Proteomimetic Polymers Trigger Potent Antigen-Specific T Cell Responses to Limit Tumor Growth

Elicitation of effective antitumor immunity following cancer vaccination requires the selective activation of distinct effector cell populations and pathways. Here we report a therapeutic approach for generating potent T cell responses using a modular vaccination platform technology capable of inducing directed immune activation, termed the Protein-like Polymer (PLP). PLPs demonstrate increased proteolytic resistance, high uptake by antigen-presenting cells (APCs), and enhanced payload-specific T cell responses. Key design parameters, namely payload linkage chemistry, degree of polymerization, and side chain composition, were varied to optimize vaccine formulations. Linking antigens to the polymer backbone using an intracellularly cleaved disulfide bond copolymerized with a diluent amount of oligo(ethylene glycol) (OEG) resulted in the highest payload-specific potentiation of antigen immunogenicity, enhancing dendritic cell (DC) activation and antigen-specific T cell responses. Vaccination with PLPs carrying either gp100, E7, or adpgk peptides significantly increased the survival of mice inoculated with B16F10, TC-1, or MC38 tumors, respectively, without the need for adjuvants. B16F10-bearing mice immunized with gp100-carrying PLPs showed increased antitumor CD8+ T cell immunity, suppressed tumor growth, and treatment synergy when paired with two distinct stimulator of interferon gene (STING) agonists. In a human papillomavirus-associated TC-1 model, combination therapy with PLP and 2'3'-cGAMP resulted in 40% of mice completely eliminating implanted tumors while also displaying curative protection from rechallenge, consistent with conferment of lasting immunological memory. Finally, PLPs can be stored long-term in a lyophilized state and are highly tunable, underscoring the unique properties of the platform for use as generalizable cancer vaccines.

Enhancing Endosomal Escape and Gene Regulation Activity for Spherical Nucleic Acids

The therapeutic potential of small interfering RNAs (siRNAs) is limited by their poor stability and low cellular uptake. When formulated as spherical nucleic acids (SNAs), siRNAs are resistant to nuclease degradation and enter cells without transfection agents with enhanced activity compared to their linear counterparts; however, the gene silencing activity of SNAs is limited by endosomal entrapment, a problem that impacts many siRNA-based nanoparticle constructs. To increase cytosolic delivery, SNAs are formulated using calcium chloride (CaCl2 ) instead of the conventionally used sodium chloride (NaCl). The divalent calcium (Ca2+ ) ions remain associated with the multivalent SNA and have a higher affinity for SNAs compared to their linear counterparts. Importantly, confocal microscopy studies show a 22% decrease in the accumulation of CaCl2 -salted SNAs within the late endosomes compared to NaCl-salted SNAs, indicating increased cytosolic delivery. Consistent with this finding, CaCl2 -salted SNAs comprised of siRNA and antisense DNA all exhibit enhanced gene silencing activity (up to 20-fold), compared to NaCl-salted SNAs regardless of sequence or cell line (U87-MG and SK-OV-3) studied. Moreover, CaCl2 -salted SNA-based forced intercalation probes show improved cytosolic mRNA detection.

Tuning DNA Dissociation from Spherical Nucleic Acids for Enhanced Immunostimulation

The stability of the core can significantly impact the therapeutic effectiveness of liposome-based drugs. While the spherical nucleic acid (SNA) architecture has elevated liposomal stability to increase therapeutic efficacy, the chemistry used to anchor the DNA to the liposome core is an underexplored design parameter with a potentially widespread biological impact. Herein, we explore the impact of SNA anchoring chemistry on immunotherapeutic function by systematically studying the importance of hydrophobic dodecane anchoring groups in attaching DNA strands to the liposome core. By deliberately modulating the size of the oligomer that defines the anchor, a library of structures has been established. These structures, combined with in vitro and in vivo immune stimulation analyses, elucidate the relationships between and importance of anchoring strength and dissociation of DNA from the SNA shell on its biological properties. Importantly, the most stable dodecane anchor, (C12)9, is superior to the n = 4-8 and 10 structures and quadruples immune stimulation compared to conventional cholesterol-anchored SNAs. When the OVA1 peptide antigen is encapsulated by the (C12)9 SNA and used as a therapeutic vaccine in an E.G7-OVA tumor model, 50% of the mice survived the initial tumor, and all of those survived tumor rechallenge. Importantly, the strong innate immune stimulation does not cause a cytokine storm compared to linear immunostimulatory DNA. Moreover, a (C12)9 SNA that encapsulates a peptide targeting SARS-CoV-2 generates a robust T cell response; T cells raised from SNA treatment kill >40% of target cells pulsed with the same peptide and ca. 45% of target cells expressing the entire spike protein. This work highlights the importance of using anchor chemistry to elevate SNA stability to achieve more potent and safer immunotherapeutics in the context of both cancer and infectious disease.

Transforming Hairpin-like siRNA-Based Spherical Nucleic Acids into Biocompatible Constructs

The design and synthesis of hairpin-like small interfering RNA spherical nucleic acids (siRNA-SNAs) based upon biocompatible liposome nanoparticle cores are described. The constructs were characterized by gel electrophoresis, dynamic light scattering, and OliGreen-based oligonucleotide quantification. These siRNA-SNA nanoconstructs enter cells 20-times more efficiently than linear siRNA in as little as 4 h, while exhibiting a 4-fold reduction in cytotoxicity compared with conventional siRNA-SNAs composed of gold nanoparticle cores. Importantly, these siRNA-SNA constructs effectively inhibit angiogenesis in vitro by silencing vascular endothelial growth factor, a key mediator of angiogenesis in a multitude of diseases, in human umbilical vein endothelial cells. This work shows how hairpin architectures can be chemically incorporated into biocompatible SNAs in a way that retains advantageous SNA properties and maximizes gene regulation capabilities.

Multi-antigen spherical nucleic acid cancer vaccines

Cancer vaccines must activate multiple immune cell types to be effective against aggressive tumours. Here we report the impact of the structural presentation of two antigenic peptides on immune responses at the transcriptomic, cellular and organismal levels. We used spherical nucleic acid (SNA) nanoparticles to investigate how the spatial distribution and placement of two antigen classes affect antigen processing, cytokine production and the induction of memory. Compared with single-antigen SNAs, a single dual-antigen SNA elicited a 30% increase in antigen-specific T cell activation and a two-fold increase in T cell proliferation. Antigen placement within dual-antigen SNAs altered the gene expression of T cells and tumour growth. Specifically, dual-antigen SNAs encapsulating antigens targeting helper T cells and with externally conjugated antigens targeting cytotoxic T cells elevated antitumour genetic pathways, stalling lymphoma tumours in mice. Additionally, when combined with the checkpoint inhibitor anti-programmed-cell-death protein-1 in a mouse model of melanoma, a specific antigen arrangement within dual-antigen SNAs suppressed tumour growth and increased the levels of circulating memory T cells. The structural design of multi-antigen vaccines substantially impacts their efficacy.

