Oral delivery of non-viral nucleic acid-based therapeutics - do we have the guts for this?

Chitosan nanovectors for siRNA delivery: New horizons for nonviral gene therapy

The growing interest in RNA-based therapeutics has positioned small interfering RNA (siRNA) as a promising tool for gene silencing with high specificity and efficacy. However, the successful clinical application of siRNA therapies requires efficient delivery systems to overcome extracellular and intracellular barriers. Chitosan, a naturally derived polysaccharide, has gained significant attention as a non-viral vector due to its biodegradability, biocompatibility, mucoadhesive properties, and capacity to enhance cellular uptake. These attributes make chitosan an attractive alternative to lipid-based nanoparticles, which currently dominate siRNA delivery platforms. Recent advancements in chitosan-based nanoformulations, including chemical modifications and functionalization strategies, have improved siRNA stability, targeting efficiency, and transfection potential, addressing key limitations such as low bioavailability and immunogenicity. Despite these advances, challenges remain in achieving optimal release kinetics, scalability, and consistent therapeutic efficacy. Future research efforts will focus on engineering chitosan derivatives with enhanced physicochemical properties, integrating multifunctional nanocarriers, and refining formulation strategies to bridge the gap between preclinical research and clinical translation. The continued development of chitosan-based siRNA therapeutics holds significant potential for advancing precision medicine and expanding treatment options for a variety of diseases, including cancer, metabolic disorders, and inflammatory conditions.

Oral delivery of stabilized lipid nanoparticles for nucleic acid therapeutics

Gastrointestinal disorders originate in the gastrointestinal tract (GIT), and the therapies can benefit from direct access to the GIT achievable through the oral route. RNA molecules show great promise therapeutically but are highly susceptible to degradation and often require a carrier for cytoplasmic access. Lipid nanoparticles (LNPs) are clinically proven drug-delivery agents, primarily administered parenterally. An ideal Orally Delivered (OrD) LNP formulation should overcome the diverse GI environment, successfully delivering the drug to the site of action. A versatile OrD LNP formulation has been developed to encapsulate and deliver siRNA and mRNA in this paper. The formulations were prepared by the systematic addition of cationic lipid to the base LNP formulation, keeping the total of cationic lipid and ionizable lipid to 50 mol%. Biorelevant media stability depicted increased resistance to bile salt mediated destabilization upon the addition of the cationic lipid, however the in vitro efficacy data underscored the importance of the ionizable lipid. Based on this, OrD LNP was selected comprising of 20% cationic lipid and 30% ionizable lipid. Further investigation revealed the enhanced efficacy of OrD LNP in vitro after incubation in different dilutions of fasted gastric, fasted intestinal media, and mucin. Confocal imaging and flow cytometry confirmed uptake while in vivo studies demonstrated efficacy with siRNA and mRNA as payloads. Taken together, this research introduces OrD LNP to deliver nucleic acid locally to the GIT.

Synthetic and Biogenic Materials for Oral Delivery of Biologics: From Bench to Bedside

The development of nucleic acid and protein drugs for oral delivery has lagged behind their production for conventional nonoral routes. Over the past decade, the evolution of DNA- and RNA-based technologies combined with the innovation of state-of-the-art delivery vehicles for nucleic acids has brought rapid advancements to the biopharmaceutical field. Nucleic acid therapies have the potential to achieve long-lasting effects, or even cures, by inhibiting or editing genes, which is not possible with conventional small-molecule drugs. However, challenges and limitations must be addressed before these therapies can provide cures for chronic conditions and rare diseases, rather than only offering temporary relief. Nucleic acids and proteins face premature degradation in the acidic, enzyme-rich stomach environment and are rapidly cleared by the liver. To overcome these challenges, various delivery vehicles have been developed to transport therapeutic compounds to the intestines, where the active compounds are released and gut microbiota and mucosal immune system also play an important role. This review provides a comprehensive overview of the promises and pitfalls associated with the oral route of administration of biologics, current delivery systems, applications of orally delivered therapeutics, and the challenges and considerations for translation of nucleic acid and protein therapeutics into clinical practice.

Modular self-emulsifying drug delivery platform to enhance cellular uptake activity in triple-negative breast cancer

Triple-negative breast cancer (TNBC) presents with resistance phenotypes to certain therapies, such as cisplatin, often requiring higher dosing, with associated acquired tumor resistance, renal toxicity, and variable patient responses. A self-emulsifying drug delivery (SEDD) formulation approach was proposed to overcome the limitations of cisplatin in TNBC, focusing on improving intracellular cisplatin and control siRNA uptake as a proof-of-principle of dual drug delivery. Four SEDD formulations were prepared and optimized for cisplatin (o/w) emulsion and FITC-siRNA (w/o) emulsion using pseudo-ternary phase diagrams to facilitate the formation of water-in-oil-water (w/o/w) emulsions. Formulations were characterized by size, polydispersity (PDI), and surface charge and tested in vitro. Cellular uptake via triplex staining of drug-loaded SEDDs was investigated. SEDDs showed enhanced internalization and promoted selective TNBC cellular uptake. The current study is a proof-of-principle for the successful co-delivery of cisplatin (small molecule) and siRNA (large molecule) via the SEDDs platform.

Breaking Through Physiological Barriers: Nanorobotic Strategies for Active Drug Delivery

Self-propelled micro/nanomotors (MNMs) represent a groundbreaking advancement in precision drug delivery, offering potential solutions to persistent challenges such as systemic toxicity, limited bioavailability, and nonspecific distribution. By transforming various energy sources into mechanical motion, MNMs are able to autonomously navigate through complex physiological environments, facilitating targeted delivery of therapeutic agents to previously inaccessible regions. However, to achieve efficient in vivo drug delivery, biomedical MNMs must demonstrate their ability to overcome crucial physiological barriers encompassing mucosal surfaces, blood flow dynamics, vascular endothelium, and cellular membrane. This review provides a comprehensive overview of the latest strategies developed to address these obstacles while also analyzing the broader challenges and opportunities associated with clinical translation. Our objective is to establish a solid foundation for future research in medical MNMs by focusing on enhancing drug delivery efficiency and advancing precision medicine, ultimately paving the way for practical theragnostic applications and wider clinical adoption.

Technologies for Targeted RNA Degradation and Induced RNA Decay

The vast majority of the human genome codes for RNA, but RNA-targeting therapeutics account for a small fraction of approved drugs. As such, there is great incentive to improve old and develop new approaches to RNA targeting. For many RNA targeting modalities, just binding is not sufficient to exert a therapeutic effect; thus, targeted RNA degradation and induced decay emerged as powerful approaches with a pronounced biological effect. This review covers the origins and advanced use cases of targeted RNA degrader technologies grouped by the nature of the targeting modality as well as by the mode of degradation. It covers both well-established methods and clinically successful platforms such as RNA interference, as well as emerging approaches such as recruitment of RNA quality control machinery, CRISPR, and direct targeted RNA degradation. We also share our thoughts on the biggest hurdles in this field, as well as possible ways to overcome them.

