Design strategies and applications of circulating cell-mediated drug delivery systems

Molecular and Biocompatibility Characterization of Red Blood Cell Membrane Targeted and Cell-Penetrating-Peptide-Modified Polymeric Nanoparticles

Red blood cells (RBCs) express a variety of immunomodulatory markers that enable the body to recognize them as self. We have shown that RBC membrane glycophorin A (GPA) receptor can mediate membrane attachment of protein therapeutics. A critical knowledge gap is whether attaching drug-encapsulated nanoparticles (NPs) to GPA and modification with cell-penetrating peptide (CPP) will impact binding, oxygenation, and the induction of cellular stress. The objective of this study was to formulate copolymer-based NPs containing model fluorescent-tagged bovine serum albumin (BSA) with GPA-specific targeting ligands such as ERY1 (ENPs), single-chain variable antibody (scFv TER-119, SNPs), and low-molecular-weight protamine-based CPP (LNPs) and to determine their biocompatibility using a variety of complementary high-throughput in vitro assays. Experiments were conducted by coincubating NPs with RBCs at body temperature, and biocompatibility was evaluated by Raman spectroscopy, hemolysis, complement lysis, and oxidative stress assays. Data suggested that LNPs effectively targeted RBCs, conferring 2-fold greater uptake in RBCs compared to ENPs and SNPs. Raman spectroscopy results indicated no adverse effect of NP attachment or internalization on the oxygenation status of RBCs. Cellular stress markers such as glutathione, malondialdehyde, and catalase were within normal limits, and complement-mediated lysis due to NPs was negligible in RBCs. Under the conditions tested, our data demonstrates that molecular targeting of the RBC membrane is a feasible translational strategy for improving drug pharmacokinetics and that the proposed high-throughput assays can prescreen diverse NPs for preclinical and clinical biocompatibility.

Responsive Nanocarriers as an Emerging Platform for Cascaded Delivery of Nucleic Acids to Cancer

Cascades of systemic and intracellular obstacles, including low stability in blood, little tumor accumulation, weak tumor penetration, poor cellular uptake, inefficient endosomal escape and deficient disassembly in the cytoplasm, must be overcome in order to deliver nucleic acid drugs for cancer therapy. Nanocarriers that are sensitive to a variety of physiological stimuli, such as pH, redox status, and cell enzymes, are substantially changing the landscape of nucleic acid drug delivery by helping to overcome cascaded systemic and intracellular barriers. This review discusses nucleic acid-based therapeutics, systemic and intracellular barriers to efficient nucleic acid delivery, and nanocarriers responsive to extracellular and intracellular biological stimuli to overcome individual barriers. In particular, responsive nanocarriers for the cascaded delivery of nucleic acids in vivo are highlighted. Developing novel cascaded nanocarriers that transform their physicochemical properties in response to various stimuli in a timely and spatially controlled manner for nucleic acid drug delivery holds great potential for translating the promise of nucleic acid drugs and achieving clinically successful cancer therapy.

Nanomaterials engineering for drug delivery: a hybridization approach

The last twenty years have witnessed great advances in biology, medicine, and materials science, leading to the development of various nanoparticle (NP)-mediated drug delivery systems. Innovation in materials science has led the generation of biodegradable, biocompatible, stimuli-responsive, and targeted delivery systems. However, currently available nanotherapeutic technologies are not efficient, which has culminated in the failure of their clinical trials. Despite huge efforts devoted to drug delivery nanotherapeutics, only a small amount of the injected material could reach the desired target. One promising strategy to enhance the efficiency of NP drug delivery is to hybridize multiple materials, where each component could play a critical role in an efficient multipurpose delivery system. This review aims to comprehensively cover different techniques, materials, advantages, and drawbacks of various systems to develop hybrid nano-vesicles for drug delivery. Attention is finally given to the hybridization benefits in overcoming the biological barriers for drug delivery. It is believed that the advent of modern nano-formulations for multifunctional hybrid carriers paves the way for future advances to achieve more efficient drug delivery systems.

