Skip to main content
eScholarship
Open Access Publications from the University of California

Scholarly Works (6 results)

  • Thesis
  • Peer Reviewed
UC San Diego Electronic Theses and Dissertations (2017)

Nanoparticle technologies have been emerging as drug-loaded carriers since they may be engineered to actively or passively target cancer cells, reduce toxicity and side effects, improve drug stability and pharamacokinetics, and enhance drug potency. Although substantial progress has been made over the years, some limitations include rapid clearance, altered drug potency, and non-specific uptake by healthy tissues. Studies have shown that size, shape, material and composition of a nanoparticle can dramatically alter its efficacy, toxicity, and biodistribution, among other functions. To address this, two different drug delivery systems, liposomal and silica-based nanoparticles, have been designed as drug delivery vehicles for oncolytic viral gene therapy and cancer immunotherapy, respectively.

Oncolytic viruses (OVs) constitute a promising class of cancer therapeutics which exploit validated genetic pathways known to be deregulated in many cancers. To overcome antibody neutralization and to enhance its efficacy, a method for liposomal encapsulation of adenovirus was developed. The encapsulation of adenovirus in non-toxic anionic lecithin-cholesterol-PEG liposomes ranging from 140 to 180 nm in diameter were prepared by self-assembly around the viral capsid. Furthermore, an immunoprecipitation (IP) technique was developed as a fast and effective method to extract non-encapsulated viruses and homogenize the liposomes remaining in solution. 78% of adenovirus plaque forming units were encapsulated and retained infectivity after IP processing. Additionally, encapsulated viruses showed to enhance transfection efficiency compared to non-encapsulated Ads.

In addition, a silica-based nanoparticle system was developed to enhance the efficacy of a Toll-like receptor 7 agonist (TLR7). TLR7 agonists have gained great interest in cancer research due to their antitumoral activity and are being investigated as potent adjuvants to treat cancer. A TLR7 agonist, 1V209, was conjugated to 100nm silica nanoparticles and its properties were assessed using various analytical methods and in vitro and in vivo assays. These studies showed that the immunostimulatory properties of 1V209 were enhanced when conjugated to 100nm silica nanoshells both in vitro and in vivo. Both liposomal and silica-based nanoparticle platforms showed to enhance the properties of oncolytic viruses and cancer immune adjuvants, respectively.

    Cover page: Development of Liposomal and Silica Nanoparticles for Oncolytic Viral Gene Therapy and Cancer Immunotherapy
    • Article
    • Peer Reviewed
    UC San Diego Previously Published Works (2014)
    There are a wide variety of silica nanoformulations being investigated for biomedical applications. Silica nanoparticles can be produced using a wide variety of synthetic techniques with precise control over their physical and chemical characteristics. Inorganic nanoformulations are often criticized or neglected for their poor tolerance; however, extensive studies into silica nanoparticle biodistributions and toxicology have shown that silica nanoparticles may be well tolerated, and in some case are excreted or are biodegradable. Robust synthetic techniques have allowed silica nanoparticles to be developed for applications such as biomedical imaging contrast agents, ablative therapy sensitizers, and drug delivery vehicles. This review explores the synthetic techniques used to create and modify an assortment of silica nanoformulations, as well as several of the diagnostic and therapeutic applications.
      • Article
      • Peer Reviewed
      UC San Diego Previously Published Works (2015)
      A quantification method to measure endocytosis was designed to assess cellular uptake and specificity of a targeting nanoparticle platform. A simple N -hydroxysuccinimide ester conjugation technique to functionalize 100-nm hollow silica nanoshell particles with fluorescent reporter fluorescein isothiocyanate and folate or polyethylene glycol (PEG) was developed. Functionalized nanoshells were characterized using scanning electron microscopy and transmission electron microscopy and the maximum amount of folate functionalized on nanoshell surfaces was quantified with UV-Vis spectroscopy. The extent of endocytosis by HeLa cervical cancer cells and human foreskin fibroblast (HFF-1) cells was investigated in vitro using fluorescence and confocal microscopy. A simple fluorescence ratio analysis was developed to quantify endocytosis versus surface adhesion. Nanoshells functionalized with folate showed enhanced endocytosis by cancer cells when compared to PEG functionalized nanoshells. Fluorescence ratio analyses showed that 95% of folate functionalized silica nanoshells which adhered to cancer cells were endocytosed, while only 27% of PEG functionalized nanoshells adhered to the cell surface and underwent endocytosis when functionalized with 200 and 900  μg , respectively. Additionally, the endocytosis of folate functionalized nanoshells proved to be cancer cell selective while sparing normal cells. The developed fluorescence ratio analysis is a simple and rapid verification/validation method to quantify cellular uptake between datasets by using an internal control for normalization.
        • Article
        • Peer Reviewed
        UC San Diego Previously Published Works (2014)
        Oncolytic viruses (OVs) constitute a promising class of cancer therapeutics which exploit validated genetic pathways known to be deregulated in many cancers. To overcome an immune response and to enhance its potential use to treat primary and metastatic tumors, a method for liposomal encapsulation of adenovirus has been developed. The encapsulation of adenovirus in non-toxic anionic lecithin-cholesterol-PEG liposomes ranging from 140 to 180 nm in diameter have been prepared by self-assembly around the viral capsid. The encapsulated viruses retain their ability to infect cancer cells. Furthermore, an immunoprecipitation (IP) technique has shown to be a fast and effective method to extract non-encapsulated viruses and homogenize the liposomes remaining in solution. 78% of adenovirus plaque forming units were encapsulated and retained infectivity after IP processing. Additionally, encapsulated viruses have shown enhanced transfection efficiency up to 4 × higher compared to non-encapsulated Ads. Extracting non-encapsulated viruses from solution may prevent an adverse in vivo immune response and may enhance treatment for multiple administrations.
          • Article
          • Peer Reviewed
          UC San Diego Previously Published Works (2016)