Current status of nucleic acid therapy and its new progress in cancer treatment

Nucleic acid is an essential biopolymer in all living cells, performing the functions of storing and transmitting genetic information and synthesizing protein. In recent decades, with the progress of science and biotechnology and the continuous exploration of the functions performed by nucleic acid, more and more studies have confirmed that nucleic acid therapy for living organisms has great medical therapeutic potential. Nucleic acid drugs began to become independent therapeutic agents. As a new therapeutic method, nucleic acid therapy plays an important role in the treatment of genetic diseases, viral infections and cancers. There are currently 19 nucleic acid drugs approved by the Food and Drug Administration (FDA). In the following review, we start from principles and advantages of nucleic acid therapy, and briefly describe development history of nucleic acid drugs. And then we give examples of various RNA therapeutic drugs, including antisense oligonucleotides (ASO), mRNA vaccines, small interfering RNA (siRNA) and microRNA (miRNA), aptamers, and small activating RNA (saRNA). In addition, we also focused on the current status of nucleic acid drugs used in cancer therapy and the breakthrough in recent years. Clinical trials of nucleic acid drugs for cancer treatment are under way, conventional radiotherapy and chemotherapy combined with the immunotherapies such as checkpoint inhibitors and nucleic acid drugs may be the main prospects for successful cancer treatment.

State-of-the-art and future perspectives in ingestible remotely controlled smart capsules for drug delivery: A GENEGUT review

An emerging concern globally, particularly in developed countries, is the rising prevalence of Inflammatory Bowel Disease (IBD), such as Crohn's disease. Oral delivery technologies that can release the active therapeutic cargo specifically at selected sites of inflammation offer great promise to maximise treatment outcomes and minimise off-target effects. Therapeutic strategies for IBD have expanded in recent years, with an increasing focus on biologic and nucleic acid-based therapies. Reliable site-specific delivery in the gastrointestinal (GI) tract is particularly crucial for these therapeutics to ensure sufficient concentrations in the targeted cells. Ingestible smart capsules hold great potential for precise drug delivery. Despite previous unsuccessful endeavours to commercialise drug delivery smart capsules, the current rise in demand and recent advancements in component development, manufacturing, and miniaturisation have reignited interest in ingestible devices. Consequently, this review analyses the advancements in various mechanical and electrical components associated with ingestible smart drug delivery capsules. These components include modules for device localisation, actuation and retention within the GI tract, signal transmission, drug release, power supply, and payload storage. Challenges and constraints associated with previous capsule design functionality are presented, followed by a critical outlook on future design considerations to ensure efficient and reliable site-specific delivery for the local treatment of GI disorders.

Charge-converting nanocarriers: Phosphorylated polysaccharide coatings for overcoming intestinal barriers

For the design of charge-converting nanocarriers (NCs), cationic lipid-based NCs containing curcumin as model drug were coated with phosphorylated starch (NC-SP) and phosphorylated dextran (NC-DP). NCs showed a drug encapsulation efficiency of 94 % and had a mean size of 175 to 180 nm. The recorded zeta potential of the core NC (cNC) was +8.3 mV, whereas it reversed to -10.6 mV and -7.4 mV after decorating with SP and DP, respectively. Furthermore, a 3-fold higher amount of curcumin having been incorporated in these NCs remained stable within 2 h of UV exposure indicating a photoprotective effect of this delivery system. Charge-converting properties were confirmed by cleavage with intestinal alkaline phosphatase (IAP) and resulted in a zeta potential shift of Δ15.4 mV for NC-SP and Δ11.2 mV for NC-DP. NC-SP and NC-DP showed enhanced mucus permeating properties compared to cNC, that were additionally confirmed by an up to 2.2-fold improved cellular uptake on mucus secreting Caco-2/HT29-MTX cells. According to these results, NC-SP and NC-DP coatings hold promise as a viable and efficient strategy for charge-converting NCs.

Oral administration of herbal oligonucleotide drug JGL-sRNA-h7 ameliorates hyperglycemia in db/db mice and beagle dogs

Type 2 diabetes mellitus is a prevalent metabolic disease, posing a considerable threat to public health. Oligonucleotide drugs have proven to be a promising field of therapy for the diseases. In this study, we reported that a herbal small RNA (sRNA), JGL-sRNA-h7 (B34735529, F1439.L002444.A11), could exhibit potent hypoglycemic effects by targeting glucose-6-phosphatase. Oral administration of sphingosine (d18:1)-JGL-sRNA-h7 bencaosomes ameliorated hyperglycemia and diabetic kidney injury better than metformin in db/db mice. Furthermore, glucose tolerance was also improved in sphingosine (d18:1)-JGL-sRNA-h7 bencaosomes-treated beagle dogs. Our study indicates that JGL-sRNA-h7 could be a promising hypoglycemic oligonucleotide drug.

Intestinal Lymphatic Biology, Drug Delivery, and Therapeutics: Current Status and Future Directions

Historically, the intestinal lymphatics were considered passive conduits for fluids, immune cells, dietary lipids, lipid soluble vitamins, and lipophilic drugs. Studies of intestinal lymphatic drug delivery in the late 20th century focused primarily on the drugs' physicochemical properties, especially high lipophilicity, that resulted in intestinal lymphatic transport. More recent discoveries have changed our traditional view by demonstrating that the lymphatics are active, plastic, and tissue-specific players in a range of biological and pathological processes, including within the intestine. These findings have, in turn, inspired exploration of lymph-specific therapies for a range of diseases, as well as the development of more sophisticated strategies to actively deliver drugs or vaccines to the intestinal lymph, including a range of nanotechnologies, lipid prodrugs, and lipid-conjugated materials that "hitchhike" onto lymphatic transport pathways. With the increasing development of novel therapeutics such as biologics, there has been interest in whether these therapeutics are absorbed and transported through intestinal lymph after oral administration. Here we review the current state of understanding of the anatomy and physiology of the gastrointestinal lymphatic system in health and disease, with a focus on aspects relevant to drug delivery. We summarize the current state-of-the-art approaches to deliver drugs and quantify their uptake into the intestinal lymphatic system. Finally, and excitingly, we discuss recent examples of significant pharmacokinetic and therapeutic benefits achieved via intestinal lymphatic drug delivery. We also propose approaches to advance the development and clinical application of intestinal lymphatic delivery strategies in the future. SIGNIFICANCE STATEMENT: This comprehensive review details the understanding of the anatomy and physiology of the intestinal lymphatic system in health and disease, with a focus on aspects relevant to drug delivery. It highlights current state-of-the-art approaches to deliver drugs to the intestinal lymphatics and the shift toward the use of these strategies to achieve pharmacokinetic and therapeutic benefits for patients.

