Incorporation of Viral Glycoprotein VSV-G Improves the Delivery of DNA by Erythrocyte Ghost into Cells Refractory to Conventional Transfection

Red Blood Cell Inspired Strategies for Drug Delivery: Emerging Concepts and New Advances

In the past five decades, red blood cells (RBCs) have been extensively explored as drug delivery systems due to their distinguishing potential in modulating the pharmacokinetic, pharmacodynamics, and biological activity of carried payloads. The extensive interests in RBC-mediated drug delivery technologies are in part derived from RBCs' unique biological features such as long circulation time, wide access to many tissues in the body, and low immunogenicity. Owing to these outstanding properties, a large body of efforts have led to the development of various RBC-inspired strategies to enable precise drug delivery with enhanced therapeutic efficacy and reduced off-target toxicity. In this review, we discuss emerging concepts and new advances in such RBC-inspired strategies, including native RBCs, ghost RBCs, RBC-mimetic nanoparticles, and RBC-derived extracellular vesicles, for drug delivery.

Erythrocyte Ghost Based Fusogenic Glycoprotein Vesicular Stomatitis Virus Glycoprotein Complexes as an Efficient Deoxyribonucleic Acid Delivery System

This study aimed to construct a new type of fused erythrocyte vector for gene delivery system. The conditioned medium of AD293 cells expressing vesicular stomatitis virus glycoprotein gene was collected, and erythrocyte ghost was prepared by hypotonic lysis. Using cationic polymer to condense deoxyribonucleic acid to form a complex, fusogenic erythrocyte ghost was incubated with this complex to obtain virion. Flow cytometry and luciferase activity analysis were used to detect the delivery of fusogenic erythrocyte ghost to deoxyribonucleic acid in AD293 cells and refractory cells, respectively. Transfection efficiency of fusogenic erythrocyte ghost in vivo was detected by confocal microscope. Vesicular stomatitis virus glycoprotein and erythrocyte ghost were effectively integrated, and fusogenic erythrocyte ghost was successfully prepared. deoxyribonucleic acid/polyethylenimine complexes form 100–300 nm particles. Fusogenic erythrocyte ghost can effectively incorporation deoxyribonucleic acid complexes. Confocal microscope observed red fluorescence close to blue fluorescence, indicating that labeled fusogenic erythrocyte ghost may trigger liver and spleen tissue endocytosis or fusion. A new delivery vector of fusogenic erythrocyte ghost was constructed. This system could enhance the delivery efficiency even in cells which refractory to conventional transfections in vitro.

Oncolytic Virotherapy in Solid Tumors: The Challenges and Achievements

Oncolytic virotherapy (OVT) is a promising approach in cancer immunotherapy. Oncolytic viruses (OVs) could be applied in cancer immunotherapy without in-depth knowledge of tumor antigens. The capability of genetic modification makes OVs exciting therapeutic tools with a high potential for manipulation. Improving efficacy, employing immunostimulatory elements, changing the immunosuppressive tumor microenvironment (TME) to inflammatory TME, optimizing their delivery system, and increasing the safety are the main areas of OVs manipulations. Recently, the reciprocal interaction of OVs and TME has become a hot topic for investigators to enhance the efficacy of OVT with less off-target adverse events. Current investigations suggest that the main application of OVT is to provoke the antitumor immune response in the TME, which synergize the effects of other immunotherapies such as immune-checkpoint blockers and adoptive cell therapy. In this review, we focused on the effects of OVs on the TME and antitumor immune responses. Furthermore, OVT challenges, including its moderate efficiency, safety concerns, and delivery strategies, along with recent achievements to overcome challenges, are thoroughly discussed.

Rhabdoviruses as vectors for vaccines and therapeutics

Appropriate choice of vaccine vector is crucial for effective vaccine development. Rhabdoviral vectors, such as rabies virus and vesicular stomatitis virus, have been used in a variety of vaccine strategies. These viruses have small, easily manipulated genomes that can stably express foreign glycoproteins due to a well-established reverse genetics system for virus recovery. Both viruses have well-described safety profiles and have been demonstrated to be effective vaccine vectors. This review will describe how these Rhabdoviruses can be manipulated for use as vectors, their various applications as vaccines or therapeutics, and the advantages and disadvantages of their use.