          Background

          We aimed to evaluate the potential for ultrasound (US) visible biodegradable nanoshells (NS) as an alternative to wire-guided localization for nonpalpable tumors in vivo.

          Methods

          VX2 tumor was injected in bilateral thighs of 22 New Zealand rabbits and after 5 to 10 days, 1 tumor was marked with a wire as a control and the contralateral tumor was injected with 1 mL of 500 nm gas-filled silica NS under Doppler US. Tumors were excised after 24 hours. Chi-square was used for significance, P = .05.

          Results

          One rabbit was excluded on postoperative day 1 due to equipment failure, no ill effects were observed from the NS. The NS were used to localize and resect 100% of marked tissue, 4/21 wires were displaced (P < .05).

          Conclusions

          We have shown that preoperatively injected US visible silica NS can be successfully used to mark nonpalpable tumors in vivo more consistently than WL.
            • Article
            • Peer Reviewed
            UC San Diego Previously Published Works (2020)
            Mono- or dual-checkpoint inhibitors for immunotherapy have changed the paradigm of cancer care; however, only a minority of patients responds to such treatment. Combining small molecule immuno-stimulators can improve treatment efficacy, but they are restricted by poor pharmacokinetics. In this study, TLR7 agonists conjugated onto silica nanoparticles showed extended drug localization after intratumoral injection. The nanoparticle-based TLR7 agonist increased immune stimulation by activating the TLR7 signaling pathway. When treating CT26 colon cancer, nanoparticle conjugated TLR7 agonists increased T cell infiltration into the tumors by > 4× and upregulated expression of the interferon γ gene compared to its unconjugated counterpart by ~2×. Toxicity assays established that the conjugated TLR7 agonist is a safe agent at the effective dose. When combined with checkpoint inhibitors that target programmed cell death protein 1 (PD-1) and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), a 10-100× increase in immune cell migration was observed; furthermore, 100 mm3 tumors were treated and a 60% remission rate was observed including remission at contralateral non-injected tumors. The data show that nanoparticle based TLR7 agonists are safe and can potentiate the effectiveness of checkpoint inhibitors in immunotherapy resistant tumor models and promote a long-term specific memory immune function.
              Cover page: Immunostimulatory TLR7 Agonist‐Nanoparticles Together with Checkpoint Blockade for Effective Cancer Immunotherapy
              Top