Cell lysis is the breaking down of the cell membrane, a technique used in scientific research for releasing cell contents to study them or purify specific contents. This can be done by physical methods or chemical methods.
How to lyse cells using physical methods
There are several ways to lyse cells using mechanical methods. The technique that is chosen can depend on the availability of machinery in the laboratory, what is most efficient, what is most cheap, and what has worked best previously for the cells in the laboratory.
- One option is to blend the cells in a laboratory blender, using the force of the rapidly rotating blades to destroy cell membranes or tissues. These blenders can come in several sizes.
- Another option is to use liquid homogenization. This process is based on using shear stress to break apart cell membranes. Your sample is placed in a tight vessel that a piston is driven into to create high pressure to break the cell membranes.
- Sonication is also a frequently used method for physical cell lysis. Sound waves at a high frequency from a probe are pulsed through an aqueous sample. This method creates heat quickly, so it is often performed in an ice bath or cold room, and only in short bursts of time.
- Some laboratories use the process of several freeze-thaw cycles to lyse cells. This process agitates cell membranes of bacteria or mammalian cells. Agitation is caused by swelling of the cells through temperature fluctuation as well as the formation of ice crystals.
- Mortar and pestle is used for cell lysis on solid samples, often samples that are frozen solid. The mortar and pestle is a classic method of putting force on the sample between the pushing on the pestle onto the mortar.
To avoid proteolysis of proteins in your lysed sample, protease inhibitors are often added. DNase and RNase can be added to very viscous samples that are not being used for ultimately purifying nucleic acids.
How to lyse cells using chemical methods
Different cells and tissue types will require their own cocktail of reagents for lysis. Chemical lysis solutions are mostly detergent based, because hydrophobic detergents effectively break down cell walls by disrupting interactions at the surface. For some cells the breaking of the membrane is more optically gentle than the physical techniques. There are several types of optimized solutions available for cell lysis. Some detergents are more mild than others. Stronger detergents can denature proteins, so it is important to choose a milder detergent if you need to isolate proteins for the study of protein structure and function. With cell lysis solutions, you must also consider how that solution may interfere with later steps in your protocol. You may want to consider pH and salt concentrations in that solution. Membranes of higher complexity or cell walls are special challenges that require extra consideration of all these possibilities as well.
The importance of how to lyse cells
Researchers now work with many different cell types and are interested in extracting various types of molecules, such as nucleic acids and proteins. It is important to consider all the factors mentioned in this article when lysing cells, and consider how to optimize your further steps as well. Once the cell is lysed, you will want to efficiently separate your molecules of interest from your lysate (concoction of lyse cells and any solution you used for lysis). This is the point where you might consider various separation methods that use fractionation, or newer more efficient techniques such as magnetic separation.