Advancing the Delivery and Therapeutic Potential of Biologics with Spherical Nucleic Acids

Kusmierz, Caroline Danielle

doi:https://doi.org/10.21985/n2-rrap-jr30

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Advancing the Delivery and Therapeutic Potential of Biologics with Spherical Nucleic Acids

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The translation of proteins as effective intracellular drug candidates is limited by the challenge of cellular entry and their vulnerability to degradation. To advance their therapeutic potential, cell-impermeable proteins can be readily transformed into protein spherical nucleic acids (ProSNAs) or encapsulated into liposomal spherical nucleic acids (L-SNAs), structures defined by the dense packing of highly oriented DNA into spherical morphologies. Such nanostructures are stable, exhibit enhanced pharmacokinetics, and are routes for transfecting proteins into cells in highly active forms. Furthermore, this modular structure constitutes a plug-and-play platform in which the core and nucleic acid shell can be independently varied to achieve desired properties and function. Small structural changes in the chemical makeup of an SNA’s components can affect the entire construct’s bioactivity; thus, this thesis investigates the structure-activity relationships of the SNA as it relates to the delivery and biodistribution of biologics. Chapter 1 introduces design rules identified through the ten years of research in the biological applications of the SNA and how these trends have been applied successfully to gene regulation, immunomodulation, and protein delivery. In the context of ProSNAs, Chapter 2 explores how structural changes to the shell’s linker and DNA sequence profoundly impact the overall uptake, activity, and pharmacokinetics of an enzymatic protein. For example, DNA-based linkers and G-quadruplex-forming sequences significantly improve cellular uptake in vitro. When translated to murine models, the ProSNA with a DNA-only shell exhibits increased blood circulation times and retention of their enzymatic activity in tissue. In Chapter 3, by employing aptamers designed to bind receptors abundant along the blood-brain barrier, a ProSNA’s biodistribution can be specifically directed to the brain. Alternatively, by encapsulating proteins derived from pathogens into L-SNAs decorated with an immunostimulatory DNA shell, vaccines can be deliberately designed for cancer or infectious diseases. Chapter 4 discusses the utility of L-SNA cancer vaccines for triple-negative breast cancer immunotherapy. In particular, the chemical identity of the constituent lipid and antigen source modulates the L-SNA’s properties and immunomodulatory activity, revealing a synergy between the cancer lysate preparation and liposome composition in formulating immunotherapeutic L-SNAs. Beyond oncology, Chapter 5 reports the development of a new SNA platform for infectious disease vaccines. For SARS-CoV-2, inoculation with SNA vaccines generate specific neutralizing antibodies on par with current commercial alternatives. Due to the structural diversity of proteins, each protein presents its own set of opportunities and challenges for various applications. This work illustrates the importance of understanding and manipulating an SNA’s structural design to greatly advance the potential of proteins in medicine for years to come.

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