Related Experiment Video
Updated: May 27, 2026
Efficient Gene Knockdown in the Liver via Intrasplenic Injection of Adeno-Associated Virus Serotype 8 (AAV8)-Delivered Small Hairpin RNA
Published on: November 1, 2024
Hepatic gene transfer in neonatal mice by adeno-associated virus serotype 8 vector
Lili Wang1, Huan Wang, Peter Bell
1Gene Therapy Program, and Division of Transfusion Medicine, Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
Insights
Neonatal gene therapy using adeno-associated viral (AAV) vectors shows promise but faces challenges with rapid cell proliferation. Delaying AAV vector injection or using a different serotype for re-administration can improve sustained gene expression.
Area of Science:
- Gene therapy
- Viral vectors
- Neonatal immunology
Background:
- Early intervention is crucial for genetic diseases with irreversible neonatal consequences.
- Neonatal gene therapy offers advantages like pre-symptomatic treatment and a less mature immune system.
- Non-integrating vectors, such as adeno-associated viral (AAV) vectors, face challenges due to rapid cell proliferation in newborns.
Purpose of the Study:
- To evaluate hepatic gene transfer efficiency and durability using self-complementary AAV8 in neonatal mice.
- To investigate strategies for improving sustained gene expression, including delayed injection and vector re-administration.
- To assess the impact of delayed injection on neutralizing antibody (NAb) responses.
Main Methods:
- Utilized self-complementary AAV8 vectors for hepatic gene transfer in neonatal mice.
- Compared gene expression levels in neonatally injected mice versus those with delayed injection.
- Analyzed the development of neutralizing antibodies (NAbs) against AAV capsids after delayed injection.
Main Results:
- Achieved robust hepatic gene transfer in neonatal mice, but expression diminished rapidly due to vector dilution from cell proliferation.
- Delayed injection age improved the duration of gene expression but increased NAb responses.
- Demonstrated that a second injection with a different AAV serotype could overcome pre-existing NAbs.
Conclusions:
- While neonatal gene therapy is promising, rapid cell proliferation challenges sustained expression with AAV vectors.
- Delayed injection is a viable strategy for genetic diseases with slow progression, balancing expression duration and NAb response.
- Sequential administration of different AAV serotypes offers a potential solution for achieving sustained therapeutic effects in severe, early-onset genetic diseases.
Abstract:
For genetic diseases that manifest at a young age with irreversible consequences, early treatment is critical and essential. Neonatal gene therapy has the advantages of achieving therapeutic effects before disease manifestation, a low vector requirement and high vector-to-cell ratio, and a relatively immature immune system. Therapeutic effects or long-term rescue of neonatal lethality have been demonstrated in several animal models. However, vigorous cell proliferation in the newborn stage is a significant challenge for nonintegrating vectors, such as adeno-associated viral (AAV) vector. Slightly delaying the injection age, and readministration at a later time, are two of the alternative strategies to solve this problem. In this study, we demonstrated robust and efficient hepatic gene transfer by self-complementary AAV8 vector in neonatal mice. However, transduction quickly decreased over a few weeks because of vector dilution caused by fast proliferation. Delaying the injection age improved sustained expression, although it also increased neutralizing antibody (NAb) responses to AAV capsid. This approach can be used to treat genetic diseases with slow progression. For genetic diseases with early onset and severe consequences, early treatment is essential. A second injection of vector of a different serotype at a later time may overcome preexisting NAb and achieve sustained therapeutic effects.
