What are the Different Types of Cell-based Assay?

What are Cell-Based Assays?

If you are a drug developer, you already know how important cell-based assays are. Cell-based assays are nothing but tests that are used to determine the effects of any particular substance on the cell. Before cell-based assays were conceptualized, drug production was highly chance-based. If any particular substance accidentally had positive effects on the cell, a new drug was discovered. However, with cell-based assays, the drug discovery process has become way more systematized and intentional. Not only can you find out the effects of a particular substance but also determine at what concentration that substance has the optimal effect.

Why Do We Need Cell-Based Assays?

Currently, the United States of America spends around $28 billion on cell-based assays. Cell-based assays don’t just help in drug development though. They increase scientific knowledge in general, which leads to the discovery of new therapeutic pathways.

Today, millions of US citizens are suffering from conditions like neurodegenerative disorders, cardiovascular diseases, cancer, obesity, arthritis, and diabetes. This is exactly what fuels the need to pump more effective new medicines into the market. Without cell-based assays, this would be impossible because it would make the process of drug development way more time-consuming. Signs of toxicity would be discovered at a later stage, forcing the authorities to pull back the drugs from the market. Cell-based assays prevent such disastrous outcomes.

What are the Various Kinds of Cell-Based Assay?

As stated before, cell-based assays are tests that inform us of the effects of introducing a new substance into the cell. These effects can be of various kinds. Thus, cell-based assays test lots of variables like fluorescence, radioactivity, luminescence, etc. The different kinds of cell-based assays are listed below.

High-throughput Screening Assays (HTS)

How do you find out what elements can work out as effective drugs? By stumbling across them at random? No. A high-throughput screening test is what you use to pick out possible drug leads before you can begin a drug discovery process. The most interesting part about these HTS tests is that multiple compounds can be tested at once under various conditions. This speaks for the feasibility and scalability of cell-based assays.

Cytotoxicity Assays

Cytotoxicity Assays are the type that you must already have been aware of. Once the possible drug leads are identified, these are all put through cytotoxicity assays to test their toxicity. During these tests, the new substance is introduced to the cells for various periods. Also, the concentration of the substance introduced is changed for each phase of the testing. Here, what is ultimately tested is the cell viability- that is, can the cells survive with this newly added substance. If yes, scientists proceed with more tests. If not, the substance is eliminated from the list of possible leads immediately. This reduces the risk of any kinds of toxicity being discovered when the drug is finally released into the market.

Cell Proliferation Assays

Cellular Proliferation Assays test the growth rate of cells. We all know that cells need to multiply to replace older, decaying cells. However, the right kind of cells needs to multiply. For example, during cancer research, it is of utmost importance to keep track of whether the substance introduced is leading to the growth of the healthy cells or the cancer cells. The former must grow while inhibiting the growth of the latter. A drug is immediately eliminated if it leads to the proliferation of diseased cells.

Cell Death Assays: Autophagy, Apoptosis, and Necrosis

Just like cell viability assays and cell proliferation assays, of course, cell death assays are of utmost importance. The scientists don’t just need to figure out if the new substance is killing off the cells, they also need to know how the cell deaths happened. Why is the cell morality pathway important? Because not all cell deaths result from abnormal causes. For example, autophagy is not just normal, it is essential. Lysosomes are organelles present inside the cell which are called “suicide bags”. They have this sinister name because they practically eat up the cell from within when it is diseased or injured. This phenomenon itself is called “autophagy.” But this process is important to prompt the rebirth of healthy cells or cell organelles. The other two processes- apoptosis or necrosis, are two other kinds of programmed cell deaths. Apoptosis is characterized by cell shrinkage, damage to the mitochondrial membrane, condensation, and DNA fragmentation. Necrosis is characterized by the swelling of the cell and damage to the cell membrane.

Dyes are used to marking the dead or dying cells so that their lethal pathway can be analyzed.

Cellular Signaling Assays

If a drug has an effect on the cell in a paracrine or autocrine manner, this can be identified through a cellular signaling assay. Intracellular calcium flux, metabolic assays, and changes in intracellular pH are all methods that are used to measure cell signaling. Changes in downstream messengers can be measured through methods like immunohistochemistry.

In Conclusion

There are various other assays like metabolic assays, receptor binding assays, gene reporter assays, and more. This article sheds light on some of the most important kinds of assays so that you can form an informed decision on which one is best suited to your needs.