Eric Song

Exploiting macrophage autophagy-lysosomal biogenesis as a therapy for atherosclerosis

Macrophages specialize in removing lipids and debris present in the atherosclerotic plaque. However, plaque progression renders macrophages unable to degrade exogenous atherogenic material and endogenous cargo including dysfunctional proteins and organelles. Here we show that a decline in the autophagy–lysosome system contributes to this as evidenced by a derangement in key autophagy markers in both mouse and human atherosclerotic plaques. By augmenting macrophage TFEB, the master transcriptional regulator of autophagy–lysosomal biogenesis, we can reverse the autophagy dysfunction of plaques, enhance aggrephagy of p62-enriched protein aggregates and blunt macrophage apoptosis and pro-inflammatory IL-1β levels, leading to reduced atherosclerosis. In order to harness this degradative response therapeutically, we also describe a natural sugar called trehalose as an inducer of macrophage autophagy–lysosomal biogenesis and show trehaloses ability to recapitulate the atheroprotective properties of macrophage TFEB overexpression. Our data support this practical method of enhancing the degradative capacity of macrophages as a therapy for atherosclerotic vascular disease.

Distribution of polymer nanoparticles by convection-enhanced delivery to brain tumors.

Glioblastoma multiforme (GBM) is a fatal brain tumor characterized by infiltration beyond the margins of the main tumor mass and local recurrence after surgery. The blood-brain barrier (BBB) poses the most significant hurdle to brain tumor treatment. Convection-enhanced delivery (CED) allows for local administration of agents, overcoming the restrictions of the BBB. Recently, polymer nanoparticles have been demonstrated to penetrate readily through the healthy brain when delivered by CED, and size has been shown to be a critical factor for nanoparticle penetration. Because these brain-penetrating nanoparticles (BPNPs) have high potential for treatment of intracranial tumors since they offer the potential for cell targeting and controlled drug release after administration, here we investigated the intratumoral CED infusions of PLGA BPNPs in animals bearing either U87 or RG2 intracranial tumors. We demonstrate that the overall volume of distribution of these BPNPs was similar to that observed in healthy brains; however, the presence of tumors resulted in asymmetric and heterogeneous distribution patterns, with substantial leakage into the peritumoral tissue. Together, our results suggest that CED of BPNPs should be optimized by accounting for tumor geometry, in terms of location, size and presence of necrotic regions, to determine the ideal infusion site and parameters for individual tumors.

PEGylated squalenoyl-gemcitabine nanoparticles for the treatment of glioblastoma

New treatments for glioblastoma multiforme (GBM) are desperately needed, as GBM prognosis remains poor, mainly due to treatment resistance, poor distribution of therapeutics in the tumor tissue, and fast metabolism of chemotherapeutic drugs in the brain extracellular space. Convection-enhanced delivery (CED) of nanoparticles (NPs) has been shown to improve the delivery of chemotherapeutic drugs to the tumor bed, providing sustained release, and enhancing survival of animals with intracranial tumors. Here we administered gemcitabine, a nucleoside analog used as a first line treatment for a wide variety of extracranial solid tumors, within squalene-based NPs using CED, to overcome the above-mentioned challenges of GBM treatment. Small percentages of poly(ethylene) glycol (PEG) dramatically enhanced the distribution of squalene-gemcitabine nanoparticles (SQ-Gem NPs) in healthy animals and tumor-bearing animals after administration by CED. When tested in an orthotopic model of GBM, SQ-Gem-PEG NPs demonstrated significantly improved therapeutic efficacy compared to free gemcitabine, both as a chemotherapeutic drug and as a radiosensitizer. Furthermore, MR contrast agents were incorporated into the SQ-Gem-PEG NP formulation, providing a way to non-invasively track the NPs during infusion.

