Attention:

Certain features of Sigma-Aldrich.com will be down for maintenance the evening of Friday August 18th starting at 8:00 pm CDT until Saturday August 19th at 12:01 pm CDT.   Please note that you still have telephone and email access to our local offices. We apologize for any inconvenience.

Cell Culture

Induced Pluripotent Stem Cell Glossary and Terms

Frequently Asked Questions
Protocols
Need technical help? Ask a Scientist


Adenovirus
Adipocyte
Adult stem cell
Allogeneic transplantation
Astrocytes
Autologous transplantation
Biomaterial
Blastocoel
Blastocyst
Bone marrow
Cancer
Cancer stem cell
Cardiomyocytes
Cell culture
Cell division
Cell line
Cell-based therapies
Chimera
Chondrocyte
Chromosome
Clone (Cell biology)
Cloning
Cord blood
Culture medium
Cytoplasm
Dedifferentiation
Degenerative disease
Differentiation
Direct reprogramming
DNA
DNA methylation
Ectoderm
Ectopic expression
Embryo
Embryoid bodies (EBs)
Embryonic stem cells
Endoderm
Enucleated cell
Epigenetic
Expression
Feeder layer
Fertilization
Fetus
Fibroblast
Fluorescence activated cell sorter (FACS)
Gag
Gamete
Gastrulation
Gene
Gene silencing
Gene target
Genomics
Germ layers
Haematopoiesis
Hematopoietic stem cells (HSCs)
Hepatocyte
Heterologous
Histocompatibility
Histones
Homologous recombination
Human embryonic stem cell (hESC)
In vitro
In vitro fertilization (IVF)
In vivo
Induced pluripotent stem cells
Inner cell mass (ICM)
Islet cell
Klf
Knock-down
Lentivirus
Lin-28 homolog
Long-term self-renewal
Meiosis
Mesenchymal stem cells
Mesoderm
Microenvironment
Mitosis
Morphology
Multiplicity of infection (MOI)
Multipotent
Myc (c-Myc)
Myocyte
Nanog
Neural stem cell
Neuron
Nucleus
Octamer-4 (Oct-4)
Oligodendrocyte
Osteoblast
Packaging plasmid
Parthenogenesis
Passage
Passage number
Phenotype
Plasmid
Plasticity
Pluripotent stem cells
Pol
Post-implantation embryo
Pre-implantation embryo
Progenitor cell
Proliferation rate
Regenerative medicine
Regulatory viral protein (Rev)
Replication incompetent
Reprogramming
Retrovirus
Self-inactivating (SIN) long terminal repeat
Self-renewal
Somatic cell
Somatic cell nuclear transfer (SCNT)
SOX 2
Stem cell
Stem cell niche
Stromal cells
Subculture
Surface markers
TAT
Telomere
Teratoma
Tetraploid complementation assay
Titer
Totipotency
Transdifferentiation
Transduction
Transfection
Trophectoderm
Trophoblast
Undifferentiated
Unipotent
Vector
Viral infectivity factor (Vif)
Viral protein r (Vpr)
Viral protein u (Vpu)

Adenovirus
A nonenveloped (naked) icosahedral virus composed of a nucleocapsid and a double-stranded linear DNA genome.

Adipocyte
The functional cell type of fat, or adipose tissue that is found throughout the body, particularly under the skin. Adipocytes store and synthesize fat for energy, thermal regulation and cushioning against mechanical shock.

Adult stem cell
Also known as somatic stem cells, they are cells that can be found in juvenile as well as adult animals and humans. They are defined by their ability to self-renew and differentiate into multiple cell types.

Allogeneic transplantation
A procedure in which a person receives cells/tissue from a genetically similar, but not identical, donor.

Astrocytes
Characteristic star-shaped glial cells in the brain and spinal cord

Autologous transplantation
A procedure in which cells/tissue are removed, stored, and later given back to the same person.

Biomaterial
A material which is composed of living matter.

Blastocoel
the fluid-filled central region of a blastocyst

Blastocyst
A structure formed in the early mammalian embryogenesis, after formation of the morula.

Bone marrow
The flexible tissue found in the interior of bones. In humans, marrow in large bones produces new blood cells.

Cancer
A class of diseases in which a group of cells display uncontrolled growth, invasion that intrudes upon and destroys adjacent tissues, and sometimes metastasis, or spreading to other locations in the body via lymph or blood.