Immune Cell-Mediated Biodegradable Theranostic Nanoparticles for Melanoma Targeting and Drug Delivery

Although tremendous efforts have been made on targeted drug delivery systems, current therapy outcomes still suffer from low circulating time and limited targeting efficiency. The integration of cell-mediated drug delivery and theranostic nanomedicine can potentially improve cancer management in both therapeutic and diagnostic applications. By taking advantage of innate immune cell's ability to target tumor cells, the authors develop a novel drug delivery system by using macrophages as both nanoparticle (NP) carriers and navigators to achieve cancer-specific drug delivery. Theranostic NPs are fabricated from a unique polymer, biodegradable photoluminescent poly (lactic acid) (BPLP-PLA), which possesses strong fluorescence, biodegradability, and cytocompatibility. In order to minimize the toxicity of cancer drugs to immune cells and other healthy cells, an anti-BRAF V600E mutant melanoma specific drug (PLX4032) is loaded into BPLP-PLA nanoparticles. Muramyl tripeptide is also conjugated onto the nanoparticles to improve the nanoparticle loading efficiency. The resulting nanoparticles are internalized within macrophages, which are tracked via the intrinsic fluorescence of BPLP-PLA. Macrophages carrying nanoparticles deliver drugs to melanoma cells via cell-cell binding. Pharmacological studies also indicate that the PLX4032 loaded nanoparticles effectively kill melanoma cells. The "self-powered" immune cell-mediated drug delivery system demonstrates a potentially significant advancement in targeted theranostic cancer nanotechnologies.

Cell-mediated delivery of synthetic nano- and microparticles

Cell mediated delivery of synthetic nano- and microparticle based drug carriers is a very promising strategy to enhance control over the distribution of drugs and improve targeting. This article will present an overview of work, which has been done to explore cell surface modification strategies for the cellular hitchhiking of synthetic nano- and microparticles. The first part of this article will present and discuss the different types of cells that have been explored for cell mediated drug delivery. The second part of this review will discuss the various chemical strategies that have been elaborated for the conjugation or immobilization of nano- and microparticles on the surface of these cells.

Engineering Cell Surfaces with Polyelectrolyte Materials for Translational Applications

Engineering cell surfaces with natural or synthetic materials is a unique and powerful strategy for biomedical applications. Cells exhibit more sophisticated migration, control, and functional capabilities compared to nanoparticles, scaffolds, viruses, and other engineered materials or agents commonly used in the biomedical field. Over the past decade, modification of cell surfaces with natural or synthetic materials has been studied to exploit this complexity for both fundamental and translational goals. In this review we present the existing biomedical technologies for engineering cell surfaces with one important class of materials, polyelectrolytes. We begin by introducing the challenges facing the cell surface engineering field. We then discuss the features of polyelectrolytes and how these properties can be harnessed to solve challenges in cell therapy, tissue engineering, cell-based drug delivery, sensing and tracking, and immune modulation. Throughout the review, we highlight opportunities to drive the field forward by bridging new knowledge of polyelectrolytes with existing translational challenges.

In vitro determination of the efficacy of scorpion venoms as anti-cancer agents against colorectal cancer cells: a nano-liposomal delivery approach

The use of liposomes in biological and medicinal sciences is a relatively new approach. The liposomal strategy greatly depends on the technological advancement in the formation of vesicles of various sizes and properties. In the current study, we encapsulated the venoms obtained from medically important scorpions such as Androctonus bicolor (AB), Androctonus crassicauda (AC), and Leiurus quinquestriatus (LQ). To begin with, our first and foremost aim was to prepare biocompatible and biodegradable nanovesicles. Additionally, we intended to enhance the anti-cancer potential of these encapsulated venoms. The liposomal venoms were prepared by rehydration and dehydration methods. Morphology, particle size, and size distribution of the liposomes were examined by scanning electron microscope (SEM), transmission electron microscope (TEM), and Zetasizer. We found that the prepared liposomes had a smooth surface and a spherical/ovoid shape and existed mainly as single unilamellar vesicles (SUVs). Furthermore, the liposomal formulation of all three venoms exhibited excellent stability and good encapsulation efficiency (EE). Additionally, the anti-cancer potential of the encapsulated venoms was also evaluated on a colorectal cancer cell line (HCT-8). The venom-loaded liposomes showed elevated anti-cancer properties such as low rate of cell survival, higher reactive oxygen species (ROS) generation, and enhancement in the number of apoptotic cells. In addition to this, cell cycle analysis revealed G0/G1 enrichment upon venom treatment. The effect of treatment was more pronounced when venom-liposome was used as compared to free venom on the HCT-8 cell line. Furthermore, we did not observe any interference of liposomal lipids used in these preparations on the progression of cancer cells. Considering these findings, we can conclude that the encapsulated scorpion venoms exhibit better efficacy and act more vigorously as an anti-cancer agent on the colorectal cancer cell line when compared with their free counterpart.

