High-Density Lipoproteins: Nature's Multifunctional Nanoparticles

Smart Nanosized Drug Delivery Systems Inducing Immunogenic Cell Death for Combination with Cancer Immunotherapy

Cancer immunotherapy, which suppresses tumor relapse and metastasis by boosting host immunity and inducing long-term immune memory effects, is emerging as a vital approach to improve the prognosis of patients. Although remarkable efficacy has been observed in some patients, challenges including low response rate, drug resistance, and immune-related adverse effects still limit the clinical application of cancer immunotherapy in broad types of tumors. Immunotherapeutic agents are used to enhance tumor immunogenicity and reverse the effects of the immunosuppressive tumor microenvironment (ITM), but the benefits of monotherapy are mild and transient due to off-target distribution of drugs. To overcome these issues, smart nanosized drug delivery systems (sNDDS) have been developed to enhance tissue specificity, co-deliver multiple drugs, prime immune cells, and amplify immune responses in tumors. Moreover, accumulating knowledge in cancer biology, immunology, and material science has also greatly promoted the development of sNDDS for enhancing cancer immunotherapy.In this Account, we will discuss the approaches of our group in designing sNDDS to induce immunogenic cell death (ICD) for combination with cancer immunotherapy. We propose a brief overview on the design of nanocarriers, intelligent moieties and immunotherapeutic agents in sNDDS. Then, we discuss the strategies to remodel ITM by leveraging ICD as well as cooperating with programmed cell death protein 1 ligand blockade and indoleamine 2,3-dioxygenase 1 inhibition. We have synthesized a series of stimuli-responsive polymers and prodrugs to fabricate sNDDS and have integrated multiple immunotherapeutic drugs into one platform for combinational immunotherapy. Last, we present an outlook on future design of sNDDS and possible directions for enhancing cancer immunotherapy. Building on the concept of enhancing tumor immunogenicity and reversing ITM, we hope this Account will contribute to the rational design of sNDDS for co-delivery of multiple drugs with amplified immunotherapeutic efficacy.

Robust anti-tumor T cell response with efficient intratumoral infiltration by nanodisc cancer immunotherapy

Potent anti-tumor T cell response and efficient intratumoral T cell infiltration are the major challenges for therapeutic cancer vaccines. To address these issues, a nano-vaccine system has been designed to promote anti-tumor T cell responses, and intratumoral infiltration was examined in various murine tumor models. Subcutaneous vaccination with nanodiscs carrying human papillomavirus (HPV)-16 E7 antigen elicits as high as ~32% E7-specific CD8 α + T cell responses in circulation, representing a 29-fold improvement over the soluble peptide vaccination. Importantly, nanodisc vaccination also promotes robust intratumoral T cell infiltration and eliminates HPV16 E6/E7-expressing TC-1 tumors at mucosal sites, including lungs, inner lip, and intravaginal tissues. In a benchmark study with a live Listeria vaccine combined with anti-PD-1 IgG, nanodiscs plus anti-PD-1 immune checkpoint blockade elicits comparable levels of T cell responses with anti-tumor efficacy. Furthermore, compared with Complete Freund's Adjuvant combined with tetanus toxoid, nanodisc vaccination in HLA-A02 mice generates >200-fold stronger IFN-γ+ T cell responses against a neoantigen from an HLA-A02 melanoma patient. Overall, these results show that the nanodisc system is a promising cancer vaccine platform for inducing anti-tumor T cell responses.

Preparation and characterization of lipid emulsions containing styrene maleic acid copolymer for the development of pH-responsive drug carriers

Lipid emulsions are potential carriers for poorly water-soluble drugs. Previously, we revealed that lipid nanoparticles complexed with styrene maleic acid copolymer (SMA) disintegrate under acidic pH. In the present study, SMA-containing lipid emulsions (SMA emulsions) were prepared and their physicochemical and biological properties were examined to test whether SMA emulsions could be used as a trigger to facilitate drug release in response to pH reduction. By sonicating lipid and SMA mixtures, homogeneously sized SMA emulsion particles were prepared as verified via dynamic light scattering and transmission electron microscopy. Upon the reduction of solution pH, disintegration of SMA emulsions was observed, which may be utilized for drug release at mildly acidic pH. In addition, the sensitivity to pH changes could be controlled by altering the lipid composition. Serum proteins bound to SMA emulsions were analyzed to predict the metabolic fate upon intravenous injection. Predictably, apolipoproteins were abundantly bound, suggesting that SMA emulsions should avoid being recognized as foreign substances. Furthermore, subcellular distribution studies using a human breast cancer cell line (MDA-MB-231) demonstrated that SMA emulsions localize to lysosomes, which have a lower pH. These results suggest that SMA emulsions could be promising pH-responsive drug carriers.

Synthetic High-density Lipoprotein Nanodiscs for Personalized Immunotherapy Against Gliomas

PURPOSE

Gliomas are brain tumors with dismal prognoses. The standard-of-care treatments for gliomas include surgical resection, radiation, and temozolomide administration; however, they have been ineffective in providing significant increases in median survival. Antigen-specific cancer vaccines and immune checkpoint blockade may provide promising immunotherapeutic approaches for gliomas.

EXPERIMENTAL DESIGN

We have developed immunotherapy delivery vehicles based on synthetic high-density lipoprotein (sHDL) loaded with CpG, a Toll-like receptor-9 agonist, and tumor-specific neoantigens to target gliomas and elicit immune-mediated tumor regression.

RESULTS

We demonstrate that vaccination with neoantigen peptide-sHDL/CpG cocktail in combination with anti-PD-L1 immune checkpoint blocker elicits robust neoantigen-specific T-cell responses against GL261 cells and eliminated established orthotopic GL261 glioma in 33% of mice. Mice remained tumor free upon tumor cell rechallenge in the contralateral hemisphere, indicating the development of immunologic memory. Moreover, in a genetically engineered murine model of orthotopic mutant IDH1 (mIDH1) glioma, sHDL vaccination with mIDH1 neoantigen eliminated glioma in 30% of animals and significantly extended the animal survival, demonstrating the versatility of our approach in multiple glioma models.

CONCLUSIONS

Overall, our strategy provides a general roadmap for combination immunotherapy against gliomas and other cancer types.

Lipoprotein-based drug delivery

Lipoproteins (LPs) are circulating heterogeneous nanoparticles produced by the liver and intestines. LPs play a major role in the transport of dietary and endogenous lipids to target cells through cell membrane receptors or cell surface-bound lipoprotein lipase. The stability, biocompatibility, and selective transport of LPs make them promising delivery vehicles for various therapeutic and imaging agents. This review discusses isolation, manufacturing, and drug loading techniques used for LP-based drug delivery, as well as recent applications for diagnosis and treatment of cancer, atherosclerosis, and other life-threatening diseases.

Choroid Plexus: The Orchestrator of Long-Range Signalling Within the CNS

Cerebrospinal fluid (CSF) is the liquid that fills the brain ventricles. CSF represents not only a mechanical brain protection but also a rich source of signalling factors modulating diverse processes during brain development and adulthood. The choroid plexus (CP) is a major source of CSF and as such it has recently emerged as an important mediator of extracellular signalling within the brain. Growing interest in the CP revealed its capacity to release a broad variety of bioactive molecules that, via CSF, regulate processes across the whole central nervous system (CNS). Moreover, CP has been also recognized as a sensor, responding to altered composition of CSF associated with changes in the patterns of CNS activity. In this review, we summarize the recent advances in our understanding of the CP as a signalling centre that mediates long-range communication in the CNS. By providing a detailed account of the CP secretory repertoire, we describe how the CP contributes to the regulation of the extracellular environment-in the context of both the embryonal as well as the adult CNS. We highlight the role of the CP as an important regulator of CNS function that acts via CSF-mediated signalling. Further studies of CP-CSF signalling hold the potential to provide key insights into the biology of the CNS, with implications for better understanding and treatment of neuropathological conditions.

