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Open Access Publications from the University of California

Scholarly Works (4 results)

  • Thesis
  • Peer Reviewed
UC Irvine Electronic Theses and Dissertations (2018)

Extracellular vesicles (EVs) have recently gained momentum in the field of therapeutic delivery due to their promise as therapeutic carriers. Biomolecules are naturally transported by EVs for cell-to-cell communication, and EV interactions with target cells are thought to be specific to cell type. Naturally produced extracellular blebs (EBs), a category of EVs that are derived specifically from blebbing of the cell membrane, transport cargo to target cells while maintaining the surface properties of the cells from which they were derived.

Although EBs have been used for preclinical drug delivery and gene therapy, obtaining sufficient samples of well-characterized blebs for clinical studies is still a major challenge. A major focus of my work has been on developing and characterizing a method for large-scale production of EBs. More specifically, this dissertation explores a method for controlling EB production by sulfhydryl blocking reagents. The optimized formulation of sulfhydryl-blocking reagents described in this dissertation led to an order of magnitude increase in EB production as characterized by protein quantification assay. Furthermore, this increase in EB production was achieved in a fraction of the time required for natural production of EBs.

With the aim of utilizing EBs for cancer therapy, the efficacy of the production method was assessed for two applications: delivery of a chemotherapeutic drug, and presentation of a model cancer antigen for immunotherapy. Studies confirmed that in tumor-challenged mice treated with chemotherapeutic-loaded, nano-sized EBs, there was significantly slowed tumor growth and improved survival compared to treatment with free drug or liposomal drug. The chemotherapeutic-loaded, nano-sized EBs demonstrated improved cellular uptake, facilitated intracellular drug release and targeted accumulation in the tumor, and they avoided accumulation in vital organs in comparison to a commercial liposomal formulation. In a separate study, antigen-presenting micro-sized EBs produced by sulfhydryl-blocking expressed H-2Kb bound to SIINFEKL and effectively activated T cells in vitro and cytotoxic T lymphocytes in vivo. Micro-sized EBs performed as well as whole cell therapy in terms of slowing tumor growth and improving survival outcomes while providing a cell-free alternative therapy.

EBs have a broad range of potential health applications beyond drug delivery and immunotherapy; these include gene therapy, immune modulation, tissue regeneration, and pathogen suppression. EB production by sulfhydryl blocking is highly promising for overcoming a current technological gap and allowing EB-based therapeutics to progress more rapidly to clinical trials.

In summary, this dissertation provides a study of an innovative method of EB production including evaluation of two therapeutic applications.

    Cover page: Chemically-induced Extracellular Blebs for Versatile Cancer Therapy
    • Article
    • Peer Reviewed
    UC Irvine Previously Published Works (2023)
    Dendritic cells (DCs) are prime targets for vaccination and immunotherapy. However, limited control over antigen presentation at a desired maturation status in these plastic materials remains a fundamental challenge in efficiently orchestrating a controlled immune response. DC-derived extracellular vesicles (EVs) can overcome some of these issues, but have significant production challenges. Herein, we employ a unique chemically-induced method for production of DC-derived extracellular blebs (DC-EBs) that overcome the barriers of DC and DC-derived EV vaccines. DC-EBs are molecular snapshots of DCs in time, cell-like particles with fixed stimulatory profiles for controlled immune signalling. DC-EBs were produced an order of magnitude more quickly and efficiently than conventional EVs and displayed stable structural integrity and antigen presentation compared to live DCs. Multi-omic analysis confirmed DC-EBs are majorly pure plasma membrane vesicles that are homogeneous at the single-vesicle level, critical for safe and effective vaccination. Immature vs. mature molecular profiles on DC-EBs exhibited molecularly modulated immune responses compared to live DCs, improving remission and survival of tumor-challenged mice via generation of antigen-specific T cells. For the first time, DC-EBs make their case for use in vaccines and for their potential in modulating other immune responses, potentially in combination with other immunotherapeutics.
      Cover page: Cell‐Free, Dendritic Cell‐Mimicking Extracellular Blebs for Molecularly Controlled Vaccination
      • Article
      • Peer Reviewed
      UC Irvine Previously Published Works (2018)
      A key design consideration in developing contrast agents is obtaining distinct, multiple signal changes in diseased tissue. Plasmonic gold nanoparticles (Au NPs) have been developed as contrast agents due to their strong surface plasmon resonance (SPR). This study aims to demonstrate that stimuli-responsive plasmonic Au nanoclusters (Au NCs) can be used as a contrast agent for optical coherence tomography (OCT) in detecting early-stage cancer. Au NPs were clustered via acid-cleavable linkers to synthesize Au NCs that disassemble under mildly acidic conditions into individual Au NPs, simultaneously diminishing SPR effect (quantified by scattering intensity) and increasing Brownian motion (quantified by Doppler variance). The acid-triggered morphological and accompanying optico-physical property changes of the acid-disassembling Au NCs were confirmed by TEM, DLS, UV/Vis, and OCT. Stimuli-responsive Au NCs were applied in a hamster check pouch model carrying early-stage squamous carcinoma tissue. The tissue was visualized by OCT imaging, which showed reduced scattering intensity and increased Doppler variance in the dysplastic tissue. This study demonstrates the promise of diagnosing early-stage cancer using molecularly programmable, inorganic nanomaterial-based contrast agents that are capable of generating multiple, stimuli-triggered diagnostic signals in early-stage cancer.
        Cover page: Stimuli-disassembling gold nanoclusters for diagnosis of early stage oral cancer by optical coherence tomographyCreative Commons 'BY' version 4.0 license
        • Article
        • Peer Reviewed
        UC Irvine Previously Published Works (2016)
        Single modal cancer therapy that targets one pathological pathway often turns out to be inefficient. For example, relapse of chronic myelogenous leukemia (CML) after inhibiting BCR-ABL fusion protein using tyrosine kinase inhibitors (TKI) (e.g., Imatinib) is of significant clinical concern. This study developed a dual modal gene therapy that simultaneously tackles two key BCR-ABL-linked pathways using viral/nonviral chimeric nanoparticles (ChNPs). Consisting of an adeno-associated virus (AAV) core and an acid-degradable polymeric shell, the ChNPs were designed to simultaneously induce pro-apoptotic BIM expression by the AAV core and silence pro-survival MCL-1 by the small interfering RNA (siRNA) encapsulated in the shell. The resulting BIM/MCL-1 ChNPs were able to efficiently suppress the proliferation of BCR-ABL+ K562 and FL5.12/p190 cells in vitro and in vivo via simultaneously expressing BIM and silencing MCL-1. Interestingly, the synergistic antileukemic effects generated by BIM/MCL-1 ChNPs were specific to BCR-ABL+ cells and independent of a proliferative cytokine, IL-3. The AAV core of ChNPs was efficiently shielded from inactivation by anti-AAV serum and avoided the generation of anti-AAV serum, without acute toxicity. This study demonstrates the development of a synergistically efficient, specific, and safe therapy for leukemia using gene carriers that simultaneously manipulate multiple and interlinked pathological pathways.
          Cover page: Viral/Nonviral Chimeric Nanoparticles To Synergistically Suppress Leukemia Proliferation via Simultaneous Gene Transduction and Silencing
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