Catalase-Laden Microdevices for Cell-Mediated Enzyme Delivery

Enzymes have been used to treat various human diseases and traumas. However, the therapeutic utility of free enzymes is impeded by their short circulation time, lack of targeting ability, immunogenicity, and inability to cross biological barriers. Cell-mediated drug delivery approach offers the unique capability to overcome these limitations, but the traditional cell-mediated enzyme delivery techniques suffer from drawbacks such as risk of intracellular degradation of and low loading capacity for the payload enzyme. This article presents the development of a novel cell-mediated enzyme delivery technique featuring the use of micrometer-sized disk-shaped particles termed microdevices. The microdevices are fabricated by layer-by-layer assembly and soft lithography with catalase being used as a model therapeutic enzyme. The amount of catalase in the microdevices can be controlled with the number of catalase layers. Catalase in the microdevices is catalytically active, and active catalase is slowly released from the microdevices. Moreover, cell-microdevice complexes are produced by attaching the catalase-laden microdevices to the external surface of both K562 cells and mouse embryonic stem cells. This technique is potentially applicable to other enzymes and cells and promises to be clinically useful.

Engineering erythrocytes for the modulation of drugs' and contrasting agents' pharmacokinetics and biodistribution

Pharmacokinetics, biodistribution, and biological activity are key parameters that determine the success or failure of therapeutics. Many developments intended to improve their in vivo performance, aim at modulating concentration, biodistribution, and targeting to tissues, cells or subcellular compartments. Erythrocyte-based drug delivery systems are especially efficient in maintaining active drugs in circulation, in releasing them for several weeks or in targeting drugs to selected cells. Erythrocytes can also be easily processed to entrap the desired pharmaceutical ingredients before re-infusion into the same or matched donors. These carriers are totally biocompatible, have a large capacity and could accommodate traditional chemical entities (glucocorticoids, immunossuppresants, etc.), biologics (proteins) and/or contrasting agents (dyes, nanoparticles). Carrier erythrocytes have been evaluated in thousands of infusions in humans proving treatment safety and efficacy, hence gaining interest in the management of complex pathologies (particularly in chronic treatments and when side-effects become serious issues) and in new diagnostic approaches.

Recent advancements in erythrocytes, platelets, and albumin as delivery systems

In the past few years, nanomaterial-based drug delivery systems have been applied to enhance the efficacy of therapeutics and to alleviate negative effects through the controlled delivery of targeting and releasing agents. However, few drug carriers can achieve high targeting efficacy, even when targeting modalities and surface markers are introduced. Immunological problems have also limited their wide applications. Biological drug delivery systems, such as erythrocytes, platelets, and albumin, have been extensively investigated because of their unique properties. In this review, erythrocytes, platelets, and albumin are described as efficient drug delivery systems. Their properties, applications, advantages, and limitations in disease treatment are explained. This review confirms that these systems can be used to facilitate a specific, biocompatible, and smart drug delivery.

