Nanovaccines formulation and applications-a review

Advances in traditional herbal formulation based nano-vaccine for cancer immunotherapy: Unraveling the enigma of complex tumor environment and multidrug resistance

Cancer is attributed to uncontrolled cell growth and is among the leading causes of death with no known effective treatment while complex tumor microenvironment (TME) and multidrug resistance (MDR) are major challenges for developing an effective therapeutic strategy. Advancement in cancer immunotherapy has been limited by the over-activation of the host immune response that ultimately affects healthy tissues or organs and leads to a feeble response of the patient's immune system against tumor cells. Besides, traditional herbal medicines (THM) have been well-known for their essential role in the treatment of cancer and are considered relatively safe due to their compatibility with the human body. Yet, poor solubility, low bio-availability, and lack of understanding about their pathophysiological mechanism halt their clinical application. Moreover, considering the complex TME and drug resistance, the most precarious and least discussed concerns for developing THM-based nano-vaccination, are identification of specific biomarkers for drug inhibitory protein and targeted delivery of bioactive ingredients of THM on the specific sites in tumor cells. The concept of THM-based nano-vaccination indicates immunomodulation of TME by THM-based bioactive adjuvants, exerting immunomodulatory effects, via targeted inhibition of key proteins involved in the metastasis of cancer. However, this concept is at its nascent stage and very few preclinical studies provided the evidence to support clinical translation. Therefore, we attempted to capsulize previously reported studies highlighting the role of THM-based nano-medicine in reducing the risk of MDR and combating complex tumor environments to provide a reference for future study design by discussing the challenges and opportunities for developing an effective and safe therapeutic strategy against cancer.

Mammalian Cell Membrane Hybrid Polymersomes for mRNA Delivery

Cell membranes are structures essential to the cell function and adaptation. Recent studies have targeted cell membranes to identify their protective and interactive properties. Leveraging these attributes of cellular membranes and their application to vaccine delivery is gaining increasing prominence. This study aimed to fuse synthetic polymeric nanoparticles with cell membranes to develop cell membrane hybrid polymersomes (HyPSomes) for enhanced vaccine delivery. We designed a platform to hybridize cell membranes with methoxy-poly(ethylene glycol)-block-polylactic acid nanoparticles by using the properties of both components. The formed HyPSomes were optimized by using dynamic light scattering, transmission electron microscopy, and Förster resonance energy transfer, and their stability was confirmed. The synthesized HyPSomes replicated the antigenic surface of the source cells and possessed the stability and efficacy of synthetic nanoparticles. These HyPSomes demonstrated enhanced cellular uptake and translation efficiency and facilitated endosome escape. HyPSomes showed outstanding capabilities for the delivery of foreign mRNAs to antigen-presenting cells. HyPSomes may serve as vaccine delivery systems by bridging the gap between synthetic and natural systems. These systems could be used in other contexts, e.g., diagnostics and drug delivery.

Current status of nano-vaccinology in veterinary medicine science

Vaccination programmes provide a safe, effective and cost-efficient strategy for maintaining population health. In veterinary medicine, vaccination not only reduces disease within animal populations but also serves to enhance public health by targeting zoonoses. Nevertheless, for many pathogens, an effective vaccine remains elusive. Recently, nanovaccines have proved to be successful for various infectious and non-infectious diseases of animals. These novel technologies, such as virus-like particles, self-assembling proteins, polymeric nanoparticles, liposomes and virosomes, offer great potential for solving many of the vaccine production challenges. Their benefits include low immunotoxicity, antigen stability, enhanced immunogenicity, flexibility sustained release and the ability to evoke both humoral and cellular immune responses. Nanovaccines are more efficient than traditional vaccines due to ease of control and plasticity in their physio-chemical properties. They use a highly targeted immunological approach which can provide strong and long-lasting immunity. This article reviews the currently available nanovaccine technology and considers its utility for both infectious diseases and non-infectious diseases such as auto-immunity and cancer. Future research opportunities and application challenges from bench to clinical usage are also discussed.

