University of Massachusetts (Amherst) scientists have discovered a process for making RNA that is purer, in higher yield, and more cost-effective, than current processes. The novel process thus eliminates a major obstacle to the design of next-generation RNA therapies. “Single-protein” diseases such as cystic fibrosis, hemochromatosis, Tay-Sachs, and sickle cell anemia involve a missing or dysregulated protein.
Patients could benefit by adding the correct protein to the mix as either a one-shot functional cure, or in addition to down-regulating the defective RNA/DNA. This straightforward approach has serious drawbacks, however, since the strategy works best when patients make the protein themselves, rather than taking it through injection or infusion.
Medicine has the means to deliver RNA effectively, which we know thanks to the mRNA COVID vaccines. The problem is quality. Current production methods for RNA can provide purity or quantity but not both, at least not cost-effectively.
According to lead researcher Elvan Cavac, PhD, keeping RNA therapeutic development programs humming along will require “lots of RNA.” Cavac knows of what he speaks regarding purity and cost-effectiveness, as he holds both a chemistry PhD and an MBA. His RNA production method re-uses its ingredients and yields between three and ten times more RNA than conventional approaches, so “it also saves time and cost.”
A conventional RNA production run
In a conventional RNA production run, as the RNA builds up in solution. T7 RNA polymerase re-binds to the newly formed RNA and extends it, resulting in strands that are longer than normal, many of which are double-stranded. Current purification methodology does a poor job of resolving this mixture. Patients receiving unnaturally long RNA can develop serious, sometimes fatal immune reactions.
Increasing the salinity of the reaction mix prevents T7 RNA polymerase from going haywire and re-binding to molecules that have already formed. At the same time the new method keeps the template DNA and T7 RNA polymerase in close proximity, on magnetic beads, which drives promoter binding and the initiation of transcription. The result: increased overall yield and purity of the target RNA sequence and only the target RNA sequence.
“Rather than having to purify RNA,” said senior author chemistry professor Craig Martin, PhD, “we’ve figured out how to make clean RNA right from the start. Our method can be more than ten times better at producing pure RNA than current processes.”
The ultimate goal is a continuous process in which ingredients enter one end of the reactor, and pure RNA emerges from the other end.
Read the full text of this seminal paper here.