Current Medicinal Chemistry - Volume 28, Issue 31, 2021

Nanoparticles are widely used in cancer therapy because of their nanoscale, high surface ratio, multifunctionality and so on. With specific construction of nanoparticles, by choosing magnetic nanomaterials or citric acid-coated nanoparticle, scientists can kill tumor cells effectively and accurately, importantly reducing the side effects of conventional chemotherapy. Scientists not only have designed nanoparticles loaded with therapeutic drugs, but also those equipped with targeted molecules. These works have made nanoparticles multifunctional nanocarriers. As multifunctional nanocarriers, nanoparticles play an important role of drug delivery and normally, enabling drug delivery to tumor tissues is a difficult task. During the period of internal circulation, it is hard to maintain the stability of the nanocarriers not attached to normal cells or serum. With the application of stimulus-responsive nanomaterials, scientists have developed many nanocarriers with controllable drug release. These controllable drug delivery systems can quickly respond to microenvironmental changes (PH, enzyme, etc.) or external stimuli (photo, heat, magnetic or electric fields). Thus, to overcome the side effects of controllable drug delivery systems in vivo, in this article, we summarize the various kinds of stimulus-responsive nanocarriers for cancer therapy and discuss the possibilities and challenges in future application.

Point-of-care (POC) testing decentralizes the diagnostic tests to the sites near the patient. Many POC tests rely on microfluidic platforms for sample-to-answer analysis. Compared to other microfluidic systems, magnetic digital microfluidics demonstrate compelling advantages for POC diagnostics. In this review, we have examined the capability of magnetic digital microfluidics-based POC diagnostic platforms. More importantly, we have categorized POC settings into three classes based on “where is the point”, “who to care” and “how to test”, and evaluated the suitability of magnetic digital microfluidics in various POC settings. Furthermore, we have addressed other technical issues associated with POC testing, such as controlled environment, sample-system interface, system integration and information connectivity. We hope this review would provide a guideline for the future development of magnetic digital microfluidics-based platforms for POC testing.

Leishmaniasis, a complex disease caused by at least 20 species of unicellular parasites of the genus Leishmania, disproportionately affects impoverished regions of about 90 tropical and sub-tropical countries. Currently available antileishmanial therapies, particularly for visceral leishmaniasis, are severely limited, with treatment outcome depending on many factors, including the immune status of the patient, comorbidities, malnutrition, and socio-economic conditions in the patient’s geographic location. There is an urgent need for new therapeutics, particularly new effective oral drugs, for visceral leishmaniasis. Despite the availability of the Leishmania genome sequence information and significant research into the biology of the parasites, antileishmanial drug development is hampered by the lack of knowledge about druggable targets in the parasite and difficulties in identifying the molecular targets of compounds that show activity. In this context, we analyzed recent progress in antileishmanial drug development programs, which take advantage of different powerful approaches, such as high-throughput screening of compound libraries, recent developments in genetic methods for assessing essentiality of parasite genes, and chemical, genetic, and proteomics-based target discovery and target validation methods.

Paclitaxel (PTX) is the first natural plant-derived chemotherapeutic drug approved by the Food and Drug Administration. However, the clinical applications of PTX are limited by some drawbacks, such as poor water solubility, rapid blood clearance, nonspecific distribution, and adverse side effects. Nanocarriers have made important contributions to drug delivery and cancer therapy in recent years. However, low drug loading capacity, nanocarrier excipients-induced toxicity or immunogenicity, and complicated synthesis technologies pose a challenge for the clinical application of nanocarriers. To address these issues, the self-delivery nanomedicine (SDNs), in which pure drug molecules directly self-assemble into nanomedicine, have been developed for drug delivery and enhancing antitumor efficacy. In this review, we comprehensively summarize the recent advances in PTX-based SDNs for cancer therapy. First, the self-assembly strategies to develop pure PTX nanodrugs are discussed. Then, the emerging strategies of co-assembly PTX and other therapeutic agents for effective combination therapy are presented, composing of combination chemotherapy, chemo-photothermal therapy, chemo-photodynamic therapy, chemo-immunotherapy, and chemo-gene therapy. Finally, the limitations and future outlook of SDNs are discussed. The rational design of these unique nanoplatforms may make a new direction to develop highly efficient drug delivery systems for cancer therapy.

