Oral Nanomedicine: Challenges and Opportunities

Proteolysis-targeting drug delivery system (ProDDS): integrating targeted protein degradation concepts into formulation design

Targeted protein degradation (TPD) has emerged as a revolutionary paradigm in drug discovery and development, offering a promising avenue to tackle challenging therapeutic targets. Unlike traditional drug discovery approaches that focus on inhibiting protein function, TPD aims to eliminate proteins of interest (POIs) using modular chimeric structures. This is achieved through the utilization of proteolysis-targeting chimeras (PROTACs), which redirect POIs to E3 ubiquitin ligases, rendering them for degradation by the cellular ubiquitin-proteasome system (UPS). Additionally, other TPD technologies such as lysosome-targeting chimeras (LYTACs) and autophagy-based protein degraders facilitate the transportation of proteins to  endo-lysosomal or autophagy-lysosomal pathways for degradation, respectively. Despite significant growth in preclinical TPD research, many chimeras fail to progress beyond this stage in the drug development. Various factors contribute to the limited success of TPD agents, including a significant hurdle of inadequate delivery to the target site. Integrating TPD into delivery platforms could surmount the challenges of in vivo applications of TPD strategies by reshaping their pharmacokinetics and pharmacodynamic profiles. These proteolysis-targeting drug delivery systems (ProDDSs) exhibit superior delivery performance, enhanced targetability, and reduced off-tissue side effects. In this review, we will survey the latest progress in TPD-inspired drug delivery systems, highlight the importance of introducing delivery ideas or technologies to the development of protein degraders, outline design principles of protein degrader-inspired delivery systems, discuss the current challenges, and provide an outlook on future opportunities in this field.

Smart Bioorthogonal Nanozymes: From Rational Design to Appropriate Bioapplications

Bioorthogonal chemistry has provided an elaborate arsenal to manipulate native biological processes in living systems. As the great advancement of nanotechnology in recent years, bioorthogonal nanozymes are innovated to tackle the challenges that emerged in practical biomedical applications. Bioorthogonal nanozymes are uniquely positioned owing to their advantages of high customizability and tunability, as well as good adaptability to biological systems, which bring exciting opportunities for biomedical applications. More intriguingly, the great advancement in nanotechnology offers an exciting opportunity for innovating bioorthogonal catalytic materials. In this comprehensive review, the significant progresses of bioorthogonal nanozymes are discussed with both spatiotemporal controllability and high performance in living systems, and highlight their design principles and recent rapid applications. The remaining challenges and future perspectives are then outlined along this thriving field. It is expected that this review will inspire and promote the design of novel bioorthogonal nanozymes, and facilitate their clinical translation.

"Two-birds-one-stone" oral nanotherapeutic designed to target intestinal integrins and regulate redox homeostasis for UC treatment

Designing highly efficient orally administrated nanotherapeutics with specific inflammatory site-targeting functions in the gastrointestinal tract for ulcerative colitis (UC) management is a noteworthy challenge. Here, we focused on exploring a specific targeting oral nanotherapy, serving as "one stone," for the directed localization of inflammation and the regulation of redox homeostasis, thereby achieving effects against "two birds" for UC treatment. Our designed nanotherapeutic agent OPNs@LMWH (oxidation-sensitive ε-polylysine nanoparticles at low-molecular weight heparin) exhibited specific active targeting effects and therapeutic efficacy simultaneously. Our results indicate that OPNs@LMWH had high integrin αM-mediated immune cellular uptake efficiency and preferentially accumulated in inflamed tissues. We also confirmed its effectiveness in the treatment experiment of colitis in mice by ameliorating oxidative stress and inhibiting the activation of inflammation-associated signaling pathways while simultaneously bolstering the protective mechanisms of the colonic epithelium. Overall, these findings underscore the compelling dual functionalities of OPNs@LMWH, which enable effective oral delivery to inflamed sites, thereby facilitating precise UC management.