CRISPR Spherical Nucleic Acids

The use of CRISPR/Cas9 systems in genome editing has been limited by the inability to efficiently deliver the key editing components to and across tissues and cell membranes, respectively. Spherical nucleic acids (SNAs) are nanostructures that provide privileged access to both but have yet to be explored as a means of facilitating gene editing. Herein, a new class of CRISPR SNAs are designed and evaluated in the context of genome editing. Specifically, Cas9 ProSNAs comprised of Cas9 cores densely modified with DNA on their exteriors and preloaded with single-guide RNA were synthesized and evaluated for their genome editing capabilities in the context of multiple cell lines. The radial orientation of the DNA on the Cas9 protein surface enhances cellular uptake, without the need for electroporation or transfection agents. In addition, the Cas9 proteins defining the cores of the ProSNAs were fused with GALA peptides on their N-termini and nuclear localization signals on their C-termini to facilitate endosomal escape and maximize nuclear localization and editing efficiency, respectively. These constructs were stable against protease digestion under conditions that fully degrade the Cas9 protein, when not transformed into an SNA, and used to achieve genome editing efficiency between 32 and 47%. Taken together, these novel constructs and advances point toward a way of significantly broadening the scope of use and impact of CRISPR-Cas9 genome editing systems.

Rational Vaccinology: Harnessing Nanoscale Chemical Design for Cancer Immunotherapy

Cancer immunotherapy is a powerful treatment strategy that mobilizes the immune system to fight disease. Cancer vaccination is one form of cancer immunotherapy, where spatiotemporal control of the delivery of tumor-specific antigens, adjuvants, and/or cytokines has been key to successfully activating the immune system. Nanoscale materials that take advantage of chemistry to control the nanoscale structural arrangement, composition, and release of immunostimulatory components have shown significant promise in this regard. In this Outlook, we examine how the nanoscale structure, chemistry, and composition of immunostimulatory compounds can be modulated to maximize immune response and mitigate off-target effects, focusing on spherical nucleic acids as a model system. Furthermore, we emphasize how chemistry and materials science are driving the rational design and development of next-generation cancer vaccines. Finally, we identify gaps in the field that should be addressed moving forward and outline future directions to galvanize researchers from multiple disciplines to help realize the full potential of this form of cancer immunotherapy through chemistry and rational vaccinology.

Spherical nucleic acids as an infectious disease vaccine platform

SignificanceUsing SARS-CoV-2 as a relevant case study for infectious disease, we investigate the structure-function relationships that dictate antiviral spherical nucleic acid (SNA) vaccine efficacy. We show that the SNA architecture can be rapidly employed to target COVID-19 through incorporation of the receptor-binding domain, and that the resulting vaccine potently activates human cells in vitro and mice in vivo. Furthermore, when challenged with a lethal viral infection, only mice treated with the SNA vaccine survived. Taken together, this work underscores the importance of rational vaccine design for infectious disease to yield vaccines that elicit more potent immune responses to effectively fight disease.

LDL-Based Lipid Nanoparticle Derived for Blood Plasma Accumulates Preferentially in Atherosclerotic Plaque

Apolipoprotein-based drug delivery is a promising approach to develop safe nanoparticles capable of targeted drug delivery for various diseases. In this work, we have synthesized a lipid-based nanoparticle (NPs) that we have called “Aposomes” presenting native apolipoprotein B-100 (apoB-100), the primary protein present in Low-Density Lipoproteins (LDL) on its surface. The aposomes were synthesized from LDL isolated from blood plasma using a microfluidic approach. The synthesized aposomes had a diameter of 91 ± 4 nm and a neutral surface charge of 0.7 mV ± mV. Protein analysis using western blot and flow cytometry confirmed the presence of apoB-100 on the nanoparticle’s surface. Furthermore, Aposomes retained liposomes’ drug loading capabilities, demonstrating a prolonged release curve with ∼80% cargo release at 4 hours. Considering the natural tropism of LDL towards the atherosclerotic plaques, we evaluated the biological properties of aposomes in a mouse model of advanced atherosclerosis. We observed a ∼20-fold increase in targeting of plaques when comparing aposomes to control liposomes. Additionally, aposomes presented a favorable biocompatibility profile that showed no deviation from typical values in liver toxicity markers (i.e., LDH, ALT, AST, Cholesterol). The results of this study demonstrate the possibilities of using apolipoprotein-based approaches to create nanoparticles with active targeting capabilities and could be the basis for future cardiovascular therapies.

Spherical Nucleic Acid Vaccine Structure Markedly Influences Adaptive Immune Responses of Clinically Utilized Prostate Cancer Targets

Cancer vaccines, which activate the immune system against a target antigen, are attractive for prostate cancer, where multiple upregulated protein targets are identified. However, many clinical trials implementing peptides targeting these proteins have yielded suboptimal results. Using spherical nucleic acids (SNAs), we explore how precise architectural control of vaccine components can activate a robust antigen-specific immune response in comparison to clinical formulations of the same targets. The SNA vaccines incorporate peptides for human prostate-specific membrane antigen (PSMA) or T-cell receptor γ alternate reading frame protein (TARP) into an optimized architecture, resulting in high rates of immune activation and cytolytic ability in humanized mice and human peripheral blood mononuclear cells (hPBMCs). Specifically, administered SNAs elevate the production and secretion of cytokines and increase polyfunctional cytotoxic T cells and effector memory. Importantly, T cells raised from immunized mice potently kill targets, including clinically relevant cells expressing the whole PSMA protein. Treatment of hPBMCs increases costimulatory markers and cytolytically active T cells. This work demonstrates the importance of vaccine structure and its ability to reformulate and elevate clinical targets. Moreover, it encourages the field to reinvestigate ineffective peptide targets and repackage them into optimally structured vaccines to harness antigen potency and enhance clinical outcomes.

