Single-pass tangential flow filtration (SPTFF) for continuous mRNA concentration and purification

The growing demand for mRNA therapeutics requires development of more efficient manufacturing strategies. Single-Pass Tangential Flow Filtration (SPTFF) has the potential to provide intensified/continuous concentration and purification of mRNA. This study provides the first analysis of SPTFF for the processing of two mRNA constructs with different length, both in the crude mixture generated by in vitro transcription. Stirred cell experiments were performed with modified polyethersulfone (mPES) and regenerated cellulose (RC) membranes over a range of molecular weight cut-offs to identify membranes with high mRNA retention, good impurity removal, and reasonable filtrate flux. The critical flux was then evaluated in tangential flow filtration modules using flux-stepping experiments. Based on these results, an SPTFF system was designed that provided 10x concentration factors at low transmembrane pressure over 12 h of continuous operation without any degradation in mRNA integrity for both constructs. These results clearly demonstrate the potential of SPTFF for intensified downstream processing of mRNA therapeutics.