Publications by authors named "Gil Covarrubias"

Nanoparticles have the potential to improve disease treatment and diagnosis due to their ability to incorporate drugs, alter pharmacokinetics, and enable tissue targeting. While considerable effort is placed on developing spherical lipid-based nanocarriers, recent evidence suggests that high aspect ratio lipid nanocarriers can exhibit enhanced disease site targeting and altered cellular interactions. However, the assembly of lipid-based nanoparticles into non-spherical morphologies has typically required incorporating additional agents such as synthetic polymers, proteins, lipid-polymer conjugates, or detergents.

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Article Synopsis
  • Immunotherapies like checkpoint inhibitors have shown limited efficacy in treating metastatic ovarian cancer (OC), prompting research into more effective methods.* -
  • Researchers created liposomal nanoparticles (NPs) coated with a polymer designed to help them bind to OC cells and release interleukin-12 (IL-12) in tumors after being administered into the abdomen.* -
  • These engineered IL-12 nanoparticles significantly improved T cell accumulation in tumors, enhanced survival in mouse models, and made tumors more responsive to checkpoint inhibitors, potentially leading to lasting immune protection.*
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  • Scientists are exploring new ways to use genetic treatments, specifically through tiny particles called lipid nanoparticles (LNPs) that can deliver medicine to cells.
  • A big problem is that these nanoparticles often end up in the liver instead of going to the right place in the body.
  • Researchers found a method to change the surface of LNPs, making them better at delivering their genetic cargo to specific cells by using different materials that help them target the right places in the body.
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Stimulator of interferon genes (STING) signaling is a promising target in cancer immunotherapy, with many ongoing clinical studies in combination with immune checkpoint blockade (ICB). Existing STING-based therapies largely focus on activating CD8 T cell or NK cell-mediated cytotoxicity, while the role of CD4 T cells in STING signaling has yet to be extensively studied in vivo. Here, a distinct CD4-mediated, protein-based combination therapy of STING and ICB as an in situ vaccine, is reported.

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The majority of patients with high grade serous ovarian cancer (HGSOC) develop recurrent disease and chemotherapy resistance. To identify drug combinations that would be effective in treatment of chemotherapy resistant disease, we examined the efficacy of drug combinations that target the three antiapoptotic proteins most commonly expressed in HGSOC-BCL2, BCL-XL, and MCL1. Co-inhibition of BCL2 and BCL-XL (ABT-263) with inhibition of MCL1 (S63845) induces potent synergistic cytotoxicity in multiple HGSOC models.

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To alter the immunosuppressive tumor microenvironment (TME), we developed an immunostimulatory nanoparticle (NP) to reprogram a tumor's dysfunctional and inhibitory antigen-presenting cells (APCs) into properly activated APCs that stimulate tumor-reactive cytotoxic T cells. Importantly, systemic delivery allowed NPs to efficiently utilize the entire microvasculature and gain access into the majority of the perivascular TME, which coincided with the APC-rich tumor areas leading to uptake of the NPs predominantly by APCs. In this work, a 60 nm NP was loaded with a STING agonist, which triggered robust production of interferon β, resulting in activation of APCs.

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Iron oxide nanoparticles (IONPs) have often been investigated for tumor hyperthermia. IONPs act as heating foci in the presence of an alternating magnetic field (AMF). It has been shown that hyperthermia can significantly alter the tumor immune microenvironment.

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The efficacy of immunotherapies is often limited by the immunosuppressive tumor microenvironment, which is populated with dysfunctional innate immune cells. To reprogram the tumor-resident innate immune cells, we developed immunostimulatory silica mesoporous nanoparticles (immuno-MSN). The cargo of immuno-MSN is a Stimulator of Interferon Gene (STING) agonist, which activates innate immune cells leading to production of interferon (IFN) β.

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The high mortality associated with glioblastoma multiforme (GBM) is attributed to its invasive nature, hypoxic core, resistant cell subpopulations and a highly immunosuppressive tumor microenvironment (TME). To support adaptive immune function and establish a more robust antitumor immune response, we boosted the local innate immune compartment of GBM using an immunostimulatory mesoporous silica nanoparticle, termed immuno-MSN. The immuno-MSN was specifically designed for systemic and proficient delivery of a potent innate immune agonist to dysfunctional antigen-presenting cells (APCs) in the brain TME.

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Nerve fibers are known to reside within malignant tumors and the greater the neuronal density the worse prognosis for the patient. Recent discoveries using tumor bearing animal models have eluded to the autonomic nervous system having a direct effect on tumor growth and metastasis. We report the first direct and chronic in vivo measurements of neural activity within tumors.

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Poor prognosis for glioblastoma (GBM) is a consequence of the aggressive and infiltrative nature of gliomas where individual cells migrate away from the main tumor to distant sites, making complete surgical resection and treatment difficult. In this manuscript, we characterize an invasive pediatric glioma model and determine if nanoparticles linked to a peptide recognizing the GBM tumor biomarker PTPmu can specifically target both the main tumor and invasive cancer cells in adult and pediatric glioma models. Using both iron and lipid-based nanoparticles, we demonstrate by magnetic resonance imaging, optical imaging, histology, and iron quantification that PTPmu-targeted nanoparticles effectively label adult gliomas.

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Deposition of nanoparticles to tumors often can be enhanced by targeting receptors overexpressed in a tumor. However, a tumor may exhibit a finite number of a biomarker that is accessible and targetable by nanoparticles, limiting the available landing spots. To explore this, we selected two different biomarkers that effectively home nanoparticles in brain tumors.

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Effective cancer immunotherapy depends on the robust activation of tumor-specific antigen-presenting cells (APC). Immune agonists encapsulated within nanoparticles (NP) can be delivered to tumor sites to generate powerful antitumor immune responses with minimal off-target dissemination. Systemic delivery enables widespread access to the microvasculature and draining to the APC-rich perivasculature.

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Metastasis is responsible for the majority of deaths of breast cancer patients. While cytotoxic drugs are available with high potency to kill breast cancer cells, they are not designed to specifically seek and navigate in the dynamic and continuously changing microenvironment of metastatic disease. To effectively delivery chemotherapeutic agents to metastasis, we designed a dual-ligand nanoparticle loaded with doxorubicin by using two different types of ligands targeting EGFR and αvβ3 integrin.

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Nanoparticles often only exploit the upregulation of a receptor on cancer cells to enhance intratumoral deposition of therapeutic and imaging agents. However, a single targeting moiety assumes that a tumor is homogenous and static. Tumoral microenvironments are both heterogenous and dynamic, often displaying variable spatial and temporal expression of targetable receptors throughout disease progression.

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This review seeks to highlight the enormous potential of targeted nanoparticles for molecular imaging applications. Being the closest point-of-contact, circulating nanoparticles can gain direct access to targetable molecular markers of disease that appear on the endothelium. Further, nanoparticles are ideally suitable to vascular targeting due to geometrically enhanced multivalent attachment on the vascular target.

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Proper vascularization remains critical to the clinical application of engineered tissues. To engineer microvessels in vitro, we and others have delivered endothelial cells through preformed channels into patterned extracellular matrix-based gels. This approach has been limited by the size of endothelial cells in suspension, and results in plugging of channels below ~30 μm in diameter.

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