A universal system to select gene-modified hepatocytes in vivo

Area of Science:

• Hepatology
• Gene Therapy
• Molecular Biology

Background:

• Gene and cell therapies show promise for liver disorders but suffer from low engraftment and modification efficiencies.
• Targeted gene modifications, especially via homologous recombination, are rare events, limiting therapeutic potential.

Purpose of the Study:

• To develop a universally applicable system for in vivo selection and expansion of gene-modified hepatocytes.
• To overcome the limitations of low efficiency in gene therapy for liver diseases.

Main Methods:

• Co-expression of a therapeutic transgene with a short hairpin RNA (shRNA) conferring drug resistance.
• Utilizing an shRNA targeting 4-OH-phenylpyruvate dioxygenase for resistance to a specific small-molecule inhibitor.
• Embedding the shRNA within a microRNA and using a recombinant adeno-associated viral vector for site-specific integration into the albumin locus.

Main Results:

• Demonstrated selective amplification of gene-modified hepatocytes in vivo.
• Achieved 10- to 1000-fold increase in transgene expression after selection.
• Reached supraphysiological levels of human factor 9 protein (50,000 ng/ml) in mice.

Conclusions:

• The developed drug resistance system provides a universally applicable method for selecting and expanding gene-modified hepatocytes.
• This approach can achieve therapeutically relevant transgene levels, significantly advancing gene therapy for liver disorders.