mRNA Size — An Important Factor You Cannot Ignore
Over the past 18 months, there has been a sharp rise in interest concerning the development of mRNA-based therapies, as highlighted by the FDA’s Emergency Use Authorization and subsequent approval of one of two novel SARS-CoV-2 mRNA vaccines.
Along with this interest comes an increase in demand for purification products to elevate productivity and alleviate the critical bottleneck that currently exists in downstream bioprocessing and manufacturing facilities.
mRNA exists in a variation of sizes, quantified by their number of nucleotides. For example, the GFP protein has a size between 300 and 1,000 nucleotides. Conversely, mRNA molecules such as the COVID-19 mRNA vaccine and Cas-9 have sizes between 2,000 and 4,000 nucleotides. Even larger, self-amplifying mRNA (SAM RNA) possesses 10,000 nucleotides. As we can see from these examples, the size of mRNA molecules is variable, covering a large range of magnitudes.
When applying this mRNA size principle to chromatography, it is important to note that different sizes of mRNA require different production processes. Currently, there is no “one-size-fits-all”-product for the purification of mRNA.
The Impact of mRNA Size on Resin Chromatography
Currently, the leading chromatography products utilize resin beads in their purification technology. Commonly used resin-based products have dead-end pores with restrictive sizes. Thus, resin chromatography technology often accommodates only a small window of mRNA sizes with decent capacity.
If your laboratory decides to work with another mRNA outside of this window, it is unlikely the resin product will be able to effectively purify the target molecule in the same way. This principle is exemplified by testing completed at Purilogics and displayed in Figure 1. As the mRNA molecular size increased, the resin dynamic binding capacity (DBC) value significantly decreased.
Membrane Chromatography: A Solution
It is clear in order to improve productivity in the mRNA processing industry, technologies that can effectively purify mRNA of various sizes at high and consistent binding capacities are necessary.
At Purilogics, we are currently developing a novel mRNA affinity membrane chromatography product, Purexa™ OdT that does exactly that. With large, straight-through, open pores, mRNA of diverse sizes can effectively bind to our membrane out of an IVT (in vitro transcription) feed stream. As illustrated in Figure 1, not only does the Purexa™ OdT membrane have higher and more consistent DBC values when compared to a commonly used resin product, it achieves these ends at residences times on the order of seconds, rather than minutes. mRNA purification using the Purexa™ OdT membrane can be completed in minutes rather than hours!
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If you are interested in learning more about our Purexa™-OdT membrane, please feel free to contact us!
