Biology subjects

Tsang, E.

Publications and source records attributed to Tsang, E..

4 recordsLinked to original sources

bioRxiv2025

Cyp7b1-inhibiting azoles as novel enhancers of hematopoietic stem and progenitor cell mobilization

Mobilized hematopoietic stem and progenitor cells (HSPCs) are essential for transplantation-based therapies, including curative gene therapies for sickle cell disease (SCD). While granulocyte colony-stimulating factor (G-CSF, filgrastim) remains the standard mobilization agent, many patients respond inadequately, and it can trigger life-threatening vaso-occlusive crises in SCD. The CXCR4 antagonist AMD3100 (plerixafor) is routinely combined with G-CSF for non-SCD settings but is ineffective as a single agent in SCD, underscoring the urgent need for alternative strategies. We previously identified 27-hydroxycholesterol (27HC) as a physiological inducer of HSPC mobilization during pregnancy. Here, we show that exogenous 27HC enhances AMD3100-induced HSPC mobilization in mice, either alone or with G-CSF. Because 27HC is metabolized by the enzyme Cyp7b1, we tested whether pharmacological Cyp7b1 inhibition could mimic this effect. Treatment with clotrimazole, an antifungal and Cyp7b1 inhibitor, significantly enhanced AMD3100-induced HSPC mobilization in wild-type, SCD, and humanized mice. Importantly, intravenous administration of voriconazole, a clinically approved systemic antifungal with Cyp7b1-binding activity, similarly augmented AMD3100-induced HSPC mobilization in wild-type and SCD mice without altering steady-state hematopoiesis. These findings establish Cyp7b1-inhibiting azoles as novel and clinically relevant enhancers of HSPC mobilization, particularly for SCD patients who cannot safely receive G-CSF but require robust HSPC yields for gene therapy. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=128 SRC="FIGDIR/small/682145v1_ufig1.gif" ALT="Figure 1"> View larger version (40K): org.highwire.dtl.DTLVardef@1fddaaforg.highwire.dtl.DTLVardef@12036f4org.highwire.dtl.DTLVardef@1f8010aorg.highwire.dtl.DTLVardef@10c4aff_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗

bioRxiv2025

Enzyme-powered DNA origami nanostructures for enhanced mucosal diffusion

Crossing mucosal barriers is a central challenge for oral drug delivery, where nanoparticle design must balance stability with mobility in complex fluids. Here, we demonstrate DNA origami as a programmable platform to investigate these processes. Using FRET analysis, we show that DNA nanostructures retain their structural integrity for extended periods in porcine intestinal fluid and mucus, establishing their suitability for biologically relevant environments. Building on this, we used single-particle tracking to assess enzyme-powered propulsion within mucus. Both urease and catalase enhanced diffusion only when anchored to the DNA origami structure, with propulsion persisting for tens of minutes. Importantly, enzyme spatial organization dictated performance: symmetric urease placement improved mobility via uniform local pH shifts, while asymmetric catalase placement enabled efficient bubble-driven propulsion. These results highlight DNA origami as a uniquely versatile tool to dissect structure-function relationships in mucus transport and provide design principles for next-generation, enzyme-powered oral delivery systems.

bioengineering↗

bioRxiv2025

Bacteriophage-Mimetic DNA Origami Needle for Targeted Membrane Penetration and Cytosolic Cargo Delivery

Inspired by the natural ability of bacteriophages to deliver genetic material directly into host cells, we employed a bottom-up approach to construct a multifunctional synthetic DNA origami needle-like structure. This origami is functionalized with trastuzumab antibodies, cholesterol, protective polymers, and two dyes, which together enable selective targeting and insertion into SKBR3 cancer cells. A disulfide-linked dye payload was attached to the apex of the needle, allowing controlled release in the cytoplasm triggered by the high intracellular glutathione concentration. Real-time tracking of the payload confirmed both successful targeting of the origami structure and subsequent direct cytosolic delivery. By mimicking fundamental mechanisms of bacteriophages, we propose that this artificial needle structure can serve as a prototypical device for the targeted delivery of small-molecule drugs directly into the cytosol.

biochemistry↗

bioRxiv2025

Overturning circulation structures the microbial functional landscape of the South Pacific

Global overturning circulation partitions the deep ocean into regions with unique physicochemical characteristics, but the extent to which these water masses represent distinct ecosystems remains unknown. Here, we integrate extensive genomic information with hydrography and water mass age to delineate microbial taxonomic and functional boundaries across the South Pacific. Prokaryotic richness steeply increases with depth in the surface ocean, forming a "phylocline", below which richness is consistently high, dipping slightly in highly aged water. Reconstructed genomes self-organize into six spatially-distinct taxonomic cohorts and ten functionally-distinct biomes that are primarily structured by wind-driven circulation at the surface and density-driven circulation at depth. Overall, water physicochemistry, modulated at depth by water age, drives microbial diversity and functional potential in the pelagic ocean.

microbiology↗