DNA Dendrons as Agents for Intracellular Delivery

Herein, a method for synthesizing and utilizing DNA dendrons to deliver biomolecules to living cells is reported. Inspired by high-density nucleic acid nanostructures, such as spherical nucleic acids, we hypothesized that small clusters of nucleic acids, in the form of DNA dendrons, could be conjugated to biomolecules and facilitate their cellular uptake. We show that DNA dendrons are internalized by 90% of dendritic cells after just 1 h of treatment, with a >20-fold increase in DNA delivery per cell compared with their linear counterparts. This effect is due to the interaction of the DNA dendrons with scavenger receptor-A on cell surfaces, which results in their rapid endocytosis. Moreover, when conjugated to peptides at a single attachment site, dendrons enhance the cellular delivery and activity of both the model ovalbumin 1 peptide and the therapeutically relevant thymosin alpha 1 peptide. These findings show that high-density, multivalent DNA ligands play a significant role in dictating cellular uptake of biomolecules and consequently will expand the scope of deliverable biomolecules to cells. Indeed, DNA dendrons are poised to become agents for the cellular delivery of many molecular and nanoscale materials.

Lipid Nanoparticle Spherical Nucleic Acids for Intracellular DNA and RNA Delivery

Lipid nanoparticle SNAs (LNP-SNAs) have been synthesized for the delivery of DNA and RNA to targets in the cytoplasm of cells. Both the composition of the LNP core and surface-presented DNA sequences contribute to LNP-SNA activity. G-rich sequences enhance the activity of LNP-SNAs compared to T-rich sequences. In the LNP core, increased cholesterol content leads to greater activity. Optimized LNP-SNA candidates reduce the siRNA concentration required to silence mRNA by 2 orders of magnitude compared to liposome-based SNAs. In addition, the LNP-SNA architectures alter biodistribution and efficacy profiles in mice. For example, mRNA within LNP-SNAs injected intravenously is primarily expressed in the spleen, while mRNA encapsulated by LNPs (no DNA on the surface) was expressed primarily in the liver with a relatively small amount in the spleen. These data show that the activity and biodistribution of LNP-SNA architectures are different from those of conventional liposomal SNAs and therefore potentially can be used to target tissues.

Bioinspired Extracellular Vesicles: Lessons Learned From Nature for Biomedicine and Bioengineering

Efficient communication is essential in all layers of the biological chain. Cells exchange information using a variety of signaling moieties, such as small molecules, proteins, and nucleic acids. Cells carefully package these messages into lipid complexes, collectively named extracellular vesicles (EVs). In this work, we discuss the nature of these cell carriers, categorize them by their origin, explore their role in the homeostasis of healthy tissues, and examine how they regulate the pathophysiology of several diseases. This review will also address the limitations of using EVs for clinical applications and discuss novel methods to engineer nanoparticles to mimic the structure, function, and features of EVs. Using lessons learned from nature and understanding how cells use EVs to communicate across distant sites, we can develop a better understanding of how to tailor the fundamental features of drug delivery carriers to encapsulate various cargos and target specific sites for biomedicine and bioengineering.

Endosomal Escape of Polymer-Coated Silica Nanoparticles in Endothelial Cells

Current investigations into hazardous nanoparticles (i.e., nanotoxicology) aim to understand the working mechanisms that drive toxicity. This understanding has been used to predict the biological impact of the nanocarriers as a function of their synthesis, material composition, and physicochemical characteristics. It is particularly critical to characterize the events that immediately follow cell stress resulting from nanoparticle internalization. While reactive oxygen species and activation of autophagy are universally recognized as mechanisms of nanotoxicity, the progression of these phenomena during cell recovery has yet to be comprehensively evaluated. Herein, primary human endothelial cells are exposed to controlled concentrations of polymer-functionalized silica nanoparticles to induce lysosomal damage and achieve cytosolic delivery. In this model, the recovery of cell functions lost following endosomal escape is primarily represented by changes in cell distribution and the subsequent partitioning of particles into dividing cells. Furthermore, multilamellar bodies are found to accumulate around the particles, demonstrating progressive endosomal escape. This work provides a set of biological parameters that can be used to assess cell stress related to nanoparticle exposure and the subsequent recovery of cell processes as a function of endosomal escape.

Cell Membrane-Based Biomimetic Nanoparticles and the Immune System: Immunomodulatory Interactions to Therapeutic Applications

Nanoparticle-based drug delivery systems have been synthesized from a wide array of materials. The therapeutic success of these platforms hinges upon their ability to favorably interact with the biological environment (both systemically and locally) and recognize the diseased target tissue. The immune system, composed of a highly coordinated organization of cells trained to recognize foreign bodies, represents a key mediator of these interactions. Although components of this system may act as a barrier to nanoparticle (NP) delivery, the immune system can also be exploited to target and trigger signaling cues that facilitate the therapeutic response stemming from systemic administration of NPs. The nano-bio interface represents the key facilitator of this communication exchange, where the surface properties of NPs govern their in vivo fate. Cell membrane-based biomimetic nanoparticles have emerged as one approach to achieve targeted drug delivery by actively engaging and communicating with the biological milieu. In this review, we will highlight the relationship between these biomimetic nanoparticles and the immune system, emphasizing the role of tuning the nano-bio interface in the immunomodulation of diseases. We will also discuss the therapeutic applications of this approach with biomimetic nanoparticles, focusing on specific diseases ranging from cancer to infectious diseases. Lastly, we will provide a critical evaluation on the current state of this field of cell membrane-based biomimetic nanoparticles and its future directions in immune-based therapy.

Electrospun anti-inflammatory patch loaded with essential oils for wound healing

Wound healing is a complex process that consists of three overlapping phases: inflammation, proliferation, and remodeling. A bacterial infection can increase inflammation and delay this process. Microorganisms are closely related to the innate immune system, such as macrophages and neutrophils, as they can start an inflammatory cascade. Essential oils play an important role in the inhibition and prevention of bacterial growth due to their ability to reduce antimicrobial resistance. The possibility to find a strategy that combines antimicrobial and anti-inflammatory properties is particularly appealing for wound healing. In this work, we showcase a variety of patches based on electrospun polycaprolactone (PCL) nanofibers loaded with natural compounds derived from essential oils, such as thymol (THY) and tyrosol (TYR), to achieve reduced inflammation. In addition, we compared the effect these essential oils have on activated macrophages when incorporated into the PCL patch. Specifically, we demonstrate that PCL-THY resulted in more efficient down-regulation of pro-inflammatory genes related to the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κb) pathway when compared to PCL-TYR and the combination patch containing TYR and THY (i.e., PCL-TYR-THY). Furthermore, PCL-THY displayed low affinity for cell attachment, which may hinder wound adherence and integration. Overall, our results indicate that THY-loaded patches could serve as promising candidates for the fabrication of dressings that incorporate bactericidal and anti-inflammatory properties while simultaneously avoiding the limitations of traditional antibiotic-loaded devices.

