Techniques for cell disruption are not all created equal. Results published in the scientific literature show the cell disruption method strongly influences the physical-chemical properties of the disintegrate, such as particle size, disruption efficiency, viscosity and protein release.
Lab Scale Cell Lysis TechniquesFrench Press
Generates high pressure in a pressure cell. A manually controlled valve releases the pressurized fluid from the pressure cell, resulting in cell rupture. Not scalable or repeatable; needs strength to close and open the valve. There are numerous hazards involved with French Presses. They are difficult and time-consuming to clean, which has to be done for every sample. Most manufacturers of French Presses have discontinued production but they are still in use, available from small companies and second hand.
High-Pressure Homogenizers (HPH)
These machines are the next best alternative to the Microfluidizer® technology for cell disruption. Prices are typically equal to, or lower than Microfluidizer® processors. Cooling, cleaning, wear (valves!) and scalability can be issued. In particular, if we look beyond simply the % of cells ruptured to the quality and usability of the ruptured suspension the Microfluidizer® technology- is the clear winner. Table 1 highlights the increased yield from a Microfluidizer® processor compared to an HPH.
Utilizes cavitational forces. Often used for very small sample volumes, the cell suspension is sonicated with an ultrasonic probe. Local high temperatures – resulting in low yields – along with scalability and noise are the main issues with this technology. Advantages are price of equipment and sample volumes (from µl) that can be processed.
Subjecting the cell suspensions to variable temperatures results in rupture of the walls. This is not a very reproducible method, the result will vary, is only suitable for very small samples in the ml range, but it is very cheap.
Adding chemicals that soften and rupture the cell walls. Chemicals can be costly and thus scalability is limited. These chemicals contaminate the preparation which may be undesirable.
Mortar and Pestle
Grinding the cell suspension. This is laborious manual work that can take several minutes, therefore not scalable and not very repeatable, only suitable for small lab samples.
Milling with Dynomills or similar equipment can lead to contamination by media and difficulty controlling temperature. Otherwise, this can be an effective way of rupturing many cell types.
It is common practice to pre-treat cell suspensions with enzymes that soften the cell walls prior to mechanical disruption. It has been reported that this technique can still be valuable when using a Microfluidizer® processor as it can reduce the pressure or number of passes required.
Production-Scale Cell Lysis Techniques
High-pressure homogenizers are the only alternative to a Microfluidizer® processor for larger volumes. These are large-scale versions of the lab units. This typically involves changes to the way the cells are ruptured to accommodate higher flow rates, resulting in inconsistency when scaling up. Multiple complex homogenizer valves may be required contributing to the downtime for these machines.
Check back with the blog for an exploration of the advantages of microfluidics for cell disruption.