Programmed Self-Assembly of Protein-Coated AIE-Featured Nanoparticles with Dual Imaging and Targeted Therapy to Cancer Cells

Modifying different functional moieties into one platform is a conventional strategy for constructing theranostic systems. However, this strategy usually suffers from the unsatisfied efficiency of each individual function. Herein, a programmed self-assembly strategy is presented to fabricate theranostic nanoparticles, which significantly exhibit a dual-modality imaging function involving fluorescence imaging and magnetic resource imaging (MRI), and an efficient targeted therapy to cancer cells. Fluorescent vesicles are first self-assembled by aggregation-induced emission (AIE)-active molecules. Gd³⁺, serving as an MRI agent, is subsequently bound to the vesicles to provide highly positive charges, which have been realized to be anticancer active. Thereafter, transferrin (Tf) protein is introduced onto the surface of Gd³⁺ coordinated vesicles, shielding the positive charges and making the nanoparticles nontoxic to cells. With the assistance of Tf protein, the constructed nanoparticles are specifically targeted to cancer cells. Moreover, Tf proteins further peel off from nanoparticles in lysosomes due to their charge reversion, resulting in highly positive charges and heavy toxicity of nanoparticles to kill cancer cells. In the nanoparticles, each of the functional components acts as double-sided adhesive tape to glue the next layer, so that the abilities of functional components are not compromised. This strategy holds great potential for theranostic nanomedicine.

Increased PIP3 activity blocks nanoparticle mRNA delivery

The biological pathways that affect drug delivery in vivo remain poorly understood. We hypothesized that altering cell metabolism with phosphatidylinositol (3,4,5)-triphosphate (PIP3), a bioactive lipid upstream of the metabolic pathway PI3K (phosphatidylinositol 3-kinase)/AKT/ mTOR (mammalian target of rapamycin) would transiently increase protein translated by nanoparticle-delivered messenger RNA (mRNA) since these pathways increase growth and proliferation. Instead, we found that PIP3 blocked delivery of clinically-relevant lipid nanoparticles (LNPs) across multiple cell types in vitro and in vivo. PIP3-driven reductions in LNP delivery were not caused by toxicity, cell uptake, or endosomal escape. Interestingly, RNA sequencing and metabolomics analyses suggested an increase in basal metabolic rate. Higher transcriptional activity and mitochondrial expansion led us to formulate two competing hypotheses that explain the reductions in LNP-mediated mRNA delivery. First, PIP3 induced consumption of limited cellular resources, "drowning out" exogenously-delivered mRNA. Second, PIP3 triggers a catabolic response that leads to protein degradation and decreased translation.

Radiolabeled liposomes and lipoproteins as lipidic nanoparticles for imaging and therapy

Radiolabeled lipidic nanoparticles, particularly liposomes and lipoproteins, are of great interest as agents for imaging and therapy, due not only to their peculiar physicochemical and biological properties, but also to their great versatility and the ability to manipulate them to obtain the desired properties. This review provides an overview of radionuclide labeling strategies for preparing diagnostic and therapeutic nanoparticles based on liposomes and lipoproteins that have been developed to date, as well as the main quality control methods and in vivo applications.

Presentation of HIV-1 envelope glycoprotein trimers on diverse nanoparticle platforms

PURPOSE OF REVIEW

We will discuss recent advances in the development of nanoparticle vaccines presenting HIV-1 envelope trimer vaccines and the immunological mechanisms by which they act.

RECENT FINDINGS

The multivalent presentation of Env trimers on nanoparticles is a promising strategy to increase Env immunogenicity. Recent studies have shed light on how Env nanoparticles increase lymph node trafficking and germinal center formation by using the lectin-mediated complement pathway and enhancing the interaction with naïve B cells. Meanwhile, research on different nanoparticle platforms has resulted in improved designs, such as liposomes with improved stability, and the emergence of novel platforms such as protein nanoparticles that self-assemble in vitro. Immmunogenicity studies with these nanoparticles delineate the advantages and expose the limitations of the different nanoparticle platforms.

SUMMARY

It is becoming increasingly clear that HIV-1 vaccine research might benefit greatly from using nanoparticles presenting Env trimers, particularly during the priming stage of immunization. Among the different nanoparticles that are being pursued, in vitro-assembling nanoparticles allow for greater control of Env quality making them a promising nanoparticle platform.

Immunotherapy for gliomas: shedding light on progress in preclinical and clinical development

INTRODUCTION

Gliomas are infiltrating brain tumors associated with high morbidity and mortality. Current standard of care includes radiation, chemotherapy, and surgical resection. Today, survival rates for malignant glioma patients remain dismal and unchanged for decades. The glioma microenvironment is highly immunosuppressive and consequently this has motivated the development of immunotherapies for counteracting this condition, enabling the immune cells within the tumor microenvironment to react against this tumor.

AREAS COVERED

The authors discuss immunotherapeutic strategies for glioma in phase-I/II clinical trials and illuminate their mechanisms of action, limitations, and key challenges. They also examine promising approaches under preclinical development.

EXPERT OPINION

In the last decade there has been an expansion in immune-mediated anti-cancer therapies. In the glioma field, sophisticated strategies have been successfully implemented in preclinical models. Unfortunately, clinical trials have not yet yielded consistent results for glioma patients. This could be attributed to our limited understanding of the complex immune cell infiltration and its interaction with the tumor cells, the selected time for treatment, the combination with other therapies and the route of administration of the agent. Applying these modalities to treat malignant glioma is challenging, but many new alternatives are emerging to by-pass these hurdles.

Phase-Change Materials for Controlled Release and Related Applications

Phase-change materials (PCMs) have emerged as a novel class of thermo-responsive materials for controlled release, where the payloads encapsulated in a solid matrix are released only upon melting the PCM to trigger a solid-to-liquid phase transition. Herein, the advances over the past 10 years in utilizing PCMs as a versatile platform for the encapsulation and release of various types of therapeutic agents and biological effectors are highlighted. A brief introduction to PCMs in the context of desired properties for controlled release and related applications is provided. Among the various types of PCMs, a specific focus is placed on fatty acids and fatty alcohols for their natural availability, low toxicity, biodegradability, diversity, high abundance, and low cost. Then, various methods capable of processing PCMs, and their mixtures with payloads, into stable suspensions of colloidal particles, and the different means for triggering the solid-to-liquid phase transition are discussed. Finally, a range of applications enabled by the controlled release system based on PCMs are presented together with some perspectives on future directions.

Reconfiguring Nature's Cholesterol Accepting Lipoproteins as Nanoparticle Platforms for Transport and Delivery of Therapeutic and Imaging Agents

Apolipoproteins are critical structural and functional components of lipoproteins, which are large supramolecular assemblies composed predominantly of lipids and proteins, and other biomolecules such as nucleic acids. A signature feature of apolipoproteins is the preponderance of amphipathic α-helical motifs that dictate their ability to make extensive non-covalent inter- or intra-molecular helix-helix interactions in lipid-free states or helix-lipid interactions with hydrophobic biomolecules in lipid-associated states. This review focuses on the latter ability of apolipoproteins, which has been capitalized on to reconstitute synthetic nanoscale binary/ternary lipoprotein complexes composed of apolipoproteins/peptides and lipids that mimic native high-density lipoproteins (HDLs) with the goal to transport drugs. It traces the historical development of our understanding of these nanostructures and how the cholesterol accepting property of HDL has been reconfigured to develop them as drug-loading platforms. The review provides the structural perspective of these platforms with different types of apolipoproteins and an overview of their synthesis. It also examines the cargo that have been loaded into the core for therapeutic and imaging purposes. Finally, it lays out the merits and challenges associated with apolipoprotein-based nanostructures with a future perspective calling for a need to develop "zip-code"-based delivery for therapeutic and diagnostic applications.

