Sustained Release Systems for Delivery of Therapeutic Peptide/Protein

PLGA-based long-acting injectable (LAI) formulations

Long-acting injectable (LAI) formulations, which deliver drugs over weeks or months, have been in use for more than three decades. Most clinically approved LAI products are formulated using poly(lactide-co-glycolide) (PLGA) polymers. Historically, the development of PLGA-based LAI formulations has relied predominantly on trial-and-error methods, primarily due to a limited understanding of the complex factors involved in LAI formulations and insufficient analytical techniques available for characterizing individual PLGA polymers of the prepared formulations. This article offers a personal perspective on recent advancements in characterization methods for PLGA polymers within final formulations, i.e., products, as well as enhanced insights into the drug release mechanisms associated with LAI products. With a deeper understanding of PLGA polymer properties and drug release mechanisms, the formulation development process can transition from traditional trial-and-error practices to a more systematic Quality by Design (QbD) approach. Additionally, this article explores the emerging role of artificial intelligence (AI) in formulation science and its potential, when applied carefully, to enhance the future development of PLGA-based LAI formulations.

Beneficial impact of MTGase-modified fish gelatin on collagen supplementation in rats: Insights from serum metabolomics and gut microbiota

Sustained release technology facilitates precise regulation of active ingredient delivery, attenuating enzymatic degradation while optimizing bioavailability in malabsorptive conditions. Microbial transglutaminase (MTGase) catalyzes isopeptide bond formation via acyl transfer reactions, conferring resistance to gastrointestinal digestion. However, the in vivo sustained release potential of MTGase-modified fish gelatin (MTGase-modified-FG) remains uncertain. In this study, enzymatic modification was performed using MTGase at graded concentrations (0.00 % (Nor), 0.06 % (LD), 0.12 % (MD), and 0.21 % (HD)), with sustained release of collagen evaluated through pharmacokinetic analysis. The results indicated that the MTGase-modified-FG supplementation exhibited a dose-dependent sustained release, extending Tmax from 2.00 ± 0.00 h (Nor) to 5.33 ± 1.15 h (HD). Notably, suboptimal crosslinking (LD/MD) enhanced skin collagen deposition, whereas excessive modification (HD) induced malabsorptive phenomena that may be attributed to the presence of excessive isopeptide bonds. Metabolomic analysis identified MTGase-modified-FG modulated the serum metabolome in collagen-related metabolites (LysoPC, Lysine, succinate), mechanistically linked to choline metabolism in cancer and lysine catabolism. Additionally, the gut microbiota remodeling was modulated by the suppression of Ruminococcus and Blautia, as well as by the expansion of Faecalibaculum and Bifidobacterium at the genus level. RT-qPCR analysis indicated that MTGase-modified-FG enhanced collagen deposition via the TGF-β/Smads and MAPK/AP-1/MMP pathways in human dermal fibroblast cells. These findings suggest that MTGase-modified confers the sustained release properties to fish gelatin, and provides a new collagen supplementation strategy for individuals with malabsorption syndromes.

Strategies to Enhance the Therapeutic Efficacy of GLP-1 Receptor Agonists through Structural Modification and Carrier Delivery

Diabetes is a metabolic disorder characterized by insufficient endogenous insulin production or impaired sensitivity to insulin. In recent years, a class of incretin-based hypoglycemic drugs, glucagon-like peptide-1 receptor agonists (GLP-1RAs), have attracted great attention in the management of type 2 diabetes mellitus (T2DM) due to their benefits, including stable glycemic control ability, a low risk of hypoglycemia, and weight reduction for patients. However, like other peptide drugs, GLP-1RAs face challenges such as instability, susceptibility to enzymatic degradation, and immunogenicity, which severely limit their clinical application. In recent years, various strategies have been developed to improve the bioavailability and therapeutic efficacy of GLP-1RAs, including structural modification and carrier-mediated delivery. This article briefly introduces the research and application status of several common GLP-1RAs and their limitations. Taking exendin-4 as an example, we focus on the research progress of improving bioavailability and therapeutic efficacy based on structural modification and carrier delivery strategies, aiming to provide reference for the development of new GLP-1RAs treatment systems.

