iPSC culture is the process of growing and maintaining induced pluripotent stem cells in a laboratory. These cells are valuable for biomedical research because they can be transformed into any other cell type. This technology allows scientists to study diseases and test drugs on human cells outside the body. The process requires a controlled environment to support cell growth and ensure the cells retain their unique properties.
Creating Induced Pluripotent Stem Cells
Induced pluripotent stem cells (iPSCs) are not sourced from embryos but are generated from adult somatic cells, which are mature cells from tissues like skin or blood. This process involves cellular “reprogramming,” a method that forces these specialized adult cells to revert to a primitive, stem-cell-like state.
The discovery of this method by Shinya Yamanaka was a significant development in stem cell research. The transformation is achieved by introducing a specific set of genes, often referred to as “Yamanaka factors,” into the adult cells. These factors initiate a cascade of events that erases the cell’s specialized identity and returns it to a pluripotent state, capable of becoming any cell type.
Maintaining and Growing iPSCs in the Lab
Keeping iPSCs alive and multiplying is a meticulous process that requires an optimal environment. The cells are grown in sterile culture dishes containing a culture medium, a nutrient-rich broth with growth factors and other components necessary for cell survival and proliferation.
To ensure the cells thrive, they are housed in incubators that maintain a constant temperature of 37°C, high humidity, and controlled levels of gases like carbon dioxide. This environment mimics the conditions inside the human body. Historically, iPSCs were grown on a layer of mouse cells, called a feeder layer, but modern techniques increasingly use feeder-free systems where the culture dishes are coated with a biological matrix.
The nutrient-rich medium is depleted quickly by the rapidly growing cells and must be replaced daily to replenish nutrients and remove waste products. This regular “feeding” is important for preventing the cells from spontaneously differentiating into unwanted cell types. Scientists must monitor the cultures daily, looking for any changes in the cells’ appearance that might signal problems.
As the cells multiply, they form dense colonies and eventually run out of space on the culture dish. To manage this, scientists perform a procedure called “passaging” or “splitting,” which is similar to repotting a plant. This involves using enzymes to gently detach the cell colonies, break them into smaller clumps, and transfer them to new dishes with ample space to grow. This process is typically done every five to seven days.
Ensuring Cell Quality and Pluripotency
A major part of iPSC culture is verifying that the cells maintain their defining characteristics. Scientists must confirm that the cells are truly pluripotent, meaning they still possess the ability to differentiate into any of the three primary germ layers. This is often done by checking for the presence of specific proteins, known as pluripotency markers, on the surface of the cells.
The rapid cell division during culturing can sometimes lead to genetic alterations. Therefore, researchers regularly assess the genetic stability of the iPSC lines. They perform chromosomal analysis, a process called karyotyping, to ensure the cells have the correct number and structure of chromosomes. Detecting abnormalities early is important for ensuring the cells are reliable and safe for research and potential therapeutic use.
Uses for Lab-Grown iPSCs
A primary application of iPSCs is in disease modeling. Scientists can take somatic cells from patients with genetic disorders, such as cystic fibrosis or Huntington’s disease, and reprogram them into iPSCs. These cells can then be differentiated into the specific cell types affected by the disease, creating a “disease in a dish.” This allows researchers to study how a disease progresses at a cellular level.
These lab-grown cells are also used in drug discovery and toxicology screening. By differentiating iPSCs into specific human cell types, like heart or liver cells, pharmaceutical companies can test thousands of compounds quickly and efficiently. This approach helps to identify promising drug candidates and flag those that may be toxic to human cells early in the development process.
Regenerative medicine is another promising field for iPSC use. The goal is to use these cells to generate healthy tissues that can be transplanted into patients to treat a wide range of conditions. Researchers are actively exploring the potential of using iPSC-derived cells to replace damaged neurons in Parkinson’s disease or generate insulin-producing cells for diabetes. While many of these therapies are still experimental, they represent an area of intense scientific investigation.