Red blood cell ghosts as promising drug carriers to target wound infections

Autologous red blood cell ghosts (RBC ghosts) can carry cytokines to the sites of inflammation. The targeting moiety of the RBC ghosts is associated with the nature of purulent inflammation, where the erythrocytes are phagocyted and encapsulated drugs are released. In the present study we have investigated the healing potential of RBC ghosts loaded with cytokine IL-1β and antibiotic. Additionally, the pharmacokinetic properties of RBC ghosts loaded with IL-1β were studied. 35 Male Wistar rats (250-300g) were used in the pharmacokinetic study and in a wound infection model where a suspension of Staphylococcus aureus was placed into a surgical cut of the skin and subcutaneous tissue in the femoral region. In order to monitor progression of the wound repair processes, wound swabs or aspiration biopsies were taken for analyses on the 1st-6th days. Wound repair dynamics assessment was based on suppression of S. aureus growth, signs of pain, time of disappearance of pus and infiltration around the wound. Visual observations, as well as microbiological and cytological analysis of wound exudates demonstrated a significant acceleration of healing processes in a group of animals treated with a local injection of IL-1β and ceftriaxone encapsulated into RBC ghosts when compared to the animals treated either with a local or IM injection of free drugs. For the pharmacokinetic study, single IV injections of either free or encapsulated IL-1β were made and the concentration of IL-1β in serum samples and tissue homogenates were determined. Encapsulation in RBC ghosts improved pharmacokinetic profiles of IL-1β by increasing the half-life, reducing its clearance, and increasing the deposition of the drug in the liver, spleen and lungs. These data suggest that RBC ghosts are effective drug carriers for targeted delivery of cytokines to the sites of inflammation, and have a potential for improving the treatment outcomes of purulent diseases.

Designing Dendrimer and Miktoarm Polymer Based Multi-Tasking Nanocarriers for Efficient Medical Therapy

To address current complex health problems, there has been an increasing demand for smart nanocarriers that could perform multiple complimentary biological tasks with high efficacy. This has provoked the design of tailor made nanocarriers, and the scientific community has made tremendous effort in meeting daunting challenges associated with synthetically articulating multiple functions into a single scaffold. Branched and hyper-branched macromolecular architectures have offered opportunities in enabling carriers with capabilities including location, delivery, imaging etc. Development of simple and versatile synthetic methodologies for these nanomaterials has been the key in diversifying macromolecule based medical therapy and treatment. This review highlights the advancement from conventional "only one function" to multifunctional nanomedicine. It is achieved by synthetic elaboration of multivalent platforms in miktoarm polymers and dendrimers by physical encapsulation, covalent linking and combinations thereof.

Drug Carrier for Photodynamic Cancer Therapy

Photodynamic therapy (PDT) is a non-invasive combinatorial therapeutic modality using light, photosensitizer (PS), and oxygen used for the treatment of cancer and other diseases. When PSs in cells are exposed to specific wavelengths of light, they are transformed from the singlet ground state (S₀) to an excited singlet state (S₁-Sn), followed by intersystem crossing to an excited triplet state (T₁). The energy transferred from T₁ to biological substrates and molecular oxygen, via type I and II reactions, generates reactive oxygen species, (¹O₂, H₂O₂, O₂*, HO*), which causes cellular damage that leads to tumor cell death through necrosis or apoptosis. The solubility, selectivity, and targeting of photosensitizers are important factors that must be considered in PDT. Nano-formulating PSs with organic and inorganic nanoparticles poses as potential strategy to satisfy the requirements of an ideal PDT system. In this review, we summarize several organic and inorganic PS carriers that have been studied to enhance the efficacy of photodynamic therapy against cancer.

Polymeric nanoparticles: the future of nanomedicine

Polymeric nanoparticles (NPs) are one of the most studied organic strategies for nanomedicine. Intense interest lies in the potential of polymeric NPs to revolutionize modern medicine. To determine the ideal nanosystem for more effective and distinctly targeted delivery of therapeutic applications, particle size, morphology, material choice, and processing techniques are all research areas of interest. Utilizations of polymeric NPs include drug delivery techniques such as conjugation and entrapment of drugs, prodrugs, stimuli-responsive systems, imaging modalities, and theranostics. Cancer, neurodegenerative disorders, and cardiovascular diseases are fields impacted by NP technologies that push scientific boundaries to the leading edge of transformative advances for nanomedicine.