Advances in Drug Delivery Integrated with Regenerative Medicine: Innovations, Challenges, and Future Frontiers

Advances in drug delivery systems adapted with regenerative medicine have transformed healthcare by introducing innovative strategies to treat (and repair in many instances) disease-impacted regions of the human body. This review provides a comprehensive analysis of the latest developments and challenges in integrating drug delivery technologies with regenerative medicine. Recent advances in drug delivery technologies, including the design of biomaterials, localized delivery techniques, and controlled release systems guided by mathematical models, are explored to illustrate their role in enhancing therapeutic precision and efficacy. Additionally, regenerative medicine approaches are analyzed, with a focus on extracellular matrix components, stem cell-based therapies, and emerging strategies for organ regeneration in both soft and hard tissue and in vitro model engineering. In particular, the review also discusses the applications of cellular components, including stem cells, immune cells, endothelial cells, and specialized cells such as chondrocytes and osteoblasts, and highlights advancements in cell delivery methods and cell-cell interaction modulation. In addition, future directions and pivotal trends emphasizing the importance of interdisciplinary collaboration and cutting-edge innovations are provided to address successful therapeutic outcomes in regenerative medicine.

Synthesis of PVA-Based Hydrogels for Biomedical Applications: Recent Trends and Advances

There is ongoing research for biomedical applications of polyvinyl alcohol (PVA)-based hydrogels; however, the execution of this has not yet been achieved at an appropriate level for commercialization. Advanced perception is necessary for the design and synthesis of suitable materials, such as PVA-based hydrogel for biomedical applications. Among polymers, PVA-based hydrogel has drawn great interest in biomedical applications owing to their attractive potential with characteristics such as good biocompatibility, great mechanical strength, and apposite water content. By designing the suitable synthesis approach and investigating the hydrogel structure, PVA-based hydrogels can attain superb cytocompatibility, flexibility, and antimicrobial activities, signifying that it is a good candidate for tissue engineering and regenerative medicine, drug delivery, wound dressing, contact lenses, and other fields. In this review, we highlight the current progresses on the synthesis of PVA-based hydrogels for biomedical applications explaining their diverse usage across a variety of areas. We explain numerous synthesis techniques and related phenomena for biomedical applications based on these materials. This review may stipulate a wide reference for future acumens of PVA-based hydrogel materials for their extensive applications in biomedical fields.

Muco-adhesive chitosan-coated polyphenol nanoparticle for treatment of infectious acute pneumonia through sustained pulmonary delivery of polymyxin B

Infectious acute pneumonia caused by bacteria has been a great challenge to human health for long time, and the rapid clearance of aerosolized antibiotics in the lungs restricts their clinical application. The development of nanoformulations with facile preparation and mucoadhesive properties for the pulmonary delivery of antibiotics is thus significant for the treatment of infectious acute pneumonia. In this study, FDA (Food and Drug Administration)-approved tannic acid (TA) was used to construct mucoadhesive nanoformulations through the facile coating of chitosan (CS) to achieve long-lasting anti-infection effects against infectious acute pneumonia. Using an antibacterial peptide, polymyxin B (PB), as the model drug, the flash nanocomplexation technique was used to prepare CS-coated TA/poly(vinyl alcohol) (PVA)/PB nanoparticles (TPBC NPs) through non-covalent interactions of each component. Investigation on acute pneumonia mice model demonstrated that, through the strong electrostatic interaction between positively charged chitosan and negatively charged mucin in the trachea, the release of polymyxin B retained in the lung for at least 24 h-post inhalation of TPBC NPs, thereby inhibiting pulmonary infection within 3 days. Combined with their great biocompatibility, mucoadhesive TPBC NPs prepared by a facile and reproducible procedure may provide a new strategy for the pulmonary delivery of antibiotics to treat infectious acute pneumonia.

Biopharmaceutical drug delivery and phototherapy using protein crystals

Biopharmaceutical drugs, including proteins, peptides, and antibodies, are renowned for their high specificity and efficacy, fundamentally transforming disease treatment paradigms. However, their structural complexity presents challenges for their formulation and delivery. Protein crystals, characterized by high purity, high stability and a porous structure for biopharmaceutical drug encapsulation, providing a potential avenue for formulating and delivering biopharmaceutical drugs. There is increasing interest in engineering protein crystals to delivery biopharmaceutical drugs for biomedical applications. This review summarizes the recent advances in biopharmaceutical drug delivery and phototherapy using protein crystals. First, we evaluate the advantages of using protein crystals for biopharmaceutical drugs delivery. Next, we outline the strategies for in vitro and in vivo crystallization to prepare protein crystals. Importantly, the review highlights the advanced applications of protein crystals in biopharmaceutical drug delivery, tumor phototherapy, and other optical fields. Finally, it provides insights into future perspectives of biopharmaceutical drug delivery using protein crystals. This comprehensive review aims to provide effective insights into design of protein crystals to simplify biopharmaceutical drug delivery and improve disease treatment.