Cancer stem cell
Cancer stem cells (CSCs) are cancer cells (found within tumors or hematological cancers) that possess characteristics associated with normal stem cells, specifically the ability to give rise to all cell types found in a particular cancer sample.

Cardiomyocytes
The functional muscle cell type of the heart that allows it to beat continuously and rhythmically

Cell culture
The complex process by which cells are grown under controlled conditions in vitro.

Cell division
The process by which a parent cell divides into two or more daughter cells.

Cell line
A permanently established cell culture that will proliferate indefinitely given appropriate fresh medium and space, usually from a clonal cell source but not always.

Cell-based therapies
Treatment in which cells are used to repair damaged or destroyed cells or tissues.

Chimera
A single animal organism with genetically distinct cells from two different zygotes.

Chondrocyte
The functional cell type that makes cartilage for joints, ear canals, trachea, epiglottis, larynx, the discs between vertebrae and the ends of ribs

Chromosome
A single piece of coiled DNA and DNA-bound proteins (histones) containing many genes, regulatory elements and other nucleotide sequences.

Clone (Cell biology)
A group of identical cells derived from a common parent cell.

Cloning
Cloning in biotechnology refers to processes used to create copies of DNA fragments (molecular cloning), cells (cell cloning), or organisms.

Cord blood
Blood that remains in the placenta and in the attached umbilical cord after childbirth. Cord blood is collected because it contains stem cells which can be used to treat hematopoietic and genetic disorders.

Culture medium
A liquid or gel designed to support the growth of cells in vitro.

Cytoplasm
A thick liquid residing between the cell membrane holding all organelles, except for the nucleus.

Dedifferentiation
Dedifferentiation is a cellular process often seen in more basal life forms such as worms and amphibians in which a partially or terminally differentiated cell reverts to an earlier developmental stage, usually as part of a regenerative process.

Degenerative disease
A disease in which the function or structure of the affected tissues or organs will progressively deteriorate over time, whether due to normal bodily wear or lifestyle choices such as exercise or eating habits.

Differentiation
The process by which a less specialized cell becomes a more specialized cell type.

Direct reprogramming
The creation of a pluripotent stem cell by the forced expression of specific genes as opposed to cell fusion or somatic cell nuclear transfer.

DNA
Deoxyribonucleic acid, or DNA, is a nucleic acid that contains the genetic instructions used in the development and functioning of living organisms

DNA methylation
A type of chemical modification of DNA that can be inherited and subsequently removed without changing the original DNA sequence.

Ectoderm
One of the germ layers formed during animal embryogenesis. The ectoderm forms: the central nervous system, the lens of the eye, cranial and sensory, the ganglia and nerves, pigment cells, head connective tissues, the epidermis, hair, and mammary glands.

Ectopic expression
The expression of a gene in an abnormal place in an organism. This can be caused by a disease, or it can be artificially produced as a way to help determine what the function of that gene is.

Embryo
A multicellular diploid eukaryote in its earliest stage of development, from the time of first cell division until birth, hatching, or germination. In human development the first 10 weeks is called an embryo.

Embryoid bodies (EBs)
Aggregates of cells derived from embryonic stem cells. Upon aggregation, differentiation is initiated and the cells begin to a limited extent to recapitulate embryonic development.

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

Endoderm
One of the germ layers formed during animal embryogenesis. The endoderm forms: the stomach, the colon, the liver, the pancreas, the urinary bladder, the lining of the urethra, the epithelial parts of trachea, the lungs, the pharynx, the thyroid, the parathyroid, and the intestines.

Enucleated cell
A cell where the nucleus, and thus all genetic information, has been removed.

Epigenetic
The study of heritable changes in phenotype (appearance) or gene expression caused by mechanisms other than changes in the underlying DNA sequence

Expression
The process by which the information in a gene is used to create proteins.

Feeder layer
Fibroblast cells (mouse or human) used in co-culture to maintain pluripotent stem cells.

Fertilization
The fusion of gametes to produce a new organism.

Fetus
A developing mammal after the embryonic stage and before birth. In humans, the fetal stage of prenatal development starts at the beginning of the 11th week in gestational age.

Fibroblast
A type of cell that synthesizes and maintains the extracellular matrix of many animal tissues. Fibroblasts provide a structural framework (stroma) for many tissues, and play a critical role in wound healing.

