Stem Cell Glossary

All the stem cell definitions you need to know

Adult Stem Cells

Adult stem cells (also called somatic stem cells or tissue-specific stem cells) are found in some, but not all of the body’s mature tissues. They can only make the types of cells found in the tissue they inhabit. For example, adult stem cells from the liver can only make more liver cells. They can only give rise to blood cells and a few other cell types.

Allogeneic Stem Cell Therapy

A type of treatment in which healthy stem cells are collected or derived from an unrelated donor, converted into a specific cell type, and transplanted into a patient. These are also sometimes referred to as “off-the-shelf” cell therapies, with the goal of creating large cell quantities from a single donor that can be readily available for transplantation. 

Autologous Stem Cell Therapy

In an autologous stem cell therapy, stem cells are collected or derived from a patient themself, and then used to create a certain cell type that is damaged or lacking in that patient, so that a transplant of these cells into the target organ will restore function. For example, cancer patients can have their blood stem cells extracted and frozen, so that once they undergo chemotherapy (which kills off blood-forming stem cells) these cells can be reintroduced to the body. Another example includes a therapy in development at NYSCF in which the stem cells of patients with age-related macular degeneration are turned into healthy eye cells that can be used to restore vision.


Astrocytes are star-shaped glial cells in the brain that perform functions such as delivering nutrients to neurons, repairing nervous tissue following injury, and facilitating signaling between cells. Read more about how these typically good brain cells can ‘go rogue’ in disease.

Basic Research

Basic research in biology attempts to understand the fundamentals of how a biological system or pathway works, so as to extend knowledge and lay the groundwork for future studies of health and disease. Many discoveries made through basic research, such as CRISPR gene editing, have proven to have a transformational impact on disease research and treatment.


A blastocyst is an early stage embryo — about 5 days old. Blastocysts are microscopic, containing roughly 150 cells. They are produced from an egg that has been fertilized in vitro but has not yet been implanted into the uterus. A blastocyst is about the same size as a cross section of a human hair. In stem cell research, blastocysts from discarded in vitro fertilization attempts can be used to create embryonic stem cells.

Bone Marrow Transplant

In a bone marrow transplant, healthy blood-forming stem cells are infused into the body to replace bone marrow that isn’t producing healthy blood.


Cardiomyocytes are the muscle cells of the heart that cause it to beat. 

Cord Blood Stem Cells

Cord blood stem cells can be extracted from the umbilical cord after childbirth. Even though these cells come from a newborn infant, they are still limited like adult stem cells and can only become certain cell types (usually blood or nerve). Unlike adult stem cells, however, they can grow indefinitely in culture. This gives researchers a limitless supply—enough to create tissue or disease models.

Clinical Trial

Clinical trials are research studies performed in people that evaluate the safety, feasibility, and efficacy of  a medical, surgical, or behavioral intervention. Clinical trials must be performed on any medical intervention like a drug or cell therapy before it can be offered on the market to patients.


The CRISPR system is a tool for precision gene editing. It can replace, modify, or delete genes of interest, allowing researchers to study the basis of genetic disease and develop treatments.

Watch a presentation from NYSCF – Robertson Investigator, Feng Zhang, PhD, who helped pioneer the revolutionary CRISPR gene editing tool.


A cell differentiates when it is converted into a new cell type to take on specialized functions, like the ability of a red blood cell to carry oxygen or a nerve cell to send an electrical signal. All of the cells in the adult body are differentiated products of the embryonic stem cells that begin our development. In stem cell research, we differentiate stem cells into disease-relevant cell types so as to study their functions “in a dish.”


‘Disease-in-a-dish’ modeling is a method of studying human disease outside of the body by culturing cells that have the properties of the diseased tissue. Many such models are generated using cells differentiated from stem cells derived from individuals with a specific disease.


Deoxyribonucleic acid (or ‘DNA’) is the molecule in each of our cells that carries our genetic information.

Drug Screening

The process of testing many drugs to determine which may be promising candidates for treatment. Stem cells allow this process to be done on human cells affected by disease.


The stage of development between fertilization and the fetal stage.

Embryonic Stem Cells

Embryonic stem cells are stem cells derived from embryos. These stem cells can become almost any other cell type in the body and can divide in culture for an extended period of time. They come from embryos that have resulted from in vitro fertilization (fertilization that takes place in a clinic, outside the body) and are donated (with donor consent) for research purposes. 


A cell that helps form connective tissue in the body. Fibroblasts are found in many organs, from our skin to our liver to our lungs. Skin fibroblasts are one of the adult cell types that can be readily converted into induced pluripotent stem cells using the Yamanaka method.

Genomic modification

Genomic modification is the stable, intentional, and directed change of a cell’s DNA sequence using biotechnological methods. CRISPR gene editing is one well-known example.


A category of central nervous system cells other than neurons that contains three types of cells: astrocytes, oligodendrocytes, and microglia. Glial cells make up the majority of the brain.


A haplotype is a group of genes that is inherited together, along the same segment of a chromosome, from one parent.

Hematopoietic Stem Cells

Cells found in the blood and bone marrow that can form mature blood cells such as red blood cells, white blood cells, and platelets. Bone marrow transplants are the way hematopoietic stem cells are used therapeutically to treat diseases like leukemia.

HLA Haplobank

A HLA haplobank is a collection of iPS cell lines that are designed to be immunological ‘matches’ to a large proportion of the population, creating the opportunity to derive immunologically compatible tissues for therapeutic transplantation as cell therapies.