Laponite nanoclays for the sustained delivery of therapeutic proteins

Protein therapeutics hold immense promise for treating a wide array of diseases. However, their efficacy is often compromised by rapid degradation and clearance. The synthetic smectite clay Laponite emerges as a promising candidate for their sustained delivery. Despite its unique properties allow to load and release proteins mitigating burst release and extending their effects, precise control over Laponite-protein interactions remains challenging since it depends on a complex interplay of factors whose implication is not fully understood yet. The aim of this review article is to shed light on this issue, providing a comprehensive discussion of the factors influencing protein loading and release, including the physicochemical properties of the nanoclay and proteins, pH, dispersion buffer, clay/protein concentration and Laponite degradation. Furthermore, we thoroughly revise the array of bioactive proteins that have been delivered from formulations containing the nanoclay, highlighting Laponite-polymer nanocomposite hydrogels, a promising avenue currently under extensive investigation.

Poly-d,l-lactic Acid (PDLLA) Application in Dermatology: A Literature Review

Poly-d,l-lactic acid (PDLLA) is a biodegradable and biocompatible polymer that has garnered significant attention in dermatology due to its unique properties and versatile applications. This literature review offers a comprehensive analysis of PDLLA's roles in various dermatological conditions and wound-healing applications. PDLLA demonstrates significant benefits in enhancing skin elasticity and firmness, reducing wrinkles, and promoting tissue regeneration and scar remodeling. Its biodegradable properties render it highly suitable for soft tissue augmentation, including facial and breast reconstruction. We discuss the critical importance of understanding PDLLA's physical and chemical characteristics to optimize its performance and safety, with a focus on how nano- and micro-particulate systems can improve delivery and stability. While potential complications, such as granuloma formation and non-inflammatory nodules, are highlighted, effective monitoring and early intervention strategies are essential. PDLLA's applications extend beyond dermatology into orthopedics and drug delivery, owing to its superior mechanical stability and biocompatibility. This review underscores the need for ongoing research to fully elucidate the mechanisms of PDLLA and to maximize its therapeutic potential across diverse medical fields.

Unlocking nature's arsenal: Nanotechnology for targeted delivery of venom toxins in cancer therapy

AIM

The aim of the present review is to shed light on the nanotechnological approaches adopted to overcome the shortcomings associated with the delivery of venom peptides which possess inherent anti-cancer properties.

BACKGROUND

Venom peptides although have been reported to demonstrate anti-cancer effects, they suffer from several disadvantages such as in vivo instability, off-target adverse effects, limited drug loading and low bioavailability. This review presents a comprehensive compilation of different classes of nanocarriers while underscoring their advantages, disadvantages and potential to carry such peptide molecules for in vivo delivery. It also discusses various nanotechnological aspects such as methods of fabrication, analytical tools to assess these nanoparticulate formulations, modulation of nanocarrier polymer properties to enhance loading capacity, stability and improve their suitability to carry toxic peptide drugs.

CONCLUSION

Nanotechnological approaches bear great potential in delivering venom peptide-based molecules as anticancer agents by enhancing their bioavailability, stability, efficacy as well as offering a spatiotemporal delivery approach. However, the challenges associated with toxicity and biocompatibility of nanocarriers must be duly addressed.

PERSPECTIVES

The everlasting quest for new breakthroughs for safer delivery of venom peptides in human subjects is fuelled by unmet clinical needs in the current landscape of chemotherapy. In addition, exhaustive efforts are required in obtaining and purifying the venom peptides followed by designing and optimizing scale up technologies.

Freezing-mediated formation of supraproteins using depletion forces

Hypothesis Long-acting formulations such as microparticles, injectable depots and implantable devices can realize spatiotemporally controlled delivery of protein drugs to extend their therapeutic in vivo half-lives. To efficiently encapsulate the protein drugs into such drug delivery systems, (sub)micron-sized protein particles are needed. The formation of micronized supraproteins can be induced through the synergistic combination of attractive depletion forces and freezing. The size of the supraproteins can be fine-tuned from submicron to several microns by adjusting the ice crystallization rate through the freeze-quench depth, which is set by the target temperature. Methods Supraprotein micron structures were prepared from protein solutions under various conditions in the presence and absence of nonadsorbing polyethylene glycol. Scanning electron microscopy and dynamic light scattering were employed to determine the sizes of the supraproteins and real-time total internal reflection fluorescent microscopy was used to follow the supraprotein formation during freezing. The protein secondary structure was measured before and after micronization by circular dichroism. A phase diagram of a protein-polyethylene glycol mixture was theoretically predicted to investigate whether the depletion interaction can elucidate the phase behavior. Findings Micronized protein supraparticles could be prepared in a controlled manner by rapid freeze-drying of aqueous mixtures of bovine serum albumin, horseradish peroxidase and lysozyme mixed with polyethylene glycol. Upon freezing, the temperature quench initiates a phase separation process which is reminiscent of spinodal decomposition. This demixing is subsequently arrested during droplet phase separation to form protein-rich microstructures. The final size of the generated protein microparticles is determined by a competition between phase separation and cooling rate, which can be controlled by target temperature. The experimental phase diagram of the aqueous protein-polyethylene glycol dispersion aligns with predictions from depletion theory for charged colloids and nonadsorbing polymers.