Exosome-like Nanovectors for Drug Delivery in Cancer

Cancer treatment still represents a formidable challenge, despite substantial advancements in available therapies being made over the past decade. One major issue is poor therapeutic efficacy due to lack of specificity and low bioavailability. The progress of nanotechnology and the development of a variety of nanoplatforms have had a significant impact in improving the therapeutic outcome of chemotherapeutics. Nanoparticles can overcome various biological barriers and localize at tumor site, while simultaneously protecting a therapeutic cargo and increasing its circulation time. Despite this, due to their synthetic origin, nanoparticles are often detected by the immune system and preferentially sequestered by filtering organs. Exosomes have recently been investigated as suitable substitutes for the shortcomings of nanoparticles due to their biological compatibility and particularly small size (i.e., 30-150 nm). In addition, exosomes have been found to play important roles in cell communication, acting as natural carriers of biological cargoes throughout the body. This review aims to highlight the use of exosomes as drug delivery vehicles for cancer and showcases the various attempts used to exploit exosomes with a focus on the delivery of chemotherapeutics and nucleic acids.

Cell membrane protein functionalization of nanoparticles as a new tumor-targeting strategy

Nanoparticles have seen considerable popularity as effective tools for drug delivery. However, non-specific targeting continues to remain a challenge. Recently, biomimetic nanoparticles have emerged as an innovative solution that exploits biologically-derived components to improve therapeutic potential. Specifically, cell membrane proteins extracted from various cells (i.e., leukocytes, erythrocytes, platelets, mesenchymal stem cells, cancer) have shown considerable promise in bestowing nanoparticles with increased circulation and targeting efficacy. Traditional nanoparticles can be detected and removed by the immune system which significantly hinders their clinical success. Biomimicry has been proposed as a promising approach to overcome these limitations. In this review, we highlight the current trends in biomimetic nanoparticles and describe how they are being used to increase their chemotherapeutic effect in cancer treatment.

Cell membrane protein functionalization of nanoparticles as a new tumor-targeting strategy

Nanoparticles have seen considerable popularity as effective tools for drug delivery. However, non-specific targeting continues to remain a challenge. Recently, biomimetic nanoparticles have emerged as an innovative solution that exploits biologically-derived components to improve therapeutic potential. Specifically, cell membrane proteins extracted from various cells (i.e., leukocytes, erythrocytes, platelets, mesenchymal stem cells, cancer) have shown considerable promise in bestowing nanoparticles with increased circulation and targeting efficacy. Traditional nanoparticles can be detected and removed by the immune system which significantly hinders their clinical success. Biomimicry has been proposed as a promising approach to overcome these limitations. In this review, we highlight the current trends in biomimetic nanoparticles and describe how they are being used to increase their chemotherapeutic effect in cancer treatment.

Electrospun Patch Functionalized with Nanoparticles Allows for Spatiotemporal Release of VEGF and PDGF-BB Promoting In Vivo Neovascularization

The use of nanomaterials as carriers for the delivery of growth factors has been applied to a multitude of applications in tissue engineering. However, issues of toxicity, stability, and systemic effects of these platforms have yet to be fully understood, especially for cardiovascular applications. Here, we proposed a delivery system composed of poly(dl-lactide- co-glycolide) acid (PLGA) and porous silica nanoparticles (pSi) to deliver vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF). The tight spatiotemporal release of these two proteins has been proven to promote neovascularization. In order to minimize tissue toxicity, localize the release, and maintain a stable platform, we conjugated two formulations of PLGA-pSi to electrospun (ES) gelatin to create a combined ES patch releasing both PDGF and VEGF. When compared to freely dispersed particles, the ES patch cultured in vitro with neonatal cardiac cells had significantly less particle internalization (2.0 ± 1.3%) compared to free PLGA-pSi (21.5 ± 6.1) or pSi (28.7 ± 2.5) groups. Internalization was positively correlated to late-stage apoptosis with PLGA-pSi and pSi groups having increased apoptosis compared to the untreated group. When implanted subcutaneously, the ES patch was shown to have greater neovascularization than controls evidenced by increased expression of α-SMA and CD31 after 21 days. Quantitative reverse transcription-polymerase chain reaction results support increased angiogenesis by the upregulation of VEGFA, VEGFR2, vWF, and COL3A1, exhibiting a synergistic effect with the release of VEGF-A164 and PDGF-BB after 21 days in vivo. The results of this study proved that the ES patch reduced cellular toxicity and may be tailored to have a dual release of growth factors promoting localized neovascularization.

Trends towards Biomimicry in Theranostics

Over the years, imaging and therapeutic modalities have seen considerable progress as a result of advances in nanotechnology. Theranostics, or the marrying of diagnostics and therapy, has increasingly been employing nano-based approaches to treat cancer. While first-generation nanoparticles offered considerable promise in the imaging and treatment of cancer, toxicity and non-specific distribution hindered their true potential. More recently, multistage nanovectors have been strategically designed to shield and carry a payload to its intended site. However, detection by the immune system and sequestration by filtration organs (i.e., liver and spleen) remains a major obstacle. In an effort to circumvent these biological barriers, recent trends have taken inspiration from biology. These bioinspired approaches often involve the use of biologically-derived cellular components in the design and fabrication of biomimetic nanoparticles. In this review, we provide insight into early nanoparticles and how they have steadily evolved to include bioinspired approaches to increase their theranostic potential.

Design and Development of Biomimetic Nanovesicles Using a Microfluidic Approach

The advancement of nanotechnology toward more sophisticated bioinspired approaches has highlighted the gap between the advantages of biomimetic and biohybrid platforms and the availability of manufacturing processes to scale up their production. Though the advantages of transferring biological features from cells to synthetic nanoparticles for drug delivery purposes have recently been reported, a standardizable, batch-to-batch consistent, scalable, and high-throughput assembly method is required to further develop these platforms. Microfluidics has offered a robust tool for the controlled synthesis of nanoparticles in a versatile and reproducible approach. In this study, the incorporation of membrane proteins within the bilayer of biomimetic nanovesicles (leukosomes) using a microfluidic-based platform is demonstrated. The physical, pharmaceutical, and biological properties of microfluidic-formulated leukosomes (called NA-Leuko) are characterized. NA-Leuko show extended shelf life and retention of the biological functions of donor cells (i.e., macrophage avoidance and targeting of inflamed vasculature). The NA approach represents a universal, versatile, robust, and scalable tool, which is extensively used for the assembly of lipid nanoparticles and adapted here for the manufacturing of biomimetic nanovesicles.

Biomimetic nanoparticles with enhanced affinity towards activated endothelium as versatile tools for theranostic drug delivery

Activation of the vascular endothelium is characterized by increased expression of vascular adhesion molecules and chemokines. This activation occurs early in the progression of several diseases and triggers the recruitment of leukocytes. Inspired by the tropism of leukocytes, we investigated leukocyte-based biomimetic nanoparticles (i.e., leukosomes) as a novel theranostic platform for inflammatory diseases.

