700. Stable Correction of Severe Metabolic Liver Disease Phenotypes in the Growing Murine Liver Using a Hybrid rAAV/piggyBac Transposon Gene Delivery System
Bibliographic record
Abstract
Liver-targeted gene therapy using adeno-associated virus-based vectors (rAAV) shows therapeutic promise in animal models and adult-focused clinical trials. This promise, however, is not directly translatable to the growing liver where rapid clearance of rAAV episomal genomes occurs in concert with hepatocellular proliferation. This phenomenon has been shown to underpin progressive loss of therapeutic efficacy, initially achieved in the neonatal period, in mouse models of early-onset urea cycle defects (UCDs). We have developed a hybrid rAAV/piggyBac transposon vector system combining the highly efficient liver-targeting properties of rAAV with stable piggyBac-mediated transposition of the transgene into the hepatocyte genome. Transposition efficiency was first tested using an EGFP expression cassette following delivery to newborn wild-type mice, with a 20-fold increase in stably gene-modified hepatocytes observed 4 weeks post-treatment compared to traditional rAAV gene delivery. We then modeled the therapeutic potential of the system in the context of severe early onset UCDs. A single treatment in the perinatal period was sufficient to confer robust and stable phenotype correction in the ornithine transcarbamylase (OTC) deficient Spfash mouse and neonatal lethal argininosuccinate synthetase (ASS) knock-out mouse. The system was next utilized in a murine model of chronic liver disease, progressive familial intrahepatic cholestasis type 3 (PFIC3), in which intervention prior to disease onset is necessary due to the development of chronic liver pathology which impedes vector delivery and hepatocyte transduction. Stable persistent expression extending into adulthood was achieved with increased mean biliary phosphatidylcholine concentration and dramatically reduced liver fibrosis. Finally, transposon integration patterns were analysed, revealing 127,286 unique integration sites which conformed to previously published piggyBac data. Conclusion: Using a hybrid rAAV/piggyBac transposon vector system we achieved stable therapeutic protection in two UCD mouse models and a murine model with chronic liver pathology. This strategy has the potential for treating a wide array of inherited liver diseases with early onset. A clinically conceivable early application of this technology in the management of severe UCDs could be as a bridging therapy while awaiting liver transplantation. Further improvement of the system will result from the development of highly human liver-tropic capsids, the use of alternative strategies to achieve transient transposase expression, and engineered refinements in the safety profile of piggyBac transposase-mediated integration.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".