Noncompetitive Active Transport Exploiting Intestinal Transferrin Receptors for Oral Delivery of Proteins by Tunable Nanoplatform

Polyester Nanoparticles with Controlled Topography for Peroral Drug Delivery Using Insulin as a Model Protein

Receptor-mediated polyester drug delivery systems have tremendous potential for improving the clinical performance of existing pharmaceutical drugs. Despite significant progress made in this area, it remains unclear how and to what extent the polyester nanoparticle surface topography would affect the in vitro, ex vivo and in vivo performance of a drug, and if there exists a correlation between in vitro and in vivo, as well as healthy versus pathophysiological states. Herein, we report a systematic investigation of the interactions between ligands and receptors as a function of the linker length, two-carbon (2C) versus four-carbon (4C). The in vitro, ex vivo and in vivo in healthy models validate the hypothesis that 4C has better reach and binding to the receptors. The results indicate that 4C offered better performance over 2C in vivo in improving the oral bioavailability of insulin (INS) by 1.1-fold (3.5-fold compared to unfunctionalized nanoparticles) in a healthy rat model. Similar observations were made in pathophysiological models; however, the effects were less prominent compared to those in healthy models. Throughout, ligand decorated nanoparticles outperformed unfunctionalized nanoparticles. Finally, a semimechanistic pharmacokinetic and pharmacodynamic (PKPD) model was developed using the experimental data sets to quantitatively evaluate the effect of P2Ns-GA on oral bioavailability and efficacy of insulin. The study presents a sophisticated oral delivery system for INS or hydrophilic therapeutic cargo, highlighting the significant impact on bioavailability that minor adjustments to the surface chemistry can have.

New concepts drive the development of delivery tools for sustainable treatment of diabetic complications

Diabetic complications, especially diabetic retinopathy, diabetic nephropathy and painful diabetic neuropathy, account for a large portion of patients with diabetes and display rising global prevalence. They are the leading causes of blindness, kidney failure and hypersensitivity to pain caused by diabetes. Current approved therapeutics against the diabetic complications are few and exhibit limited efficacy. The enhanced cell-specificity, stability, biocompatibility, and loading capacity of drugs are essential for the mitigation of diabetic complications. In the article, we have critically discussed the recent studies over the past two years in material sciences and biochemistry. The insightful concepts in these studies drive the development of novel nanoparticles and mesenchymal stem cells-derived extracellular vesicles to meet the need for treatment of diabetic complications. Their underlying biochemical principles, advantages and limitations have been in-depth analyzed. The nanoparticles discussed in the article include double-headed nanodelivery system, nanozyme, ESC-HCM-B system, soft polymer nanostars, tetrahedral DNA nanostructures and hydrogels. They ameliorate the diabetic complication through attenuation of inflammation, apoptosis and restoration of metabolic homeostasis. Moreover, mesenchymal stem cell-derived extracellular vesicles efficiently deliver therapeutic proteins to the retinal cells to suppress the angiogenesis, inflammation, apoptosis and oxidative stress to reverse diabetic retinopathy. Collectively, we provide a critical discussion on the concept, mechanism and therapeutic applicability of new delivery tools to treat these three devastating diabetic complications.

Rationally Designed Naringenin-Conjugated Polyester Nanoparticles Enable Folate Receptor-Mediated Peroral Delivery of Insulin

Receptor-mediated transcytosis of nanoparticles is paramount for the effective delivery of various drugs. Here, we report the design and synthesis of highly functional nanoparticles with specific targeting toward the folate receptor (FR) for the peroral delivery of insulin. In doing so, we demonstrate naringenin (NAR), a citrous flavonoid, as a targeting ligand to FR, with a similar affinity as folic acid. The NAR-decorated nanoparticles indicated a 4-fold increase in FR colocalization compared to unfunctionalized nanoparticles. The NAR-conjugated precision polyester allows for high insulin loading and entrapment efficiencies. As a result, insulin-laden NAR-functional nanoparticles offered a 3-fold higher bioavailability in comparison to unfunctionalized nanoparticles. This work generated a promising contribution to folate-receptor-mediated peroral delivery of insulin, utilizing polymeric nanoparticles decorated with a natural ligand, NAR.