Effective atherosclerotic plaque inflammation inhibition with targeted drug delivery by hyaluronan conjugated atorvastatin nanoparticles

Atherosclerosis is associated with inflammation in the arteries, which is a major cause of heart attacks and strokes. Reducing the extent of local inflammation at atherosclerotic plaques can be an attractive strategy to combat atherosclerosis. While statins can exhibit direct anti-inflammatory activities, the high dose required for such a therapy renders it unrealistic due to their low systemic bioavailabilities and potential side effects. To overcome this, a new hyaluronan (HA)-atorvastatin (ATV) conjugate was designed with the hydrophobic statin ATV forming the core of the nanoparticle (HA-ATV-NP). The HA on the NPs can selectively bind with CD44, a cell surface receptor overexpressed on cells residing in atherosclerotic plaques and known to play important roles in plaque development. HA-ATV-NPs exhibited significantly higher anti-inflammatory effects on macrophages compared to ATV alone in vitro. Furthermore, when administered in an apolipoprotein E (ApoE)-knockout mouse model of atherosclerosis following a 1-week treatment regimen, HA-ATV-NPs markedly decreased inflammation in advanced atherosclerotic plaques, which were monitored through contrast agent aided magnetic resonance imaging. These results suggest CD44 targeting with HA-ATV-NPs is an attractive strategy to reduce harmful inflammation in atherosclerotic plaques.

High Density Lipoprotein and Its Precursor Protein Apolipoprotein A1 as Potential Therapeutics to Prevent Anthracycline Associated Cardiotoxicity

Cardiovascular disease and cancer are the leading causes of death in developed societies. Despite their effectiveness, many cancer therapies exhibit deleterious cardiovascular side effects such as cardiotoxicity and heart failure. The cardiotoxic effects of anthracyclines such as doxorubicin are the most well-characterized of cardiotoxic anti-cancer therapies. While other anti-neoplastic drugs also induce cardiotoxicity, often leading to heart failure, they are beyond the scope of this review. This review first summarizes the mechanisms of doxorubicin-induced cardiotoxicity. It then reviews emerging preclinical evidence that high density lipoprotein and its precursor protein apolipoprotein A1, which are known for their protective effects against ischemic cardiovascular disease, may also protect against doxorubicin-induced cardiotoxicity both directly and indirectly, when used therapeutically.

Probing the Assembly of HDL Mimetic, Drug Carrying Nanoparticles Using Intrinsic Fluorescence

Reconstituted high-density lipoprotein (HDL) containing apolipoprotein A-I (Apo A-I) mimics the structure and function of endogenous (human plasma) HDL due to its function and potential therapeutic utility in atherosclerosis, cancer, neurodegenerative diseases, and inflammatory diseases. Recently, a new class of HDL mimetics has emerged, involving peptides with amino acid sequences that simulate the the primary structure of the amphipathic alpha helices within the Apo A-I protein. The findings reported in this communication were obtained using a similar amphiphilic peptide (modified via conjugation of a myristic acid residue at the amino terminal aspartic acid) that self-assembles (by itself) into nanoparticles while retaining the key features of endogenous HDL. The studies presented here involve the macromolecular assembly of the myristic acid conjugated peptide (MYR-5A) into nanomicellar structures and its characterization via steady-state and time-resolved fluorescence spectroscopy. The structural differences between the free peptide (5A) and MYR-5A conjugate were also probed, using tryptophan fluorescence, Fӧrster resonance energy transfer (FRET), dynamic light scattering, and gel exclusion chromatography. To our knowledge, this is the first report of a lipoprotein assembly generated from a single ingredient and without a separate lipid component. The therapeutic utility of these nanoparticles (due to their capablity to incorporate a wide range of drugs into their core region for targeted delivery) was also investigated by probing the role of the scavenger receptor type B1 in this process. SIGNIFICANCE STATEMENT: Although lipoproteins have been considered as effective drug delivery agents, none of these nanoformulations has entered clinical trials to date. A major challenge to advancing lipoprotein-based formulations to the clinic has been the availability of a cost-effective protein or peptide constituent, needed for the assembly of the drug/lipoprotein nanocomplexes. This report of a robust, spontaneously assembling drug transport system from a single component could provide the template for a superior, targeted drug delivery strategy for therapeutics of cancer and other diseases (Counsell and Pohland, 1982).

Macrophage subsets in atherosclerosis as defined by single-cell technologies

Macrophages play a major role in the pathogenesis of atherosclerosis. Many studies have shone light on the different phenotypes and functions that macrophages can acquire upon exposure to local cues. The microenvironment of the atherosclerotic plaque contains a plethora of macrophage-controlling factors, such as cytokines, oxidised low-density lipoproteins and cell debris. Previous research has determined macrophage function within the plaque mainly by using immunohistochemistry and bulk analysis. The recent development and rapid progress of single-cell technologies, such as cytometry by time of flight and single-cell RNA sequencing, now enable comprehensive mapping of the wide range of cell types and their phenotypes present in atherosclerotic plaques. In this review we discuss recent advances applying these technologies in defining macrophage subsets residing in the atherosclerotic arterial wall of mice and men. Resulting from these studies, we describe three main macrophage subsets: resident-like, pro-inflammatory and anti-inflammatory foamy TREM2hi macrophages, which are found in both mouse and human atherosclerotic plaques. Furthermore, we discuss macrophage subset-specific markers and functions. More insights into the characteristics and phenotype of immune cells within the atherosclerotic plaque may guide future clinical approaches to treat disease. © 2020 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Clearance of two organic nanoparticles from the brain via the paravascular pathway

The elaboration of nanotechnology offers valuable therapeutic options to overcome the blood-brain barrier and enable the treatment of brain diseases. However, to date, limit work has been done to reveal the fate of nanoparticles within the brain, which largely hinders their safe and effective applications. Here we demonstrated that the commonly-used organic nanoparticles reconstituted high density lipoprotein and poly(ethylene glycol)-b-poly(lactic acid) nanoparticles were cleared relatively fast from the brain (half-life <5 h). Notably, through various transgenic mice and pharmacological inhibition approaches, we revealed that the paravascular glymphatic pathway plays a key role (about 80%) in the brain clearance of the nanoparticles, and disclosed that microglia-mediated transportation is essential for facilitating nanoparticles elimination through the paravascular route. In addition, we witnessed a significant decline in the brain clearance of both of the nanoparticles in Alzheimer's model mice where the glymphatic system is impaired. These findings provide insightful data on the fate of nanoparticles in the brain, which would shed new light into the rational design and safe application of nanoparticles for brain drug delivery.

Synthetic HDL Nanoparticles Delivering Docetaxel and CpG for Chemoimmunotherapy of Colon Adenocarcinoma

Colon carcinomas comprise over two-thirds of all colorectal cancers with an overall 5-year survival rate of 64%, which rapidly decreases to 14% when the cancer becomes metastatic. Depending on the stage of colon carcinoma at diagnosis, patients can undergo surgery to attempt complete tumor resection or move directly to chemotherapy with one or a combination of drugs. As with most cancers, colon carcinomas do not always respond to chemotherapies, so targeted therapies and immunotherapies have been developed to aid chemotherapy. We report the development of a local combination therapy for colon carcinoma whereby chemo- and immunotherapeutic entities are delivered intratumorally to maximize efficacy and minimize off-target side effects. A hydrophobic chemotherapeutic agent, docetaxel (DTX), and cholesterol-modified Toll-like receptor 9 (TLR9) agonist CpG (cho-CpG) oligonucleotide are co-loaded in synthetic HDL (sHDL) nanodiscs. In vivo survival analysis of MC-38 tumor-bearing mice treated intratumorally with DTX-sHDL/CpG (median survival; MS = 43 days) showed significant improvement in overall survival compared to mice treated with single agents, free DTX (MS = 23 days, p < 0.0001) or DTX-sHDL (MS = 28 days, p < 0.0001). Two of seven mice treated with DTX-sHDL/CpG experienced complete tumor regression. None of the mice experienced any systemic toxicity as indicated by body weight maintenance and normal serum enzyme and protein levels. In summary, we have demonstrated that chemo- and immunotherapies can be co-loaded into sHDLs, delivered locally to the tumor, and can be used to improve survival outcomes significantly compared to chemotherapy alone.

