Stem Cell Glossary
Adult Stem Cells
Adult stem cells (also called somatic 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.
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.
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.
The CRISPR/Cas system is a tool for high-precision gene editing. It can replace, modify, or delete certain genes, allowing researchers to study the basis of genetic disease and develop treatments.
A cell differentiates when it changes to take on its specialized functions, like the ability of a red blood cell to carry oxygen or a nerve cell to send an electrical signal.
A disease-in-a-dish is a method of modeling 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 iPSCs derived from individuals with a specific disease.
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.
Genomic modification is the stable, intentional, and directed change of a cell’s DNA sequence using biotechnology.
A haplotype is a group of genes that is inherited together from a single parent.
A HLA Haplobank is a panel or repository of iPS cell lines that are homozygous for HLA types and could be used to derive immunologically-compatible tissues for therapeutic transplantation.
Investigational New Drug Application (IND)
An IND is a key step in 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.
Induced pluripotent stem cells (iPS cells) are produced by artificially “turning back the clock” of adult cells to a more embryonic-like state. iPS cells 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, but it does not reduce the need for embryonic stem cells.
Mitochondria are cell structures that generate chemical energy to power cellular processes. They also serve as sites for numerous metabolic processes and reactions.
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 and 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 is a potential therapy that can replace mutant maternal mitochondria with healthy mitochondria from an unaffected individual prior to in vitro fertilization, protecting a child from inheriting disease.
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. They come from blastocysts leftover from infertility treatments that would otherwise be destroyed. Smaller than the point of a needle, these blastocysts are grown in a Petri dish. They are small clumps of cells, 5 to 7 days old — long before a fetus would be formed.
RNA-Seq is an analytical method that can reveal the identities and quantities of RNAs expressed from genes in a cellular sample.
Somatic cell nuclear transfer (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 as the “parent” cell.
Stem Cell Tourism
Stem cell tourism is the process of seeking or receiving stem cell-based treatments for disease or injury from clinics or practitioners that offer untested or unproven therapies.