Vago, F. | bioRxiv Science

bioRxiv2025

Identifying differential effects from eleven mixing techniques on mRNA lipid nanoparticle physicochemistry and biological performance

Lipid nanoparticle (LNP) formulation requires a mixing step. Many studies, especially from academic groups, utilize either microfluidic mixers or hand mixing to prepare LNPs, but commercial-scale processes use turbulent-flow mixers. This discrepancy in mixing techniques has been underexplored, as LNPs made by different techniques may exhibit different performance, such that bench-scale results cannot be replicated using materials manufactured at scale. We here isolate and interrogate the effect of primary mixing. Lipid nanoparticles are produced from ten mixers (one used in two ways), holding all other formulation parameters constant, to directly compare across techniques. LNPs produced from the different mixers exhibit widely different physical properties and biological performance. Notably, manual pipetting common in academic practice yields particles that do not resemble those produces by turbulent-flow mixers. Findings are connected mechanistically to physicochemical characteristics that arise from the different flow regimes. Further establishing the relationship between mixing and LNP properties is critical. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=132 SRC="FIGDIR/small/687311v1_ufig1.gif" ALT="Figure 1"> View larger version (33K): org.highwire.dtl.DTLVardef@79cac0org.highwire.dtl.DTLVardef@1ee037eorg.highwire.dtl.DTLVardef@12763eforg.highwire.dtl.DTLVardef@111e394_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

bioRxiv2023

Cross-β helical filaments of Tau and TMEM106B in Gray and White Matter of Multiple System Tauopathy with presenile Dementia

BackgroundThe Microtubule-Associated Protein Tau (MAPT) is one of the proteins that are central to neurodegenerative diseases. The nature of intracellular tau aggregates is determined by the cell types whether neuronal or glial, the participating tau isoforms, and the structure of the amyloid filament. The transmembrane protein 106B (TMEM106B) has recently emerged as another significant player in neurodegeneration and aging. In the central nervous system, the composition of the gray and white matter differs considerably. The gray matter consists of nerve cell bodies, dendrites, unmyelinated axons, synaptic terminals, astrocytes, oligodendrocytes (satellite cells) and microglia. The white matter differs from the gray for the presence of axonal tracts as the only neuronal component and for the absence of nerve cell bodies, dendrites and synaptic terminals. Cryogenic electron microscopy (cryo-EM) studies have unveiled the structure of tau and TMEM106B, from the cerebral cortex, in several neurodegenerative diseases; however, whether tau and TMEM106B filaments from the gray and white matter share a common fold requires additional investigation. MethodsWe isolated tau and TMEM106B from the cerebral cortex and white matter of the frontal lobes of two individuals affected by multiple system tauopathy with presenile dementia (MSTD), a disease caused by the MAPT intron 10 mutation +3. We used immunostaining, biochemical, genetics and cryo-EM methods to characterize tau and TMEM106B. ResultsWe determined that tau filaments in the gray and the white matter of MSTD individuals can induce tau aggregation and have identical AGD type 2 folds. TMEM106B amyloid filaments were also found in the gray and white matter of MSTD; the filament folds were identical in the two anatomical regions. ConclusionsOur findings show for the first time that in MSTD two types of amyloid filaments extracted from the gray matter have identical folds to those extracted from the white matter. Whether in this genetic disorder there is a relationship in the pathogenesis of the tau and TMEM106B filaments, remains to be determined. Furthermore, additional studies are needed for other proteins and other neurodegenerative diseases to establish whether filaments extracted from the gray and white matter would have identical folds.

neuroscience↗