An investigation of nano- and micron-sized carriers based on calcium carbonate and polylactic acid for oral administration of siRNA

BACKGROUND

Oral delivery of small interfering RNAs (siRNAs) draws significant attention, but the gastrointestinal tract (GIT) has many biological barriers that limit the drugs' bioavailability. The aim of this work was to investigate the potential of micro- and nano-sized CaCO3 and PLA carriers for oral delivery of siRNA and reveal a relationship between the physicochemical features of these carriers and their biodistribution.

RESEARCH DESIGN AND METHODS

In vitro stability of carriers was investigated in simulated gastric and intestinal fluids. Toxicity and cellular uptake were investigated on Caco-2 cells. The biodistribution profiles of the developed CaCO3 and PLA carriers were examined using different visualization methods, including SPECT, fluorescence imaging, radiometry, and histological analysis. The delivery efficiency of siRNA loaded carriers was investigated both in vitro and in vivo.

RESULTS

Micro-sized carriers were accumulated in the stomach and later localized in the colon tissues. The nanoscale particles (100-250 nm) were distributed in the colon tissues. nPLA was also detected in small intestine. The developed carriers can prevent siRNA from premature degradation in GIT media.

CONCLUSION

Our results reveal how the physicochemical properties of the particles, including their size and material type can affect their biodistribution profile and oral delivery of siRNA.

Principle, application and challenges of development siRNA-based therapeutics against bacterial and viral infections: a comprehensive review

While significant progress has been made in understanding and applying gene silencing mechanisms and the treatment of human diseases, there have been still several obstacles in therapeutic use. For the first time, ONPATTRO, as the first small interfering RNA (siRNA) based drug was invented in 2018 for treatment of hTTR with polyneuropathy. Additionally, four other siRNA based drugs naming Givosiran, Inclisiran, Lumasiran, and Vutrisiran have been approved by the US Food and Drug Administration and the European Medicines Agency for clinical use by hitherto. In this review, we have discussed the key and promising advances in the development of siRNA-based drugs in preclinical and clinical stages, the impact of these molecules in bacterial and viral infection diseases, delivery system issues, the impact of administration methods, limitations of siRNA application and how to overcome them and a glimpse into future developments.

Physiological Barriers and Strategies of Lipid-Based Nanoparticles for Nucleic Acid Drug Delivery

Lipid-based nanoparticles (LBNPs) are currently the most promising vehicles for nucleic acid drug (NAD) delivery. Although their clinical applications have achieved success, the NAD delivery efficiency and safety are still unsatisfactory, which are, to a large extent, due to the existence of multi-level physiological barriers in vivo. It is important to elucidate the interactions between these barriers and LBNPs, which will guide more rational design of efficient NAD vehicles with low adverse effects and facilitate broader applications of nucleic acid therapeutics. This review describes the obstacles and challenges of biological barriers to NAD delivery at systemic, organ, sub-organ, cellular, and subcellular levels. The strategies to overcome these barriers are comprehensively reviewed, mainly including physically/chemically engineering LBNPs and directly modifying physiological barriers by auxiliary treatments. Then the potentials and challenges for successful translation of these preclinical studies into the clinic are discussed. In the end, a forward look at the strategies on manipulating protein corona (PC) is addressed, which may pull off the trick of overcoming those physiological barriers and significantly improve the efficacy and safety of LBNP-based NADs delivery.

Oral bioavailability of a noncoding RNA drug, TY1, that acts on macrophages

All approved RNA therapeutics require parenteral delivery. Here we demonstrate an orally bioavailable formulation wherein synthetic noncoding (nc) RNA, packaged into lipid nanoparticles, is loaded into casein-chitosan (C2) micelles. We used the C2 formulation to deliver TY1, a 24-nucleotide synthetic ncRNA which targets the DNA damage response pathway in macrophages. C2-formulated TY1 (TY1C2) efficiently packages and protects TY1 against degradative enzymes. In healthy mice, oral TY1C2 was well-tolerated and nontoxic. Oral TY1C2 exhibited disease-modifying bioactivity in 2 models of tissue injury: 1) rat myocardial infarction, where a single oral dose of TY1C2 was cardioprotective, on par with intravenously-delivered TY1; and 2) mouse acute lung injury, where a single dose of TY1C2 attenuated pulmonary inflammation. Mechanistic dissection revealed that TY1C2 is not absorbed into the systemic circulation but is, instead, taken up by intestinal macrophages, namely those of the lamina propria and Peyer's patches. This route of absorption may rationalize why an antisense oligonucleotide against Factor VII, which acts on hepatocytes, is not effective when administered in the C2 formulation. Thus, some (but not all) ncRNA drugs are bioavailable when delivered by mouth. Oral RNA delivery and uptake, relying on uptake via the gastrointestinal immune system, has broad-ranging therapeutic implications.

Strategies for non-viral vectors targeting organs beyond the liver

In recent years, nanoparticles have evolved to a clinical modality to deliver diverse nucleic acids. Rising interest in nanomedicines comes from proven safety and efficacy profiles established by continuous efforts to optimize physicochemical properties and endosomal escape. However, despite their transformative impact on the pharmaceutical industry, the clinical use of non-viral nucleic acid delivery is limited to hepatic diseases and vaccines due to liver accumulation. Overcoming liver tropism of nanoparticles is vital to meet clinical needs in other organs. Understanding the anatomical structure and physiological features of various organs would help to identify potential strategies for fine-tuning nanoparticle characteristics. In this Review, we discuss the source of liver tropism of non-viral vectors, present a brief overview of biological structure, processes and barriers in select organs, highlight approaches available to reach non-liver targets, and discuss techniques to accelerate the discovery of non-hepatic therapies.

Strategies to reduce the risks of mRNA drug and vaccine toxicity

mRNA formulated with lipid nanoparticles is a transformative technology that has enabled the rapid development and administration of billions of coronavirus disease 2019 (COVID-19) vaccine doses worldwide. However, avoiding unacceptable toxicity with mRNA drugs and vaccines presents challenges. Lipid nanoparticle structural components, production methods, route of administration and proteins produced from complexed mRNAs all present toxicity concerns. Here, we discuss these concerns, specifically how cell tropism and tissue distribution of mRNA and lipid nanoparticles can lead to toxicity, and their possible reactogenicity. We focus on adverse events from mRNA applications for protein replacement and gene editing therapies as well as vaccines, tracing common biochemical and cellular pathways. The potential and limitations of existing models and tools used to screen for on-target efficacy and de-risk off-target toxicity, including in vivo and next-generation in vitro models, are also discussed.

