A pharmaceutical investigation into exosomes

Immune cells: potential carriers or agents for drug delivery to the central nervous system

Drug delivery systems (DDS) have recently emerged as a promising approach for the unique advantages of drug protection and targeted delivery. However, the access of nanoparticles/drugs to the central nervous system (CNS) remains a challenge mainly due to the obstruction from brain barriers. Immune cells infiltrating the CNS in the pathological state have inspired the development of strategies for CNS foundation drug delivery. Herein, we outline the three major brain barriers in the CNS and the mechanisms by which immune cells migrate across the blood-brain barrier. We subsequently review biomimetic strategies utilizing immune cell-based nanoparticles for the delivery of nanoparticles/drugs to the CNS, as well as recent progress in rationally engineering immune cell-based DDS for CNS diseases. Finally, we discuss the challenges and opportunities of immune cell-based DDS in CNS diseases to promote their clinical development.

Innovations in Stem Cell Therapy for Diabetic Wound Healing

Significance: The global burden of diabetic wounds, particularly diabetic foot ulcers, continues to have large economic and social impact throughout the world. Current strategies are not sufficient to overcome this burden of disease. Finding newer, more advanced regenerative cell and tissue-based strategies to reduce morbidity remains paramount. Recent Advances: Recent advances in stem cell therapies are discussed. We also highlight the practical issues of translating these advancing technologies into the clinical setting. Critical Issues: We discuss the use of somatic and induced pluripotent stem cells and the stromal vascular fraction, as well as innovations, including the use of 3D bioprinting of skin. We also explore related issues of using regenerative techniques in clinical practice, including the current regulatory landscape and translatability of in vivo research. Future Directions: Advances in stem cell manipulation showcase the best therapeutic resources available to enhance mechanisms of wound healing such as angiogenesis, cell proliferation, and collagen synthesis; potential methods include changing the scaffold microenvironment, including relative oxygen tension, and the use of gene modification and nanotechnology. Secretome engineering, particularly the use of extracellular vesicles, may be another potential cell-derived therapeutic that may enable use of cell-free translational therapy.

Small extracellular vesicles as key players in cancer development caused by human oncogenic viruses

Background

Exosomes are the smallest group of extracellular vesicles in size from 30 to 150 nm, surrounded by a lipid bilayer membrane, and originate from multivesicular bodies secreted by different types of cells, such as virus-infected cells. The critical role of exosomes is information transfer among cells, representing a unique way for intercellular communication via a load of many kinds of molecules, including various signaling proteins and nucleic acids. In this review, we aimed to comprehensively investigate the role of exosomes in promoting human oncogenic viruses-associated cancers.

Methods

Our search was conducted for published researches between 2000 and 2022 by using several international databases includeing Scopus, PubMed, and Web of Science as well as Google scholar. We also reviewed additional evidence from relevant published articles.

Results

It has been shown that exosomes can create the conditions for viral spread in viral infections. Exosome secretion in a human tumor virus can switch on the cell signaling pathways by transferring exosome-encapsulated molecules, including viral oncoproteins, signal transduction molecules, and virus-encoded miRNAs, into various cells.

Conclusion

Given the role of exosomes in viruses-associated cancers, they can also be considered as molecular targets in diagnosis and treatment.

Determination of the Loading Capacity and Recovery of Extracellular Vesicles Derived from Human Embryonic Kidney Cells and Urine Matrices on Capillary-Channeled Polymer (C-CP) Fiber Columns

Extracellular vesicles (EVs) are 50–1000 nm membranous vesicles secreted from all cells that play important roles in many biological processes. Exosomes, a smaller-sized subset of EVs, have become of increasing interest in fundamental biochemistry and clinical fields due to their rich biological cargos and their roles in processes such as cell-signaling, maintaining homeostasis, and regulating cellular functions. To be implemented effectively in fundamental biochemistry and clinical diagnostics fields of study, and for their proposed use as vectors in gene therapies, there is a need for new methods for the isolation of large concentrations of high-purity exosomes from complex matrices in a timely manner. To address current limitations regarding recovery and purity, described here is a frontal throughput and recovery analysis of exosomes derived from human embryonic kidney (HEK) cell cultures and human urine specimens using capillary-channeled polymer (C-CP) fiber stationary phases via high performance liquid chromatography (HPLC). Using the C-CP fiber HPLC method for EV isolations, the challenge of recovering purified EVs from small sample volumes imparted by the traditional techniques was overcome while introducing significant benefits in processing, affordability (~5 $ per column), loading (~1012 particles), and recovery (1011–1012 particles) from whole specimens without further processing requirements.