Erythrocytes as Carriers: From Drug Delivery to Biosensors

Drug delivery using natural biological carriers, especially erythrocytes, is a rapidly developing field. Such erythrocytes can act as carriers that prolong the drug's action due to its gradual release from the carrier; as bioreactors with encapsulated enzymes performing the necessary reactions, while remaining inaccessible to the immune system and plasma proteases; or as a tool for targeted drug delivery to target organs, primarily to cells of the reticuloendothelial system, liver and spleen. To date, erythrocytes have been studied as carriers for a wide range of drugs, such as enzymes, antibiotics, anti-inflammatory, antiviral drugs, etc., and for diagnostic purposes (e.g. magnetic resonance imaging). The review focuses only on drugs loaded inside erythrocytes, defines the main lines of research for erythrocytes with bioactive substances, as well as the advantages and limitations of their application. Particular attention is paid to in vivo studies, opening-up the potential for the clinical use of drugs encapsulated into erythrocytes.

Reversible Fusion Proteins as a Tool to Enhance Uptake of Virus-Functionalized LbL Microcarriers

For the efficient treatment of an increasing number of diseases the development of new therapeutics as well as novel drug delivery systems is essential. Such drug delivery systems (DDS) must not only consider biodegradability and protective packaging but must also target and control the release of active substances, which is one of the most important points in DDS application. We highlight the improvement of these key aspects, the increased interaction rate of Layer-by-Layer (LbL) designed microcarriers as a promising DDS after functionalization with vesicular stomatitis virus (VSV). We make use of the unique conformational reversibility of the fusion protein of VSV as a surface functionalization of LbL microcarriers. This reversibility allows for VSV to be used both as a tool for assembly onto the DDS and as an initiator for an efficient cellular uptake. We could show that the evolutionary optimized viral fusion machinery can be successfully combined with a biophysical DDS for optimization of its cellular interaction.

Emergence of synthetic mRNA: In vitro synthesis of mRNA and its applications in regenerative medicine

The field of gene therapy has evolved over the past two decades after the first introduction of nucleic acid drugs, such as plasmid DNA (pDNA). With the development of in vitro transcription (IVT) methods, synthetic mRNA has become an emerging class of gene therapy. IVT mRNA has several advantages over conventional pDNA for the expression of target proteins. mRNA does not require nuclear localization to mediate protein translation. The intracellular process for protein expression is much simpler and there is no potential risk of insertion mutagenesis. Having these advantages, the level of protein expression is far enhanced as comparable to that of viral expression systems. This makes IVT mRNA a powerful alternative gene expression system for various applications in regenerative medicine. In this review, we highlight the synthesis and preparation of IVT mRNA and its therapeutic applications. The article includes the design and preparation of IVT mRNA, chemical modification of IVT mRNA, and therapeutic applications of IVT mRNA in cellular reprogramming, stem cell engineering, and protein replacement therapy. Finally, future perspectives and challenges of IVT mRNA are discussed.

Oncolytic virus delivery: from nano-pharmacodynamics to enhanced oncolytic effect

With the advancement of a growing number of oncolytic viruses (OVs) to clinical development, drug delivery is becoming an important barrier to overcome for optimal therapeutic benefits. Host immunity, tumor microenvironment and abnormal vascularity contribute to inefficient vector delivery. A number of novel approaches for enhanced OV delivery are under evaluation, including use of nanoparticles, immunomodulatory agents and complex viral–particle ligands along with manipulations of the tumor microenvironment. This field of OV delivery has quickly evolved to bioengineering of complex nanoparticles that could be deposited within the tumor using minimal invasive image-guided delivery. Some of the strategies include ultrasound (US)-mediated cavitation-enhanced extravasation, magnetic viral complexes delivery, image-guided infusions with focused US and targeting photodynamic virotherapy. In addition, strategies that modulate tumor microenvironment to decrease extracellular matrix deposition and increase viral propagation are being used to improve tumor penetration by OVs. Some involve modification of the viral genome to enhance their tumoral penetration potential. Here, we highlight the barriers to oncolytic viral delivery, and discuss the challenges to improving it and the perspectives of establishing new modes of active delivery to achieve enhanced oncolytic effects.