NIH/3T3 cells are a widely utilized immortalized mouse fibroblast cell line, serving as a foundational tool in biological research. These cells are derived from the connective tissue of mouse embryos and possess a spindle-shaped appearance. Their consistent growth patterns and ability to divide indefinitely in laboratory settings make them a reliable model system for various scientific investigations. These cells are frequently employed to explore fundamental cellular mechanisms and responses to different conditions.
Origin and Defining Characteristics
The “NIH” in NIH/3T3 refers to the National Institutes of Health, where this cell line was established. The “3T3” portion of the name describes the specific culturing protocol developed by scientists George Todaro and Howard Green in 1962. This protocol involved transferring cells every three days (“3-day transfer”) with an initial inoculum of 3 x 10^5 cells (“3 x 10^5 cells”) to prevent overgrowth and maintain optimal conditions.
NIH/3T3 cells are fibroblasts, a type of cell found in connective tissue that provides structural support. A defining characteristic is their immortalized nature, allowing them to proliferate continuously in a laboratory environment without undergoing cellular senescence. Despite their indefinite growth, these cells retain contact inhibition, stopping their division when they form a dense, single layer in a culture dish. This characteristic allows them to serve as a valuable non-cancerous baseline in many studies.
Role in Cancer Research
NIH/3T3 cells are used in oncology research, particularly for understanding cellular transformation. Their contact inhibition makes them an ideal model for observing how normal cells acquire cancerous properties. When these cells lose contact inhibition, they begin to pile up in disorganized clumps, forming “foci” in a culture dish.
This phenomenon is the basis of transformation assays, also known as focus formation assays, used to identify oncogenes. Oncogenes are genes that, when activated, can promote uncontrolled cell growth and division. A classic example involves the discovery of the Ras oncogene, where DNA from human tumor cells was introduced into NIH/3T3 cells. The appearance of foci indicated the introduced Ras gene transformed the NIH/3T3 cells into a cancerous state, providing insight into cancer development.
General Laboratory Applications
Beyond cancer research, NIH/3T3 cells are widely applied in other areas of laboratory science. They are highly susceptible to transfection, a process where foreign DNA is introduced into cells. This high efficiency makes them a workhorse for studies aiming to understand gene function and expression.
These cells also serve as a model system for investigating fundamental cellular processes. Scientists use NIH/3T3 cells to dissect cell signaling pathways, study cell cycle control, and analyze cellular responses to various growth factors.
Culturing and Handling in the Lab
Maintaining NIH/3T3 cells requires specific environmental conditions. They are typically cultured in a liquid growth medium, such as Dulbecco’s Modified Eagle Medium (DMEM), which provides the necessary nutrients. This medium is supplemented with serum, like fetal bovine serum (FBS), which supplies growth factors and proteins.
Cells are incubated in a controlled environment, usually at 37 degrees Celsius with a 5% carbon dioxide (CO2) atmosphere. To ensure their continued healthy growth, scientists regularly perform passaging or “splitting.” This involves detaching the cells from their culture vessel, diluting them, and transferring a portion to a new vessel.