Next-Generation Vaccines: Nanovaccines in the Fight against SARS-CoV-2 Virus and beyond SARS-CoV-2

The virus responsible for the coronavirus viral pandemic is the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Emerging SARS-CoV-2 variants caused by distinctive mutations within the viral spike glycoprotein of SARS-CoV-2 are considered the cause for the rapid spread of the disease and make it challenging to treat SARS-CoV-2. The manufacturing of appropriate efficient vaccines and therapeutics is the only option to combat this pandemic. Nanomedicine has enabled the delivery of nucleic acids and protein-based vaccines to antigen-presenting cells to produce protective immunity against the coronavirus. Nucleic acid-based vaccines, particularly mRNA nanotechnology vaccines, are the best prevention option against the SARS-CoV-2 pandemic worldwide, and they are effective against the novel coronavirus and its multiple variants. This review will report on progress made thus far with SARS-CoV-2 vaccines and beyond employing nanotechnology-based nucleic acid vaccine approaches.

The Influence of Nanoparticle on Vaccine Responses against Bacterial Infection

Nowadays, nanovaccine is considered as an evolving method in the field of vaccination to induce immunity in the human body against various diseases, including bacterial or viral diseases as well as virulent tumors. Nanovaccines are more efficient than traditional vaccines since they could potentially induce both humoral and cellular immune reactions. Various studies have shown that nanoparticles with multiple compounds have been designed as delivery systems or as adjuvants for vaccines. Nanoparticles could function as a drug delivery tool, as an adjuvant to promote antigen processing, and as an immune modulator to induce immune responses. These nanoparticles generate immune responses through activating immune cells as well as through the production of antibody responses. Design engineering of nanoparticles (NPs) used to produce nanovaccines to induce immunity in the human body needs comprehensive information about the ways they interact with the component of immune system. Challenges remain due to the lack of sufficient and comprehensive information about the nanoparticles' mode of action. Several studies have described the interactions between various classes of nanoparticles and the immune system in the field of prevention of bacterial infections. The results of some studies conducted in recent years on the interaction between nanoparticles and biosystems have considerably affected the methods used to design nanoparticles for medical applications. In this review, NPs’ characteristics influencing their interplay with the immune system were discussed in vivo. The information obtained could lead to the development of strategies for rationalizing the design of nanovaccines in order to achieve optimum induction of immune response.

Think like a Virus: Toward Improving Nanovaccine Development against SARS-CoV-2

There is no doubt that infectious diseases present global impact on the economy, society, health, mental state, and even political aspects, causing a long-lasting dent, and the situation will surely worsen if and when the viral spread becomes out of control, as seen during the still ongoing coronavirus disease 2019 (COVID-19) pandemic. Despite the considerable achievements made in viral prevention and treatment, there are still significant challenges that can be overcome through careful understanding of the viral mechanism of action to establish common ground for innovating new preventative and treatment strategies. Viruses can be regarded as devil nanomachines, and one innovative approach to face and stop the spread of viral infections is the development of nanoparticles that can act similar to them as drug/vaccine carriers. Moreover, we can use the properties that different viruses have in designing nanoparticles that reassemble the virus conformational structures but that do not present the detrimental threats to human health that native viruses possess. This review discusses the current preventative strategies (i.e., vaccination) used in facing viral infections and the associated limitations, highlighting the importance of innovating new approaches to face viral infectious diseases and discussing the current nanoapplications in vaccine development and the challenges that still face the nanovaccine field.

