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Glossary

Adult stem cell
See tissue stem cell.

Allogeneic
Describes the relationship of a tissue (or cell) donor and recipient as two genetically different individuals. Most tissue donations are allogeneic unless the donor and recipient are identical twins (see syngeneic).

Apoptosis
The process of cell death that is controlled by a cell death biological pathway. It is also commonly called 'programmed cell death'.

Autologous
Describes tissues (or cells) that were originally extracted or derived from a patient's body and can be used for treatment of disease. Often autologous cell treatments require ex vivo growth to increase the number of cells available before they are used.

Blastocyst
An early stage embryo that is formed approximately 5 days after fertilization of a human egg and is made of roughly 150 cells.

Cell
The smallest unit of life and the building block for larger (multi-cellular) organisms. A cell contains genetic information in a nucleus and a membrane to separate the internal components of the cell from the outer environment.

Cell banks
Storage facilities for collections of carefully defined cells and cell lines. Many different types of cells, from human stem cells to insect cells, are cryogenically preserved, stored in cell banks and later thawed for use in medicine or research.

Cell culture
The process of growing cells in an in vitro (laboratory) setting.

Cell division
The process of a cell dividing itself to create two new cells. A 'parent cell' must duplicate all genetic material and cell components before dividing into two 'daughter cells'.

Cell line
A population of cells grown in vitro that have a specific genetic background (genotype) and physical characteristics (phenotype).

Cell migration
The movement of cells, often in response to an environmental stimulus (physical or chemical).

Cell renewal
The natural process of tissue stem cells replacing cells within the body, often because they have become worn, damaged or have died.

Cell reprogramming
The changing of a specialized cell’s function. Cell reprogramming can occur naturally in some organisms. The term is most often used in reference to laboratory manipulation of specialized cells, such as skin cells, to create iPS cells or other progenitor cell types.

Cell therapy
Medical treatments that use cells as the active agent (as opposed to drugs) to assist in healing a patient. Cell therapies are a form of regenerative medicine.

Central nervous system (CNS)
The brain and spinal column compose the central nervous system.

Chemotherapies
Medical treatments that involve the use of chemical compounds. Though chemotherapies can be used for many reasons, they are most often associated with cancer treatments.

Clinical translation
The process of turning scientific knowledge and discoveries into clinical treatments. This involves everything from scientific research, pre-clinical trials, clinical trials and product development.

Clinical trials

A series of tightly regulated studies to test the safety and efficacy of new therapies. All new medical treatments must go through clinical trials before being given governmental approval for widespread use.

Cord blood stem cells
Stem cells that are isolated from the blood of the umbilical cord.

Cornea
The clear outer surface of the eye, which protects the pupil, iris, lens and other inner parts of the eye from the external environment. It is created by limbal stem cells.

Cryogenic preservation
The process of preserving tissues and cells for later use by cooling and storing them at very low temperatures, often in liquid nitrogen at -135°C or colder. Also known as 'cryopreservation.'

Culture medium
The liquid containing nutrients and other factors used to facilitate growth and maintenance of cells in the laboratory.

De-differentiation
The loss of specialized characteristics of a cell.

Development
The biological process of a cell dividing, growing, and differentiating to create complex tissues, organs, and ultimately a whole organism. The developmental process is what allows a fertilized egg to grow and mature into an adult.

Differentiation
The process of gaining specialized cellular functions by an immature cell. Fully differentiated cells (or terminally differentiated cells) cannot further alter their specialized functions.

DNA
Molecules found in all living cells that contain all the genetic information for life. Information in DNA is coded within its chemical structure. Formally DNA is called deoxyribonucleic acid.

Embryo
The stage of development during the first eight weeks of pregnancy; from the first cell division of the fertilized egg until becoming a fetus.

Embryonic stem cells
The pluripotent cells derived from the inner cell mass of the blastocyst.