Targeting peptide-decorated biomimetic lipoproteins improve deep penetration and cancer cells accessibility in solid tumor

The limited penetration of nanoparticles and their poor accessibility to cancer cell fractions in tumor remain essential challenges for effective anticancer therapy. Herein, we designed a targeting peptide-decorated biomimetic lipoprotein (termed as BL-RD) to enable their deep penetration and efficient accessibility to cancer cell fractions in a tumor, thereby improving the combinational chemo-photodynamic therapy of triple negative breast cancer. BL-RD was composed of phospholipids, apolipoprotein A1 mimetic peptide (PK22), targeting peptide-conjugated cytotoxic mertansine (RM) and photodynamic agents of DiIC18(5) (DiD). The counterpart biomimetic lipoprotein system without RM (termed as BL-D) was fabricated as control. Both BL-D and BL-RD were nanometer-sized particles with a mean diameter of less than 30 nm and could be efficiently internalized by cancer cells. After intravenous injection, they can be specifically accumulated at tumor sites. When comparing to the counterpart BL-D, BL-RD displayed superior capability to permeate across the tumor mass, extravasate from tumor vasculature to distant regions and efficiently access the cancer cell fractions in a solid tumor, thus producing noticeable depression of the tumor growth. Taken together, BL-RD can be a promising delivery nanoplatform with prominent tumor-penetrating and cancer cells-accessing capability for effective tumor therapy.

Prospects of biological and synthetic pharmacotherapies for glioblastoma

Introduction: The field of neuro-oncology has experienced significant advances in recent years. More is known now about the molecular and genetic characteristics of glioma than ever before. This knowledge leads to the understanding of glioma biology and pathogenesis, guiding the development of targeted therapeutics and clinical trials. The goal of this review is to describe the state of basic, translational, and clinical research as it pertains to biological and synthetic pharmacotherapy for gliomas.Areas covered: Challenges remain in designing accurate preclinical models and identifying patients that are likely to respond to a particular targeted therapy. Preclinical models for therapeutic assessment are critical to identify the most promising treatment approaches.Expert opinion: Despite promising new therapeutics, there have been no significant breakthroughs in glioma treatment and patient outcomes. Thus, there is an urgent need to better understand the mechanisms of treatment resistance and to design effective clinical trials.

Circulating microRNAs as biomarkers in cancer diagnosis

MicroRNAs (miRNAs) are a group of tiny molecules of 18-22 nucleotide long noncoding RNA that regulate the post-transcriptional gene expression through translational inhibition and/or mRNA destabilization. Because of their involvement in important developmental processes, it is highly likely that the altered expression of miRNAs could be associated with abnormal conditions like suboptimal growth or diseases. Thus, the expression of miRNAs can be used as biomarkers in pathophysiological conditions. Recently, a handful of miRNAs are detected in cell-free conditions including biofluids and cell culture media and they exhibit specific expression patterns that are associated with altered physiological conditions. Extracellular miRNAs are not only extremely stable outside cells in a variety of biofluids but also they are easy to acquire. These characteristics led to the idea of using extracellular miRNAs as a potential biomarker for the onset and prognosis of cancer. Although miRNAs have been proposed as a potential diagnostic tool for cancer detection, their application in the routine clinical investigation is yet to come. First, this review will provide an insight into the extracellular miRNAs, particularly, their release mechanisms and characteristics, and the potential of extracellular miRNAs as a biomarker in cancer detection. Finally, it will discuss the potential of using extracellular miRNAs in different cancer diagnoses and challenges associated with the clinical application of extracellular miRNAs as noninvasive biomarkers.

Development of synthetic high-density lipoprotein-based ApoA-I mimetic peptide-loaded docetaxel as a drug delivery nanocarrier for breast cancer chemotherapy

In this study, a synthetic high-density lipoprotein (sHDL), peptide-based nanocarrier loaded with docetaxel (DTX) was constructed, against breast cancer. The thermodynamic and molecular dynamic analyses were conducted to examine the stability of nanoparticles synthesized from mimetic peptide 5 A and various types of phospholipids. Furthermore, the cellular uptake and in vivo fluorescence imaging analysis experiments, with scavenger receptor B-I (SR-BI) were carried out to examine the tumor-targeting ability of sHDL. The nanoparticles were investigated for their pharmacodynamic and cytotoxic effects to show their effectivity as anti-tumor agents. The results showed that the synthesized sHDL nanoparticles exhibited a high payload of DTX, sustained drug release properties, and excellent biocompatibility. Moreover, DTX-sHDL nanoparticles enhanced the uptake of DTX, increased the cytotoxicity against MCF-7 cells, and reduced the off-target side-effects to normal cells. Finally, experiments in 4T1 cell line-bearing mice indicate that inhibition of tumor growth by DTX-sHDL nanoparticles was superior to that of free DTX group. Thus, the sHDL nanoparticles are a promising drug delivery vehicle for improving the efficacy of anti-cancer drugs.

High density lipoprotein mimicking nanoparticles for atherosclerosis

Atherosclerosis is a major contributor to many cardiovascular events, including myocardial infarction, ischemic stroke, and peripheral arterial disease, making it the leading cause of death worldwide. High-density lipoproteins (HDL), also known as "good cholesterol", have been shown to demonstrate anti-atherosclerotic efficacy through the removal of cholesterol from foam cells in atherosclerotic plaques. Because of the excellent anti-atherosclerotic properties of HDL, in the past several years, there has been tremendous attention in designing HDL mimicking nanoparticles (NPs) of varying functions to image, target, and treat atherosclerosis. In this review, we are summarizing the recent progress in the development of HDL mimicking NPs and their applications for atherosclerosis.

Nanostructured lipid carriers accumulate in atherosclerotic plaques of ApoE-/- mice

Nanostructured lipid carriers (NLC) might represent an interesting approach for the identification and targeting of rupture-prone atherosclerotic plaques. In this study, we evaluated the biodistribution, targeting ability and safety of ⁶⁴Cu-fonctionalized NLC in atherosclerotic mice. ⁶⁴Cu-chelating-NLC (51.8±3.1 nm diameter) with low dispersity index (0.066±0.016) were produced by high pressure homogenization at tens-of-grams scale. 24 h after injection of ⁶⁴Cu-chelated particles in ApoE^-/- mice, focal regions of the aorta showed accumulation of particles on autoradiography that colocalized with Oil Red O lipid mapping. Signal intensity was significantly greater in aortas isolated from ApoE^-/- mice compared to wild type (WT) control (8.95 [7.58, 10.16]×10⁸ vs 4.59 [3.11, 5.03]×10⁸ QL/mm², P < 0.05). Moreover, NLC seemed safe in relevant biocompatibility studies. NLC could constitute an interesting platform with high clinical translation potential for targeted delivery and imaging purposes in atherosclerosis.