Application of Nanoparticles in Tumour Targeted Drug Delivery and Vaccine

Cancer is a major cause of death worldwide, and nearly 1 in 6 deaths each year is caused by cancer. Traditional cancer treatment strategies cannot completely solve cancer recurrence and metastasis. With the development of nanotechnology, the study of nanoparticles (NPs) has gradually become a hotspot of medical research. NPs have various advantages. NPs exploit the enhanced permeability and retention (EPR) of tumour cells to achieve targeted drug delivery and can be retained in tumours long-term. NPs can be used as a powerful design platform for vaccines as well as immunization enhancers. Liposomes, as organic nanomaterials, are widely used in the preparation of nanodrugs and vaccines. Currently, most of the anticancer drugs that have been approved and entered clinical practice are prepared from lipid materials. However, the current clinical conversion rate of NPs is still extremely low, and the transition of NPs from the laboratory to clinical practice is still a substantial challenge. In this paper, we review the in vivo targeted delivery methods, material characteristics of NPs and the application of NPs in vaccine preparation. The application of nanoliposomes is also emphasized. Furthermore, the challenges and limitations of NPs are briefly discussed.

Oral organic nanovaccines against bacterial and viral diseases

Vaccines have saved millions of humans and animals from deadly diseases. Many vaccines are still under development to fight against lethal diseases. Indeed, subunit vaccines are a versatile approach with several advantageous attributes, but they lack strong immunogenicity. Nanotechnology is an avenue to vaccine development because nanoparticles may serve as nanocarriers and adjuvants, which are critical aspects for oral vaccines. This review provides an update of oral organic nanovaccines, describing suitable nanomaterials for oral vaccine design and recent (last five-year view) oral nanovaccine developments to fight against those principal pathogens causing human and animal diseases.

Nanocarriers-Assisted Needle-Free Vaccine Delivery Through Oral and Intranasal Transmucosal Routes: A Novel Therapeutic Conduit

Drug delivery using oral route is the most popular, convenient, safest and least expensive approach. It includes oral transmucosal delivery of bioactive compounds as the mucosal cavity offers an intriguing approach for systemic drug distribution. Owing to the dense vascular architecture and high blood flow, oral mucosal layers are easily permeable and can be an ideal site for drug administration. Recently, the transmucosal route is being investigated for other therapeutic candidates such as vaccines for their efficient delivery. Vaccines have the potential to trigger immune reactions and can act as both prophylactic and therapeutic conduit to a variety of diseases. Administration of vaccines using transmucosal route offers multiple advantages, the most important one being the needle-free (non-invasive) delivery. Development of needle-free devices are the most recent and pioneering breakthrough in the delivery of drugs and vaccines, enabling patients to avoid needles, reducing anxiety, pain and fear as well as improving compliance. Oral, nasal and aerosol vaccination is a novel immunization approach that utilizes a nanocarrier to administer the vaccine. Nanocarriers improve the bioavailability and serve as adjuvants to elicit a stronger immune response, resulting in increased effectiveness of vaccination. Drugs and vaccines with lower penetration abilities can also be delivered transmucosally while maintaining their biological function. The development of micro/nanocarriers for transmucosal delivery of macromolecules, vaccines and other substances is currently drawing much attention and a number of studies were performed recently. This comprehensive review is aimed to summarize the most recent investigations on needle-free and non-invasive approaches for the delivery of vaccines using oral transmucosal route, their strengths and associated challenges. The oral transmucosal vaccine delivery by nanocarriers is the most upcoming advancement in efficient vaccine delivery and this review would help further research and trials in this field.

Chemical Conjugation Strategies for the Development of Protein-Based Subunit Nanovaccines

The production of subunit nanovaccines relies heavily on the development of a vaccine delivery system that is safe and efficient at delivering antigens to the target site. Nanoparticles have been extensively investigated for vaccine delivery over the years, as they often possess self-adjuvanting properties. The conjugation of antigens to nanoparticles by covalent bonds ensures co-delivery of these components to the same subset of immune cells in order to trigger the desired immune responses. Herein, we review covalent conjugation strategies for grafting protein or peptide antigens onto other molecules or nanoparticles to obtain subunit nanovaccines. We also discuss the advantages of chemical conjugation in developing these vaccines.

