干细胞工程名词解释

Cancer stem cells are defined as those with the ability to self-renew while generating a daughter progenitor. They are malignant for the progenitor to undergo further differentiation into more mature progenitors into phenotypically diverse cancer cells. To cure cancer it is imperative to devise therapies that effectively target the cancer stem cells.

iPS cells, namely induced pluripotent stem cells, were first produced in 2006 from mouse cells and in 2007 from human cells. They are a type of pluripotent stem cell artificially derived from a non-pluripotent cell, typically an adult somatic cell, by inducing a "forced" expression of specific genes, such as oct4, sox2, nanog, klf4, c-myc and so forth. They are similar to natural pluripotent stem cells, such as ES cells, in many respects, such as the expression of certain stem cell genes, chromatin methylation patterns, doubling time, embryoid body formation and potency of differentiability, but the full extent of their relation to natural pluripotent stem cells is still being assessed

cell reprogramming, is the process of directing mature cells to a primitive state of gene expression. Somatic cell nuclear transfer, cell fusion, and introduction of specific transcriptional factors are three main strategies of cell reprogramming.

stem cells are biological cells that can differentiate into diverse specialized cell types. There are two types of stem cells: embryonic stem cells that are isolated from the inner cell mass of blastocysts, and adult stem cells that are found in various tissues. The classical definition of a stem cell requires it possess two properties: self-renewal - the ability to go through numerous cycles of cell division while maintaining the undifferentiated state. Potency - the capacity to differentiate into specialized cell types. In the strictest sense, this requires stem cells to be either totipotent or pluripotent - to be able to give rise to any mature cell type, although multipotent or unipotent progenitor cells are sometimes referred to as stem cells.

Epigenetic is the study of heritable changes in phenotype or gene expression caused by mechanisms other than changes in the DNA sequence. These changes may remain through cell divisions for the remainder of the cell's life and may also last for multiple generations. However, there is no change in the underlying DNA sequence of the organism; instead, non-genetic factors cause the organism's genes to behave differently.

Embryonic stem cells are pluripotent stem cells derived from the inner cell mass of the blastocyst, an early-stage embryo. They have two distinctive properties: the pluripotency of differentiation, and the capacity of self-renewal. They can differentiate into all derivatives of the three primary germ layers, which include more than 220 types of cells in the adult body. They also can maintain their undifferentiated state when they are in the continuous process of division.

gene targeting is a genetic technique that uses homologous recombination to change an endogenous gene. The method can be used to delete a gene, remove exons, add a gene, and introduce point mutations. Gene targeting can be permanent or conditional. Gene targeting

requires the creation of a specific vector for each gene of interest. However, it can be used for any gene, regardless of transcriptional activity or gene size.

可塑性plasticity refers to the ability of a cell to change its phenotype in response to changes in the environment.

Somatic cells nuclear transfer is a laboratory technique for creating a clonal embryo, using an ovum with a donor nucleus. It can be used in embryonic stem cell research, or in regenerative medicine, such as "therapeutic cloning". It can also be used as the first step in the process of reproductive cloning, but it will break human ethics if it is applied in human cloning.

Genomic imprinting is a mark about parental origin, namely a genetic phenomenon by which certain genes are expressed in a parent-of-origin-specific manner. It is an inheritance process independent of the classical Mendelian inheritance. Imprinted genes are either expressed only from the allele inherited from the mother , or from the allele inherited from the father. It is also an epigenetic process that involves methylation and histone modifications in order to achieve gene expression without altering the genetic sequence. These epigenetic marks are established in the germline and are maintained throughout all somatic cells of an organism.

Transdifferentiation is an irreversible switch of one differentiated cell type to another. It takes place when 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. It is a type of metaplasia, which includes all cell fate switches, including the interconversion of stem cells.

Stem cell niche is the microenvironment in which stem cells are found, which interacts with stem cells to regulate stem cell fate. Niche can be in reference to the in vivo or in vitro stem cell microenvironment. During embryonic development, various niche factors act on embryonic stem cells to alter gene expression, and induce their proliferation or differentiation for the development of the fetus. Within the human body, stem cell niches maintain adult stem cells in a quiescent state, but after tissue injury, the surrounding micro-environment actively signals to stem cells to either promote self renewal or differentiation to form new tissues.

Aseptic technique refers to a procedure that is performed under sterile conditions. This includes medical and laboratory techniques, such as with microbiological cultures. It includes techniques like flame sterilization.

自我更新self-renew means that embryonic stem cells can maintain their undifferentiated state when they are in the continuous process of division. It is the distinctive prosperity of embryonic stem cells or iPS cells.

分化differentiation is the process by which a less specialized cell becomes a more specialized

cell type. Differentiation occurs numerous times as the organism grows from a simple zygote to a complex system of tissues and cell types. Differentiation dramatically changes a cell's size, shape, membrane potential, metabolic activity, and responsiveness to signals. It is under the exact and rigorous control of the expression of various genes.

细胞周期The cell cycle is the series of events that takes place in a cell leading to its division and duplication. It can be divided in two brief periods: interphase, during which the cell grows, accumulating nutrients needed for mitosis and duplicating its DNA; and M phase, during which the cell divides into two distinct cells . The cell cycle is a vital process by which a zygote develops into a mature organism, as well as a process by which various tissues and organs are renewed.

治疗性克隆therapeutic cloning means using the technique of cloning to create embryos in the laboratory for medical purposes. The use of cloning techniques to obtain human embryos is in order to extract embryonic stem cells or pluripotent stem cells. These stem cells, in the right conditions, can develop into any types of cells, issues as well as organs, which can be used for medical treatment.