Conformation-Switchable Polypeptides as Molecular Gates for Controllable Drug Release

The control over secondary structure has been widely studied to regulate the properties of polypeptide materials, which is used to change their functions in situ for various biomedical applications. Herein, we designed and constructed enzyme-responsive polypeptides as gating materials for mesoporous silica nanoparticles (MSNs), which underwent a distorted structure-to-helix transition to promote the release of encapsulated drugs. The polypeptide conjugated on the MSN surface adopted a negatively charged, distorted, flexible conformation, covering the pores of MSN to prevent drug leakage. Upon triggering by alkaline phosphatase (ALP) overproduced by tumor cells, the polypeptide transformed into positively charged, α-helical, rigid conformation with potent membrane-penetrating capabilities, which protruded from the MSN surface to uncover the pores. Such a transition thus enabled cancer-selective drug release and cellular internalization to efficiently kill tumor cells. This study highlights the important role of chain flexibility in modulating the biological function of polypeptides and provides a new application paradigm for synthetic polypeptides with secondary-structure transition.

Biomaterials for Protein Delivery: Opportunities and Challenges to Clinical Translation

The development of biomaterials for protein delivery is an emerging field that spans materials science, bioengineering, and medicine. In this review, we highlight the immense potential of protein-delivering biomaterials as therapeutic options and discuss the multifaceted challenges inherent to the field. We address current advancements and approaches in protein delivery that leverage stimuli-responsive materials, harness advanced fabrication techniques like 3D printing, and integrate nanotechnologies for greater targeting and improved stability, efficacy, and tolerability profiles. We also discuss the demand for highly complex delivery systems to maintain structural integrity and functionality of the protein payload. Finally, we discuss barriers to clinical translation, such as biocompatibility, immunogenicity, achieving reliable controlled release, efficient and targeted delivery, stability issues, scalability of production, and navigating the regulatory landscape for such materials. Overall, this review summarizes insights from a survey of the current literature and sheds light on the interplay between innovation and the practical implementation of biomaterials for protein delivery.

Immune Potentiation of PLGA Controlled-Release Vaccines for Improved Immunological Outcomes

With the emergence of SARS-CoV-2 and the continued emergence of new infectious diseases, there is a need to improve and expand current vaccine technology. Controlled-release subunit vaccines provide several benefits over current vaccines on the market, including the use of less antigen and fewer boost doses. Previously, our group reported molecules that alter NF-κB signaling improved the vaccine's performance and improved adjuvant-related tolerability. In this report, we test how these immune potentiators will influence responses when included as part of a controlled-release poly(lactic-co-glycolic) vaccine formulation. Murine in vivo studies revealed that SN50 and honokiol improved antibody levels at early vaccine time points. Microparticles with SN50 produced strong antibody levels over a longer period compared to microparticles without SN50. The same particles also increased T-cell activity. All of the immune potentiators tested further promoted Th2 humoral responses already exhibited by the control CpG OVA microparticle formulation. Overall, under controlled-release conditions, immune potentiators enhance the existing effects of controlled-release formulations, making it a potentially beneficial additive for controlled-release vaccine formulations.

A Superlong-Acting Growth Hormone-Polypeptide Fusion for Growth Hormone Deficiency Treatment

Recombinant human growth hormone (rhGH) is clinically used to treat growth hormone deficiency (GHD). However, daily administration of rhGH is required due to its poor stability and short blood circulation, which causes pains and burdens as well as inconvenience to patients. In this study, a method for genetically fusing rhGH to a thermosensitive polymer of elastin-like polypeptide (ELP) is reported, using which the rhGH-ELP thermosensitive fusion protein can be purified by the thermosensitivity of ELP instead of chromatography. The ELP fusion not only drastically improves the stability of rhGH, but also enables the in situ formation of a sustained-release depot of rhGH-ELP upon subcutaneous (SC) injection, which exhibits gentle release with a platform-to-trough fluctuation in blood and a very long circulatory half-life of 594.6 h. In contrast, rhGH exhibits a peak-to-trough fluctuation in blood with a very short circulatory half-life of 0.7 h. As a result, a single subcutaneous injection of rhGH-ELP can consecutively promote the linear growth of rats and the development of major tissues and organs over 3 weeks without obvious side effects, whereas rhGH is required to be injected daily to achieve similar therapeutic results.