A quantitativeex vivostudy of the interactions between reconstituted high-density lipoproteins and human leukocytes

Knowledge of the interactions between nanoparticles and immune cells is required for optimal design of nanoparticle-based drug delivery systems, either when aiming to avoid phagocytic clearance of the nanoparticles or promote an immune response by delivering therapeutic agents to specific immune cells. Several studies have suggested that reconstituted high-density lipoproteins (rHDL) are attractive drug delivery vehicles. However, detailed studies of rHDL interactions with circulating leukocytes are limited. Here, we evaluated the association of discoidal rHDL with leukocytes in human whole blood (HWB) using quantitative approaches. We found that while the rHDL of various lipid compositions associated preferentially with monocytes, the degree of association depended on the lipid composition. However, consistent with the long circulation half-life of rHDL, we show that only a minor fraction of the rHDL associated with the leukocytes. Furthermore, we used three-dimensional fluorescence microscopy and imaging flow cytometry to evaluate the possible internalization of rHDL cargo into the cells, and we show increased internalization of rHDL cargo in monocytes relative to granulocytes. The preferential rHDL association with monocytes and the internalization of rHDL cargo could possibly be mediated by the scavenger receptor class B type 1 (SR-BI), which we show is expressed to a higher extent on monocytes than on the other major leukocyte populations. Our work implies that drug-loaded rHDL can deliver its cargo to monocytes in circulation, which could lead to some off-target effects when using rHDL for systemic drug delivery, or it could pave the way for novel immunotherapeutic treatments aiming to target the monocytes.

We used novel quantitative methods to study the interactions between reconstituted high-density lipoproteins (rHDL) and human leukocytes – showing that rHDL cargo are preferentially taken up by monocytes.

Drug orientations within statin-loaded lipoprotein nanoparticles by 19F solid-state NMR

NMR measurements of 19F chemical shift anisotropy and 1H-19F dipolar couplings provide unprecedented information on the molecular orientations of two fluorine-containing statin drugs within the heterogeneous environment of reconstituted high-density lipoprotein (rHDL) nanoparticles, a drug delivery system under clinical investigation.

Biomimetic drug-delivery systems for the management of brain diseases

Acting as a double-edged sword, the blood-brain barrier (BBB) is essential for maintaining brain homeostasis by restricting the entry of small molecules and most macromolecules from blood. However, it also largely limits the brain delivery of most drugs. Even if a drug can penetrate the BBB, its accumulation in the intracerebral pathological regions is relatively low. Thus, an optimal drug-delivery system (DDS) for the management of brain diseases needs to display BBB permeability, lesion-targeting capability, and acceptable safety. Biomimetic DDSs, developed by directly utilizing or mimicking the biological structures and processes, provide promising approaches for overcoming the barriers to brain drug delivery. The present review summarizes the biological properties and biomedical applications of the biomimetic DDSs including the cell membrane-based DDS, lipoprotein-based DDS, exosome-based DDS, virus-based DDS, protein template-based DDS and peptide template-based DDS for the management of brain diseases.

Synthetic high-density lipoprotein nanoparticles for the treatment of Niemann-Pick diseases

BACKGROUND

Niemann-Pick disease type C is a fatal and progressive neurodegenerative disorder characterized by the accumulation of unesterified cholesterol in late endosomes and lysosomes. We sought to develop new therapeutics for this disorder by harnessing the body's endogenous cholesterol scavenging particle, high-density lipoprotein (HDL).

METHODS

Here we design, optimize, and define the mechanism of action of synthetic HDL (sHDL) nanoparticles.

RESULTS

We demonstrate a dose-dependent rescue of cholesterol storage that is sensitive to sHDL lipid and peptide composition, enabling the identification of compounds with a range of therapeutic potency. Peripheral administration of sHDL to Npc1 I1061T homozygous mice mobilizes cholesterol, reduces serum bilirubin, reduces liver macrophage size, and corrects body weight deficits. Additionally, a single intraventricular injection into adult Npc1 I1061T brains significantly reduces cholesterol storage in Purkinje neurons. Since endogenous HDL is also a carrier of sphingomyelin, we tested the same sHDL formulation in the sphingomyelin storage disease Niemann-Pick type A. Utilizing stimulated Raman scattering microscopy to detect endogenous unlabeled lipids, we show significant rescue of Niemann-Pick type A lipid storage.

CONCLUSIONS

Together, our data establish that sHDL nanoparticles are a potential new therapeutic avenue for Niemann-Pick diseases.

Nanoparticle Delivery of Immunostimulatory Agents for Cancer Immunotherapy

Immunostimulatory agents, including adjuvants, cytokines, and monoclonal antibodies, hold great potential for the treatment of cancer. However, their direct administration often results in suboptimal pharmacokinetics, vulnerability to biodegradation, and compromised targeting. More recently, encapsulation into biocompatible nanoparticulate carriers has become an emerging strategy for improving the delivery of these immunotherapeutic agents. Such approaches can address many of the challenges facing current treatment modalities by endowing additional protection and significantly elevating the bioavailability of the encapsulated payloads. To further improve the delivery efficiency and subsequent immune responses associated with current nanoscale approaches, biomimetic modifications and materials have been employed to create delivery platforms with enhanced functionalities. By leveraging nature-inspired design principles, these biomimetic nanodelivery vehicles have the potential to alter the current clinical landscape of cancer immunotherapy.

Engineering patient-specific cancer immunotherapies

Research into the immunological processes implicated in cancer has yielded a basis for the range of immunotherapies that are now considered the fourth pillar of cancer treatment (alongside surgery, radiotherapy and chemotherapy). For some aggressive cancers, such as advanced non-small-cell lung carcinoma, combination immunotherapies have resulted in unprecedented treatment efficacy for responding patients, and have become frontline therapies. Individualized immunotherapy, enabled by the identification of patient-specific mutations, neoantigens and biomarkers, and facilitated by advances in genomics and proteomics, promises to broaden the responder patient population. In this Perspective, we give an overview of immunotherapies leveraging engineering approaches, including the design of biomaterials, delivery strategies and nanotechnology solutions, for the realization of individualized cancer treatments such as nanoparticle vaccines customized with neoantigens, cell therapies based on patient-derived dendritic cells and T cells, and combinations of theranostic strategies. Developments in precision cancer immunotherapy will increasingly rely on the adoption of engineering principles.

Targeting Foam Cell Formation in Atherosclerosis: Therapeutic Potential of Natural Products

Foam cell formation and further accumulation in the subendothelial space of the vascular wall is a hallmark of atherosclerotic lesions. Targeting foam cell formation in the atherosclerotic lesions can be a promising approach to treat and prevent atherosclerosis. The formation of foam cells is determined by the balanced effects of three major interrelated biologic processes, including lipid uptake, cholesterol esterification, and cholesterol efflux. Natural products are a promising source for new lead structures. Multiple natural products and pharmaceutical agents can inhibit foam cell formation and thus exhibit antiatherosclerotic capacity by suppressing lipid uptake, cholesterol esterification, and/or promoting cholesterol ester hydrolysis and cholesterol efflux. This review summarizes recent findings on these three biologic processes and natural products with demonstrated potential to target such processes. Discussed also are potential future directions for studying the mechanisms of foam cell formation and the development of foam cell-targeted therapeutic strategies.

The Composition of Reconstituted High-Density Lipoproteins (rHDL) Dictates the Degree of rHDL Cargo- and Size-Remodeling via Direct Interactions with Endogenous Lipoproteins

The application of reconstituted high-density lipoproteins (rHDL) as a drug-carrier has during the past decade been established as a promising approach for effective receptor-mediated drug delivery, and its ability to target tumors has recently been confirmed in a clinical trial. The rHDL mimics the endogenous HDL, which is known to be highly dynamic and undergo extensive enzyme-mediated remodulations. Hence, to reveal the physiological rHDL stability, a thorough characterization of the dynamics of rHDL in biologically relevant environments is needed. We employ a size-exclusion chromatography (SEC) method to evaluate the dynamics of discoidal rHDL in fetal bovine serum (FBS), where we track both the rHDL lipids (by the fluorescence from lipid-conjugated fluorophores) and apoA-I (by human apoA-I ELISA). We show by using lipoprotein depleted FBS and isolated lipoproteins that rHDL lipids can be transferred to endogenous lipoproteins via direct interactions in a nonenzymatic process, resulting in rHDL compositional- and size-remodeling. This type of dynamics could lead to misinterpretations of fluorescence-based rHDL uptake studies due to desorption of labile lipophilic fluorophores or off-target side effects due to desorption of incorporated drugs. Importantly, we show how the degree of rHDL remodeling can be controlled by the compositional design of the rHDL. Understanding the correlation between the molecular properties of the rHDL constituents and their collective dynamics is essential for improving the rHDL-based drug delivery platform. Taken together, our work highlights the need to carefully consider the compositional design of rHDL and test its stability in a biological relevant environment, when developing rHDL for drug delivery purposes.