Fluorescence activated cell sorter (FACS)
Fluorescence-activated cell sorting (FACS) is a specialized type of flow cytometry. It provides a method for sorting a heterogeneous mixture of biological cells into two or more containers, one cell at a time, based upon the specific light scattering and fluorescent characteristics of each cell.

Gag
A lentiviral packaging element that encodes for a structural precursor protein.

Gamete
A cell that fuses with another cell during fertilization (conception).

Gastrulation
A phase early in the embryonic development of most animals, during which the single-layered blastula is reorganized into a trilaminar ("three-layered") structure known as the gastrula.

Gene
A locatable region of genomic sequence, corresponding to a unit of inheritance, which is associated with regulatory regions, transcribed regions, and or other functional sequence regions.

Gene silencing
Targeting or interfering with a specific gene and preventing its expression.

Gene target
A gene or its product (protein) which plays a critical role in disease.

Genomics
The systematic study of genes and their function.

Germ layers
In humans during the gastrula stage three germ layers form (ectoderm, endoderm, and mesoderm) and are the forerunners of all adult tissues and organs.

Haematopoiesis
The formation of blood cellular components. All cellular blood components are derived from haematopoietic stem cells.

Hematopoietic stem cells (HSCs)
Multipotent stem cells that give rise to all the blood cell types from the myeloid (monocytes and macrophages, neutrophils, basophils, eosinophils, erythrocytes, megakaryocytes/platelets, dendritic cells), and lymphoid lineages (T-cells, B-cells, NK-cells).

Hepatocyte
A cell of the main tissue of the liver. Hepatocytes make up 70-80% of the liver's cytoplasmic mass

Heterologous
Not homologous or uniform. In the context of cells, heterologous is a mixed or divergent cell population or of a divergent origin.

Histocompatibility
The property of having the same, or mostly the same, alleles of a set of genes called the major histocompatibility complex.

Histones
The chief protein components of chromatin. They act as spools around which DNA winds, and they play a role in gene regulation.

Homologous recombination
A type of genetic recombination in which nucleotide sequences are exchanged between two similar or identical molecules of DNA

Human embryonic stem cell (hESC)
A pluripotent stem cell derived from the inner cell mass of the blastocyst.

In vitro
Refers to studies in experimental biology that are conducted using components of an organism that have been isolated from their usual biological context in order to permit a more detailed or more convenient analysis that can be done with whole organisms.

In vitro fertilization (IVF)
A process by which egg cells are fertilized by sperm outside the body.

In vivo
Refers to work that is conducted with living organisms in their normal, intact state.

Induced pluripotent stem cells
Adult cells reprogrammed to an embryonic stem cell–like state by being forced to express factors important for maintaining the "stemness" of embryonic stem cells.

Inner cell mass (ICM)
Also known as an embryoblast, is a cluster of cells during the blastocyst stage of early embryogenesis of mammals

Islet cell
The functional cell of the pancreas that is responsible for secreting insulin, glucogon, gastrin and somatostatin. Together, these molecules regulate a number of processes including carbohydrate and fat metabolism, blood glucose levels and acid secretions into the stomach.

Klf
The Krüppel-like family of transcription factors, named for their homology to the Drosophila Krüppel protein. All KLF family members are characterized by their three Cys2 His2 zinc fingers located at the C-terminus, separated by a highly conserved H/C link.

Knock-down
Reduction of gene expression via RNA interference, mediated by short interfering RNA (siRNA) or short hairpin (shRNA).

Lentivirus
A genus of slow viruses of the Retroviridae family, characterized by a long incubation period. Lentiviruses can deliver a significant amount of genetic information into the DNA of the host cell, so they are one of the most efficient methods of a gene delivery vector.

Lin-28 homolog
Also known as LIN28, is a human gene. It is marker of undifferentiated human embryonic stem cells and has been used to enhance the efficiency of the formation of induced pluripotent stem (iPS) cells from human fibroblasts. It encodes a cytoplasmic mRNA-binding protein that binds to and enhances the translation of the Igf2 mRNA. Lin28 has also been shown to bind to the let-7 pre-miRNA and block production of the mature let-7 microRNA in mouse embryonic stem cells.

