Recent advances in mechanical force-assisted transdermal delivery of macromolecular drugs

Smart Physical-Based Transdermal Drug Delivery System:Towards Intelligence and Controlled Release

Transdermal drug delivery systems based on physical principles have provided a stable, efficient, and safe strategy for disease therapy. However, the intelligent device with real-time control and precise drug release is required to enhance treatment efficacy and improve patient compliance. This review summarizes the recent developments, application scenarios, and drug release characteristics of smart transdermal drug delivery systems fabricated with physical principle. Special attention is paid to the progress of intelligent design and concepts in of physical-based transdermal drug delivery technologies for real-time monitoring and precise drug release. In addition, facing with the needs of clinical treatment and personalized medicine, the recent progress and trend of physical enhancement are further highlighted for transdermal drug delivery systems in combination with pharmaceutical dosage forms to achieve better transdermal effects and facilitate the development of smart medical devices. Finally, the next generation and future application scenarios of smart physical-based transdermal drug delivery systems are discussed, a particular focus in vaccine delivery and tumor treatment.

DNA-Based Nonviral Gene Therapy─Challenging but Promising

Over the past decades, significant progress has been made in utilizing nucleic acids, including DNA and RNA molecules, for therapeutic purposes. For DNA molecules, although various DNA delivery systems have been established, viral vector systems are the go-to choice for large-scale commercial applications. However, viral systems have certain disadvantages such as immune response, limited payload capacity, insertional mutagenesis and pre-existing immunity. In contrast, nonviral systems are less immunogenic, not size limited, safer, and easier for manufacturing compared with viral systems. What's more, nonviral DNA vectors have demonstrated their capacity to mediate specific protein expression in vivo for diverse therapeutic objectives containing a wide range of diseases such as cancer, rare diseases, neurodegenerative diseases, and infectious diseases, yielding promising therapeutic outcomes. However, exogenous plasmid DNA is prone to degrade and has poor immunogenicity in vivo. Thus, various strategies have been developed: (i) designing novel plasmids with special structures, (ii) optimizing plasmid sequences for higher expression, and (iii) developing more efficient nonviral DNA delivery systems. Based on these strategies, many interesting clinical results have been reported. This Review discusses the development of DNA-based nonviral gene therapy, including novel plasmids, nonviral delivery systems, clinical advances, and prospects. These developments hold great potential for enhancing the efficacy and safety of nonviral gene therapy and expanding its applications in the treatment of various diseases.

The use of electroporation to deliver DNA-based vaccines

INTRODUCTION

Nucleic acids represent a promising platform for creating vaccines. One disadvantage of this approach is its relatively low immunogenicity. Electroporation (EP) is an effective way to increase the DNA vaccines immunogenicity. However, due to the different configurations of devices used for EP, EP protocols optimization is required not only to enhance immunogenicity, but also to ensure greater safety and tolerability of the EP procedure.

AREA COVERED

An data analysis for recent years on the DNA vaccines delivery against viral and parasitic infections using EP was carried out. The study of various EP physical characteristics, such as frequency, pulse duration, pulse interval, should be considered along with the immunogenic construct design and the site of delivery of the vaccine, through the study of the immunogenic and protective characteristics of the latter.

EXPERT OPINION

Future research should focus on regulating the humoral and cellular response required for protection against infectious agents by modifying the EP protocol. Significant efforts will be directed to establishing the possibility of redirecting the immune response toward the Th1 or Th2 response by changing the EP physical parameters. It will allow for an individual selective approach during EP, depending on the pathogen type of an infectious disease.

Polysaccharide hydrogel platforms as suitable carriers of liposomes and extracellular vesicles for dermal applications

Lipid-based nanocarriers have been extensively investigated for their application in drug delivery. Particularly, liposomes are now clinically established for treating various diseases such as fungal infections. In contrast, extracellular vesicles (EVs) - small cell-derived nanoparticles involved in cellular communication - have just recently sparked interest as drug carriers but their development is still at the preclinical level. To drive this development further, the methods and technologies exploited in the context of liposome research should be applied in the domain of EVs to facilitate and accelerate their clinical translation. One of the crucial steps for EV-based therapeutics is designing them as proper dosage forms for specific applications. This review offers a comprehensive overview of state-of-the-art polysaccharide-based hydrogel platforms designed for artificial and natural vesicles with application in drug delivery to the skin. We discuss their various physicochemical and biological properties and try to create a sound basis for the optimization of EV-embedded hydrogels as versatile therapeutic avenues.

