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Overview of mRNA extraction

The “central dogma” states that DNA gets transcribed into mRNA which is then translated into a protein. The mRNA strands for messenger ribonucleic acid as it is the messenger between the directions of DNA and the creation of proteins by the ribosome. Researchers and industry laboratories extract mRNA from cells to study processes occurring in the cell. mRNA only accounts for 5% of the RNA in the cell so it is important to have a technique which will specifically purify this type of RNA. RNA is also very sensitive to Rnase contamination, which is found all over your skin as an antimicrobial. To avoid contamination it is helpful to have an efficient and simple method for mRNA extraction. A common method for mRNA extraction is the use of magnetic beads. 

The China Association for Chemical Laboratory Practice (CACLP) Expo is the biggest and most influential IVD-exhibition in the Asian giant. We attended the 2018 edition, held in the city of Chongqing from March 17th to March 19th. Here are the impressions about the event of some colleagues and our CSO.

The last two decades have seen an explosive growth in the use of magnetic beads in Life Science, with sustained double figure sales increase all across the industry. The main driver of this success has been the use of magnetic beads as a solid phase on Chemiluminescence Immunoassays (CLIA) kits. Thanks to its easy automation, this technique has become the preferred choice for high throughput In Vitro Diagnostic.

Renewed version of ‘The Basic Guide to Scale-Up Biomagnetic Separation Processes’ e-book is already available (FREE)!

Scaling up biomagnetic separation process is not just about quantity and quality of the production. One of the main concerns is the operational safety of using ‘big magnets’. As most of the classical magnetic separators are assemblies of permanent magnets in an open configuration, the use of large versions of these devices raises legitimate concerns about the risk for the operators and other laboratory/production equipment. As we will discussed later, the problem does not longer exist using advanced biomagnetic separation systems, but understanding the risks is also key for successfully implement in production environment.

Successfully scaling-up biomagnetic separation processes relies on determining the right working conditions. Having a constant magnetic force in the whole working volume guarantees the in-lot consistency, but manufacturing also needs to guarantee the lot-to-lot consistency.

Almost all life science magnetic beads projects start at small volume. The high cost of the biomolecules (antibodies, protein, nucleic acids….) and the uncertainties involved –what would be the right surface and protocol to coat the beads- make sound to work initially at scales of few milliliters.

As previously discussed, the problem is not working at small scale, but that we don’t pay careful attention when defining the biomagnetic separation conditions. If we leave this task for later stages of the development, we may find important bottlenecks for the scaling-up and, many times, jeopardize the whole project, as the initial conditions may not be scalable at a reasonable cost.

To scale-up a Biomagnetic Separation process, selecting the correct working conditions is beyond paramount. Almost any set of conditions may appear to work well enough at very small volume. Classical magnetic separators generate inhomogeneous magnetic force, having some beads magnetically saturated on regions near the retention areas and non-saturated beads in the rest of the working volume. For tubes of one milliliter or less the separation may apparently seems working fine, as the irreversible aggregation problem would not be noticed, the separation time is short and the magnetic beads losses not appreciable.

 To successfully scale-up a biomagnetic separation process it is necessary to understand how the magnetic beads behave. The separation speed depends on the balance between the magnetic force (generated by the field pattern and the moment of the beads) and the drag force (caused by the buffer viscosity). Thus, it is important to understand how this two forces act on a real magnetic bead suspension.