Epiblast stem cells
A type of stem cell derived from an early post-implantation embryo that shares some properties with embryonic stem cells, such as the ability to produce all the differentiated cell types of the body. EpiSCs are similar to pluripotent embryo cells that are just about to choose a differentiation pathway.

Epidermal stem cells
Tissue stem cells found in skin (epidermis) that generate the many different cells that form skin.

Ex vivo
The growth of cells or tissues in the laboratory that have been extracted from a person or organism. Growth conditions are typically chosen to minimize cell alterations.

Experimental control
A standard or benchmark measurement which is used to evaluate the outcome of an experiment. The most common form of experimental control is a 'negative control', where the item to be tested is omitted and the expected result is ‘no change at all’.

Fetus
The developmental stage following the embryo stage of development until birth. The fetus resembles a newborn baby and has formed most major tissues and organs.

Gene therapy
Manipulation of the genetic components of cells for the purpose of medical treatment. Often the goal of gene therapy is to fix natural mutations that lead to disease.

Genes
Segments of DNA that are associated with hereditary traits passed from parent to offspring. Genes encode information to make RNA and proteins, which allow cells to perform specialized functions.

Gene expression
Active production by a cell of the gene product. The product could be either an RNA molecule or a protein that is encoded by the gene. The production of a gene product is often regulated by other proteins. Genes are often regulated by transcription factors.

Genetic
Anything relating to how genes and DNA allow hereditary traits and information to be passed on from one generation to another.

Genetically modified organism (GMO)
Any living organism that contains artificially altered genetic material.

Genome
The genetic material of an organism. It is encoded either in DNA or, for many types of viruses, in RNA.

Genotype
The specific DNA sequence (genetic background) of a living organism. The term 'genotype' describes the entire genetic background of an organism, but often researchers use the term to refer to a specific inherited mutation in a gene.

Growth factor
A natural protein that stimulates cells to multiply.

Haematopoiesis
The formation of different cells that make up blood.

Haematopoietic stem cells
Tissue stem cells responsible for generating cells found in our blood and immune system.

Hepatocyte
A specialized cell type of the liver. These cells are primarily responsible for making bile for digestion, regulating sugar levels in the blood, detoxifying metabolic waste, and making proteins for blood plasma.

Immortal cell line
A cell line that has the ability to undergo cell division indefinitely, also known as a 'continuous cell line'. Immortal cell lines permit researchers to work with the same cells in vitro for long periods of time and to greatly amplify the number of cells in a culture.

Immune system
Biological processes, organs, tissues and cells that provide the body with resistance to infections. The immune system primarily works by destroying anything that it sees as foreign to the body.

Immunological rejection
The failure of a patient's body to acquire and integrate transplanted tissue, often due to a detrimental reaction by the immune system.

In vitro
A biological process or experiment that takes place under controlled laboratory conditions, outside of a living organism.

In vivo
A biological process or experiment that occurs within a living organism.

Induced pluripotent stem (iPS) cells
Stem cells created from fully differentiated tissue cells that have been artificially stimulated to become pluripotent cells similar to embryonic stem cells.

Inner cell mass
A cluster of pluripotent cells found within a blastocyst from which embryonic stem cells can be derived.

Limbal stem cells
Tissue stem cells responsible for generating the cornea of the eye.

Medical translation
See clinical translation.

Mesenchymal stem cell
A multipotent stem cell derived from bone marrow or fat that has the ability to differentiate into many (but not all) cell types that make bone, tendon, fat, cartilage, and others tissues.

Multipotent cells
Stem cells with the ability to generate a subset of specialized cell types, typically found within the same organ.

Neuron
A specialized cell that can rapidly send electrical signals. Neurons are found in the brain, spinal cord and throughout the rest of the body. They allow for sensory reception, thought processes, consciousness, movement and other functions.

Organ
A group of specialized tissues organized to form a distinct structure in the body and work together to carry out functions needed for the whole organism. Examples include the lungs, heart, liver, etc.

