Directed Evolution of AAV for Cardiovascular Endothelial Cells

Abstract

• Objective: Explore stable transduction of cardiac endothelial cells (ECs) using AAV.
• Methods: Screen two AAV libraries in a transgenic mouse model.
• Findings: Identified AAV variants (EC71 and EC73) with enhanced cardiac EC transduction and reduced liver infection, maintaining expression for 4 months.
• Application: EC71 used to deliver eNOS gene in heart failure model, showing improved cardiac function.

Introduction

• Background: Vascular endothelium is key in cardiovascular treatment.
• Challenges: Adenovirus vectors induce immune responses, limiting long-term gene expression.
• Solution: AAV vectors are safer, but natural serotypes poorly transduce ECs.
• Advancements:
  • Previous work on AAV capsid engineering improved tissue tropism.
  • Directed evolution techniques applied for better AAV targeting.

Methods & Approach

• Directed Evolution: AAV libraries combined and screened in transgenic mice.
• Screening: Utilized DNA shuffling and random peptide display.
• Selection: Isolated cardiac ECs via FACS and PCR for AAV variant identification.
• AAV Variants: EC71 and EC73 emerged with unique peptide inserts.

Results

Enhanced Transduction

• Comparative Study: EC71 and EC73 vs AAV1 and AAV2.
• Findings:
  • EC71 and EC73 showed higher cardiac EC transduction and lower liver transduction.
  • Persistent transgene expression observed.

Transduction in Human and Rodent ECs

• In Vitro Testing: Lower infectivity in EC71 and EC73 compared to AAV1/AAV2 in HUVECs and rodent ECs.

Gene Therapy Application

• Heart Failure Model: EC71 used to deliver eNOS, showing partial improvement in cardiac function.

Discussion

• Implications: EC71 and EC73 provide improved AAV vectors for cardiovascular treatment.
• Limitations: Further optimization needed for broad therapeutic application.
• Future Directions:
  • Better capsid engineering techniques.
  • Larger studies to verify results.
• Conclusion: Directed evolution enhances AAV utility for cardiac gene therapy.

Figures and Data

• Figures: Illustrate experimental setup, transduction efficiency, and gene therapy effects.

Materials and Methods

• AAV Library Generation: DNA shuffling and peptide display methods.
• Screening Protocol: FACS and PCR utilized for AAV variant selection in mice.
• Transduction Analysis: Comparison in various models and conditions.

Acknowledgements and References

• Funding: Supported by multiple Chinese foundations and research programs.
• Contributors: Extensive contributions from various researchers and institutions.

This summary provides a concise overview of the research and findings related to the directed evolution of AAV for cardiovascular applications, highlighting significant advancements in gene therapy delivery systems.