Methods: Leukosomes were assembled by combining phospholipids and membrane proteins from leukocytes. For imaging applications, phospholipids modified with rhodamine and gadolinium were used. Leukosomes incubated with antibodies blocking lymphocyte function-associated antigen 1 (LFA-1) and CD45 were administered to explore their roles in targeting inflammation. In addition, relaxometric assessment of NPs was evaluated.

Results: Liposomes and leukosomes were both spherical in shape with sizes ranging from 140-170 nm. Both NPs successfully integrated 8 and 13 µg of rhodamine and gadolinium, respectively, and demonstrated less than 4% variation in physicochemical features. Leukosomes demonstrated a 16-fold increase in breast tumor accumulation relative to liposomes. Furthermore, quantification of leukosomes in tumor vessels demonstrated a 4.5-fold increase in vessel lumens and a 14-fold increase in vessel walls. Investigating the targeting mechanism of action revealed that blockage of LFA-1 on leukosomes resulted in a 95% decrease in tumor accumulation. Whereas blockage of CD45 yielded a 60% decrease in targeting and significant increases in liver and spleen accumulation. In addition, when administered in mice with atherosclerotic plaques, leukosomes exhibited a 4-fold increase in the targeting of inflammatory vascular lesions. Lastly, relaxometric assessment of NPs demonstrated that the incorporation of membrane proteins into leukosomes did not impact the r₁ and r₂ relaxivities of the NPs, demonstrating 6 and 30 mM^-1s^-1, respectively.

Conclusion: Our study demonstrates the ability of leukosomes to target activated vasculature and exhibit superior accumulation in tumors and vascular lesions. The versatility of the phospholipid backbone within leukosomes permits the incorporation of various contrast agents. Furthermore, leukosomes can potentially be loaded with therapeutics possessing diverse physical properties and thus warrant further investigation toward the development of powerful theranostic agents.

Inflammation and Cancer: In Medio Stat Nano

Cancer treatment still remains a challenge due to the several limitations of currently used chemotherapeutics, such as their poor pharmacokinetics, unfavorable chemical properties, as well as inability to discriminate between healthy and diseased tissue. Nanotechnology offered potent tools to overcome these limitations. Drug encapsulation within a delivery system permitted i) to protect the payload from enzymatic degradation/ inactivation in the blood stream, ii) to improve the physicochemical properties of poorly water-soluble drugs, like paclitaxel, and iii) to selectively deliver chemotherapeutics to the cancer lesions, thus reducing the off-target toxicity, and promoting the intracellular internalization. To accomplish this purpose, several strategies have been developed, based on biological and physical changes happening locally and systemically as a consequence of tumorigenesis. Here, we will discuss the role of inflammation in the different steps of tumor development and the strategies based on the use of nanoparticles that exploit the inflammatory pathways in order to selectively target the tumor-associated microenvironment for therapeutic and diagnostic purposes.

Bio-inspired engineering of cell- and virus-like nanoparticles for drug delivery

The engineering of future generations of nanodelivery systems aims at the creation of multifunctional vectors endowed with improved circulation, enhanced targeting and responsiveness to the biological environment. Moving past purely bio-inert systems, researchers have begun to create nanoparticles capable of proactively interacting with the biology of the body. Nature offers a wide-range of sources of inspiration for the synthesis of more effective drug delivery platforms. Because the nano-bio-interface is the key driver of nanoparticle behavior and function, the modification of nanoparticles' surfaces allows the transfer of biological properties to synthetic carriers by imparting them with a biological identity. Modulation of these surface characteristics governs nanoparticle interactions with the biological barriers they encounter. Building off these observations, we provide here an overview of virus- and cell-derived biomimetic delivery systems that combine the intrinsic hallmarks of biological membranes with the delivery capabilities of synthetic carriers. We describe the features and properties of biomimetic delivery systems, recapitulating the distinctive traits and functions of viruses, exosomes, platelets, red and white blood cells. By mimicking these biological entities, we will learn how to more efficiently interact with the human body and refine our ability to negotiate with the biological barriers that impair the therapeutic efficacy of nanoparticles.

Hyaluronic acid coatings as a simple and efficient approach to improve MSC homing toward the site of inflammation

A major challenge in regenerative medicine is to improve therapeutic cells' delivery and targeting using an efficient and simple protocol. Mesenchymal stem cells (MSC) are currently employed for the treatment of inflammatory-based diseases, due to their powerful immunosoppressive potential. Here we report a simple and versatile method to transiently overexpress the hyaluronic acid (HA) receptor, CD44, on MSC membranes, to improve their homing potential towards an inflammatory site without affecting their behavior. The effect of HA-coatings on murine MSC was functionally determined both, in vitro and in vivo as a consequence of the transient CD44 overexpression induced by HA. Data obtained from the in vitro migration assay demonstrated a two-fold increase in the migratory potential of HA-treated MSC compared to untreated cells. In an LPS-induced inflamed ear murine model, HA-treated MSC demonstrated a significantly higher inflammatory targeting as observed at 72 hrs as compared to untreated cells. This increased accumulation for HA-treated MSC yielded a substantial reduction in inflammation as demonstrated by the decrease in the expression of pro-inflammatory markers and by the induction of a pro-regenerative environment.

Chlorin e6 Functionalized Theranostic Multistage Nanovectors Transported by Stem Cells for Effective Photodynamic Therapy

Approaches to achieve site-specific and targeted delivery that provide an effective solution to reduce adverse, off target side effects are urgently needed for cancer therapy. Here, we utilized a Trojan-horse-like strategy to carry photosensitizer Chlorin e6 conjugated porous silicon multistage nanovectors with tumor homing mesenchymal stem cells for targeted photodynamic therapy and diagnosis. The inherent versatility of multistage nanovectors permitted the conjugation of photosensitizers to enable precise cell death induction (60%) upon photodynamic therapy, while simultaneously retaining the loading capacity to load various payloads, such as antitumor drugs and diagnostic nanoparticles. Furthermore, the mesenchymal stem cells that internalized the multistage nanovectors conserved their proliferation patterns and in vitro affinity to migrate and infiltrate breast cancer cells. In vivo administration of the mesenchymal stem cells carrying photosensitizer-conjugated multistage nanovectors in mice bearing a primary breast tumor confirmed their tropism toward cancer sites exhibiting similar targeting kinetics to control cells. In addition, this approach yielded in a > 70% decrease in local tumor cell viability after in vivo photodynamic therapy. In summary, these results show the proof-of-concept of how photosensitizer conjugated multistage nanovectors transported by stem cells can target tumors and be used for effective site-specific cancer therapy while potentially minimizing potential negative side effects.