Efficient extracellular vesicles freeze-dry method for direct formulations preparation and use

Despite the great knowledge achieved in the field of extracellular vesicles (EVs), the short lifetime of EVs liquid formulation still hampers the transfer of EVs technology to clinical applications. In this context, freeze-dried EVs would be advantageous thanks to the enhanced stability of solid formulations. Although some previous attempts have already been reported, the efficiency of EVs lyophilization methodologies used remains insufficient, and the characterization of the resulting EVs is still incomplete. The current work aims to describe an alternative and easy-to-be-applied methodology for EVs lyophilization. The use of sucrose as lyoprotectant at 8.5%wt improved the cryopreservation efficiency. After the subsequent cycles of freeze-drying, properties such as size, morphology, purity, EVs specific markers, biocompatibility and the maintenance of their functionality were confirmed in freeze-dried EVs samples. To sum up, we have designed a methodology for the lyophilization of extracellular vesicles that enables the preservation of the physicochemical properties and functionality of EVs.

Recent progresses in exosome-based systems for targeted drug delivery to the brain

Despite the multiple ongoing and novel initiatives for developing brain-targeted drug delivery systems, insurmountable obstacles remain. A perfect drug delivery device that can bypass the brain-blood barrier and boost therapeutic efficacy is urgently needed for clinical applications. Exosomes hold unrivaled benefits as a drug delivery vehicle for treating brain diseases due to their endogenous and innate attributes. Unique properties, such as the ability to penetrate physical barriers, biocompatibility, innate targeting features, ability to leverage natural intracellular trafficking pathways, favored tumor homing, and stability, make exosomes suitable for brain-targeted drug delivery. Herein, we provide an overview of recent exosome-based drug delivery nanoplatforms and discuss how these inherent vesicles can be used to deliver therapeutic agents to the brain to cure neurodegenerative diseases, brain tumors, and other brain disorders. Moreover, we review the current roadblocks associated with exosomes and other brain-targeted drug delivery systems and discuss future directions for achieving successful therapy outcomes.

NK Cells in the Tumor Microenvironment as New Potential Players Mediating Chemotherapy Effects in Metastatic Melanoma

Until the last decade, chemotherapy was the standard treatment for metastatic cutaneous melanoma, even with poor results. The introduction of immune checkpoints inhibitors (ICIs) radically changed the outcome, increasing 5-year survival from 5% to 60%. However, there is still a large portion of unresponsive patients that would need further therapies. NK cells are skin-resident innate cytotoxic lymphocytes that recognize and kill virus-infected as well as cancer cells thanks to a balance between inhibitory and activating signals delivered by surface molecules expressed by the target. Since NK cells are equipped with cytotoxic machinery but lack of antigen restriction and needing to be primed, they are nowadays gaining attention as an alternative to T cells to be exploited in immunotherapy. However, their usage suffers of the same limitations reported for T cells, that is the loss of immunogenicity by target cells and the difficulty to penetrate and be activated in the suppressive tumor microenvironment (TME). Several evidence showed that chemotherapy used in metastatic melanoma therapy possess immunomodulatory properties that may restore NK cells functions within TME. Here, we will discuss the capability of such chemotherapeutics to: i) up-regulate melanoma cells susceptibility to NK cell-mediated killing, ii) promote NK cells infiltration within TME, iii) target other immune cell subsets that affect NK cells activities. Alongside traditional systemic melanoma chemotherapy, a new pharmacological strategy based on nanocarriers loaded with chemotherapeutics is developing. The use of nanotechnologies represents a very promising approach to improve drug tolerability and effectiveness thanks to the targeted delivery of the therapeutic molecules. Here, we will also discuss the recent developments in using nanocarriers to deliver anti-cancer drugs within the melanoma microenvironment in order to improve chemotherapeutics effects. Overall, we highlight the possibility to use standard chemotherapeutics, possibly delivered by nanosystems, to enhance NK cells anti-tumor cytotoxicity. Combined with immunotherapies targeting NK cells, this may represent a valuable alternative approach to treat those patients that do not respond to current ICIs.