Long-term self-renewal
The ability to replicate by cell division into the same non-specialized cell type over long periods (many months to years).

Meiosis
A special type of cell division beginning with one diploid cell and ending with four haploid cells containing one copy of each chromosome.

Mesenchymal stem cells
Multipotent stem cells that can differentiate into a variety of cell types, including: osteoblasts (bone cells), chondrocytes (cartilage cells) and adipocytes (fat cells).

Mesoderm
One of the germ layers formed during animal embryogenesis. The mesoderm forms: skeletal muscle, the skeleton, the dermis of skin, connective tissue, the urogenital system, the heart, blood (lymph cells), and the spleen.

Microenvironment
The molecules and compounds in the fluid surrounding a cell in an organism or in the laboratory.

Mitosis
The process by which a eukaryotic cell separates the chromosomes in its cell nucleus into two identical sets in two nuclei.

Morphology
The study of the form and structure of a cell or organism and their specific structural features.

Multiplicity of infection (MOI)
Represents the average number of viral particles per single cell. The MOI is calculated by dividing the total number of transducing unites by the number of cells plated.

Multipotent
The ability to generate progeny of several distinct cell types.

Myc (c-Myc)
An oncogene that codes for a protein that binds to the DNA of other genes. When c-Myc is mutated, or overexpressed, the protein doesn't bind correctly, and often causes cancer.

Myocyte
The functional cell type of muscles

Nanog
A transcription factor critically involved with self-renewal of undifferentiated embryonic stem cells.

Neural stem cell
The self-renewing, multipotent cells that generate the main phenotypes of the nervous system.

Neuron
An electrically excitable cell that processes and transmits information by electrical and chemical signaling. Chemical signaling occurs via synapses, specialized connections with other cells.

Nucleus
A membrane-enclosed organelle found in eukaryotic cells. It contains most of the cell's genetic material, organized as multiple long linear DNA molecules in complex with a large variety of proteins, such as histones, to form chromosomes.

Octamer-4 (Oct-4)
It is a homeodomain transcription factor of the POU family. This protein is critically involved in the self-renewal of undifferentiated embryonic stem cells. As such, it is frequently used as a marker for undifferentiated cells. Oct-4 expression must be closely regulated; too much or too little will actually cause differentiation of the cells.

Oligodendrocyte
A variety of neuroglia. Their main function is the insulation of axons (the long projection of nerve cells) in the central nervous system (the brain and spinal cord) of some vertebrates.

Osteoblast
The functional cell type responsible for making bone

Packaging plasmid
Lentiviral vectors that contain all necessary elements to efficiently generate active viral particles. For improved safety, third generation packaging plasmids have necessary element separated between 2 or 3 plasmids, eliminating the possibility of homologous recombination and generation of wild-type virus.

Parthenogenesis
A form of asexual reproduction found in females, where growth and development of embryos occurs without fertilization by a male.

Passage
The process in which cells are disassociated, washed, and seeded into new culture vessels.

Passage number
The number of passages a line of cultured cells has undergone since derivation. Through of as an indication of cell culture age and expected stability.

Phenotype
Any observable characteristic or trait of a cell or organism: such as morphology, development, biochemical or physiological properties, behavior, and products of behavior.

Plasmid
An extra-chromosomal DNA molecule separate from the chromosomal DNA which is capable of replicating independently of the chromosomal DNA.

Plasticity
The ability of a cell or organism to change its phenotype in response to changes in the environment.

Pluripotent stem cells
A cell that can self-renew indefinitely and give rise to any fetal or adult cell type.

Pol
A lentiviral packaging element that encodes for a structural precursor protein.

Post-implantation embryo
An embryo that has attached to the uterine wall.

Pre-implantation embryo
An embryo that has not attached to the uterine wall.

Progenitor cell
A cell with limited differentiation potential and ability to self-renew.

Proliferation rate
The time between cell divisions

Regenerative medicine
The process of creating living, functional tissues to repair or replace tissue or organ function lost due to damage, or congenital defects.

Regulatory viral protein (Rev)
A lentiviral packaging element that binds to Rev Response Element (RRE) sequences, allowing the cytoplasmic export of viral RNAs.

Replication incompetent
Lentiviral particles that are incapable of producing additional viral particles, due to the elimination of wild-type enhancers in the long terminal repeat region.