Improved i.p. drug delivery with bioadhesive nanoparticles

Significance Resistance to platinum-based chemotherapies and paclitaxel is common in recurrence of both high-grade ovarian and endometrial cancers. Paclitaxel resistance has been correlated with overexpression of class III β-tubulin, the preferential target of the epothilones, microtubule-stabilizing agents. Epothilone B (EB) is manifold more effective than paclitaxel, but clinical use is limited by side effects. To reduce side effects, we encapsulated EB into bioadhesive nanoparticles (BNPs), reasoning that bioadhesive nanoparticles loaded with epothilone B (EB/BNPs) would interact with abdominal tissues and gradually release EB in proximity of peritoneal cancer implants, thus maintaining EB concentration at the site of action and limiting systemic exposure and toxicity. Our experiments show the higher therapeutic activity and limited toxicity of EB/BNPs compared with nonadhesive nanoparticles loaded with EB or carrier-free EB. The i.p. administration of chemotherapy in ovarian and uterine serous carcinoma patients by biodegradable nanoparticles may represent a highly effective way to suppress peritoneal carcinomatosis. However, the efficacy of nanoparticles loaded with chemotherapeutic agents is currently hampered by their fast clearance by lymphatic drainage. Here, we show that a unique formulation of bioadhesive nanoparticles (BNPs) can interact with mesothelial cells in the abdominal cavity and significantly extend the retention of the nanoparticles in the peritoneal space. BNPs loaded with a potent chemotherapeutic agent [epothilone B (EB)] showed significantly lower systemic toxicity and higher therapeutic efficacy against i.p. chemotherapy-resistant uterine serous carcinoma-derived xenografts compared with free EB and non-BNPs loaded with EB.

Nanoparticle targeting to the endothelium during normothermic machine perfusion of human kidneys

Anti-CD31 antibody conjugation can enhance nanoparticle accumulation in the vascular endothelium of human kidneys during ex vivo normothermic machine perfusion. Particle perfusion for organ transplant Ischemia-reperfusion injury, which occurs when a tissue or organ is temporarily cut off from blood flow, is a major issue limiting organ viability for transplantation. Tietjan et al. devised a way to target the injury-sensitive endothelium of organs during ex vivo perfusion. Using nanoparticles conjugated to an antibody targeting a protein expressed on endothelial cells, the authors demonstrated that they could perfuse human kidneys and that nanoparticles accumulated in kidney endothelial cells. In addition to expanding the pool of viable organs for transplant, this approach could potentially be used to deliver targeted therapies to organs during ex vivo perfusion rather than treating the transplant recipient systemically. Ex vivo normothermic machine perfusion (NMP) is a new clinical strategy to assess and resuscitate organs likely to be declined for transplantation, thereby increasing the number of viable organs available. Short periods of NMP provide a window of opportunity to deliver therapeutics directly to the organ and, in particular, to the vascular endothelial cells (ECs) that constitute the first point of contact with the recipient’s immune system. ECs are the primary targets of both ischemia-reperfusion injury and damage from preformed antidonor antibodies, and reduction of perioperative EC injury could have long-term benefits by reducing the intensity of the host’s alloimmune response. Using NMP to administer therapeutics directly to the graft avoids many of the limitations associated with systemic drug delivery. We have previously shown that polymeric nanoparticles (NPs) can serve as depots for long-term drug release, but ensuring robust NP accumulation within a target cell type (graft ECs in this case) remains a fundamental challenge of nanomedicine. We show that surface conjugation of an anti-CD31 antibody enhances targeting of NPs to graft ECs of human kidneys undergoing NMP. Using a two-color quantitative microscopy approach, we demonstrate that targeting can enhance EC accumulation by about 5- to 10-fold or higher in discrete regions of the renal vasculature. In addition, our studies reveal that NPs can also nonspecifically accumulate within obstructed regions of the vasculature that are poorly perfused. These quantitative preclinical human studies demonstrate the therapeutic potential for targeted nanomedicines delivered during ex vivo NMP.

Anti-tumor Activity of miniPEG-γ-Modified PNAs to Inhibit MicroRNA-210 for Cancer Therapy

MicroRNAs (miRs) are frequently overexpressed in human cancers. In particular, miR-210 is induced in hypoxic cells and acts to orchestrate the adaptation of tumor cells to hypoxia. Silencing oncogenic miRs such as miR-210 may therefore offer a promising approach to anticancer therapy. We have developed a miR-210 inhibition strategy based on a new class of conformationally preorganized antisense γ peptide nucleic acids (γPNAs) that possess vastly superior RNA-binding affinity, improved solubility, and favorable biocompatibility. For cellular delivery, we encapsulated the γPNAs in poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs). Our results show that γPNAs targeting miR-210 cause significant delay in growth of a human tumor xenograft in mice compared to conventional PNAs. Further, histopathological analyses show considerable necrosis, fibrosis, and reduced cell proliferation in γPNA-treated tumors compared to controls. Overall, our work provides a chemical framework for a novel anti-miR therapeutic approach using γPNAs that should facilitate rational design of agents to potently inhibit oncogenic microRNAs.