Bioinspired pH-Responsive Microalgal Hydrogels for Oral Insulin Delivery with Both Hypoglycemic and Insulin Sensitizing Effects

The oral form of insulin is more convenient and has better patient compliance than subcutaneous or intravenous insulin. Current oral insulin preparations, however, cannot overcome the enzyme barrier, chemical barrier, and epithelial barrier of the gastrointestinal tract completely. In this study, a microalgae-based oral insulin delivery strategy (CV@INS@ALG) was developed using Chlorella vulgaris (CV)-based insulin delivery system cross-linking with sodium alginate (ALG). CV@INS@ALG could overcome the gastrointestinal barrier, protect insulin from harsh gastric conditions, and achieve a pH-responsive drug release in the intestine. CV@INS@ALG might contribute to two mechanisms of insulin absorption, including direct insulin release from the delivery system and endocytosis by M cells and macrophages. In the streptozotocin (STZ)-induced type 1 diabetic mouse model, CV@INS@ALG showed a more effective and long-lasting hypoglycemic effect than direct insulin injection and did not cause any damage to the intestinal tract. Additionally, the long-term oral administration of the carrier CV@ALG effectively ameliorated gut microbiota disorder, and significantly increased the abundance of probiotic Akkermansia in db/db type 2 diabetic mice, thereby enhancing the insulin sensitivity of mice. Microalgal insulin delivery systems could be degraded and metabolized in the intestinal tract after oral administration, showing good biodegradability and biosafety. This insulin delivery strategy based on microalgal biomaterials provides a natural, efficient, and multifunctional solution for oral insulin delivery.

Receptor-targeted nanoparticles modulate cannabinoid anticancer activity through delayed cell internalization

Δ9-tetrahydrocannabinol (Δ9-THC) is known for its antitumor activity and palliative effects. However, its unfavorable physicochemical and biopharmaceutical properties, including low bioavailability, psychotropic side effects and resistance mechanisms associated to dosing make mandatory the development of successful drug delivery systems. In this work, transferring (Tf) surface-modified Δ9-THC-loaded poly(lactide-co-glycolic) nanoparticles (Tf-THC-PLGA NPs) were proposed and evaluated as novel THC-based anticancer therapy. Furthermore, in order to assess the interaction of both the nanocarrier and the loaded drug with cancer cells, a double-fluorescent strategy was applied, including the chemical conjugation of a dye to the nanoparticle polymer along with the encapsulation of either a lipophilic or a hydrophilic dye. Tf-THC PLGA NPs exerted a cell viability decreased down to 17% vs. 88% of plain nanoparticles, while their internalization was significantly slower than plain nanoparticles. Uptake studies in the presence of inhibitors indicated that the nanoparticles were internalized through cholesterol-associated and clathrin-mediated mechanisms. Overall, Tf-modification of PLGA NPs showed to be a highly promising approach for Δ9-THC-based antitumor therapies, potentially maximizing the amount of drug released in a sustained manner at the surface of cells bearing cannabinoid receptors.

Nanotechnologies for the delivery of biologicals: Historical perspective and current landscape

Biological macromolecule-based therapeutics irrupted in the pharmaceutical scene generating a great hope due to their outstanding specificity and potency. However, given their susceptibility to degradation and limited capacity to overcome biological barriers new delivery technologies had to be developed for them to reach their targets. This review aims at analyzing the historical seminal advances that shaped the development of the protein/peptide delivery field, along with the emerging technologies on the lead of the current landscape. Particularly, focus is made on technologies with a potential for transmucosal systemic delivery of protein/peptide drugs, followed by approaches for the delivery of antigens as new vaccination strategies, and formulations of biological drugs in oncology, with special emphasis on mAbs. Finally, a discussion of the key challenges the field is facing, along with an overview of prospective advances are provided.

Oral delivery of proteins and peptides: Challenges, status quo and future perspectives

Proteins and peptides (PPs) have gradually become more attractive therapeutic molecules than small molecular drugs due to their high selectivity and efficacy, but fewer side effects. Owing to the poor stability and limited permeability through gastrointestinal (GI) tract and epithelia, the therapeutic PPs are usually administered by parenteral route. Given the big demand for oral administration in clinical use, a variety of researches focused on developing new technologies to overcome GI barriers of PPs, such as enteric coating, enzyme inhibitors, permeation enhancers, nanoparticles, as well as intestinal microdevices. Some new technologies have been developed under clinical trials and even on the market. This review summarizes the history, the physiological barriers and the overcoming approaches, current clinical and preclinical technologies, and future prospects of oral delivery of PPs.