Oral TNF-α siRNA delivery via milk-derived exosomes for effective treatment of inflammatory bowel disease

Oral administration facilitates the direct delivery of drugs to lesions within the small intestine and colon, making it an ideal approach for treating patients with inflammatory bowel disease. However, multiple physical barriers impede the delivery of oral RNA drugs through the gastrointestinal tract. Herein, we developed a novel oral siRNA delivery system that protects nucleic acids in extreme environments by employing exosomes derived from milk to encapsulate tumor necrosis factor-alpha (TNF-α) siRNA completely. The remarkable structural stability of milk-derived exosomes (M-Exos), as opposed to those from HEK293T cells, makes them exceptional siRNA carriers. Results demonstrate that milk exosomes loaded with TNF-α siRNA (M-Exo/siR) can effectively inhibit the expression of TNF-α-related inflammatory cytokines. Moreover, given that milk exosomes are composed of unique lipids with high bioavailability, orally administered M-Exo/siR effectively reach colonic tissues, leading to decreased TNF-α expression and successful alleviation of colitis symptoms in a dextran sulfate sodium-induced inflammatory bowel disease murine model. Hence, milk-derived exosomes carrying TNF-α siRNA can be effectively employed to treat inflammatory bowel disease. Indeed, using exosomes naturally derived from milk may shift the current paradigm of oral gene delivery, including siRNA.

Potentials of ionic liquids to overcome physical and biological barriers

Over the last decades, ionic liquids (IL) have shown great potential in non-invasive delivery starting from synthetic small molecules to biological large molecules. ILs are emerging as a particular class of drug delivery systems due to their unique physiochemical properties, simple surface modification, and functionalization. These features of IL help achieve specific design principles that are essential for a non-invasive drug delivery system. In this review, we have discussed IL and their applications in non-invasive drug delivery systems. We evaluated state-of-the-art development and advances of IL aiming to mitigate the biological and physical barriers to improve transdermal and oral delivery, summarized in this review. We also provided an overview of the various factors determining the systemic transportation of IL-based formulation. Additionally, we have emphasized how the ILs facilitate the transportation of therapeutic molecules by overcoming biological barriers.

Oral Administration of Cancer Vaccines: Challenges and Future Perspectives

Cancer vaccines, a burgeoning strategy in cancer treatment, are exploring innovative administration routes to enhance patient and medical staff experiences, as well as immunological outcomes. Among these, oral administration has surfaced as a particularly noteworthy approach, which is attributed to its capacity to ignite both humoral and cellular immune responses at systemic and mucosal tiers, thereby potentially bolstering vaccine efficacy comprehensively and durably. Notwithstanding this, the deployment of vaccines through the oral route in a clinical context is impeded by multifaceted challenges, predominantly stemming from the intricacy of orchestrating effective oral immunogenicity and necessitating strategic navigation through gastrointestinal barriers. Based on the immunogenicity of the gastrointestinal tract, this review critically analyses the challenges and recent advances and provides insights into the future development of oral cancer vaccines.

Polyphosphate coated nanoparticles: Enzyme-activated charge-reversal gene delivery systems

AIM

The current study aimed to develop enzyme-activated charge-reversal lipid nanoparticles (LNPs) as novel gene delivery systems.

METHODS

Palmitic acid was covalently bound to protamine being utilised as transfection promoter to anchor it on the surfaces of LNPs. Green fluorescent protein (GFP) encoding plasmid DNA (pDNA) was ion paired with various cationic counter ions to achieve high encapsulation in LNPs. Protamine-decorated LNPs were prepared by solvent injection method followed by coating with sodium tripolyphosphate (TPP) to generate a bio-inert anionic outer surface. Resulting LNPs were characterised regarding size, polydispersity, zeta potential and encapsulation efficiency. Enzyme-triggered charge-reversal of LNPs was investigated using isolated alkaline phosphatase (ALP) monitoring changes in zeta potential as well as monophosphate release. Furthermore, monophosphate release, cell viability and transfection efficiency were evaluated on a human alveolar epithelial (A549) cell line.

RESULTS

Protamine-decorated and TPP-coated (Prot-pDNA/DcChol-TPP) LNPs displayed a mean size of 298.8 ± 17.4 nm and a zeta potential of -13.70 ± 0.61 mV. High pDNA encapsulation was achieved with hydrophobic ion pairs of pDNA with 3ß-[N-(N',N'-dimethylaminoethane)-carbamoyl]cholesterol hydrochloride (DcChol). Zeta potential of Prot-pDNA/DcChol-TPP LNPs reversed to positive values with a total Δ26.8 mV shift upon incubation with ALP. Conformably, a notable amount of monophosphate was released upon incubation of Prot-pDNA/DcChol-TPP LNPs with isolated as well as cell-associated ALP. A549 cells well tolerated LNPs displaying more than 95 % viability. Compared with naked pDNA, unmodified LNPs and control LNPs, Prot-pDNA/DcChol-TPP LNPs showed a significantly increased transfection efficiency.

CONCLUSION

Prot-pDNA/DcChol-TPP LNPs can be regarded as promising gene delivery systems.

Synthesis and application of spermine-based amphiphilic poly(β-amino ester)s for siRNA delivery

Small interfering RNA (siRNA) can trigger RNA interference (RNAi) to therapeutically silence disease-related genes in human cells. The approval of siRNA therapeutics by the FDA in recent years generated a new hope in novel and efficient siRNA therapeutics. However, their therapeutic application is still limited by the lack of safe and efficient transfection vehicles. In this study, we successfully synthesized a novel amphiphilic poly(β-amino ester) based on the polyamine spermine, hydrophobic decylamine and 1,4-butanediol diacrylate, which was characterized by 1H NMR spectroscopy and size exclusion chromatography (SEC, Mn = 6000 Da). The polymer encapsulated siRNA quantitatively from N/P 5 on as assessed by fluorescence intercalation while maintaining optimal polyplex sizes and zeta potentials. Biocompatibility and cellular delivery efficacy were also higher than those of the commonly used cationic, hyperbranched polymer polyethylenimine (PEI, 25 kDa). Optimized formulations mediated around 90% gene silencing in enhanced green fluorescence protein expressing H1299 cells (H1299-eGFP) as determined by flow cytometry. These results suggest that spermine-based, amphiphilic poly(β-amino ester)s are very promising candidates for efficient siRNA delivery.