Development of a HPLC fluorometric method for the quantification of enfuvirtide following in vitro releasing studies on thermosensitive in situ forming gel

Due to the presence of peptidase and protease in the gastrointestinal tract, peptides are subjected to digestion and inactivation when administrated orally. To avoid degradation and maintain the desired efficacy of peptide drugs, there is a demand to develop transdermal and intradermal delivery systems. This requires efficient and specific analytical methods to separate and quantify the peptide drugs from the formulation and the skin matrix in the early stages of pharmaceutical development. A high-performance liquid chromatography (HPLC) system equipped with a fluorometric detector was used to quantify enfuvirtide, which is the first fusion inhibitor for HIV treatment. The HPLC method was developed and validated according to the ICH Q2(R1) guidelines. The viability of the method was demonstrated during in vitro studies, where samples were analysed following intradermal administration of a thermosensitive in situ forming gel. Compared with previously reported methods, this assay proved efficient, sensitive and accurate, with a detection limit of 0.74 μg/mL and a run time of 9 min, mitigating the use of any internal standards and detergents. The addition of an organic solvent to the samples successfully solved the problem of low recovery caused by the adsorption of the drug to the plastic consumables in the sample treatment process. The amount of enfuvirtide releasing from the in situ gel through skin after 7 hours was 16.25 ± 7.08 μg, which was significantly lower than the reconstituted FUZEON^® itself (26.68 ± 10.45 μg), showing a longer release profile. The results may be beneficial as a constructive input for future enfuvirtide quantification within a preclinical setting through in vitro release studies across the skin.

Ultrasound-targeted microbubble destruction remodels tumour microenvironment to improve immunotherapeutic effect

Cancer immunotherapy (CIT) has gained increasing attention and made promising progress in recent years, especially immune checkpoint inhibitors such as antibodies blocking programmed cell death 1/programmed cell death ligand 1 (PD-1/PD-L1) and cytotoxic T lymphocyte-associated protein 4 (CTLA-4). However, its therapeutic efficacy is only 10-30% in solid tumours and treatment sensitivity needs to be improved. The complex tissue environment in which cancers originate is known as the tumour microenvironment (TME) and the complicated and dynamic TME is correlated with the efficacy of immunotherapy. Ultrasound-targeted microbubble destruction (UTMD) is an emerging technology that integrates diagnosis and therapy, which has garnered much traction due to non-invasive, targeted drug delivery and gene transfection characteristics. UTMD has also been studied to remodel TME and improve the efficacy of CIT. In this review, we analyse the effects of UTMD on various components of TME, including CD8⁺ T cells, tumour-infiltrating myeloid cells, regulatory T cells, natural killer cells and tumour vasculature. Moreover, UTMD enhances the permeability of the blood-brain barrier to facilitate drug delivery, thus improving CIT efficacy in vivo animal experiments. Based on this, we highlight the potential of immunotherapy against various cancer species and the clinical application prospects of UTMD.

Improved DNA Vaccine Delivery with Needle-Free Injection Systems

DNA vaccines have inherent advantages compared to other vaccine types, including safety, rapid design and construction, ease and speed to manufacture, and thermostability. However, a major drawback of candidate DNA vaccines delivered by needle and syringe is the poor immunogenicity associated with inefficient cellular uptake of the DNA. This uptake is essential because the target vaccine antigen is produced within cells and then presented to the immune system. Multiple techniques have been employed to boost the immunogenicity and protective efficacy of DNA vaccines, including physical delivery methods, molecular and traditional adjuvants, and genetic sequence enhancements. Needle-free injection systems (NFIS) are an attractive alternative due to the induction of potent immunogenicity, enhanced protective efficacy, and elimination of needles. These advantages led to a milestone achievement in the field with the approval for Restricted Use in Emergency Situation of a DNA vaccine against COVID-19, delivered exclusively with NFIS. In this review, we discuss physical delivery methods for DNA vaccines with an emphasis on commercially available NFIS and their resulting safety, immunogenic effectiveness, and protective efficacy. As is discussed, prophylactic DNA vaccines delivered by NFIS tend to induce non-inferior immunogenicity to electroporation and enhanced responses compared to needle and syringe.