Nanoantibiotics: a new paradigm for the treatment of surgical infection

Infections following orthopedic device implantations often impose a substantial health burden and result in high medical costs. Currently, preventative methods are often employed following an orthopedic implant to reduce risk of infection; however, contamination of the surgical site can still occur. Although antibiotics have demonstrated a substantial reduction in bacterial growth and maintenance, biofilm formation around the implant can often minimize efficacy of the antibiotic. Recently, nanotechnology has garnered significant interest, resulting in the development of several antibiotic delivery strategies that exhibit extended release and increased efficacy. In this review, treatment methods of orthopedic-device-related infections will be discussed and an overview of antimicrobial-based nanotechnologies will be provided. Specifically, nonmetal-, metal- and oxide-based nanotechnologies, incorporating antibacterial strategies, will be discussed.

Ghee Butter as a Therapeutic Delivery System

Solid lipid nanoparticles carrying a chemotherapeutic payload (i.e., temozolomide, TMZ) were synthesized using ghee, a clarified butter commonly used in traditional medicine and food products. Ghee solid lipid nanoparticles (GSLN) were characterized through dynamic light scattering, scanning electron microscopy, and UV-visible spectrometry. Formulations were generated with varying ratios of surfactant to lipid, resulting in a maximum TMZ entrapment efficiency of ˜70%. Optimal formulations were found to have an average size and polydispersity of ˜220 nm and 0.340, respectively. Release kinetics revealed TMZ-loaded GSLN (TMZ@GSLN) retained 10% of its pay-load at 2 h with ˜53% released in 5 h. Metabolic activity on human umbilical vein endothelial cells (HUVEC) revealed GSLN treatment resulted in an increase in viability following 3 d while treatment of glioblastoma LN-229 cells with TMZ@GSLN resulted in a significant decrease. Evaluation of diffusion of TMZ across a reconstructed HUVEC monolayer demonstrated TMZ@GSLN resulted in a significantly higher diffusion of drug when compared to free TMZ. This data suggests GSLN pose a promising delivery vehicle for TMZ-based therapeutics. Collectively, this data demonstrates GSLN exhibit favorable drug carrier properties with anti-proliferative properties in glioblastoma cancer cells.

Multistage Nanovectors Enhance the Delivery of Free and Encapsulated Drugs

Nanoparticles have considerable potential for cancer imaging and therapy due to their small size and prolonged circulation. However, biological barriers can impede the delivery of a sufficient dose of a drug to the target site, thereby also resulting in the accumulation of toxic compounds within healthy tissues, and systemic toxicity. Multistage nanovectors (MSV) preferentially accumulate on inflamed endothelium, and can thus serve as carriers for drugs and nanoparticles. Herein, we describe the loading of free (i.e., melittin) and nano-encapsulated (i.e., doxorubicin-loaded micelles) drugs into MSV, and report the impact of surface charge and pore size on drug loading. For both drug formulations, negatively charged MSV (i.e., oxidized) with larger pores were shown to retain higher concentrations of payloads compared to positively charged (i.e., APTES-modified) MSV with small pores. Treatment of human umbilical vein endothelial cells (HUVEC) with melittin-loaded MSV (MEL@MSV) resulted in an 80% reduction in cell viability after 3 days. Furthermore, MEL@MSV conjugated with antivascular endothelial growth factor receptor 2 (VEGFR2) antibodies displayed preferential targeting and delivery of MEL to activated HUVEC expressing VEGFR2. Treatment of HUVEC and MCF7 cells with doxorubicin-loaded micelles (DOXNP@MSV) resulted in a 23% and 47% reduction in cell viability, respectively. Taken together, these results demonstrate increased loading of a payload in oxidized, large pore MSV, and effective delivery of free and nano-encapsulated drugs to endothelial and cancer cells.

Biomimetic proteolipid vesicles for targeting inflamed tissues

A multitude of micro- and nanoparticles have been developed to improve the delivery of systemically administered pharmaceuticals, which are subject to a number of biological barriers that limit their optimal biodistribution. Bioinspired drug-delivery carriers formulated by bottom-up or top-down strategies have emerged as an alternative approach to evade the mononuclear phagocytic system and facilitate transport across the endothelial vessel wall. Here, we describe a method that leverages the advantages of bottom-up and top-down strategies to incorporate proteins derived from the leukocyte plasma membrane into lipid nanoparticles. The resulting proteolipid vesicles-which we refer to as leukosomes-retained the versatility and physicochemical properties typical of liposomal formulations, preferentially targeted inflamed vasculature, enabled the selective and effective delivery of dexamethasone to inflamed tissues, and reduced phlogosis in a localized model of inflammation.

Proteomic Profiling of a Biomimetic Drug Delivery Platform

Current delivery platforms are typically designed for prolonged circulation that favors superior accumulation of the payload in the targeted tissue. The design of efficient surface modifications determines both a longer circulation time and targeting abilities of particles. The optimization of synthesis protocols to efficiently combine targeting molecules and elements that allow for an increased circulation time can be challenging and almost impossible when several functional elements are needed. On the other hand, in the last decade, the development of bioinspired technologies was proposed as a new approach with which to increase particle safety, biocompatibility and targeting, while maintaining the synthesis protocols simple and reproducible. Recently, we developed a new drug delivery system inspired by the biology of immune cells called leukolike vector (LLV) and formed by a nanoporous silicon core and a shell derived from the leucocyte cell membrane. The goal of this study is to investigate the protein content of the LLV. Here we report the proteomic profiling of the LLV and demonstrate that our approach can be used to modify the surface of synthetic particles with more than 150 leukocyte membrane associated proteins that determine particle safety, circulation time and targeting abilities towards inflamed endothelium.