Microenvironment-responsive metal-phenolic network release platform with ROS scavenging, anti-pyroptosis, and ECM regeneration for intervertebral disc degeneration

Intervertebral disc degeneration (IVDD) can be caused by aging, injury, and genetic factors. The pathological changes associated with IVDD include the excessive accumulation of reactive oxygen species (ROS), cellular pyroptosis, and extracellular matrix (ECM) degradation. There are currently no approved specific molecular therapies for IVDD. In this study, we developed a multifunctional and microenvironment-responsive metal-phenolic network release platform, termed TMP@Alg-PBA/PVA, which could treat (IL-1β)-induced IVDD. The metal-phenolic network (TA-Mn-PVP, TMP) released from this platform targeted mitochondria to efficiently scavenge ROS and reduce ECM degradation. Pyroptosis was suppressed through the inhibition of the IL-17/ERK signaling pathway. These findings demonstrate the versatility of the platform. And in a rat model of IVDD, TMP@Alg-PBA/PVA exhibited excellent therapeutic effects by reducing the progression of the disease. TMP@Alg-PBA/PVA, therefore, presents clinical potential for the treatment of IVDD.

Oral biomimetic virus vaccine hydrogel for robust abscopal antitumour efficacy

Remarkable progress has been made in tumour immunotherapy in recent decades. However, the clinical outcomes of therapeutic interventions remain unpredictable, largely because of inefficient immune responses. To address this challenge and optimise immune stimulation, we present a novel administration route for enhancing the bioavailability of immunotherapeutic drugs. Our approach involves the development of an oral tumour vaccine utilising virus-like particles derived from the Hepatitis B virus core (HBc) antigen. The external surfaces of these particles are engineered to display the model tumour antigen OVA, whereas the interiors are loaded with cytosine phosphoguanosine oligodeoxynucleotide (CpG ODN), resulting in a construct called CpG@OVAHBc with enhanced antigenicity and immune response. For oral delivery, CpG@OVAHBc is encapsulated in a crosslinked dextran hydrogel called CpG@OVAHBc@Dex. The external hydrogel shield safeguards the biomimetic virus particles from degradation by gastric acid and proteases. Upon exposure to intestinal flora, the hydrogel disintegrates, releasing CpG@OVAHBc at the intestinal mucosal site. Owing to its virus-like structure, CpG@OVAHBc exhibits enhanced adhesion to the mucosal surface, facilitating uptake by microfold cells (M cells) and subsequent transmission to antigen-presenting cells. The enzyme-triggered release of this oral hydrogel ensures the integrity of the tumour vaccine within the digestive tract, allowing targeted release and significantly improving bioavailability. Beyond its efficacy, this oral hydrogel vaccine streamlines drug administration, alleviates patient discomfort, and enhances treatment compliance without the need for specialised injection methods. Consequently, our approach expands the horizons of vaccine development in the field of oral drug administration.

Supramolecular Lipid Nanoparticles Based on Host-Guest Recognition: A New Generation Delivery System of mRNA Vaccines For Cancer Immunotherapy

Dendritic cell (DC) maturation is a crucial process for antigen presentation and the initiation of T cell-mediated immune responses. Toll-like receptors play pivotal roles in stimulating DC maturation and promoting antigen presentation. Here, a novel message RNA (mRNA) cancer vaccine is reported that boosts antitumor efficacy by codelivering an mRNA encoding tumor antigen and a TLR7/8 agonist (R848) to DC using supramolecular lipid nanoparticles (SMLNP) as a delivery platform, in which a new ionizable lipid (N2-3L) remarkably enhances the translation efficiency of mRNA and a β-cyclodextrin (β-CD)-modified ionizable lipid (Lip-CD) encapsulates R848. The incorporation of R848 adjuvant into the mRNA vaccine through noncovalent host-guest complexation significantly promotes DC maturation and antigen presentation after vaccination, thus resulting in superior antitumor efficacy in vivo. Moreover, the antitumor efficacy is further boosted synergized with immune checkpoint blockade by potentiating the anticancer capability of cytotoxic T lymphocytes infiltrated in tumor sites. This work indicates that SMLNP shows brilliant potential as next-generation delivery system in the development of mRNA vaccines with high efficacy.