Oral Delivery of Biologics for Precision Medicine

The emerging field of precision medicine is rapidly growing, fostered by the advances in genome mapping and molecular diagnosis. In general, the translation of these advances into precision treatments relies on the use of biological macromolecules, whose structure offers a high specificity and potency. Unfortunately, due to their complex structure and limited ability to overcome biological barriers, these macromolecules need to be administered via injection. The scientific community has devoted significant effort to making the oral administration of macromolecules plausible thanks to the implementation of drug delivery technologies. Here, an overview of the current situation and future prospects in the field of oral delivery of biologics is provided. Technologies in clinical trials, as well as recent and disruptive delivery systems proposed in the literature for local and systemic delivery of biologics including peptides, antibodies, and nucleic acids, are described. Strategies for the specific targeting of gastrointestinal regions-stomach, small bowel, and colon-cell populations, and internalization pathways, are analyzed. Finally, challenges associated with the clinical translation, future prospects, and identified opportunities for advancement in this field are also discussed.

Oral delivery of nanoparticle urolithin A normalizes cellular stress and improves survival in mouse model of cisplatin-induced AKI

The popular anticancer drug cisplatin causes many adverse side effects, the most serious of which is acute kidney injury (AKI). Emerging evidence from laboratory and clinical studies suggests that the AKI pathogenesis involves oxidative stress pathways; therefore, regulating such pathways may offer protection. Urolithin A (UA), a gut metabolite of the dietary tannin ellagic acid, possesses antioxidant properties and has shown promise in mouse models of AKI. However, therapeutic potential of UA is constrained by poor bioavailability. We aimed to improve oral bioavailability of UA by formulating it into biodegradable nanoparticles that use a surface-conjugated ligand targeting the gut-expressed transferrin receptor. Nanoparticle encapsulation of UA led to a sevenfold enhancement in oral bioavailability compared with native UA. Treatment with nanoparticle UA also significantly attenuated the histopathological hallmarks of cisplatin-induced AKI and reduced mortality by 63% in the mouse model. Expression analyses indicated that nanoparticle UA therapy coincided with oxidative stress mitigation and downregulation of nuclear factor erythroid 2-related factor 2- and P53-inducible genes. Additionally, normalization of miRNA (miR-192-5p and miR-140-5p) implicated in AKI, poly(ADP-ribose) polymerase 1 levels, antiapoptotic signaling, intracellular NAD+, and mitochondrial oxidative phosphorylation were observed in the treatment group. Our findings suggest that nanoparticles greatly increase the oral bioavailability of UA, leading to improved survival rates in AKI mice, in part by reducing renal oxidative and apoptotic stress.

Rational Design of Nanocarriers for Intracellular Protein Delivery

Protein/antibody therapeutics have exhibited the advantages of high specificity and activity even at an extremely low concentration compared to small molecule drugs. However, they are accompanied by unfavorable physicochemical properties such as fragile tertiary structure, large molecular size, and poor penetration of the membrane, and thus the clinical use of protein drugs is hindered by inefficient delivery of proteins into the host cells. To overcome the challenges associated with protein therapeutics and enhance their biopharmaceutical applications, various protein-loaded nanocarriers with desired functions, such as lipid nanocapsules, polymeric nanoparticles, inorganic nanoparticles, and peptides, are developed. In this review, the different strategies for intracellular delivery of proteins are comprehensively summarized. Their designed routes, mechanisms of action, and potential therapeutics in live cells or in vivo are discussed in detail. Furthermore, the perspective on the new generation of delivery systems toward the emerging area of protein-based therapeutics is presented as well.

Oral delivery of nanoparticle urolithin A normalizes cellular stress and improves survival in mouse model of cisplatin-induced AKI

The popular anticancer drug cisplatin causes many adverse side effects, the most serious of which is acute kidney injury (AKI). Emerging evidence from laboratory and clinical studies suggests that the AKI pathogenesis involves oxidative stress pathways; therefore, regulating such pathways may offer protection. Urolithin A (UA), a gut metabolite of the dietary tannin ellagic acid, possesses antioxidant properties and has shown promise in mouse models of AKI. However, therapeutic potential of UA is constrained by poor bioavailability. We aimed to improve oral bioavailability of UA by formulating it into biodegradable nanoparticles that use a surface-conjugated ligand targeting the gut-expressed transferrin receptor. Nanoparticle encapsulation of UA led to a sevenfold enhancement in oral bioavailability compared with native UA. Treatment with nanoparticle UA also significantly attenuated the histopathological hallmarks of cisplatin-induced AKI and reduced mortality by 63% in the mouse model. Expression analyses indicated that nanoparticle UA therapy coincided with oxidative stress mitigation and downregulation of nuclear factor erythroid 2-related factor 2- and P53-inducible genes. Additionally, normalization of miRNA (miR-192-5p and miR-140-5p) implicated in AKI, poly(ADP-ribose) polymerase 1 levels, antiapoptotic signaling, intracellular NAD+, and mitochondrial oxidative phosphorylation were observed in the treatment group. Our findings suggest that nanoparticles greatly increase the oral bioavailability of UA, leading to improved survival rates in AKI mice, in part by reducing renal oxidative and apoptotic stress.