Oral delivery of RNAi for cancer therapy

Cancer is a major health concern worldwide and is still in a continuous surge of seeking for effective treatments. Since the discovery of RNAi and their mechanism of action, it has shown promises in targeted therapy for various diseases including cancer. The ability of RNAi to selectively silence the carcinogenic gene makes them ideal as cancer therapeutics. Oral delivery is the ideal route of administration of drug administration because of its patients' compliance and convenience. However, orally administered RNAi, for instance, siRNA, must cross various extracellular and intracellular biological barriers before it reaches the site of action. It is very challenging and important to keep the siRNA stable until they reach to the targeted site. Harsh pH, thick mucus layer, and nuclease enzyme prevent siRNA to diffuse through the intestinal wall and thereby induce a therapeutic effect. After entering the cell, siRNA is subjected to lysosomal degradation. Over the years, various approaches have been taken into consideration to overcome these challenges for oral RNAi delivery. Therefore, understanding the challenges and recent development is crucial to offer a novel and advanced approach for oral RNAi delivery. Herein, we have summarized the delivery strategies for oral delivery RNAi and recent advancement towards the preclinical stages.

Polyplex designs for improving the stability and safety of RNA therapeutics

Nanoparticle-based delivery systems have contributed to the recent clinical success of RNA therapeutics, including siRNA and mRNA. RNA delivery using polymers has several distinct properties, such as enabling RNA delivery into extra-hepatic organs, modulation of immune responses to RNA, and regulation of intracellular RNA release. However, delivery systems should overcome safety and stability issues to achieve widespread therapeutic applications. Safety concerns include direct damage to cellular components, innate and adaptive immune responses, complement activation, and interaction with surrounding molecules and cells in the blood circulation. The stability of the delivery systems should balance extracellular RNA protection and controlled intracellular RNA release, which requires optimization for each RNA species. Further, polymer designs for improving safety and stability often conflict with each other. This review covers advances in polymer-based approaches to address these issues over several years, focusing on biological understanding and design concepts for delivery systems rather than material chemistry.

Oral non-viral gene delivery platforms for therapeutic applications

Since gene therapy can regulate gene and protein expression directly, it has a great potential to prevent or treat a variety of genetic or acquired diseases through vaccines such as viral infections, cystic fibrosis, and cancer. Owing to their high efficacy, in vivo gene therapy trials are usually conducted intravenously, which is usually costly and invasive. There are several advantages to oral drug administration over intravenous injections, such as better patient compliance, ease of use, and lower cost. However, gene therapy is successful if the oligonucleotides can cross the cell membrane easily and reach the nucleus after the endosomal escape. In order to accomplish this task and deliver the cargo to the intended location, appropriate delivery systems should be introduced. This review summarizes oral delivery systems developed for effective gene delivery, vaccination, and treatment of various diseases. Studies have also shown that oral delivery approaches are potentially applicable to treat various diseases, especially inflammatory bowel disease, stomach, and colorectal cancers. Also, the current review provides an update overview on the development of non-viral and oral gene delivery techniques for gene therapy and vaccination purposes.

Biodegradable Cationic and Ionizable Cationic Lipids: A Roadmap for Safer Pharmaceutical Excipients

Cationic and ionizable cationic lipids are broadly applied as auxiliary agents, but their use is associated with adverse effects. If these excipients are rapidly degraded to endogenously occurring metabolites such as amino acids and fatty acids, their toxic potential can be minimized. So far, synthesized and evaluated biodegradable cationic and ionizable cationic lipids already showed promising results in terms of functionality and safety. Within this review, an overview about the different types of such biodegradable lipids, the available building blocks, their synthesis and cleavage by endogenous enzymes is provided. Moreover, the relationship between the structure of the lipids and their toxicity is described. Their application in drug delivery systems is critically discussed and placed in context with the lead compounds used in mRNA vaccines. Moreover, their use as preservatives is reviewed, guidance for their design is provided, and an outlook on future developments is given.

Oligonucleotide Formulations Prepared by High-Speed Electrospinning: Maximizing Loading and Exploring Downstream Processability

The aim of this study was to develop antisense oligonucleotide tablet formulations using high-speed electrospinning. Hydroxypropyl-beta-cyclodextrin (HPβCD) was used as a stabilizer and as an electrospinning matrix. In order to optimize the morphology of the fibers, electrospinning of various formulations was carried out using water, methanol/water (1:1), and methanol as solvents. The results showed that using methanol could be advantageous due to the lower viscosity threshold for fiber formation enabling higher potential drug loadings by using less excipient. To increase the productivity of electrospinning, high-speed electrospinning technology was utilized and HPβCD fibers containing 9.1% antisense oligonucleotide were prepared at a rate of ~330 g/h. Furthermore, to increase the drug content of the fibers, a formulation with a 50% drug loading was developed. The fibers had excellent grindability but poor flowability. The ground fibrous powder was mixed with excipients to improve its flowability, which enabled the automatic tableting of the mixture by direct compression. The fibrous HPβCD–antisense oligonucleotide formulations showed no sign of physical or chemical degradation over the 1-year stability study, which also shows the suitability of the HPβCD matrix for the formulation of biopharmaceuticals. The obtained results demonstrate possible solutions for the challenges of electrospinning such as scale-up and downstream processing of the fibers.

Surface design of nanocarriers: Key to more efficient oral drug delivery systems

As nanocarriers (NCs) can improve the solubility of drugs, prevent their degradation by gastrointestinal (GI) enzymes and promote their transport across the mucus gel layer and absorption membrane, the oral bioavailability of these drugs can be substantially enhanced. All these properties of NCs including self-emulsifying drug delivery systems (SEDDS), solid lipid nanoparticles (SLNs), nanostructured lipid carriers (NLCs), liposomes, polymeric nanoparticles, inorganic nanoparticles and polymeric micelles depend mainly on their surface chemistry. In particular, interaction with food, digestive enzymes, bile salts and electrolytes, diffusion behaviour across the mucus gel layer and fate on the absorption membrane are determined by their surface. Bioinert surfaces limiting interactions with gastrointestinal fluid and content as well as with mucus, adhesive surfaces providing an intimate contact with the GI mucosa and absorption enhancing surfaces can be designed. Furthermore, charge converting surfaces shifting their zeta potential from negative to positive directly at the absorption membrane and surfaces providing a targeted drug release are advantageous. In addition to these passive surfaces, even active surfaces cleaving mucus glycoproteins on their way through the mucus gel layer can be created. Within this review, we provide an overview on these different surfaces and discuss their impact on the performance of NCs in the GI tract.

Design of lipid-based nanoparticles for delivery of therapeutic nucleic acids

The successful development of nonviral delivery systems for nucleic acids has been reported extensively over the past number of years. Among them, lipid-based nanoparticles (LNPs) represent the most advanced platform. This review provides an overview of the state-of-the-art in LNP technology, focusing on the delivery of a range of nucleic acids. Recent advances in the development of an efficient and safe lipid-based system are critically analyzed with a particular emphasis on the rationale behind the design of LNPs and on attempts to elucidate the resulting molecular assembly and structure, their interactions with cellular proteins and biodistribution. In addition, manufacturing methods including microfluidics and their potential to influence stability and scale-up are summarized.

