Chimeric Mice Engrafted With Canine Hepatocytes Exhibits Similar AAV Transduction Efficiency to Hemophilia B Dog.

Wenwei Shao,Amanda Dobbins,Junjiang Sun,Xiaojing Chen,Timothy C Nichols,Chengwen Li,R Jude Samulski,Elizabeth P Merricks

doi:10.3389/fphar.2022.815317

Abstract

Adeno-associated virus (AAV) mediated gene therapy has been successfully applied in clinical trials, including hemophilia. Novel AAV vectors have been developed with enhanced transduction and specific tissue tropism. Considering the difference in efficacy of AAV transduction between animal models and patients, the chimeric xenograft mouse model with human hepatocytes has unique advantages of studying AAV transduction efficiency in human hepatocytes. However, it is unclear whether the results in humanized mice can predict AAV transduction efficiency in human hepatocytes. To address this issue, we studied the AAV transduction efficacy in canine hepatocytes in both canine hepatocyte xenografted mice and real dogs. After administration of AAV vectors from different serotypes into canine hepatocyte xenograft mice, AAV8 induced the best canine hepatocyte transduction followed by AAV9, then AAV3, 7, 5 and 2. After administration of AAV/cFIX (cFIX-opt-R338L) vectors in hemophilia B dogs, consistent with the result in chimeric mice, AAV8 induced the highest cFIX protein expression and function, followed by AAV9 and then AAV2. These results suggest that mice xenografted with hepatocytes from different species could be used to predict the AAV liver transduction in real species and highlight this potential platform to explore novel AAV variants for future clinical applications.

Highlights

Adeno-associated virus (AAV) has been employed in hundreds of clinical trials worldwide as an in vivo gene therapy vector due to its unique beneficial properties including long-term transgene expression and low immunogenicity
Given the ethical concerns in comparing transduction efficiencies from different AAV serotypes or variants/mutants in humans and limited data that can be obtained from current clinical trials, in this study, we investigated whether AAV transduction in canine hepatocytes of chimeric mice could predict the result in real dogs
We found that AAV8 was the best serotype to transduce canine hepatocytes in chimeric mice, followed by AAV9, AAV3, 5, 7 and 2 with the lowest efficiency

Summary

Introduction

Adeno-associated virus (AAV) has been employed in hundreds of clinical trials worldwide as an in vivo gene therapy vector due to its unique beneficial properties including long-term transgene expression and low immunogenicity. To cure a monogenic disease, a reasonable AAV serotype should be chosen for a specific tropism and precise targeting effect in vivo. In humans, there is a lack of direct evidence to verify the specific targeting capabilities of AAV serotypes due to the limited number of patients involved in clinical trials and the related ethical constraints. Gene therapy for hemophilia A/B, which are directly caused by mutations in coagulation factor VIII/IX (Furie and Furie, 1988; Giannelli and Green, 1996), has shown promising results. Different AAV serotypes [AAV2 (Manno et al, 2006), AAV5 (Rangarajan et al, 2017), AAV8 (Nathwani et al, 2014)] and variants/mutants (AAVrh (NCT02618915) with liver tropism in mouse and non-human primate models have been used in clinical trials in patients with hemophilia. AAVs have been well-recognized as an ideal in vivo gene carrier to cure hemophilia and other disorders

Methods

Results

Conclusion