Oral Drug Delivery Technologies-A Decade of Developments

Advanced drug delivery technologies, in general, enable drug reformulation and administration routes, together contributing to life-cycle management and allowing the innovator to maintain the product monopoly. Over the years, there has been a steady shift from mere life-cycle management to drug repurposing-applying delivery technologies to tackle solubility and permeability issues in early stages or safety and efficacy issues in the late stages of drug discovery processes. While the drug and the disease in question primarily drive the choice of route of administration, the oral route, for its compliance and safety attributes, is the most preferred route, particularly when it comes to chronic conditions, including pain, which is not considered a disease but a symptom of a primary cause. Therefore, the attempt of this review is to take a stock of the advances in oral delivery technologies that are applicable for injectable to oral transformation, improve risk-benefit profiles of existing orals, and apply them in the early discovery program to minimize the drug attrition rates.

Next-Generation Noncompetitive Nanosystems Based on Gambogic Acid: In silico Identification of Transferrin Receptor Binding Sites, Regulatory Shelf Stability, and Their Preliminary Safety in Healthy Rodents

A major challenge in drug delivery is to enhance the transport of drugs across biological barriers, such as the small intestine, the blood-brain barrier, and the blood-retinal/ocular barrier, and to effectively reach the site of action while minimizing the systemic impact. In recent years, piggybacking cell surface receptors have been considered a viable strategy for active drug delivery across the biological barriers. However, the ligands used to target drugs to plasma membrane receptors often have to compete against endogenous ligands, thereby limiting their binding to the cell surface and their transport across barriers. To address this problem, gambogic acid (GA) was identified as a noncompetitive ligand specific to the transferrin receptor (TfR), a receptor present on various barriers. However, the binding sites of the GA on TfR remain unknown, an essential step toward establishing structure-activity relationships. In silico binding site prediction tools, blind docking, and molecular docking simulation confirm that the GA binding site on the TfR is independent of the transferrin-bound iron binding sites. The GA-conjugated polyesters were processed into nanoparticles suitable for drug delivery applications that possess excellent storage stability under regulatory conditions. Traditionally, GA has been used as an anticancer compound that warrants safety assessment. The preliminary studies in healthy rodents on 10-repeated oral doses show no adverse effects. This work will generate paradigm shifting, new knowledge in the field of nanomedicines using unique noncompetitive nanosystems that do not compete with endogenous transferrin.

Delivery of Nanoparticles across the Intestinal Epithelium via the Transferrin Transport Pathway

The aim of this study was to probe whether the transferrin (Tf) transport pathway can be exploited for intestinal delivery of nanoparticles. Tf was adsorbed on 100 nm model polystyrene nanoparticles (NP), followed by size characterisation of these systems. Cell uptake of Tf and Tf-adsorbed NP was investigated in intestinal epithelial Caco-2 cells cultured on multi-well plates and as differentiated polarised monolayers. Tf-NP demonstrated a remarkably higher cell uptake compared to unmodified NP in both non-polarised (5-fold) and polarised cell monolayers (16-fold difference). Application of soluble Tf significantly attenuated the uptake of Tf-NP. Notably, Tf-NP displayed remarkably higher rate (23-fold) of epithelial transport across Caco-2 monolayers compared to unmodified NP. This study therefore strongly suggests that the Tf transport pathway should be considered as a candidate biological transport route for orally-administered nanomedicines and drugs with poor oral bioavailability.

Double-headed nanosystems for oral drug delivery

We demonstrate a novel strategy to engineer double-headed nanosystems by chemical modification of the carboxyl terminal polyester with a linker that offers tripodal arrangement of ligands on the particle surfaces. The in vivo results suggest that the bioavailability of encapsulated curcumin is proportional to the ligand density rendered by double-headed nanosystems.

Ex Vivo Rat Eye Model for Investigating Transport of Next Generation Precision-Polyester Nanosystems

We present for the first time a robust ex vivo rat eye model for investigating the transport of precision-polyester nanosystems (P2Ns) across the blood-retinal barrier, intended for systemic administration. The P2Ns-GA actively transport exploiting transferrin receptors present in the inner retinal barrier and colocalize in ganglion cells. Such delivery approaches have the potential to deliver drugs to posterior segments of the eye, which is still a major challenge in treating posterior ocular disorders.