocyte Antigens (HLA): These marker proteins found on most cells are used by the immune system
to recognize which cells belong to the body and which cells do not.
In vitro fertilization: A process by which egg cells are fertilised by sperm outside of the body (in vitro).
Induced Pluripotent Stem Cells (iPSCs): Pluripotent stem cells that are reprogrammed from specialized somatic
cells through forced expression of genetic factors that are important for maintaining stem cell properties of
embryonic stem cells. iPSCs have similar properties to ESCs, but are not derived from the blastocyst.
Leukemia: A type of cancer of the white blood forming cell in bone marrow.
Leukocytes: Also known as white blood cells, leukocytes are the cells that defend the body against both
infectious disease and foreign materials.
Lymphoblast: Immature white blood cells found in bone marrow.
Mesoderm: A germ layer found during embryonic development. Mesoderm tissue gives rise to a number of
supportive tissues of the body, including cartilage, bone, muscle and connective tissue.
Multipotency: The property of a single cell to give rise to a limited number of cell types within the body.
Multipotent stem cells have restricted developmental potential, possessing the ability to generate cells of only
one particular tissue lineage (e.g., such as blood cells).
Peripheral Blood Stem Cell Transplant (PBSC transplant): This procedure involves the transfer of healthy
hematopoietic stem cell (HSC) obtained from a donor’s circulating blood to a patient with a disease such as
leukemia.
Pluripotency: The property of a single cell to give rise to all cells of the embryo proper which go on to form the
body but not the cells which develop into extraembryonic support tissues. Pluripotent stem cells, including
embryonic stem cells (ESC) and induced pluripotent stem cells (iPSCs), can differentiate into all cell types of the
body.
Copyright Let’s Talk Science ©2011.
Developed in collaboration with Stem Cell Network.
STEM CELLS – GLOSSARY
Potency: The potential for an unspecialized cell to differentiate into at least one specialized cell
type. Different stem cell populations are broadly classified by their potency – their ability to
differentiate into one (unipotent), many (multipotent and pluripotent) or all (totipotent) specialized
cell types of the body.
Preimplantation genetic diagnosis (PGD) (also known as embryo screening): Genetic testing procedures
performed on embryos or oocytes during the process of IVF and before fertilization. PGD has potential to be
used to screen for genetic conditions or chromosomal disorders that could lead to certain diseases, to match the
HLA types of a potential sibling donor, to sex select embryos or to determine a genetic predisposition to cancer.
Progenitor cells: Progenitor cells are precursor cells to a specific differentiated cell type. Unlike stem cells,
progenitor cells have a limited ability to replicate themselves (self-renewal).
Regenerative Medicine: A field of medicine devoted to the treatment of disease with stem cells and
bioengineered tissue. The goal of regenerative medicine is to coax stem cells into clinically relevant cell types
for cell transplantation therapies or bioengineered tissue that can be used to repair or replace damaged or
destroyed cell populations or tissues.
Relapse: Occurs when a disease recurs in a patient.
Remission: The absence of a particular disease activity in a patient. In the case of ALL, a patient is said to be in
remission when 99% of the cancerous lymphoblasts have been destroyed.
Somatic Cells: All cells of an organism, excluding germ cells (cells that give rise to gametes) and undifferentiated
stem cells.
Syngeneic stem cell transplant: A type of stem cell transplant in which the stem cells from an identical twin are
transplanted into a patient.
Tissue-resident Stem Cells (also known as Somatic Stem Cells or Adult Stem Cells): Stem cells that reside in a
specific tissue of the mature organism. Tissue-resident stem cells can give rise to all specialized cell types of the
particular tissue in which they reside, but they cannot differentiate into specialized cell types of other tissues.
Totipotency: The property of a single cell to give rise to all cells of the embryo proper and extraembryonic
support tissues. Cells of the very early embryo are totipotent. To date, no stem cell line has been shown to
possess this property.
Trophoectoderm: the cells which give rise to extraembryonic structures such as the placenta, of the blastocyst
Unrelated Bone Marrow Donor Registry: A database of individuals who would be willing to be bone marrow
donors.
Copyright Let’s Talk Science ©2011.
Developed in collaboration with Stem Cell Network.