Pathogen
Any disease-causing factor or microorganism.

Peripheral nervous system (PNS)

All neurons that are found outside of the brain and spinal cord.

Personalized medicine
Medical treatments that are custom tailored to treat the complication and meet the immunological needs of a patient.

Phenotype
The physical (observable) characteristics of a cell, tissue, or organism. These characteristics are the materialization or expression of the information encoded by the genotype.

Pluripotent cells
Stem cells with the ability to generate all the specialized cell types of an organism. Pluripotent cells can form the cells of an embryo, but lack the ability to create the supporting cells and tissues needed to permit the development of a whole organism.

Precursor cell
During cell differentiation, this is the last distinguishable cell type before a cell is fully differentiated and specialized.

Primary cell culture
An in vitro culture of cells that was generated directly from in vivo tissue.

Principle Investigator (PI)
The researcher, clinician, or scientist that takes overall responsibility for research work in a laboratory.

Progenitor cells
During cell differentiation from a stem cell to a fully differentiated specialized cell, several distinguishable cell types may arise. Progenitor cells are these in-between cells that are more specialized and come after stem cells, but precede the final specialized cell state.

Proliferation
The multiplying of cells through repeated cell division.

Regenerative medicine
Medical treatments that restore complete function to tissues and organs that are damaged by age, injury, or disease. These treatments range from drugs that stimulate tissue regeneration to methods of cell and tissue replacement.

Reprogramming
See cell reprogramming.

Self-renewal
The ability of a cell to repeatedly undergo cell division and create new cells exactly like the original 'parent' cell. This is one of the defining properties of stem cells.

Somatic cells

See specialized cells.

Somatic stem cells
See tissue stem cells.

Specialized cells
Cells that are fully differentiated and have specific roles within a tissue or organ. Examples include the ability of muscle cells to contract and stomach cells to produce acid for digestion.

Stem cells
Cells that have the ability to both self-renew and differentiate. Stem cells are critical for development, growth, cell renewal, and healing.

Stem cell line
Cells that have been well characterized, have specific phenotypes, and can be indefinitely grown in the laboratory. These cells often are used for experimentation because they are homogenous and are used in other laboratories. This permits researchers to easily conduct experiments on the same cells and more accurately compare experimental results.

Stem cell niche
Stem cell populations in the body live in stem cell niches, each different type of stem cell with its own niche. The niche supplies the necessary environment and many of the cues that direct stem cell activity, and this is why changes in the niche are equally important to changes in stem cells themselves.

Syngeneic
When a tissue (or cell) donor and recipient are genetically identical. This is only possible in the situation that the donor and recipient are identical twins.

Terminally differentiated cells
Cells that cannot undergo changes in their identity or specialized functions.

Tissue
A group of cells that perform similar specialized functions.

Tissue stem cells
Tissue stem cells can both self-renew and give rise to at least one more specialized (differentiated) cell type. They can be unipotent, meaning that they only make one type of specialized cell (e.g. the spermatogonial stem cell) or multipotent, meaning they can generate several types of specialized cells. Under normal circumstances, tissue stem cells generate only the cell types that make up the or organ / tissue system they reside in. Also known as 'adult' or 'somatic' stem cells.

Totipotent cells
Cells with the ability to give rise to any type of differentiated cells including extraembryonic tissues (need to distinguish form pluripotent cells) undergo development into complete organisms. An example of such a cell is the zygote.

Transcription factor

Proteins that bind to DNA, often at or near the beginning of a gene, and regulate the amount of RNA or protein produced that is coded by a gene. Transcription factors can both increase or decrease the gene expression (the amount of gene products a cell produces).

Transgenic
An organism that contains artificially introduced genetic material.

Unipotent
A cell that only has the ability to differentiate into a single specialized cell type. This is often the case of precursor cells.

Zygote
A totipotent cell formed by the unification of a sperm and egg.