Investigational New Drug Application (IND)

An IND is a mandatory step in the development of a new drug or medical treatment, in which the US Food and Drug Administration (FDA) is notified that a novel therapeutic will be used experimentally in a clinical trial.

In Vitro

Taking place outside a living organism. In stem cell research, for example, this can refer to studies of cells that are done “in a dish.”

In Vivo

Taking place inside a living organism. In stem cell research, for example, this can refer to studies of cells within or transplanted into a living organism like a mouse model.

Induced Pluripotent Stem Cells (iPSCs)

Induced pluripotent stem cells (iPSCs) are produced by artificially “turning back the clock” of adult cells to a more embryonic-like state using the Yamanaka method. iPS cells can be produced from blood cells or skin fibroblasts; they have many characteristics of embryonic stem cells, but they are not identical. This breakthrough technology is very useful for research, allowing us to create disease models in a dish that retain the genetic background of the donor, though embryonic stem cells still serve a vital research purpose as a gold standard reference.


A structure in the back of the retina responsible for central vision. Cells in the macula called ‘retinal pigmented epithelial cells’ are lost in age-related macular degeneration.

Mesenchymal Stem Cells

Mesenchymal stem cells are multipotent stem cells found in bone marrow that are important for making and repairing skeletal tissues.


A type of glial cells, termed the ‘immune cells of the central nervous system,’ that play roles in inflammation and infection and that have been implicated in neurodegenerative diseases.


Mitochondria are cell structures that generate chemical energy to power cellular processes. They also host numerous essential metabolic processes and reactions.

Mitochondrial replacement therapy (MRT)

We have 2 types of DNA in our cells: DNA inherited from both our parents located in cell nuclei, and DNA inherited only from the mother found in mitochondria. This can be problematic if a mother carries a disease passed down through mitochondrial DNA, as her child will always inherit it. Mitochondrial replacement therapy is a preventative method that can replace mutant maternal mitochondria with healthy mitochondria from an unaffected individual prior to in vitro fertilization, protecting a child from inheriting disease.

Multipotent Stem Cells

Cells that can give rise to several different cell types. Most adult stem cells, like blood stem cells found in the bone marrow, are multipotent.


The central nervous system cells that send electrical and chemical signals to each other, forming connections between the brain and the rest of the body.


Oligodendrocytes are glial cells that create myelin – a substance that coats neurons and acts as insulation to help them send signals. Myelin is damaged in some neurodegenerative diseases like multiple sclerosis.

Pancreatic Beta Cells

Pancreatic beta cells help the pancreas produce insulin. These are the cells attacked by the immune system in type 1 diabetes.


Parthenogenesis is the activation of an unfertilized egg by chemical means. These chemical signals cause the egg to begin to divide much as it would after normal fertilization. Scientists believe that these dividing cells could also be used to derive embryonic stem cells. However, these embryonic stem cells would carry the genes from only the woman from whom the unfertilized eggs were retrieved.

Pluripotent Stem Cells

Pluripotent stem cells are early stage cells that can become any type of cell in the body. The two major types of PSCs used in research are embryonic stem cells and induced pluripotent stem cells.  

Progenitor Cells

Progenitor cells are descendants of stem cells that are primed to turn into specialized cell types. For example, neural progenitor cells can only become neurons.


In stem cell research, scientists can reprogram skin or blood cells to revert back into an embryonic-like state. The cells created through the reprogramming process are called induced pluripotent stem cells.

Regenerative Medicine

A branch of medicine aimed at restoring function by replacing or repairing damaged tissues in the body. One prominent example is cell replacement therapy, which often uses stem cells to create replacement cells that restore function.


Ribonucleic acid (or ‘RNA’) is a molecule that is transcribed from DNA and often used to create functional proteins in our cells. There is also a lot of ‘non-coding’ RNA in our cells that does not encode proteins but plays other important roles. 


RNA-Seq is an analytical method that can reveal the identities and quantities of RNAs expressed from genes in a cellular sample.

Retinal Pigmented Epithelial Cells

Retinal pigmented epithelial cells or ‘RPE cells’ are eye cells that live in the macula and help give rise to central vision. These are the cells that dysfunction in age-related macular degeneration.

Somatic cell nuclear transfer (SCNT) 

SCNT is a method for generating embryonic stem cells. Stem cells generated by SCNT are the gold standard for stem cell research. In this technique, the nucleus of an egg cell is removed and replaced with the nucleus of an adult cell, like a skin or blood cell.


Self-renewal is the ability of a stem cell to produce more stem cells with identical characteristics to the “parent” cell.

Stem Cell Line

A stem cell line is a group of stem cells collected or created from a single person that can be infinitely propagated for research or treatment.

Stem Cell Tourism

Stem cell tourism is the process of traveling abroad to receive stem cell-based treatments for disease or injury from clinics that offer untested or unproven therapies. Originally, such therapies were primarily offered in other countries, but now the need to go abroad has diminished due to the boom of predatory clinics popping up around the United States.

Watch a recent panel discussion by scientists and patient advocates on what you need to know about stem cell tourism.

Tissue-Specific Stem Cells

See ‘adult stem cells’

Totipotent Stem Cells

Cells that can give rise to every cell type in the body.

Translational Research

Research aimed at translating results from basic research into results that directly benefit patients, such as advancing the understanding of disease or developing more effective treatments.


A fertilized egg cell created when a sperm cell fuses with an egg cell



iPS Derived Neuron Precursor