Nanoparticles as delivery vehicles for antiviral therapeutic drugs

With the ongoing COVID-19 pandemic still escalating, many researchers are turning to nanotechnology as a method of treatment not only for this pandemic, but in preparation for the pandemics of the future. Given both a wide variety of biomaterials at their disposal and the recent rise of nanotechnology, scientists now have the means to release and distribute therapeutic drugs in a variety of ways. Such a variety permits medical professionals the ability to choose biomaterials and methods that would provide the best release and treatment methodologies for the viral ailment they are attempting to remedy. This integrative review discusses context of previous pandemics, viral pathogenesis, issues associated with the current state of antiviral delivery systems, numerous biomaterials used for this purpose, and further information regarding the ongoing global COVID-19 pandemic.

Nanoparticles and Vaccine Development

In spite of the progress of conventional vaccines, improvements are required due to concerns about the low immunogenicity of the toxicity, instability, and the need for multiple administrations of the vaccines. To overcome the mentioned problems, nanotechnology has recently been incorporated into vaccine development. Nanotechnology increasingly plays an important role in vaccine development nanocarrier-based delivery systems that offer an opportunity to increase the cellular and humoral immune responses. The use of nanoparticles in vaccine formulations allows not only enhanced immunogenicity and stability of antigen, but also targeted delivery and slow release. Over the past decade, nanoscale size materials such as virus-like particles, liposomes, ISCOMs, polymeric, inorganic nanoparticles and emulsions have gained attention as potential delivery vehicles for vaccine antigens, which can both stabilize vaccine antigens and act as adjuvants. This advantage is attributable to the nanoscale particle size, which facilitates uptake by Antigen- Presenting Cells (APCs), then leading to efficient antigen recognition and presentation. Modifying the surfaces of nanoparticles with different targeting moieties permits the delivery of antigens to specific receptors on the cell surface, thereby stimulating selective and specific immune responses. This review provides an overview of recent advances in nanovaccinology.

Biomaterials as Local Niches for Immunomodulation

A major function of the immune system is to detect threat from foreign invaders, tissue damage, or cancer and to mount a counter response that resolves the threat, restores homeostasis, and supplies immunological memory to prevent a second assault. Our increasing understanding of the immune system has opened up numerous avenues for modulating immune responses against infections, cancer, and autoimmunity. However, agents used for immunomodulation have been traditionally administered systemically via bolus injection, leading to unintended consequences by disrupting homeostasis at nontarget sites. Consequently, systemic hyperactivation and hypoactivation can result from bolus administration of immune-activators and immunosuppressants, respectively. Macroscale biomaterial scaffolds can instead be placed at the intended target site to provide both localized, controlled release of immunomodulatory agents and control over local immune cell trafficking and function, potentially maximizing therapeutic efficacy and limiting systemic exposure. These scaffolds have found utility in the area of cancer immunotherapy, especially in situ cancer vaccination where controlled release of factors such as granulocyte-macrophage colony-stimulating factor (GM-CSF) and the local presentation of tumor antigen and danger signals lead to the recruitment of immature dendritic cells and facilitate their activation and antigen presentation. These cells eventually migrate into secondary lymphoid organs where they prime tumor specific T cells for downstream tumor clearance. Scaffolds can also be used in adoptive T cell therapy to generate large numbers of potent antigen specific T cells or chimeric antigen receptor (CAR) T cells in vitro for subsequent delivery to patients. Macroscale biomaterial scaffolds have also found utility beyond cancer immunotherapy and have been developed to promote immune tolerance by regulatory T cell induction and to expedite tissue regeneration. The design of these macroscale biomaterial scaffolds considers their biocompatibility, biodegradability, mode of delivery, porosity, and kinetics of therapeutic cargo release. Consequently, the numerous approaches that have been developed to fabricate biomaterial scaffolds are aimed at tuning these parameters to achieve the desired therapeutic outcome. This Account will discuss the use of biomaterial scaffolds as niches for immunomodulation and will focus on (1) approaches that have been used to fabricate various biomaterial systems being employed as niches for immunomodulation and (2) how these biomaterial systems have been used to modulate immune responses, specifically in area of cancer immunotherapy, where we will discuss the role of macroscale biomaterial scaffolds for in situ vaccination and in vitro T cell expansion. We will also briefly discuss the utility of biomaterial scaffolds beyond cancer, drawing examples from tolerance and tissue regeneration.