One-pot synthesis of pH-responsive hybrid nanogel particles for the intracellular delivery of small interfering RNA

This report describes a novel, one-pot synthesis of hybrid nanoparticles formed by a nanostructured inorganic silica core and an organic pH-responsive hydrogel shell. This easy-to-perform, oil-in-water emulsion process synthesizes fluorescently-doped silica nanoparticles wrapped within a tunable coating of cationic poly(2-diethylaminoethyl methacrylate) hydrogel in one step. Transmission electron microscopy and dynamic light scattering analysis demonstrated that the hydrogel-coated nanoparticles are uniformly dispersed in the aqueous phase. The formation of covalent chemical bonds between the silica and the polymer increases the stability of the organic phase around the inorganic core as demonstrated by thermogravimetric analysis. The cationic nature of the hydrogel is responsible for the pH buffering properties of the nanostructured system and was evaluated by titration experiments. Zeta-potential analysis demonstrated that the charge of the system was reversed when transitioned from acidic to basic pH and vice versa. Consequently, small interfering RNA (siRNA) can be loaded and released in an acidic pH environment thereby enabling the hybrid particles and their payload to avoid endosomal sequestration and enzymatic degradation. These nanoparticles, loaded with specific siRNA molecules directed towards the transcript of the membrane receptor CXCR4, significantly decreased the expression of this protein in a human breast cancer cell line (i.e., MDA-MB-231). Moreover, intravenous administration of siRNA-loaded nanoparticles demonstrated a preferential accumulation at the tumor site that resulted in a reduction of CXCR4 expression.

Cell source determines the immunological impact of biomimetic nanoparticles

Recently, engineering the surface of nanotherapeutics with biologics to provide them with superior biocompatibility and targeting towards pathological tissues has gained significant popularity. Although the functionalization of drug delivery vectors with cellular materials has been shown to provide synthetic particles with unique biological properties, these approaches may have undesirable immunological repercussions upon systemic administration. Herein, we comparatively analyzed unmodified multistage nanovectors and particles functionalized with murine and human leukocyte cellular membrane, dubbed Leukolike Vectors (LLV), and the immunological effects that may arise in vitro and in vivo. Previously, LLV demonstrated an avoidance of opsonization and phagocytosis, in addition to superior targeting of inflammation and prolonged circulation. In this work, we performed a comprehensive evaluation of the importance of the source of cellular membrane in increasing their systemic tolerance and minimizing an inflammatory response. Time-lapse microscopy revealed LLV developed using a cellular coating derived from a murine (i.e., syngeneic) source resulted in an active avoidance of uptake by macrophage cells. Additionally, LLV composed of a murine membrane were found to have decreased uptake in the liver with no significant effect on hepatic function. As biomimicry continues to develop, this work demonstrates the necessity to consider the source of biological material in the development of future drug delivery carriers.

Multistage vector delivery of sulindac and silymarin for prevention of colon cancer

Familial adenomatous polyposis (FAP) is an inherited condition secondary to germline mutations in the APC gene, thus resulting in the formation of hundreds of colonic adenomas that eventually progress into colon cancer. Surgical removal of the colon remains the only treatment option to avoid malignancy, as long-term exposure to chemopreventive agents such as sulindac (a non-steroidal anti-inflammatory drug) and silymarin (phytoestrogen) is not feasible. Here, we have developed a multistage silicon-based drug delivery platform for sulindac and silymarin that preferentially interacts with colon cancer cells as opposed to normal intestinal mucosa. Preferential binding and internalization of these drugs into colon cancer cells was obtained using a targeting strategy against the protein meprin A, which we demonstrate is overexpressed in human colon cancer cells and in the small intestine of Apc(Min/+) mice. We propose that this delivery system could potentially be used to reduce drug-induced side effects in FAP patients, thus enabling long-term prevention of adenoma formation.

Physicochemical properties affect the synthesis, controlled delivery, degradation and pharmacokinetics of inorganic nanoporous materials

Controlling size, shape and uniformity of porous constructs remains a major focus of the development of porous materials. Over the past two decades, we have seen significant developments in the fabrication of new, porous-ordered structures using a wide range of materials, resulting in properties well beyond their traditional use. Porous materials have been considered appealing, due to attractive properties such as pore size length, morphology and surface chemistry. Furthermore, their utilization within the life sciences and medicine has resulted in significant developments in pharmaceutics and medical diagnosis. This article focuses on various classes of porous materials, providing an overview of principle concepts with regard to design and fabrication, surface chemistry and loading and release kinetics. Furthermore, predictions from a multiscale mathematical model revealed the role pore length and diameter could have on payload release kinetics.

Abstract 4536: Biomimetic carriers modulate tumor vascular barrier function

Introduction

We showed that nanoporous silicon (NPS) particles coated with leukocyte cellular membranes -Leukolike Vectors (LLV) - possess cell-like properties. These biomimetic carriers can escape macrophage uptake, delay sequestration by the reticulo-endothelial system, target tumor inflamed vasculature and accumulate within the cancer parenchyma. We characterized the content and function of the leukocyte's proteins transferred onto the LLV coating and evaluated their interaction with inflamed cancer vasculature.

Experimental Procedures

The leukocyte membrane coating was analyzed with several biochemistry techniques. In vitro experiments were performed using reconstructed inflamed endothelia. Flow chamber systems were used to simulate vessel flow dynamics and study LLV docking, firm adhesion and transcytosis. In vivo experiments were performed with Intra Vital Microscopy (IVM) to image in real time LLV behavior in BALB/c mice carrying syngeneic breast cancers.

Results

LLV were studied using dynamic light scattering and scanning electron microscopy to characterize particles size (1 μm), pore sizes (60 nm) and surface properties (positive charge and uniform coating). Biochemical analyses revealed that we successfully transferred on the surface of the LLV critical protein among which LFA-1, MAC1, and CD45. Upon interaction of the LLV with inflamed endothelia we found that VE-cadherin expression was substantially reduced. We also described the differential process of cell internalization and showed that LLV escaped the endo-lysosomal compartment during intracellular trafficking.

IVM showed delayed sequestration by spleen and liver macrophages, increased circulation half-life and increased targeting of tumor associated inflamed vasculature. To further demonstrate the ability of our biomimetic carrier to affect the biology of tumor endothelia, we evaluated the extravasation of an intravascular 70 kDa FITC dextran reporter. We measured the increase in vessel permeability and tissue diffusion over time and confirmed that LLV were able to favor the extravasation of the reporter molecule in the cancer parenchyma.

Conclusion

Our work showed for the first time that is possible to transfer biologically active leukocyte membrane proteins onto synthetic particles. Our biomimetic carriers retain favorable cell-like functions that can enhance the kinetics of oncotransport by decreasing endothelial cellular junctions and increasing diffusion of a therapeutic payload within the tumor tissue. We envision that biomimetic drug delivery systems derived from the infiltrating immune cells of a cancer patient could represent the next generation of personalized treatments.

Note: This abstract was not presented at the meeting.