Hydrophobicity drives the systemic distribution of lipid-conjugated siRNAs via lipid transport pathways

Efficient delivery of therapeutic RNA beyond the liver is the fundamental obstacle preventing its clinical utility. Lipid conjugation increases plasma half-life and enhances tissue accumulation and cellular uptake of small interfering RNAs (siRNAs). However, the mechanism relating lipid hydrophobicity, structure, and siRNA pharmacokinetics is unclear. Here, using a diverse panel of biologically occurring lipids, we show that lipid conjugation directly modulates siRNA hydrophobicity. When administered in vivo, highly hydrophobic lipid-siRNAs preferentially and spontaneously associate with circulating low-density lipoprotein (LDL), while less lipophilic lipid-siRNAs bind to high-density lipoprotein (HDL). Lipid-siRNAs are targeted to lipoprotein receptor-enriched tissues, eliciting significant mRNA silencing in liver (65%), adrenal gland (37%), ovary (35%), and kidney (78%). Interestingly, siRNA internalization may not be completely driven by lipoprotein endocytosis, but the extent of siRNA phosphorothioate modifications may also be a factor. Although biomimetic lipoprotein nanoparticles have been explored for the enhancement of siRNA delivery, our findings suggest that hydrophobic modifications can be leveraged to incorporate therapeutic siRNA into endogenous lipid transport pathways without the requirement for synthetic formulation.

Development, synthesis, and 68Ga-Labeling of a Lipophilic complexing agent for atherosclerosis PET imaging

Cardiovascular disease is the leading cause of mortality and morbidity worldwide. Atherosclerosis accounts for 50% of deaths in western countries. This multifactorial pathology is characterized by the accumulation of lipids and inflammatory cells within the vascular wall, leading to plaque formation. We describe herein the synthesis of a PCTA-based ⁶⁸Ga³⁺ chelator coupled to a phospholipid biovector 1,2-distearoyl-sn-glycero-3-phosphoethanolamine (DSPE), which is the main constituent of the phospholipid moiety of High-Density Lipoprotein (HDL) phospholipid moiety. The resulting ⁶⁸Ga-PCTA-DSPE inserted into HDL particles was compared to ¹⁸F-FDG as a PET agent to visualize atherosclerotic plaques. Our agent markedly accumulated within mouse atheromatous aortas and more interestingly in human endarterectomy carotid samples. These results support the potential use of ⁶⁸Ga-PCTA-DSPE-HDL for atherosclerosis PET imaging.

Hepatocellular Carcinoma Growth Retardation and PD-1 Blockade Therapy Potentiation with Synthetic High-density Lipoprotein

The long progression-free survival (PFS) of patients with inoperable hepatocellular carcinoma (HCC) tumors is an unmet clinical need. Imaging-guided in situ ablation and vaccination with nanoplatforms could be a promising way to achieve durable disease control and long PFS. In the present work, we show that a biomimetic nanoplatform, namely, synthetic high-density lipoprotein (sHDL), can transport photothermal agent DiR and other drugs preferentially into the cytosol of HCC cells, enabling imaging-guided combination therapy for HCC in vivo. With a single injection, the sHDLs reduced the tumor burden, triggered immunogenic cell death (ICD), promoted dendritic cell (DC) maturation, and induced CD8⁺ T cell responses, which together sensitized the tumors to PD-1 blockade. Tumor remission and immune protection were achieved using sHDL loaded with DiR and a stimulator of interferon genes agonist vadimezan, in conjunction with a PD-1 blockade. The replacement of vadimezan with the chemotherapeutic mertansine potentiated ICD of HCC cells, but the drug interfered with DC maturation and subsequent CD8⁺ T cell priming, resulting in unsatisfactory disease control. Our work provides a generalizable nanoplatform for the combined photothermal ablation and immunotherapy of HCC and highlights the importance of cancer-cell-specific ICD induction and simultaneous DC activation during in situ vaccination.

Artificial High Density Lipoprotein Nanoparticles in Cardiovascular Research

Lipoproteins are endogenous nanoparticles which are the major transporter of fats and cholesterol in the human body. They play a key role in the regulatory mechanisms of cardiovascular events. Lipoproteins can be modified and manipulated to act as drug delivery systems or nanocarriers for contrast agents. In particular, high density lipoproteins (HDL), which are the smallest class of lipoproteins, can be synthetically engineered either as nascent HDL nanodiscs or spherical HDL nanoparticles. Reconstituted HDL (rHDL) particles are formed by self-assembly of various lipids and apolipoprotein AI (apo-AI). A variety of substances including drugs, nucleic acids, signal emitting molecules, or dyes can be loaded, making them efficient nanocarriers for therapeutic applications or medical diagnostics. This review provides an overview about synthesis techniques, physicochemical properties of rHDL nanoparticles, and structural determinants for rHDL function. We discuss recent developments utilizing either apo-AI or apo-AI mimetic peptides for the design of pharmaceutical rHDL formulations. Advantages, limitations, challenges, and prospects for clinical translation are evaluated with a special focus on promising strategies for the treatment and diagnosis of atherosclerosis and cardiovascular diseases.

Mimetic sHDL nanoparticles: A novel drug-delivery strategy to target triple-negative breast cancer

BACKGROUND

Withanolides are naturally derived heat shock protein 90 inhibitors that are potent in preclinical models of triple negative breast cancers. Conjugation to synthetic high-density lipoprotein nanoparticles improves solubility and targets delivery to the scavenger receptor B1. Triple negative breast cancers highly overexpress the scavenger receptor B1, and we hypothesize that encapsulation of the novel withalongolide A 4,19,27-triacetate by synthetic high-density lipoprotein will have enhanced efficacy against triple negative breast cancers in vivo.

METHODS

Validated human triple negative breast cancer cell lines were evaluated for the scavenger receptor B1 expression by quantitative polymerase chain reaction and Western blot. Withalongolide A 4,19,27-triacetate inhibitory concentration₅₀ values were obtained using CellTiter-Glo assays (Promega, Madison, WI, USA). The scavenger receptor B1-mediated drug uptake was evaluated in vitro under fluorescence microscopy and in vivo with IVIS imaging of mouse xenografts (MD-MBA-468LN). To evaluate drug efficacy, mice were treated with synthetic high-density lipoprotein alone, withalongolide A 4,19,27-triacetate alone, withalongolide A 4,19,27-triacetate synthetic high-density lipoprotein, and chemotherapy or Prussian blue stain (control).

RESULTS

Triple negative breast cancer cell lines had greater scavenger receptor B1 expression by quantitative polymerase chain reaction and Western blot versus controls. Fluorescent-labeled synthetic high-density lipoprotein uptake was scavenger receptor B1-mediated in vitro, and in vivo tumor uptake using IVIS imaging demonstrated significantly increased tumor radiant efficiency versus control. Inhibitory concentration₅₀ for withalongolide A 4,19,27-triacetate-treated cells with or without synthetic high-density lipoprotein encapsulation were 70-fold to 200-fold more potent than synthetic high-density lipoprotein alone. In triple negative breast cancer mouse xenografts, treatment with synthetic high-density lipoprotein withalongolide A 4,19,27-triacetate resulted in a 54% decrease in tumor volume compared with the control or with synthetic high-density lipoprotein alone.

