Experiment Proposal (crux): Plasma p-tau217-Triggered Exosome Dosing Maximizes lncRNA-0021 Therapeutic Window in AD — Exosome engineering challenges including cargo loading efficiency, batch variabi

AIMS

HYPOTHESES

PROTOCOL SUMMARY

Phase 1 - lncRNA-0021 Molecular Validation: (1) Perform 5'RACE and 3'RACE on patient-derived hippocampal tissue to obtain full-length lncRNA-0021 sequence; (2) Validate tissue-specific expression via RT-qPCR across AD (n=30) and age-matched controls (n=30); (3) Establish reference standard for quantification. Phase 2 - Cargo Loading Optimization: (4) Prepare native exosomes from dendritic cell culture via ultracentrifugation (100,000g, 2h) with tangential flow filtration; (5) Test three loading methods: electroporation (optimized: 400V, 150μF, 8ms), cationic lipid transfection, and endogenous overexpression via modified Lamp2b vector; (6) Quantify loading efficiency via ddPCR and Northern blot; (7) Assess cargo integrity via bioanalyzer and Agilent small RNA panel. Phase 3 - Batch Variability Assessment: (8) Prepare 5 independent exosome batches on different days; (9) Characterize each batch: NTA for size/concentration, flow cytometry for tetraspanin markers, Western blot for exosome markers (Alix, TSG101) and contamination markers (GRP94, Calnexin); (10) Perform HEK-APP reporter cell uptake assay (FITC-labeled exosomes, 4h incubation) to measure functional delivery; (11) Calculate coefficient of variation for all parameters with acceptance criteria: CV ≤20% for critical metrics. Phase 4 - Targeting Ligand Incorporation: (12) Clone Lamp2b-RGD or Lamp2b-CDX fusion constructs; (13) Produce exosomes from transfected cells; (14) Verify surface expression via biotinylation assay and flow cytometry with anti-HA tag detection; (15) Perform in vitro BBB transmigration assay using iPSC-derived brain endothelial monolayers; (16) Quantify transendothelial delivery efficiency. Phase 5 - Biomarker-Triggered Dosing: (17) Use 5xFAD mice at 6 months (established amyloid pathology); (18) Group mice (n=12/group) by plasma p-tau217 tertiles; (19) Administer engineered exosomes (1×10¹⁰ particles) via tail vein; (20) Harvest brain tissue at 2h, 6h, 24h post-injection; (21) Quantify lncRNA-0021 via ddPCR and target gene modulation via RT-qPCR; (22) Correlate CNS delivery with plasma p-tau217 at injection.

PREDICTED OBSERVATIONS

If H1-H3 are true: electroporation will yield ≥15% loading efficiency with consistent 10-20% batch CV; Lamp2b fusion will display targeting ligands at ≥60% with preserved exosome morphology; engineered exosomes will demonstrate significantly higher brain parenchymal uptake versus non-targeted controls. If H4 is true: high plasma p-tau217 group will show 2-3 fold greater CNS lncRNA-0021 delivery compared to low p-tau217 group, establishing the biomarker-triggered dosing principle. Overall, this would confirm exosome engineering feasibility for the therapeutic approach.

FALSIFICATION CRITERIA

H1 falsified if no loading method achieves ≥10% efficiency with ≥50% cargo integrity after 24h incubation; H2 falsified if batch CV exceeds 30% for functional uptake despite meeting quality specifications; H3 falsified if targeting ligand fusion reduces exosome yield by >50% or abolishes tetraspanin expression; H4 falsified if plasma p-tau217 levels show no correlation with CNS exosome delivery (r<0.3, p>0.05), indicating BBB permeability is not regulated by p-tau217 dynamics. Critical falsification: if lncRNA-0021 molecular identity cannot be confirmed or shows no detectable expression in relevant AD tissue, the entire therapeutic hypothesis becomes non-actionable.

DATASET DEPENDENCIES