Phenylboronic Acid-Functionalized Polyplexes Tailored to Oral CRISPR Delivery

Effective delivery of the CRISPR-Cas9 components is crucial to realizing the therapeutic potential. Although many delivery approaches have been developed for this application, oral delivery has not been explored due to the degradative nature of the gastrointestinal tract. For this issue, we developed a series of novel phenylboronic acid (PBA)-functionalized chitosan-polyethylenimine (CS-PEI) polymers for oral CRISPR delivery. PBA functionalization equipped the polyplex with higher stability, smooth transport across the mucus, and efficient endosomal escape and cytosolic unpackaging in the cells. From a library of 12 PBA-functionalized CS-PEI polyplexes, we identified a formulation that showed the most effective penetration in the intestinal mucosa after oral gavage to mice. The optimized formulation performed feasible CRISPR-mediated downregulation of the target protein and reduction in the downstream cholesterol. As the first oral CRISPR carrier, this study suggests the potential of addressing the needs of both local and systemic editing in a patient-compliant manner.

The discovery and development of RNA-based therapies for treatment of HIV-1 infection

INTRODUCTION

Long-term control of HIV-1 infection can potentially be achieved using autologous stem cell transplants with gene-modified cells. Non-coding RNAs represent a diverse class of therapeutic agents including ribozymes, RNA aptamers and decoys, small interfering RNAs, short hairpin RNAs, and U1 interference RNAs that can be designed to inhibit HIV-1 replication. They have been engineered for delivery as drugs to complement current HIV-1 therapies and as gene therapies for a potential HIV-1 functional cure.

AREAS COVERED

This review surveys the past three decades of development of these RNA technologies with a focus on their efficacy and safety for treating HIV-1 infections. We describe the mechanisms of each RNA-based agent, targets they have been developed against, efforts to enhance their stability and efficacy, and we evaluate their performance in past and ongoing preclinical and clinical trials.

EXPERT OPINION

RNA-based technologies are among the top candidates for gene therapies where they can be stably expressed for long-term suppression of HIV-1. Advances in both gene and drug delivery strategies and improvements to non-coding RNA stability and antiviral properties will cooperatively drive forward progress in improving drug therapy and engineering HIV-1 resistant cells.

Nanotechnology as a tool to overcome macromolecules delivery issues

Nanocarriers can deliver drugs to specific organs or cells, potentially bridging the gap between a drug's function and its interaction with biological systems such as human physiology. The untapped potential of nanotechnology stems from its ability to manipulate materials, allowing control over physical and chemical properties and overcoming drug-related problems, e.g., poor solubility or poor bioavailability. For example, most protein drugs are administered parenterally, each with challenges and peculiarities. Some problems faced by bioengineered macromolecule drugs leading to poor bioavailability are short biological half-life, large size and high molecular weight, low permeability through biological membranes, and structural instability. Nanotechnology emerges as a promising strategy to overcome these problems. Nevertheless, the delivery system should be carefully chosen considering loading efficiency, physicochemical properties, production conditions, toxicity, and regulations. Moving from the bench to the bedside is still one of the major bottlenecks in nanomedicine, and toxicological issues are the greatest challenges to overcome. This review provides an overview of biotech drug delivery approaches, associated nanotechnology novelty, toxicological issues, and regulations.

Oral delivery of nucleic acid therapeutics: Challenges, strategies, and opportunities

In recent decades, advances in chemical synthesis and delivery systems have accelerated the development of therapeutic nucleic acids, several of which have been approved by the Us Food and Drug Administration (FDA). Oral nucleic acid delivery is preferred because of its simplicity and patient compliance, but it still presents distinct challenges. The negative charge, hydrophilicity, and large molecular weight of nucleic acids combined with in vivo gastrointestinal (GI) barriers (e.g., acidic pH, enzymes, mucus, and intestinal epithelial cells) severely hinder their delivery efficacy. Recently, various nanoparticles (NPs), ranging from polymeric to lipid-based (L)NPs and extracellular vesicles (EVs), have been extensively explored to address these obstacles. In this review, we describe the physiological barriers in the GI tract and summarize recent advances in NP-based oral nucleic acid therapeutics.

Oral Delivery of Nucleic Acid Therapies for Local and Systemic Action

Nucleic acid (NA) therapy has gained importance over the past decade due to its high degree of selectivity and minimal toxic effects over conventional drugs. Currently, intravenous (IV) or intramuscular (IM) formulations constitute majority of the marketed formulations containing nucleic acids. However, oral administration is traditionally preferred due to ease of administration as well as higher patient compliance. To leverage the benefits of oral delivery for NA therapy, the NA of interest must be delivered to the target site avoiding all degrading and inhibiting factors during its transition through the gastrointestinal tract. The oral route presents myriad of challenges to NA delivery, making formulation development challenging. Researchers in the last few decades have formulated various delivery systems to overcome such challenges and several reviews summarize and discuss these strategies in detail. However, there is a need to differentiate between the approaches based on target so that in future, delivery strategies can be developed according to the goal of the study and for efficient delivery to the desired site. The goal of this review is to summarize the mechanisms for target specific delivery, list and discuss the formulation strategies used for oral delivery of NA therapies and delineate the similarities and differences between local and systemic targeting oral delivery systems and current challenges.

Recent Advances in Delivery Systems for Genetic and Other Novel Vaccines

Vaccination is one of the most successful and cost-effective prophylactic measures against diseases, especially infectious diseases including smallpox and polio. However, the development of effective prophylactic or therapeutic vaccines for other diseases such as cancer remains challenging. This is often due to the imprecise control of vaccine activity in vivo which leads to insufficient/inappropriate immune responses or short immune memory. The development of new vaccine types in recent decades has created the potential for improving the protective potency against these diseases. Genetic and subunit vaccines are two major categories of these emerging vaccines. Owing to their nature, they rely heavily on delivery systems with various functions, such as effective cargo protection, immunogenicity enhancement, targeted delivery, sustained release of antigens, selective activation of humoral and/or cellular immune responses against specific antigens, and reduced adverse effects. Therefore, vaccine delivery systems may significantly affect the final outcome of genetic and other novel vaccines and are vital for their development. This review introduces these studies based on their research emphasis on functional design or administration route optimization, presents recent progress, and discusses features of new vaccine delivery systems, providing an overview of this field.