Freeze-Dried Mesenchymal Stem Cell-Secretome Pharmaceuticalization: Optimization of Formulation and Manufacturing Process Robustness

Producing mesenchymal stem cell (MSC)-secretome for dose escalation studies and clinical practice requires scalable and good manufacturing practice (GMP)-compliant production procedures and formulation into a standardized medicinal product. Starting from a method that combines ultrafiltration and freeze-drying to transform MSC-secretome into a pharmaceutical product, the lyosecretome, this work aims to: (i) optimize the lyosecretome formulation; (ii) investigate sources of variability that can affect the robustness of the manufacturing process; (iii) modify the ultrafiltration step to obtain a more standardized final product. Design of experiments and principal component analysis of the data were used to study the influence of batch production, lyophilization, mannitol (M)/sucrose (S) binary mixture, selected as cryoprotectant excipients, and the total amount of excipients on the extracellular vesicles (EV) particle size, the protein and lipid content and the in vitro anti-elastase. The different excipients ratios did not affect residual moisture or EV particle size; simultaneously, proteins and lipids were better preserved in the freeze-dried product using the maximum total concentration of excipients (1.5% w/v) with a M:S ratio of about 60% w/w. The anti-elastase activity was instead better preserved using 0.5% w/w of M as excipient. The secretome batch showed to be the primary source of variability; therefore, the manufacturing process has been modified and then validated: the final product is now concentrated to reach a specific protein (and lipid) concentration instead of cell equivalent concentration. The new standardization approach led to a final product with more reproducible quali-quantitative composition and higher biological activity.

Long-Term Antitumor CD8+ T Cell Immunity Induced by Endogenously Engineered Extracellular Vesicles

Simple Summary

The induction of an effective immune response against tumor cells is of a great benefit in the battle against cancers. We recently characterized a novel, safe, and cost-effective strategy to induce an efficient CD8⁺ T cell immune response against potentially whatever antigen. This technique is based on in vivo engineering of exosomes/extracellular vesicles (EVs), i.e., nanovesicles constitutively released by all healthy cells. Immunogenic EVs are generated by intramuscular injection of a DNA vector expressing an EV-anchoring protein fused with the antigen of interest. In this paper, we applied our vaccine platform to counteract the growth of tumors expressing antigens of Human Papilloma Virus (HPV). We demonstrated that this method is instrumental in curing mice already developing HPV-related tumors. In addition, cured mice were shown to resist a second tumor cell implantation. These results could be of relevance for a possible translation into the clinic of our technology.

Abstract

We developed an innovative method to induce antigen-specific CD8⁺ T cytotoxic lymphocyte (CTL) immunity based on in vivo engineering of extracellular vesicles (EVs). This approach employs a DNA vector expressing a mutated HIV-1 Nef protein (Nef^mut) deprived of the anti-cellular effects typical of the wild-type isoform, meanwhile showing an unusual efficiency of incorporation into EVs. This function persists even when foreign antigens are fused to its C-terminus. In this way, Nef^mut traffics large amounts of antigens fused to it into EVs spontaneously released by the recipient cells. We previously provided evidence that mice injected with a DNA vector expressing the Nef^mut/HPV16-E7 fusion protein developed an E7-specific CTL immune response as detected 2 weeks after the second immunization. Here, we extended and optimized the anti-HPV16 CD8⁺ T cell immune response induced by the endogenously engineered EVs, and evaluated the therapeutic antitumor efficacy over time. We found that the co-injection of DNA vectors expressing Nef^mut fused with E6 and E7 generated a stronger anti-HPV16 immune response compared to that observed in mice injected with the single vectors. When HPV16-E6 and -E7 co-expressing tumor cells were implanted before immunization, all mice survived at day 44, whereas no mice injected with either void or Nef^mut-expressing vectors survived until day 32 after tumor implantation. A substantial part of immunized mice (7 out of 12) cleared the tumor. When the cured mice were re-challenged with a second tumor cell implantation, none of them developed tumors. Both E6- and E7-specific CD8⁺ T immunities were still detectable at the end of the observation time. We concluded that the immunity elicited by engineered EVs, besides counteracting and curing already developed tumors, was strong enough to guarantee the resistance to additional tumor attacks. These results can be of relevance for the therapy of both metastatic and relapsing tumors.

Scalable Production and Isolation of Extracellular Vesicles: Available Sources and Lessons from Current Industrial Bioprocesses

Potential applications of extracellular vesicles (EVs) are attracting increasing interest in the fields of medicine, cosmetics, and nutrition. However, the manufacturing of EVs is currently characterized by low yields. This limitation severely hampers progress in research at the laboratory and clinical scales, as well as the realization of successful and cost-effective EV-based products. Moreover, the high level of heterogeneity of EVs further complicates reproducible manufacturing on a large scale. In this review, possible directions toward the scalable production of EVs are discussed. In particular, two strategies are considered: i) the optimization of upstream unit operations and ii) the exploitation of well-established and mature technologies already in use in other industrial bioprocesses.