Citation Format: Alessandro Parodi, Roberto Palomba, Michael Evangelopoulos, Claudia Corbo, Ennio Tasciotti. Biomimetic carriers modulate tumor vascular barrier function. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4536. doi:10.1158/1538-7445.AM2015-4536

Abstract 4586: The Leukosome: A biomimetic liposome for the targeting of inflamed tumor vasculature

The development of targeted cancer treatments with increased therapeutic efficacy is still a major challenge in drug delivery. To date, nanoscale platforms are able to extend their circulation time and accumulate in the tumor through surface functionalization with polyethylene glycol and with antibodies, peptides or ligands directed against tumor biomarkers, respectively. Despite these modifications, the mononuclear phagocytic system efficiently clears these particles from circulation while opsonization proteins prevent the proper recognition between targeting ligands and target biomarkers. Additionally, most cancers are characterized by strong inflammation and increased affinity for circulating leukocytes. The surface of the leukocyte is enriched with transmembrane proteins that determine self-tolerance, adhesion, and negotiation of the inflamed vascular barrier. As result, leukocytes can efficiently recognize and infiltrate the tumor tissues.

The Leukosome is a liposomal formulation based on leukocyte membranes able to provide biocompatibility, self-tolerance and targeting. The Leukosome was enriched with up to 82 different leukocyte membrane proteins in their intact native, active configuration with the appropriate post-translational modification and orientation. Among them, CD45 favored extended circulation time and avoided unspecific clearance, while Leukocyte Associated Function-1 facilitated the targeting to and permeability of the tumor inflamed vasculature.

The Leukosome retained loading capabilities similar to current liposomal formulations but sustained the release of the chemotherapeutic drug for twice as long. The physical (size, surface charge and polydispersity index), chemical (surface composition and modification, loading and release kinetics), biochemical (protein content and stability), and biological (inhibition of particle clearance, tumor targeting, effect on the vascular barrier function) properties of the Leukosomes confirmed our ability to mimic the biological features and functions of leukocytes. Compared to unmodified liposomes, Leukosomes showed 5-fold increase in circulation time, 50-fold reduction of liver accumulation and 70-fold accumulation of the payload in breast, pancreatic and melanoma models in mouse. We believe this platform will provide a superior tool for the targeting and personalization of therapeutic intervention in cancer.

Citation Format: Roberto Molinaro, Alessandro Parodi, Nima Taghipour, Brandon Brown, Dickson Kirui, Michael Evangelopoulos, Francesca Taraballi, Claudia Corbo, Ennio Tasciotti. The Leukosome: A biomimetic liposome for the targeting of inflamed tumor vasculature. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4586. doi:10.1158/1538-7445.AM2014-4586

The effect of multistage nanovector targeting of VEGFR2 positive tumor endothelia on cell adhesion and local payload accumulation

Nanovectors are a viable solution to the formulation of poorly soluble anticancer drugs. Their bioaccumulation in the tumor parenchyma is mainly achieved exploiting the enhanced permeability and retention (EPR) effect of the leaky neovasculature. In this paper we demonstrate that multistage nanovectors (MSV) exhibit rapid tumoritropic homing independent of EPR, relying on particle geometry and surface adhesion. By studying endothelial cells overexpressing vascular endothelial growth factor receptor-2 (VEGFR2), we developed MSV able to preferentially target VEGFR2 expressing tumor-associated vessels. Static and dynamic targeting revealed that MSV conjugated with anti-VEGFR2 antibodies displayed greater than a 4-fold increase in targeting efficiency towards VEGFR2 expressing cells while exhibiting minimal adherence to control cells. Additionally, VEGFR2 conjugation bestowed MSV with a significant increase in breast tumor targeting and in the delivery of a model payload while decreasing their accumulation in the liver. Surface functionalization with an anti-VEGFR2 antibody provided enhanced affinity towards the tumor vascular endothelium, which promoted enhanced adhesion and tumoritropic accumulation of a reporter molecule released by the MSV.

Degradation and biocompatibility of multistage nanovectors in physiological systems

The careful scrutiny of drug delivery systems is essential to evaluate and justify their potential for the clinic. Among the various studies necessary for preclinical testing, the impact of degradation is commonly overlooked. In this article, we investigate the effect of fabrication (porosity and nucleation layer) and environment (buffer and pH) factors on the degradation kinetics of multistage nanovectors (MSV) composed of porous silicon. The degradation by-products of MSV were exposed to endothelial cells and analyzed for detrimental effects on cellular internalization, architecture, proliferation, and cell cycle. Increases in porosity resulted in accelerated degradation exhibiting smaller-sized particles at comparable times. Removal of the nucleation layer (thin layer of small pores formed during the initial steps of etching) triggered a premature collapse of the entire central porous region of MSV. Variations in buffers prompted a faster degradation rate yielding smaller MSV within faster time frames, whereas increases in pH stimulated erosion of MSV and thus faster degradation. In addition, exposure to these degradation by-products provoked negligible impact on the proliferation and cell cycle phases on primary endothelial cells. In this study, we propose methods that lay the foundation for future investigations toward understanding the impact of the degradation of drug delivery platforms.

Synthetic nanoparticles functionalized with biomimetic leukocyte membranes possess cell-like functions

The therapeutic efficacy of systemic drug-delivery vehicles depends on their ability to evade the immune system, cross the biological barriers of the body and localize at target tissues. White blood cells of the immune system--known as leukocytes--possess all of these properties and exert their targeting ability through cellular membrane interactions. Here, we show that nanoporous silicon particles can successfully perform all these actions when they are coated with cellular membranes purified from leukocytes. These hybrid particles, called leukolike vectors, can avoid being cleared by the immune system. Furthermore, they can communicate with endothelial cells through receptor-ligand interactions, and transport and release a payload across an inflamed reconstructed endothelium. Moreover, leukolike vectors retained their functions when injected in vivo, showing enhanced circulation time and improved accumulation in a tumour.

Multifunctional to multistage delivery systems: The evolution of nanoparticles for biomedical applications

Nanomaterials are advancing in several directions with significant progress being achieved with respect to their synthesis, functionalization and biomedical application. In this review, we will describe several classes of prototypical nanocarriers, such as liposomes, silicon particles, and gold nanoshells, in terms of their individual function as well as their synergistic use. Active and passive targeting, photothermal ablation, and drug controlled release constitute some of the crucial functions identified to achieve a medical purpose. Current limitations in targeting, slow clearance, and systemic as well as local toxicity are addressed in reference to the recent studies that attempted to comprehend and solve these issues. The demand for a more sophisticated understanding of the impact of nanomaterialson the body and of their potential immune response underlies this discussion. Combined components are then discussed in the setting of multifunctional nanocarriers, a class of drug delivery systems we envisioned, proposed, and evolved in the last 5 years. In particular, our third generation of nanocarriers, the multistage vectors, usher in the new field of nanomedicine by combining several components onto multifunctional nanocarriers characterized by emerging properties and able to achieve synergistic effects.