In Vivo Evaluation of a Gastro-Resistant HPMC-Based “Next Generation Enteric” Capsule

Many orally dosed APIs are bioavailable only when formulated as an enteric dosage form to protect them from the harsh environment of the stomach. However, an enteric formulation is often accompanied with a higher development effort in the first place and the potential degradation of fragile APIs during the coating process. Ready-to-use enteric hard capsules would be an easily available alternative to test and develop APIs in enteric formulations, while decreasing the time and cost of process development. In this regard, Lonza Capsugel® Next Generation Enteric capsules offer a promising approach as functional capsules. The in vivo performance of these capsules was observed with two independent techniques (MRI and caffeine in saliva) in eight human volunteers. No disintegration or content release in the stomach was observed, even after highly variable individual gastric residence times (range 7.5 to 82.5 min), indicating the reliable enteric properties of these capsules. Seven capsules disintegrated in the distal part of the small intestine; one capsule showed an uncommonly fast intestinal transit (15 min) and disintegrated in the colon. The results for this latter capsule by MRI and caffeine appearance differed dramatically, whereas for all other capsules disintegrating in the small intestine, the results were very comparable, which highlights the necessity for reliable and complementary measurement methods. No correlation could be found between the gastric residence time and disintegration after gastric emptying, which confirms the robust enteric formulation of those capsules.

Oral Nanomedicines for siRNA Delivery to Treat Inflammatory Bowel Disease

RNA interference (RNAi) therapies have significant potential for the treatment of inflammatory bowel diseases (IBD). Although administering small interfering RNA (siRNA) via an oral route is desirable, various hurdles including physicochemical, mucus, and cellular uptake barriers of the gastrointestinal tract (GIT) impede both the delivery of siRNA to the target site and the action of siRNA drugs at the target site. In this review, we first discuss various physicochemical and biological barriers in the GI tract. Furthermore, we present recent strategies and the progress of oral siRNA delivery strategies to treat IBD. Finally, we consider the challenges faced in the use of these strategies and future directions of oral siRNA delivery strategies.

Lipid Nanoparticles as Delivery Vehicles for Inhaled Therapeutics

Lipid nanoparticles (LNPs) have emerged as a powerful non-viral carrier for drug delivery. With the prevalence of respiratory diseases, particularly highlighted by the current COVID-19 pandemic, investigations into applying LNPs to deliver inhaled therapeutics directly to the lungs are underway. The progress in LNP development as well as the recent pre-clinical studies in three main classes of inhaled encapsulated drugs: small molecules, nucleic acids and proteins/peptides will be discussed. The advantages of the pulmonary drug delivery system such as reducing systemic toxicity and enabling higher local drug concentration in the lungs are evaluated together with the challenges and design considerations for improved formulations. This review provides a perspective on the future prospects of LNP-mediated delivery of inhaled therapeutics for respiratory diseases.

Nucleic acid strategies for infectious disease treatments: The nanoparticle-based oral delivery route

Therapies based on orally administrated nucleic acids have significant potential for the treatment of infectious diseases, including chronic inflammatory diseases such as inflammatory bowel disease (IBD)-associated with the gastrointestinal (GI) tract, and infectious and acute contagious diseases like coronavirus disease 2019 (COVID-19). This is because nucleic acids could precisely regulate susceptibility genes in regulating the pro- and anti-inflammatory cytokines expression related to the infections. Unfortunately, gene delivery remains a major hurdle due to multiple intracellular and extracellular barriers. This review thoroughly discusses the challenges of nanoparticle-based nucleic acid gene deliveries and strategies for overcoming delivery barriers to the inflammatory sites. Oral nucleic acid delivery case studies were also present as vital examples of applications in infectious diseases such as IBD and COVID-19.

Nucleic acid-based therapy for brain cancer: Challenges and strategies

Nucleic acid-based therapy emerges as a powerful weapon for the treatment of tumors thanks to its direct, effective, and lasting therapeutic effect. Encouragingly, continuous nucleic acid-based drugs have been approved by the Food and Drug Administration (FDA) and the European Medicines Agency (EMA). Despite the tremendous progress, there are few nucleic acid-based drugs for brain tumors in clinic. The most challenging problems lie on the instability of nucleic acids, difficulty in traversing the biological barriers, and the off-target effect. Herein, nucleic acid-based therapy for brain tumor is summarized considering three aspects: (i) the therapeutic nucleic acids and their applications in clinical trials; (ii) the various administration routes for nucleic acid delivery and the respective advantages and drawbacks. (iii) the strategies and carriers for improving stability and targeting ability of nucleic acid drugs. This review provides thorough knowledge for the rational design of nucleic acid-based drugs against brain tumor.

Phosphate decorated lipid-based nanocarriers providing a prolonged mucosal residence time

The aim of this study was to develop phosphate decorated lipid-based nanocarriers including self-emulsifying drug delivery systems (SEDDS), solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC) to extend their mucosal residence time. All nanocarriers contained tetradecyltrimethylammonium bromide (TTAB) and polyoxyethylene (9) nonylphenol monophosphate ester (PNPP) for surface decoration. Zeta potential, cytotoxicity, charge conversion and phosphate release studies using isolated intestinal alkaline phosphatase (IAP) and Caco-2 cells were performed. Moreover, the residence time of nanocarriers was determined on porcine intestinal mucosa. Results showed a shift from negative to positive zeta potential due to the addition of TTAB and charge conversion back to a negative zeta potential when also PNPP was added. Up to a concentration of 0.3 %, lipid-based nanocarriers were not toxic. Charge conversion studies with IAP revealed the highest zeta potential shift for NLC_TTAB-PNPP with almost Δ22 mV. Phosphate release studies using isolated IAP as well as Caco-2 cells showed a fast phosphate release for SEDDS_TTAB-PNPP, SLN_TTAB-PNPP and NLC_TTAB-PNPP. SLN _TTAB-PNPP and NLC _TTAB-PNPP provided the highest increase in mucosal residence time that was 4-fold more prolonged than that of blank formulations. In conclusion, phosphate modified lipid-based nanocarriers can essentially prolong the intestinal residence time of their payload.

Beyond GalNAc! Drug delivery systems comprising complex oligosaccharides for targeted use of nucleic acid therapeutics

Nucleic Acid Therapeutics (NATs) are establishing a leading role for the management and treatment of genetic diseases following FDA approval of nusinersen, patisiran, and givosiran in the last 5 years, the breakthrough of milasen, with more approvals undoubtedly on the way. Givosiran takes advantage of the known interaction between the hepatocyte specific asialoglycoprotein receptor (ASGPR) and N-acetyl galactosamine (GalNAc) ligands to deliver a therapeutic effect, underscoring the value of targeting moieties. In this review, we explore the history of GalNAc as a ligand, and the paradigm it has set for the delivery of NATs through precise targeting to the liver, overcoming common hindrances faced with this type of therapy. We describe various complex oligosaccharides (OSs) and ask what others could be used to target receptors for NAT delivery and the opportunities awaiting exploration of this chemical space.