PROTAC Degraders of Androgen Receptor-Integrated Dissolving Microneedles for Androgenetic Alopecia and Recrudescence Treatment via Single Topical Administration

Androgenetic alopecia (AGA) is a transracial and cross-gender disease worldwide with a youth-oriented tendency, but it lacks effective treatment. The binding of androgen receptor (AR) and androgen plays an essential role in the occurrence and progression of AGA. Herein, novel proteolysis targeting chimera degrader of AR (AR-PROTAC) is synthesized and integrated with dissolving microneedles (PROTAC-MNs) to achieve AR destruction in hair follicles for AGA treatment. The PROTAC-MNs possess adequate mechanical capabilities for precise AR-PROTAC delivery into the hair follicle-residing regions for AR degradation. After applying only once topically, the PROTAC-MNs achieve an accelerated onset of hair regeneration as compared to the daily application of the first-line topical drug minoxidil. Intriguingly, PROTAC-MNs via single administration still realize superior hair regeneration in AGA recrudescence, which is the major drawback of minoxidil in clinical practice. With the degradation of AR, the PROTAC-MNs successfully regulate the signaling cascade related to hair growth and activate hair follicle stem cells. Furthermore, the PROTAC-MNs do not cause systemic toxicity or androgen deficiency-related chaos in vivo. Collectively, these AR-degrading dissolving microneedles with long-lasting efficacy, one-step administration, and high biocompatibility provide a great therapeutic potential for AGA treatment.

Design and Analysis: Servo-Tube-Powered Liquid Jet Injector for Drug Delivery Applications

The current state of commercially available needle-free liquid jet injectors for drug delivery offers no way of controlling the output pressure of the device in real time, as the driving mechanism for these injectors provides a fixed delivery pressure profile. In order to improve the delivery efficiency as well as the precision of the targeted tissue depth, it is necessary to develop a power source that can accurately control the plunger velocity. The duration of a liquid jet injection can vary from 10 to 100 ms, and it generate acceleration greater than 2 g (where g is the gravity); thus, a platform for real-time control must exhibit a response time greater than 1 kHz and good accuracy. Improving the pioneering work by Taberner and others whereby a Lorentz force actuator based upon a voice coil is designed, this study presents a prototype injector system with greater controllability based on the use of a fully closed-loop control system and a classical three-phase linear motor consisting of three fixed coils and multiple permanent magnets. Apart from being capable of generating jets with a required stagnation pressure of 15–16 MPa for skin penetration and liquid injection, as well as reproducing typical injection dynamics using commercially available injectors, the novelty of this proposed platform is that it is proven to be capable of shaping the real-time jet injection pressure profile, including pulsed injection, so that it can later be tailored for more efficient drug delivery.

Ultrasound triggered organic mechanoluminescence materials

Ultrasound induced organic mechanoluminescence materials have become one of the focal topics in wireless light sources since they exhibit high spatiotemporal resolution, biocompatibility and excellent tissue penetration depth. These properties promote great potential in ultrahigh sensitive bioimaging with no background noise and noninvasive nanodevices. Recent advances in chemistry, nanotechnology and biomedical research are revolutionizing ultrasound induced organic mechanoluminescence. Herein, we try to summarize some recent researches in ultrasound induced mechanoluminescence that use various materials design strategies based on the molecular conformational changes and cycloreversion reaction. Practical applications, like noninvasive bioimaging and noninvasive optogenetics, are also presented and prospected.

Beneath the Skin: A Review of Current Trends and Future Prospects of Transdermal Drug Delivery Systems

The ideal drug delivery system has a bioavailability comparable to parenteral dosage forms but is as convenient and easy to use for the patient as oral solid dosage forms. In recent years, there has been increased interest in transdermal drug delivery (TDD) as a non-invasive delivery approach that is generally regarded as being easy to administer to more vulnerable age groups, such as paediatric and geriatric patients, while avoiding certain bioavailability concerns that arise from oral drug delivery due to poor absorbability and metabolism concerns. However, despite its many merits, TDD remains restricted to a select few drugs. The physiology of the skin poses a barrier against the feasible delivery of many drugs, limiting its applicability to only those drugs that possess physicochemical properties allowing them to be successfully delivered transdermally. Several techniques have been developed to enhance the transdermal permeability of drugs. Both chemical (e.g., thermal and mechanical) and passive (vesicle, nanoparticle, nanoemulsion, solid dispersion, and nanocrystal) techniques have been investigated to enhance the permeability of drug substances across the skin. Furthermore, hybrid approaches combining chemical penetration enhancement technologies with physical technologies are being intensively researched to improve the skin permeation of drug substances. This review aims to summarize recent trends in TDD approaches and discuss the merits and drawbacks of the various chemical, physical, and hybrid approaches currently being investigated for improving drug permeability across the skin.

