CAREER: Extracellular Barriers to Adeno-Associated Viral Gene Therapy

Gene therapy offers the means to potentially cure or halt the progression of diseases with known genetic origins (e.g. cystic fibrosis) or with known genetic modifiers (e.g. cancer). Virus-based approaches have been primarily used for gene therapy applications, as they possess the natural ability to efficiently deliver genetic cargo to target tissues.

Adeno-associated virus (AAV) has emerged as a leading therapeutic gene delivery system and recently became the 1st virus to be granted approval by the Food and Drug Administration (FDA) for clinical use. Given its growing and broad potential utility, it is important to understand how AAV traffics and distributes throughout the body to ensure it is a safe and effective modality for gene therapy applications.

Prior work has shown that the interactions of AAV with components of the bloodstream and tissues like the brain, liver, and heart can cause inactivation or limit penetration of AAV within target organs. The aim of this NSF CAREER project is to develop the tools necessary to comprehensively assess these biological barriers to AAV gene therapy in order to optimize its performance and maximize therapeutic benefits in diseases such as arthritis, cancer, and hemophilia.

The project includes a synergistic education plan that promotes research exposure and awareness of career opportunities for URM students, enhances undergraduate courses and provides training opportunities in research for undergraduate, graduate, and postdoctoral researchers from diverse backgrounds. Specific activities include developing a summer research immersion and educational lab activity development program for science teachers in Baltimore City and incorporating new lab modules focused on nano- and microparticle transport in blood into an undergraduate course on biofluids.

The long-term goal of this CAREER project is to build quantitative tools to support the development and rational design of gene therapies using natural and novel bioengineered AAVs. Though AAV shows serotype-dependent interactions with serum proteins in the blood that can either inhibit or enhance AAV-mediated gene transfer, it is unknown if these interactions with serum proteins promote or compromise the stability of AAV in circulation.

In addition, target receptors used for cell entry by many AAV serotypes (e.g. heparan sulfate) are present at high levels in the extracellular matrix (ECM), which could lead to adhesion of AAV to the ECM and as a result, poor distribution in target tissues. However, these potential barriers to effective AAV gene therapy have not been studied. To address this issue, the investigator will pursue three research objectives: (1) characterize AAV-serum interactions and protein corona formation, (2) examine AAV stability in whole blood under physiological flow conditions, and (3) evaluate AAV diffusion through ECM and ex vivo tissues.

The investigator will use expertise in measuring and modeling protein adsorption at interfaces, protein-mediated particle aggregation, and diffusion of nanoscale particles in 3D biological matrices to understand the behavior of AAV in the blood and tissue microenvironment. The results of these objectives will be interpreted with analytical models to determine (1) how competitive adsorption of serum proteins and protein corona formation on AAV particles influences their stability in circulation and (2) how tissue-specific properties of ECM (e.g. density and composition) influence distribution of AAV within target organs.

If successful, this work will establish new assays that are generalizable to viral gene therapeutics and can be used as an additional screening tool for pre-clinical studies.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.