Utilization and Potential of RNA-Based Therapies in Cardiovascular Disease

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RNA-based therapeutics have the potential to reach previously “undruggable” pathways in cardiovascular disease

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RNA-based therapeutics constitute a vast array of technologies, including unique forms, chemistries, and modalities of delivery

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Rapid development of RNA-based vaccines was made possible by decades of foundational work

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Specificity and efficacy of targeting and determination of mechanism(s) of action remain a distinct challenge

Cardiovascular disease (CVD) remains the largest cause of mortality worldwide. The development of new effective therapeutics is a major unmet need. The current review focuses broadly on the concept of nucleic acid (NA)–based therapies, considering the use of various forms of NAs, including mRNAs, miRNAs, siRNA, and guide RNAs, the latter specifically for the purpose of CRISPR-Cas directed gene editing. We describe the current state-of-the-art of RNA target discovery and development, the status of RNA therapeutics in the context of CVD, and some of the challenges and hurdles to be overcome.

Measuring the process and rate of exogenous DNA degradation during digestion in mice

This study aimed to perform qualitative and quantitative examination of DNA degradation during the digestion process in the mouse gut through PCR, qPCR and short tandem repeat (STR) analysis. Human blood leukocytes were gavaged into the digestive tract in mice. GAPDH, TH01, TPOX and D7S820 genes in the contents of the stomach and small intestine were analyzed with PCR and qPCR at various times pre- and post-gavage. Through STR analysis, 21 human genomic DNA loci were analyzed. The half-life of DNA degradation, and the relationship between the average peak area and digestion time were determined. The PCR results showed bands of amplified genes at pre-gavage (0 min) and post-gavage (40, 80 and 120 min) from the mouse stomach contents, whereas no DNA bands from small intestinal chyme were observed after gavage. The qPCR results revealed a significant decrease in DNA concentrations during 40–120 min in the mouse stomach after gavage. At 120 min, 85.62 ± 8.10% of the DNA was degraded, and the half-life of exogenous DNA degradation in the mouse stomach was 70.50 ± 5.46 min. At various digestion times, almost no target genes were detected in the mouse small intestinal chyme. STR analysis showed a decrease in allele numbers with bowel advancement in the small intestine in mice. The degradation of exogenous DNA was higher in the mouse stomach during the first 2 h, and almost complete degradation was observed within 40 min after entering the small intestine in mice.

Ionic Liquids for Enhanced Drug Delivery: Recent Progress and Prevailing Challenges

Ionic liquids (ILs) are a class of nonmolecular compounds composed only of ions. Compared with traditional organic solvents, ILs have the advantages of wide chemical space, diverse and flexible structures, negligible vapor pressure, and high thermal stability, which make them widely used in many fields of modern science, such as chemical synthesis and catalytic decomposition, electrochemistry, biomass conversion, and biotransformation biotechnology. Because of their special characteristics, ILs have been favored in the pharmaceutical field recently, especially for the development of efficient drug delivery systems. So far, ILs have been successfully designed to promote the dissolution of poorly soluble drugs and the destruction of physiological barriers, such as the tight junction between the stratum corneum and the intestinal epithelium. In addition, ILs can also be combined with other drug strategies to stabilize the structure of small molecules. This Review mainly introduces the application of ILs in drug delivery, emphasizes the potential mechanism of ILs, and presents the key research directions of ILs in the future.

Nanomedicine for increasing the oral bioavailability of cancer treatments

Abstract

Oral administration is an appealing route of delivering cancer treatments. However, the gastrointestinal tract is characterized by specific and efficient physical, chemical, and biological barriers that decrease the bioavailability of medications, including chemotherapeutics. In recent decades, the fields of material science and nanomedicine have generated several delivery platforms with high potential for overcoming multiple barriers associated to oral administration. This review describes the properties of several nanodelivery systems that improve the bioavailability of orally administered therapeutics, highlighting their advantages and disadvantages in generating successful anticancer oral nanomedicines.

Graphical Abstract

Fate of Tableted Freeze-Dried siRNA Lipoplexes in Gastrointestinal Environment

The incorporation of siRNA into nanocarriers is mandatory to facilitate its intracellular delivery, as siRNA itself cannot enter cells. However, the incorporation of these nanocarriers into oral, solid dosage forms and their fate in the gastrointestinal environment is yet to be explored. In the present work, the fate of, (i) naked siRNA, (ii) freshly prepared siRNA lipoplexes, and (iii) tableted siRNA lipoplexes, in simulated gastric and intestinal fluids was studied. The siRNA, either released from or protected within the lipoplexes, was quantified by gel electrophoresis and siRNA efficacy was assessed in cell transfection. The freshly prepared lipoplexes kept their siRNA load and transfection efficiency totally preserved during 1 h of incubation in simulated gastric fluid at 37 °C. However, in simulated intestinal fluid, despite no release of siRNA from lipoplexes after 6 h of incubation, gene silencing efficacy was dramatically decreased even after 1 h of exposure. The lipoplexes obtained from tablets efficiently protected siRNA in simulated gastric fluid, thus preserving the gene silencing efficacy, whereas their incubation in simulated intestinal fluid resulted in a marked siRNA release and decreased gene silencing efficacy. These results provided a detailed explanation for understanding the fate of siRNA in gastrointestinal conditions, when simply loaded in lipoplexes or formulated in the form of tablets.

Future Perspectives of Oral Delivery of Next Generation Therapies for Treatment of Skin Diseases

Gene therapies have conspicuously bloomed in recent years as evidenced by the increasing number of cell-, gene-, and oligo-based approved therapies. These therapies hold great promise for dermatological disorders with high unmet need, for example, epidermolysis bullosa or pachyonychia congenita. Furthermore, the recent clinical success of clustered regularly interspaced short palindromic repeats (CRISPR) for genome editing in humans will undoubtedly contribute to defining a new wave of therapies. Like biologics, naked nucleic acids are denatured inside the gastrointestinal tract and need to be administered via injections. For a treatment to be effective, a sufficient amount of a given regimen needs to reach systemic circulation. Multiple companies are racing to develop novel oral drug delivery approaches to circumvent the proteolytic and acidic milieu of the gastrointestinal tract. In this review, we provide an overview of the evolution of the gene therapy landscape, with a deep focus on gene and oligonucleotide therapies in clinical trials aimed at treating skin diseases. We then examine the progress made in drug delivery, with particular attention on the peptide field and drug-device combinations that deliver macromolecules into the gastrointestinal tract. Such novel devices could potentially be applied to administer other therapeutics including genes and CRISPR-based systems.