Background: Parkinson’s disease (PD) is one of the most common neurological disorders that can severely affect the ability to perform daily activities. The clinical presentation of PD includes motor and nonmotor symptoms. The motor symptoms generally involve movement conditions like tremors, rigidity, slowness, and impaired balance. In contrast, the nonmotor symptoms are often not apparent but can affect various organ systems, such as the urinary and gastrointestinal systems, and mental health. Gene mutations and toxic environmental factors have contributed significantly to PD; nevertheless, its cause and underlying mechanism remain unknown. Currently, treatments such as dopamine agonists, RNA molecules, and antioxidants can, to some extent, alleviate the motor symptoms triggered by PD. However, these medicines cannot effectively halt ongoing dopaminergic damage, mainly because the blood-brain barrier (BBB) lowers the efficiency of drug delivery. Recently, extracellular vesicles (EVs), a novel drug delivery platform, have been widely used in various neurological diseases, including stroke and brain tumors, because of their excellent biocompatibility, their ability to penetrate the BBB without toxicity, and their target specificity. EVs thus provide a promising therapeutic for treating PD. Objective: This review focuses on novel therapies based on EVs in practice. Herein, we briefly introduce the biogenesis, composition, isolation, and characterization of EVs, and we discuss strategies for loading therapeutic agents onto EVs and recent applications for PD treatment. Moreover, we discuss perspectives on the direction of preclinical and clinical studies regarding novel and effective therapies. Methods: A literature search regarding PD treatment based on extracellular vesicles was performed in PubMed (updated in June 2020). Treatment, therapy, drug delivery, extracellular vesicles, and their combinations were the search queries. Both systematic reviews and original publications were included. Searched results were selected and compared based on relevance. Articles published in the last five years were given top priority. Conclusion: PD is a heterogeneous disease that can be treated by using pharmacologic approaches (e.g. dopamine agonists and levodopa) and nonpharmacologic approaches (e.g. music), based on symptoms and progression level in patients. Even though current treatments have demonstrated effectiveness, clinical challenges remain because the BBB reduces the medication received and lowers the efficacy of drug delivery, which impairs the treatment’s effect. Therefore, EVs, as an emerging delivery platform, are highly promising for PD treatment since they can readily cross the BBB with high therapeutic efficiency through the loading or functionalization process. However, defining a safe source of EVs, reliably purifying and isolating EVs with high yield, and improving the efficacy of therapeutic loading in EVs remain challenging in this field. Therefore, future investigations should focus on generating large-scale exosomal carriers and designing new effective drugs encapsulated in EVs for better efficacy.

Cancer is composed of a series of uncontrollable cells, which finally form tumors to negatively impact the functions of the body and induce other serious diseases, even leading to death. During the last decades, scientists have devoted great efforts to study cancer; however, there are no effective diagnoses and treatments. Nanomaterials have attracted great attention in the biomedical field in recent years, which are widely used as optical imaging probes and delivery systems for cancer therapy. Among the numerous nanomaterials, polymeric nanoparticles occupy a prominent position because of their tunable micro-size, multifunctional surface, prominent biocompatibility and high drug-carrying capacity. These significant advantages of polymeric nanomaterials have significance over the traditional nanomaterials and have become a potential therapy for cancer. In this review, we focus on the applications of polymeric nanoparticles in cancer theranostics, especially as the drug delivery systems for cancer treatment. This review provides an overview on the advancement of synthesis, application of polymeric nanoparticles- based drug delivery systems and highlights the evaluation for cancer therapy.

Nanoparticles hold great promise in tumor targeting and molecular imaging because they can co-deliver therapeutic drugs and imaging agents to the tumor site with a single entity. Nanoparticles modified with ligands against moieties overexpressed on tumor tissues have gained increasing attention due to their active targeting mechanisms. Peptides are well suited for nanoparticle targeting modifications because they are small, easy to synthesize and typically non-immunogenic. Herein, we review the peptide-modified nanoparticles used for tumor targeting therapy and molecular imaging based on the classification of peptide-targeting ligands. The development of targeting peptides and nanoparticles will also be discussed.

Photodynamic Therapy (PDT), as a clinically approved modality for the treatment of various disordered diseases including cancer, has received great advances in recent years. By preferentially accumulating non-toxic Photosensitizers (PSs) in the pathological area, and in situ generation of cytotoxic reactive oxygen species (ROS) under local irradiation by a light source with appropriate wavelength, PDT works in a dual-selective manner. Over the past decades, numerous studies and reviews on PDT mainly focused on activable PSs and the newly emerging PSs in PDT. However, to the best of our knowledge, there are few articles on the systematic introduction of light sources and limited reports about targeted strategies in PDT. This review comprehensively summarizes various light sources applied in PDT together with typical enhanced targeting strategies, and outlines their advantages and disadvantages, respectively. The clinical applications and future perspectives in light sources are also partly presented and discussed.

Osteoarthritis (OA) is a degenerative disease of cartilage and bones, which results in severely compromised quality of life in the aged population. However, currently, no ideal treatment strategies have been developed to prevent OA progression. Cell therapies, such as chondrocyte and MSC transplantation, have been extensively tested and evaluated in clinical trials. Yet, to day, the clinical efficacy of articular injection of stem cells in OA has not been convincingly demonstrated. Recent studies have indicated that exosomes, one type of Extracellular Vesicles (EVs) play an important regulatory role in the pathogenesis of OA, suggesting the prospective therapeutic application of exosomes in OA treatment. In this review, we systematically summarized the paracrine effects of exosomes derived from MSCs and chondrocytes on cartilage regeneration, the use of exosomes as a delivery vehicle for OA treatment, the effectiveness of such treatments in OA animal models, and the future perspective of exosome-mediated drug delivery as a cell- free therapy of OA.

There is a momentous surge in the development of stem cell technology, such as therapeutic and diagnostic tools. Stem cell-derived cells are currently used in various clinical trials. However, key issues and challenges faced involve the low differentiation efficiency, integration and functioning of transplanted stem cells-derived cells. Extraction of bone marrow, adipose or other mesenchymal stem cells (MSCs) involves invasive methods, specialized skills and expensive technologies. Urine-derived cells, on the other hand, are obtained by non-invasive methods; samples can be obtained repeatedly from patients of any age. Urine-derived cells are used to generate reprogrammed or induced pluripotent stem cells (iPSCs) which can be cultured and differentiated into various types of cell lineages for biomedical investigations and drug testing in vitro or in vivo using model animals of human diseases. Urine cells-derived iPSCs (UiPSCs) have emerged as a major area of research having immense therapeutic significance. Given that preliminary preclinical studies are successful in terms of safety and as a regenerative tool, the UiPSCs will pave the way to the development of various types of autologous stem cell therapies.