Hyperactive piggyBac transposons for sustained and robust liver-targeted gene therapy

Area of Science:

• Gene Therapy
• Molecular Biology
• Hematology

Background:

• Nonviral vectors are promising for gene therapy but often show transient, low gene expression.
• Viral vectors can cause immune complications, necessitating safer alternatives.

Purpose of the Study:

• To evaluate piggyBac transposons for liver-directed gene therapy of hemophilia B in mice.
• To enhance nonviral vector performance for stable therapeutic protein secretion.

Main Methods:

• Utilized a hyperactive piggyBac transposase, optimized liver-specific promoter, and hyperfunctional Factor IX (FIX) transgene.
• Modified transposon terminal repeats to improve vector performance.
• Administered low doses of transposon/transposase to hemophilic mice.

Main Results:

• Achieved a 400-fold improvement in vector performance in hepatocytes, resulting in stable, supraphysiologic human FIX activity for over a year.
• Demonstrated FIX-specific immune tolerance induction.
• Showed successful expression of supraphysiologic Factor VIII levels and no tumor induction in a cancer-prone mouse model.

Conclusions:

• Latest generation piggyBac transposons are potent and relatively safe for gene therapy.
• This versatile platform enables stable, robust secretion of therapeutic proteins, addressing limitations of previous nonviral methods.