CONCLUSION

The synthetic high-density lipoprotein withalongolide A 4,19,27-triacetate nanoconjugates are potent against triple negative breast cancers and show improved scavenger receptor B1-mediated targeting. Treatment with synthetic high-density lipoprotein-encapsulated withalongolide A 4,19,27-triacetate is able to significantly decrease the growth of tumor in mice compared with the control and has better efficacy than the current standard of care, warranting further evaluation as a novel therapeutic agent.

Bioinspired lipoproteins-mediated photothermia remodels tumor stroma to improve cancer cell accessibility of second nanoparticles

The tumor stromal microenvironments (TSM) including stromal cells and extracellular matrix (ECM) form an abominable barrier hampering nanoparticles accessibility to cancer cells, significantly compromising their antitumor effects. Herein, we report a bioinspired lipoprotein (bLP) that can induce efficient photothermia to remodel TSM and improve second bLP accessibility to cancer cells for antitumor therapy. The multiple stromal cells and ECM components in TSM are remarkably disrupted by bLP-mediated photothermal effects, which cause a 4.27-fold enhancement of second bLP accumulation in tumor, deep penetration in whole tumor mass and 27.0-fold increase of accessibility to cancer cells. Of note, this bLP-mediated TSM-remodeling to enhance cancer cell accessibility (TECA) strategy produces an eminent suppression of tumor growth and results in a 97.4% inhibition of lung metastasis, which is superior to the counterpart liposomes. The bLP-mediated TECA strategy provides deeper insights into enhancing nanoparticle accessibility to cancer cells for antitumor therapy.

The stromal cells and extracellular matrix hamper nanoparticle access to cancer cells and their anti-cancer efficacy. Here, the authors report a bioinspired lipoprotein (bLP) for photothermal remodelling of tumour stroma and show this to improve subsequent bLP accessibility to cancer cells.

The role of high-density lipoproteins in antitumor drug delivery

High-density lipoproteins (HDLs) are the smallest lipoprotein with the highest level of protein in their surface. The main role of HDLs are reverse transport of cholesterol from peripheral tissues to the liver. More recently, HDLs have been considered as a new drug delivery system because of their small size, proper surface properties, long circulation time, biocompatibility, biodegradability, and low immune stimulation. Delivery of anticancer drug to the tumor tissue is a major obstacle against successful chemotherapy, which is because of the toxicity and poor aqueous solubility of these drugs. Loading chemotherapeutic drugs in the lipid core of HDLs can overcome the aforementioned problems and increase the efficiency of drug delivery. In this review, we discuss the use of HDLs particles in drug delivery to the tumor tissue and explain some barriers and limitations that exist in the use of HDLs as an ideal delivery vehicle.

Identifying and targeting angiogenesis-related microRNAs in ovarian cancer

Current anti-angiogenic therapy for cancer is based mainly on inhibition of the vascular endothelial growth factor pathway. However, due to the transient and only modest benefit from such therapy, additional approaches are needed. Deregulation of microRNAs (miRNAs) has been demonstrated to be involved in tumor angiogenesis and offers opportunities for a new therapeutic approach. However, effective miRNA-delivery systems are needed for such approaches to be successful. In this study, miRNA profiling of patient data sets, along with in vitro and in vivo experiments, revealed that miR-204-5p could promote angiogenesis in ovarian tumors through THBS1. By binding with scavenger receptor class B type 1 (SCARB1), reconstituted high-density lipoprotein-nanoparticles (rHDL-NPs) were effective in delivering miR-204-5p inhibitor (miR-204-5p-inh) to tumor sites to suppress tumor growth. These results offer a new understanding of miR-204-5p in regulating tumor angiogenesis.

Membrane fusogenic high-density lipoprotein nanoparticles

Membrane fusion under mildly acidic pH occurs naturally during viral infection in cells and has been exploited in the field of nanoparticle-mediated drug delivery to circumvent endosomal entrapment of the cargo. Herein, we aimed to confer virus-like fusogenic activity to HDL in the form of a ca. 10-nm disc comprising a discoidal lipid bilayer and two copies of a lipid-binding protein at the edge. A series of HDL mutants were prepared with a mixture of three lipids and a cell-penetrating peptide (TAT, penetratin, or Arg8) fused to the protein. In a lipid-mixing assay with anionic liposomes at pH 5.5, one HDL mutant showed the fusogenic activity higher than known fusogenic liposomes. In live mammalian cells, this HDL mutant showed high plasma membrane-binding activity in the presence of serum independent of pH. In the absence of serum, a mildly acidic pH dependency for binding to the plasma membrane and the subsequent lipid mixing between them was observed for this mutant. We propose a novel strategy to develop HDL-based drug carriers by taking advantage of the HDL lipid/protein composite structure.

Sequential Targeting TGF-β Signaling and KRAS Mutation Increases Therapeutic Efficacy in Pancreatic Cancer

Pancreatic cancer is a highly aggressive malignancy that strongly resists extant treatments. The failure of existing therapies is majorly attributed to the tough tumor microenvironment (TME) limiting drug access and the undruggable targets of tumor cells. The formation of suppressive TME is regulated by transforming growth factor beta (TGF-β) signaling, while the poor response and short survival of almost 90% of pancreatic cancer patients results from the oncogenic KRAS mutation. Hence, simultaneously targeting both the TGF-β and KRAS pathways might dismantle the obstacles of pancreatic cancer therapy. Here, a novel sequential-targeting strategy is developed, in which antifibrotic fraxinellone-loaded CGKRK-modified nanoparticles (Frax-NP-CGKRK) are constructed to regulate TGF-β signaling and siRNA-loaded lipid-coated calcium phosphate (LCP) biomimetic nanoparticles (siKras-LCP-ApoE3) are applied to interfere with the oncogenic KRAS. Frax-NP-CGKRK successfully targets the tumor sites through the recognition of overexpressed heparan sulfate proteoglycan, reverses the activated cancer-associated fibroblasts (CAFs), attenuates the dense stroma barrier, and enhances tumor blood perfusion. Afterward, siKras-LCP-ApoE3 is efficiently internalized by the tumor cells through macropinocytosis and specifically silencing KRAS mutation. Compared with gemcitabine, this sequential-targeting strategy significantly elongates the lifespans of pancreatic tumor-bearing animals, hence providing a promising approach for pancreatic cancer therapy.

Atherosclerosis Treatment with Stimuli-Responsive Nanoagents: Recent Advances and Future Perspectives

Atherosclerosis is the root of approximately one-third of global mortalities. Nanotechnology exhibits splendid prospects to combat atherosclerosis at the molecular level by engineering smart nanoagents with versatile functionalizations. Significant advances in nanoengineering enable nanoagents to autonomously navigate in the bloodstream, escape from biological barriers, and assemble with their nanocohort at the targeted lesion. The assembly of nanoagents with endogenous and exogenous stimuli breaks down their shells, facilitates intracellular delivery, releases their cargo to kill the corrupt cells, and gives imaging reports. All these improvements pave the way toward personalized medicine for atherosclerosis. This review systematically summarizes the recent advances in stimuli-responsive nanoagents for atherosclerosis management and its progress in clinical trials.

Nanotherapeutics Engineered to Cross the Blood-Brain Barrier for Advanced Drug Delivery to the Central Nervous System

Drug delivery to the brain remains challenging mainly due to the blood-brain barrier (BBB) that regulates the entrance of substances to the brain. Advances in nanotechnology have enabled the engineering of nanomedicines for biomedical applications including enhanced drug delivery into the brain. In this review, we describe strategies of nanomedicines engineered to traverse the BBB and deliver therapeutic molecules to target brain sites. We highlight the representative applications with materials including polymers, lipids, and inorganic elements for brain drug delivery. We finalize this review with the current challenges and future perspective of nanotherapeutics for advanced drug delivery to the brain.

