Caspase staining is a laboratory assay used to detect signs of cell death, termed apoptosis. In this test, a technician looks for proteins involved in the cascade of reactions that lead to full cellular death. Kits are available and it is also possible to design a custom stain for a specific application. Researchers may use caspase staining as a tool to learn more about the processes involved in cell death. It can also be used for diagnostic purposes in some cases.
Cysteine-Aspartic Proteases, shortened as caspases, regulate the processes involved in cell death. Cells are programmed to automatically undergo apoptosis when they have outlived their usefulness or are compromised. This involves a series of reactions controlled by caspases. When this process goes wrong, a cell can keep growing and multiplying even though there is something wrong with it, potentially leading to malignant neoplasms.
Several components are involved in caspase staining. One is a chemical that can attach to a caspase. Another is a flag attached to that chemical so the technician can determine if caspases are present in a sample being evaluated in the lab. Commonly, caspase staining involves the use of fluorescent tagging, where the sample can be illuminated to see if it lights up, indicating that the chemical adhered to some or all of the cells on the plate.
Technicians can select from several different types of caspase staining kits that identify different proteins, indicating different stages in the process of apoptosis. These can range from early chemical signals preparing the cell to wind down to fully necrotic cells. With the use of microscopy, the technician can also make observations to see what happens to neighboring cells when one cell starts to die, and how chain reactions may move across a sample of cells in culture.
Like other laboratory procedures, caspase staining is usually standardized in a facility, with clear directions provided in a lab manual. This ensures that no matter who performs the test, it will be performed in the same way. Consistency is critical for the integrity of results, and testing methods may be a topic of discussion in scientific papers or challenges to forensic evidence, so technicians need to be able to show proof of how they performed the testing. People accustomed to using a different method because they trained in another facility or program may be asked to follow the lab manual for consistency reasons.