Pain management with transdermal drug administration: A review

Pain management is an urgent issue to solve with complex mechanisms. Localized acute pain requires rapid and accurate delivery of drugs with less distribution in the blood circulation while chronic pain requires controlled release of drugs with long drug retention time. The transdermal route, a promising way with high patient compliance was known for painless delivery, long drug retention time, stable blood concentration, easily controlled dosage and release rate as well as the fewer side effects. This review presents transdermal route for pain management according to the different sites of action which drugs aim to reach, and illustrates different analgesic mechanisms, dosage forms, transdermal enhancements and clinical applications. In addition, the review concludes the difference of pain types and presents the future aims of pain management, thereby providing a reference for researches focusing on percutaneous analgesia.

The Effect of Microbubble-Assisted Ultrasound on Molecular Permeability across Cell Barriers

The combination of ultrasound and microbubbles (USMB) has been applied to enhance drug permeability across tissue barriers. Most studies focused on only one physicochemical aspect (i.e., molecular weight of the delivered molecule). Using an in vitro epithelial (MDCK II) cell barrier, we examined the effects of USMB on the permeability of five molecules varying in molecular weight (182 Da to 20 kDa) and hydrophilicity (LogD at pH 7.4 from 1.5 to highly hydrophilic). Treatment of cells with USMB at increasing ultrasound pressures did not have a significant effect on the permeability of small molecules (molecular weight 259 to 376 Da), despite their differences in hydrophilicity (LogD at pH 7.4 from −3.2 to 1.5). The largest molecules (molecular weight 4 and 20 kDa) showed the highest increase in the epithelial permeability (3-7-fold). Simultaneously, USMB enhanced intracellular accumulation of the same molecules. In the case of the clinically relevant anti- C-X-C Chemokine Receptor Type 4 (CXCR4) nanobody (molecular weight 15 kDa), USMB enhanced paracellular permeability by two-fold and increased binding to retinoblastoma cells by five-fold. Consequently, USMB is a potential tool to improve the efficacy and safety of the delivery of drugs to organs protected by tissue barriers, such as the eye and the brain.

Highlights in ultrasound-targeted microbubble destruction-mediated gene/drug delivery strategy for treatment of malignancies

Ultrasound is one of the safest and most advanced medical imaging technologies that is widely used in clinical practice. Ultrasound microbubbles, traditionally used for contrast-enhanced imaging, are increasingly applied in Ultrasound-targeted Microbubble Destruction (UTMD) technology which enhances tissue and cell membrane permeability through cavitation and sonoporation, to result in a promising therapeutic gene/drug delivery strategy. Here, we review recent developments in the application of UTMD-mediated gene and drug delivery in the diagnosis and treatment of tumors, including the concept, mechanism of action, clinical application status, and advantages of UTMD. Furthermore, the future perspectives that should be paid more attention to in this field are prospected.

Synergies between therapeutic ultrasound, gene therapy and immunotherapy in cancer treatment

Due to the ease of use and excellent safety profile, ultrasound is a promising technique for both diagnosis and site-specific therapy. Ultrasound-based techniques have been developed to enhance the pharmacokinetics and efficacy of therapeutic agents in cancer treatment. In particular, transfection with exogenous nucleic acids has the potential to stimulate an immune response in the tumor microenvironment. Ultrasound-mediated gene transfection is a growing field, and recent work has incorporated this technique into cancer immunotherapy. Compared with other gene transfection methods, ultrasound-mediated gene transfection has a unique opportunity to augment the intracellular uptake of nucleic acids while safely and stably modulating the expression of immunostimulatory cytokines. The development and commercialization of therapeutic ultrasound systems further enhance the potential translation. In this Review, we introduce the underlying mechanisms and ongoing preclinical studies of ultrasound-based techniques in gene transfection for cancer immunotherapy. Furthermore, we expand on aspects of therapeutic ultrasound that impact gene therapy and immunotherapy, including tumor debulking, enhancing cytokines and chemokines and altering nanoparticle pharmacokinetics as these effects of ultrasound cannot be fully dissected from targeted gene therapy. We finally explore the outlook for this rapidly developing field.