Cell Bank

A facility where cell lines are kept frozen and stored for later use. Cell banks include master cell banks (MCBs) and working cell banks (WCBs). MCBs house primary cell strains that are kept stored and not used for production purposes. WCBs house cells used in pharmaceutical production grown from those maintained in an MCB so that their stability and uniformity are well characterized.

Cell Culture Technology

The growing of cells outside of living organisms. With mammalian cell culture, it is sometimes possible to replace animal testing with cell testing when evaluating the safety and efficacy of medicines.

Cell Lines

Generations of cells grown from original primary cells. Primary cells are cultured directly from a living organism. With the exception of some derived from tumors, most primary cell cultures have limited life spans. After a certain number of population doublings, cells usually stop dividing, though they remain alive. An established or immortalized cell line has acquired the ability to proliferate indefinitely through either random mutation or deliberate modification.

Cell Viability

Determining whether a cell population is living or dead. Testing for cell viability usually involves looking at a sample cell population and staining the cells or applying chemicals.

Chemical Library (or Compound Library)

A collection of stored chemicals that may be used in high-throughput screening for drug development. The larger the chemical library, the better the chance that high-throughput screening will find a hit (a potential drug candidate).

Chinese Hamster Ovary Cells (CHO cells)

A cell line often used in biological and medical research, first introduced in the 1960s. CHO cells are used in studies of genetics, toxicity screening, nutrition and gene expression, particularly expression of recombinant proteins. CHO cells are the most commonly used mammalian hosts for industrial production of protein therapeutics.


A process by which complex mixtures of different molecules may be separated from each other. This is accomplished by subjecting the mixture to many repeated partitionings between a flowing phase and a stationary phase.


A threadlike linear strand of DNA and proteins in a cell that houses genes. Chromosomes are large enough to be seen under a microscope. In humans, all cells other than germ cells usually contain 46 chromosomes: 22 pairs of autosomes and either a pair of X chromosomes (in females) or an X chromosome and a Y chromosome (in males). In each pair of chromosomes, one chromosome is inherited from the father and one from the mother.


A step in the downstream phase of manufacturing a biologic. After the protein product is harvested, which may include removing intracellular proteins from cells, clarification steps separate the protein from cellular debris. Individual proteins are then separated using chromatography methods.

Clinical Trial

A type of research study that evaluates the safety and efficacy of new drugs, medical devices and biologics in human subjects. These tests are required by regulatory agencies as a precondition of regulatory clearance to market.


The replication of a DNA sequence from one organism to create an exact genetic copy; processes used to create copies of DNA fragments (molecular cloning), cells (cell cloning) or organisms.


A string of exactly three mRNA bases that code for a specific amino acid during translation of mRNA into DNA.

Colony Hybridization

The screening of a library with a labeled probe (radioactive, bioluminescent, etc.) to identify a specific sequence of DNA, RNA, enzyme, protein or antibody.

Column Chromatography

A type of chromatography that uses a column for containing and separating a mixture. It is a commonly used method of purifying proteins.

Combinatorial Chemistry

A discipline in which a large number of new chemicals are created, compiled into a library and screened for potential therapeutic use.