Guijarro L, García-Honduvilla N, Álvarez-Mon M, Buján J, García-Gallego S. Dendrimers and Dendritic Materials: From Laboratory to Medical Practice in Infectious Diseases

Infectious diseases are one of the main global public health risks, predominantly caused by viruses, bacteria, fungi, and parasites. The control of infections is founded on three main pillars: prevention, treatment, and diagnosis. However, the appearance of microbial resistance has challenged traditional strategies and demands new approaches. Dendrimers are a type of polymeric nanoparticles whose nanometric size, multivalency, biocompatibility, and structural perfection offer boundless possibilities in multiple biomedical applications. This review provides the reader a general overview about the uses of dendrimers and dendritic materials in the treatment, prevention, and diagnosis of highly prevalent infectious diseases, and their advantages compared to traditional approaches. Examples of dendrimers as antimicrobial agents per se, as nanocarriers of antimicrobial drugs, as well as their uses in gene transfection, in vaccines or as contrast agents in imaging assays are presented. Despite the need to address some challenges in order to be used in the clinic, dendritic materials appear as an innovative tool with a brilliant future ahead in the clinical management of infectious diseases and many other health issues.

Advanced nanomedicine characterization by DLS and AF4-UV-MALS: Application to a HIV nanovaccine

Nanoformulations are complex systems where physicochemical properties determine their therapeutic efficacy and safety. In the case of nanovaccines, particle size and shape play a crucial role on the immune response generated. Furthermore, the antigen's integrity is also a key aspect to control when producing a nanovaccine. The determination of all those physicochemical properties is still an analytical challenge and the lack of well-established methods hinders the access of new therapeutics to the market. In this work, robust methods for the characterization of a novel HIV nanoparticle-based vaccine produced in good manufacturing practice (GMPs)-like environment were developed. With slightly polydisperse particles (< 0.2) close to 180 nm of size, batch-mode Dynamic Light Scattering (DLS) was validated to be used as a quality control technique in the pilot production plant. In addition, a high size resolution method using Asymmetrical Flow Field Flow Fractionation (AF4) demonstrated its ability to determine not only size and size distribution but also shape modification across the size and accurate quantification of the free active ingredient. Results showed a monomodal distribution of particles from 60 to 700 nm, most of them (> 90%) with size lower than 250 nm, consistent with more traditional techniques, and revealed a slight change in the structure of the particles induced by the presence of the antigen. Finally, a batch to batch variability lower than 20% was obtained by both DLS and AF4 methods indicating that preparation method was highly reproducible.

Drug-Loaded Biocompatible Nanocarriers Embedded in Poloxamer 407 Hydrogels as Therapeutic Formulations

Hydrogels are three-dimensional networks of hydrophilic polymers able to absorb and retain a considerable amount of water or biological fluid while maintaining their structure. Among these, thermo-sensitive hydrogels, characterized by a temperature-dependent sol–gel transition, have been massively used as drug delivery systems for the controlled release of various bioactives. Poloxamer 407 (P407) is an ABA-type triblock copolymer with a center block of hydrophobic polypropylene oxide (PPO) between two hydrophilic polyethyleneoxide (PEO) lateral chains. Due to its unique thermo-reversible gelation properties, P407 has been widely investigated as a temperature-responsive material. The gelation phenomenon of P407 aqueous solutions is reversible and characterized by a sol–gel transition temperature. The nanoencapsulation of drugs within biocompatible delivery systems dispersed in P407 hydrogels is a strategy used to increase the local residence time of various bioactives at the injection site. In this mini-review, the state of the art of the most important mixed systems made up of colloidal carriers localized within a P407 hydrogel will be provided in order to illustrate the possibility of obtaining a controlled release of the entrapped drugs and an increase in their therapeutic efficacy as a function of the biomaterial used.