A cell line is a population of cells that can be grown continuously in a laboratory, providing scientists with a consistent tool for research. The HT-29 cell line is a widely used human cell line derived from a colon tumor. It serves as a model in biological and medical studies, allowing for the investigation of cellular processes in a controlled environment.
Origin and Cellular Properties
The HT-29 cell line was established in 1964 from a primary colorectal adenocarcinoma from a 44-year-old Caucasian female. These cells are categorized as epithelial, originating from tissue that lines surfaces and cavities. In the lab, they grow as an adherent layer, attaching to the surface rather than floating in the growth medium. This mirrors how epithelial cells form structured layers within the human intestine.
Genetically, HT-29 cells are aneuploid, meaning they possess an abnormal number of chromosomes. The modal chromosome number is 71, a deviation from the 46 found in typical human cells. This aneuploidy includes seventeen distinct marker chromosomes and is a common feature of cancer cells, reflecting the genetic instability that drives tumor development. The cells also carry mutations in genes such as p53, which is involved in controlling cell growth and division.
Modeling the Intestinal Environment
A significant attribute of the HT-29 cell line is its capacity for differentiation, the process where a cell changes to a more specialized type. Under standard laboratory conditions, HT-29 cells grow as an undifferentiated sheet. However, scientists can induce these cells to transform into specific cell types found in the lining of the human intestine.
By altering the culture conditions, researchers can guide HT-29 cells to develop into absorptive enterocytes or mucus-producing goblet cells. A common method to trigger this change involves replacing the glucose in the nutrient medium with galactose. Another technique is the addition of chemical inducers like sodium butyrate. This ability to create a functional model of the intestinal lining makes the HT-29 line a valuable tool for gastrointestinal research.
Key Research Applications
In cancer research, HT-29 cells are used for studying the molecular pathways of colorectal cancer. Scientists use them to test the effectiveness of chemotherapeutic drugs like 5-fluorouracil and oxaliplatin, which are standard treatments for this type of cancer. The cells’ known genetic mutations allow for targeted investigations into how such alterations contribute to tumor progression.
In pharmacology, differentiated HT-29 monolayers are used to study how drugs are absorbed, transported, and metabolized across the intestinal wall, providing insights into drug bioavailability. For nutrition and gut health studies, these cells help researchers understand how nutrients are taken up from food and how the intestinal lining interacts with gut bacteria.
When differentiated into goblet cells, the HT-29 line provides a platform to study the protective mucus layer of the intestine. This is relevant for investigating conditions with a compromised mucus barrier, such as inflammatory bowel disease (IBD). Researchers can use co-culture systems, combining HT-29 cells with other intestinal cell lines like Caco-2, to create more complex models of the gut environment.
Laboratory Culturing Conditions
HT-29 cells require a carefully controlled environment for growth. The cells are grown in a nutrient-rich growth medium, with McCoy’s 5A Medium being a common choice. This medium is supplemented with fetal bovine serum (FBS), typically at a 10% concentration, which provides growth factors and hormones to support cell proliferation.
The cells are housed in a sterile incubator that maintains conditions similar to the human body. The temperature is kept constant at 37°C, and the atmosphere is humidified with 5% carbon dioxide. This CO2 interacts with the bicarbonate buffering system in the growth medium to maintain a stable pH of around 7.4. Under these conditions, HT-29 cells have a population doubling time of approximately one day.