Rational Design of Photosynthesis-Inspired Nanomedicines

The sun is the most abundant source of energy on earth. Phototrophs have discovered clever strategies to harvest this light energy and convert it to chemical energy for biomass production. This is achieved in light-harvesting complexes, or antennas, that funnel the exciton energy into the reaction centers. Antennas contain an array of chlorophylls, linear tetrapyrroles, and carotenoid pigments spatially controlled by neighboring proteins. This fine-tuned regulation of protein-pigment arrangements is crucial for survival in the conditions of both excess and extreme light deficit. Photomedicine and photodiagnosis have long been utilizing naturally derived and synthetic monomer dyes for imaging, photodynamic and photothermal therapy; however, the precise regulation of damage inflicted by these therapies requires more complex architectures. In this Account, we discuss how two mechanisms found in photosynthetic systems, photoprotection and light harvesting, have inspired scientists to create nanomedicines for more effective and precise phototherapies. Researchers have been recapitulating natural photoprotection mechanisms by utilizing carotenoids and other quencher molecules toward the design of photodynamic molecular beacons (PDT beacons) for disease-specific photoactivation. We highlight the seminal studies describing peptide-linked porphyrin-carotenoid PDT beacons, which are locally activated by a disease-specific enzyme. Examples of more advanced constructs include tumor-specific mRNA-activatable and polyionic cell-penetrating PDT beacons. An alternative approach toward harnessing photosynthetic processes for biomedical applications includes the design of various nanostructures. This Account will primarily focus on organic lipid-based micro- and nanoparticles. The phenomenon of nonphotochemical quenching, or excess energy release in the form of heat, has been widely explored in the context of porphyrin-containing nanomedicines. These quenched nanostructures can be implemented toward photoacoustic imaging and photothermal therapy. Upon nanostructure disruption, as a result of tissue accumulation and subsequent cell uptake, activatable fluorescence imaging and photodynamic therapy can be achieved. Alternatively, processes found in nature for light harvesting under dim conditions, such as in the deep sea, can be harnessed to maximize light absorption within the tissue. Specifically, high-ordered dye aggregation that results in a bathochromic shift and increased absorption has been exploited for the collection of more light with longer wavelengths, characterized by maximum tissue penetration. Overall, the profound understanding of photosynthetic systems combined with rapid development of nanotechnology has yielded a unique field of nature-inspired photomedicine, which holds promise toward more precise and effective phototherapies.

Promoting the Delivery of Nanoparticles to Atherosclerotic Plaques by DNA Coating

Many nanoparticle-based carriers to atherosclerotic plaques contain peptides, lipoproteins, and sugars, yet the application of DNA-based nanostructures for targeting plaques remains infrequent. In this work, we demonstrate that DNA-coated superparamagnetic iron oxide nanoparticles (DNA-SPIONs), prepared by attaching DNA oligonucleotides to poly(ethylene glycol)-coated SPIONs (PEG-SPIONs), effectively accumulate in the macrophages of atherosclerotic plaques following an intravenous injection into apolipoprotein E knockout (ApoE^-/-) mice. DNA-SPIONs enter RAW 264.7 macrophages faster and more abundantly than PEG-SPIONs. DNA-SPIONs mostly enter RAW 264.7 cells by engaging Class A scavenger receptors (SR-A) and lipid rafts and traffic inside the cell along the endolysosomal pathway. ABS-SPIONs, nanoparticles with a similarly polyanionic surface charge as DNA-SPIONs but bearing abasic oligonucleotides also effectively bind to SR-A and enter RAW 264.7 cells. Near-infrared fluorescence imaging reveals evident localization of DNA-SPIONs in the heart and aorta 30 min post-injection. Aortic iron content for DNA-SPIONs climbs to the peak (∼60% ID/g) 2 h post-injection (accompanied by profuse accumulation in the aortic root), but it takes 8 h for PEG-SPIONs to reach the peak aortic amount (∼44% ID/g). ABS-SPIONs do not appreciably accumulate in the aorta or aortic root, suggesting that the DNA coating (not the surface charge) dictates in vivo plaque accumulation. Flow cytometry analysis reveals more pronounced uptake of DNA-SPIONs by hepatic endothelial cells, splenic macrophages and dendritic cells, and aortic M2 macrophages (the cell type with the highest uptake in the aorta) than PEG-SPIONs. In summary, coating nanoparticles with DNA is an effective strategy of promoting their systemic delivery to atherosclerotic plaques.

High-Density Lipoprotein-Mimicking Nanodiscs for Chemo-immunotherapy against Glioblastoma Multiforme

Glioblastoma multiforme (GBM) is an aggressive primary brain tumor, for which there is no cure. Treatment effectiveness for GBM has been limited due to tumor heterogeneity, an immunosuppressive tumor microenvironment (TME), and the presence of the blood-brain barrier, which hampers the transport of chemotherapeutic compounds to the central nervous system (CNS). High-density lipoprotein (HDL)-mimicking nanodiscs hold considerable promise to achieve delivery of bioactive compounds into tumors. Herein, we tested the ability of synthetic HDL nanodiscs to deliver chemotherapeutic agents to the GBM microenvironment and elicit tumor regression. To this end, we developed chemo-immunotherapy delivery vehicles based on sHDL nanodiscs loaded with CpG, a Toll-like receptor 9 (TLR9) agonist, together with docetaxel (DTX), a chemotherapeutic agent, for targeting GBM. Our data show that delivery of DTX-sHDL-CpG nanodiscs into the tumor mass elicited tumor regression and antitumor CD8+ T cell responses in the brain TME. We did not observe any overt off-target side effects. Furthermore, the combination of DTX-sHDL-CpG treatment with radiation (IR), which is the standard of care for GBM, resulted in tumor regression and long-term survival in 80% of GBM-bearing animals. Mice remained tumor-free upon tumor cell rechallenge in the contralateral hemisphere, indicating the development of anti-GBM immunological memory. Collectively, these data indicate that sHDL nanodiscs constitute an effective drug delivery platform for the treatment of GBM, resulting in tumor regression, long-term survival, and immunological memory when used in combination with IR. The proposed delivery platform has significant potential for clinical translation.

In-Situ imaging detection of cell membrane and intracellular cholesterol via cascade reactions

Herein, an effective membrane-to-intracellular cholesterol detection strategy was designed based on cascade reactions. A biochip array was firstly fabricated by consecutively immobilizing luminol modified gold nanoparticles (Au@luminol), soybean peroxidase (SBP) and cholesterol oxidase (ChoX) on the cellulose acetate (CA) membrane functionalized home-made micropore array. When cholesterol existed, it was oxidized by ChoX generating H₂O₂, which further triggered the CL reaction under the SBP catalysis, the CL signals were collected by a charge-coupled device (CCD). The proposed strategy exhibited a wide linear range from 0.12 μM to 1000 μM and relatively low detection limit (LOD) of 0.08 μM. Furthermore，it could be used to in-situ detect membrane cholesterol and intracelluar esterified cholesterol in HepG2 cells. After activated HepG2 cells were added to the modified biochip, membrane cholesterol was detected directly. Intracelluar esterified cholesterol was detected through the introduction of triton X-100 and cholesteryl esterase (ChoE). Additionally, the cholesterol content in cells was changed after stimulated by drugs, such as apolipoprotein A-I (ApoA-I), pitavastatin or probucol. The correlation of the CL signal with the amount of cholesterol confirmed that our strategy was feasible to simultaneously detect membrane and intracellular cholesterol at different cellular states. The proposed strategy exhibited excellent sensitivity, selectivity, stability, and reproducibility in a simple, cheap way, which opened a new door for studying clinic treatment of the cholesterol-related diseases.