Local DNA Repair Inhibition for Sustained Radiosensitization of High-Grade Gliomas

High-grade gliomas, such as glioblastoma (GBM) and diffuse intrinsic pontine glioma (DIPG), are characterized by an aggressive phenotype with nearly universal local disease progression despite multimodal treatment, which typically includes chemotherapy, radiotherapy, and possibly surgery. Radiosensitizers that have improved the effects of radiotherapy for extracranial tumors have been ineffective for the treatment of GBM and DIPG, in part due to poor blood–brain barrier penetration and rapid intracranial clearance of small molecules. Here, we demonstrate that nanoparticles can provide sustained drug release and minimal toxicity. When administered locally, these nanoparticles conferred radiosensitization in vitro and improved survival in rats with intracranial gliomas when delivered concurrently with a 5-day course of fractionated radiotherapy. Compared with previous work using locally delivered radiosensitizers and cranial radiation, our approach, based on the rational selection of agents and a clinically relevant radiation dosing schedule, produces the strongest synergistic effects between chemo- and radiotherapy approaches to the treatment of high-grade gliomas. Mol Cancer Ther; 16(8); 1456–69. ©2017 AACR.

Improved threshold selection for the determination of volume of distribution of nanoparticles administered by convection-enhanced delivery

Nanotechnology, in conjunction with convection-enhanced delivery (CED), has gained traction as a promising method to treat many debilitating neurological diseases, including gliomas. One of the key parameters to evaluate the effectiveness of delivery is the volume of distribution (Vd) of nanoparticles within the brain parenchyma. Measurements of Vd are commonly made using fluorescent reporter systems. However, reported analyses lack accurate and robust methods for determining Vd. Current methods face the problems of varying background intensities between images, high intensity aggregates that can shift intensity distributions, and faint residual backgrounds that can occur as artifacts of fluorescent imaging. These problems can cause inaccurate results to be reported when a percentage of the maximum intensity is set as the threshold value. Here we show an implementation of Otsus method more reliably selects accurate threshold values than the fixed-threshold method. We also introduce a goodness of fit value η that quantifies the appropriateness of using Otsus method to calculate Vd. Adoption of Otsus method and reporting of η may help standardize fluorescent image analysis of nanoparticles administered by convection-enhanced delivery.

In utero nanoparticle delivery for site-specific genome editing

Genetic diseases can be diagnosed early during pregnancy, but many monogenic disorders continue to cause considerable neonatal and pediatric morbidity and mortality. Early intervention through intrauterine gene editing, however, could correct the genetic defect, potentially allowing for normal organ development, functional disease improvement, or cure. Here we demonstrate safe intravenous and intra-amniotic administration of polymeric nanoparticles to fetal mouse tissues at selected gestational ages with no effect on survival or postnatal growth. In utero introduction of nanoparticles containing peptide nucleic acids (PNAs) and donor DNAs corrects a disease-causing mutation in the β-globin gene in a mouse model of human β-thalassemia, yielding sustained postnatal elevation of blood hemoglobin levels into the normal range, reduced reticulocyte counts, reversal of splenomegaly, and improved survival, with no detected off-target mutations in partially homologous loci. This work may provide the basis for a safe and versatile method of fetal gene editing for human monogenic disorders.The correction of genetic defects in utero could allow for improved outcomes of gene therapy. Here, the authors demonstrate safe delivery of nanoparticles to fetal mouse tissues, and show that nanoparticles containing peptide nucleic acids to edit the beta-globin gene are effective in a mouse model of beta-thalassemia.

4.30 Nanomaterials for Drug Delivery to the Brain

Nanomaterials have emerged as important and versatile platforms for the delivery of therapeutics to the brain. This article describes the complex anatomy and physiology of the brain, which create challenges in treating diseases of the central nervous system, and current strategies using nanomedicines to address these challenges. We discuss various approaches to overcome the blood-brain barrier, examples of successful incorporation of therapeutics with nanomaterials, and strategies to achieve efficient delivery of nanomedicines into specific cells.