Reprogramming
A process that transforms a more specialized cell into a pluripotent stem cell by way of remodeling and erasure of epigenetic modifications.

Retrovirus
Any virus belonging to the viral family Retroviridae. They are enveloped viruses possessing an RNA genome, and replicate via a DNA intermediate. Retroviruses rely on the enzyme reverse transcriptase to perform the reverse transcription of its genome from RNA into DNA, which can then be integrated into the host's genome with an integrase enzyme. The virus then replicates as part of the cell's DNA.

Self-inactivating (SIN) long terminal repeat
The basal/enhancer control elements from wild-type lentiviral promoters were replaced in the long terminal repeat by transcriptional control elements from heterologous viral or cellular promoters. This replacement renders the virus replication incompetent.

Self-renewal
The ability to go through numerous cycles of cell division while still maintaining an undifferentiated state.

Somatic cell
Any biological cell forming the body of an organism, other than a gamete.

Somatic cell nuclear transfer (SCNT)
A laboratory technique for creating an ovum with a donor nucleus. In SCNT the nucleus, which contains the organism's DNA, of a somatic cell is removed and the rest of the cell discarded. At the same time, the nucleus of an egg cell is removed. The nucleus of the somatic cell is then inserted into the enucleated egg cell. After being inserted into the egg, the somatic cell nucleus is reprogrammed by the host cell. The egg, now containing the nucleus of a somatic cell, is stimulated with a shock and will begin to divide. After many mitotic divisions in culture, this single cell forms a blastocyst with almost identical DNA to the original organism.

SOX 2
SRY (sex determining region Y)-box 2, is a transcription factor that is essential to maintain self-renewal of undifferentiated embryonic stem cells. This intronless gene encodes a member of the SRY-related HMG-box (SOX) family of transcription factors involved in the regulation of embryonic development and in the determination of cell fate.

Stem cell
A cell that can self-renew or give rise to a specialized cell type.

Stem cell niche
The microenvironment in which stem cells are found in vivo that facilitates a balance of self-renewal and differentiation.

Stromal cells
Connective tissue cells of any organ

Subculture
A new cell culture made by transferring some or all cells from a previous culture to fresh growth medium.

Surface markers
A distinctive marker that can be found on the surface of a cell.

TAT
A lentiviral packaging element required for the efficient elongation of nascent viral transcripts.

Telomere
A region of repetitive DNA sequence at the end of a chromosome, which protects the end of the chromosome from deterioration or from fusion with neighboring chromosomes.

Teratoma
An encapsulated tumor with tissue or organ components resembling normal derivatives of all three germ layers.

Tetraploid complementation assay
An assay that can be used to test a stem cell's potency. Two mammalian embryos are combined to form a tetraploid embryo. Diploid pluripotent stem cells are then injected into the embryo and if truly pluripotent develops into the embryo proper and produces a live animal.

Titer
The number of transducing units per mL.

Totipotency
The ability of a single cell to divide and produce all the differentiated cells in an organism, including extraembryonic tissues.

Transdifferentiation
A process where a non-stem cell transforms into a different type of cell, or when an already differentiated stem cell creates cells outside its already established differentiation path.

Transduction
The integration of exogenous genetic sequences into a host genome through viral particles.

Transfection
Describes the introduction of foreign material into eukaryotic cells using a virus vector or other means of transfer.

Trophectoderm
Cells forming the outer layer of a blastocyst, which provide nutrients to the embryo and develop into a large part of the placenta.

Trophoblast
A layer of cells surrounding the inner cell mass and the blastocyst cavity.

Undifferentiated
A cell that has not developed into a specialized cell type.

Unipotent
Cells restricted to producing/differentiating into only a single-cell type.

Vector
Any vehicle used to transfer foreign genetic material into another cell. The vector itself is generally a DNA sequence that consists of an insert (transgene) and a larger sequence that serves as the "backbone" of the vector. The purpose of a vector to transfer genetic information to another cell is typically to isolate, multiply, or express the insert in the target cell.

Viral infectivity factor (Vif)
A lentiviral packaging element that blocks a cellular inhibitor of viral replication.

Viral protein r (Vpr)
A lentiviral packaging element that participates in the viral RNA into the nucleus for chromosomal integration.

Viral protein u (Vpu)
A lentiviral packaging element that is localized at the cell membrane, facilitating the viral release.

back to top