Advanced Formulation Approaches for Proteins

Proteins and peptides are highly desirable as therapeutic agents, being highly potent and specific. However, there are myriad challenges with processing them into patient-friendly formulations: they are often unstable and have a tendency to aggregate or degrade upon storage. As a result, the vast majority of protein actives are delivered parenterally as solutions, which has a number of disadvantages in terms of cost, accessibility, and patient experience. Much work has been undertaken to develop new delivery systems for biologics, but to date this has led to relatively few products on the market. In this chapter, we review the challenges faced when developing biologic formulations, discuss the technologies that have been explored to try to overcome these, and consider the different delivery routes that can be applied. We further present an overview of the currently marketed products and assess the likely direction of travel in the next decade.

Nanoengineered injectable hydrogels derived from layered double hydroxides and alginate for sustained release of protein therapeutics in tissue engineering applications

Chronic Kidney Disease (CKD) which involves gradual loss of kidney function is characterized by low levels of a glycoprotein called Erythropoietin (EPO) that leads to red blood cell  deficiency and anemia. Recombinant human EPO (rhEPO) injections that are administered intravenously or subcutaneously is the current gold standard for treating CKD. The rhEPO injections have very short half-lives and thus demands frequent administration with a risk of high endogenous EPO levels leading to severe side effects that could prove fatal. To this effect, this work provides a novel approach of using lamellar inorganic solids with a brucite-like structure for controlling the release of protein therapeutics such as rhEPO in injectable hydrogels. The nanoengineered injectable system was formulated by incorporating two-dimensional layered double hydroxide (LDH) clay materials with a high surface area into alginate hydrogels for sustained delivery. The inclusion of LDH in the hydrogel network not only improved the mechanical properties of the hydrogels (5-30 times that of alginate hydrogel) but also exhibited a high binding affinity to proteins without altering their bioactivity and conformation. Furthermore, the nanoengineered injectable hydrogels (INHs) demonstrated quick gelation, injectability, and excellent adhesion properties on human skin. The in vitro release test of EPO from conventional alginate hydrogels (Alg-Gel) showed 86% EPO release within 108 h while INHs showed greater control over the initial burst and released only 24% of EPO in the same incubation time. INH-based ink was successfully used for 3D printing, resulting in scaffolds with good shape fidelity and stability in cell culture media. Controlled release of EPO from INHs facilitated superior angiogenic potential in ovo (chick chorioallantoic membrane) compared to Alg-Gel. When subcutaneously implanted in albino mice, the INHs formed a stable gel in vivo without inducing any adverse effects. The results suggest that the proposed INHs in this study can be utilized as a minimally invasive injectable platform or as 3D printed patches for the delivery of protein therapeutics to facilitate tissue regeneration.

Experimental and mathematical approaches for drug delivery for the treatment of wet age-related macular degeneration

Several chronic eye diseases affect the posterior segment of the eye. Among them age-related macular degeneration can cause vision loss if left untreated and is one of the leading causes of visual impairment in the world. Most treatments are based on intravitreally injected therapeutics that inhibit the action of vascular endothelial growth factor. However, due to the need for monthly injections, this method is associated with poor patient compliance. To address this problem, numerous drug delivery systems (DDSs) have been developed. This review covers a selection of particulate systems, non-stimuli responsive hydrogels, implants, and composite systems that have been developed in the last few decades. Depending on the type of DDS, polymer material, and preparation method, different mechanical properties and drug release profiles can be achieved. Furthermore, DDS development can be optimized by implementing mathematical modeling of both drug release and pharmacokinetic aspects. Several existing mathematical models for diffusion-controlled, swelling-controlled, and erosion-controlled drug delivery from polymeric systems are summarized. Compartmental and physiologically based models for ocular drug transport and pharmacokinetics that have studied drug concentration profiles after intravitreal delivery or release from a DDS are also reviewed. The coupling of drug release models with ocular pharmacokinetic models can lead to obtaining much more efficient DDSs for the treatment of age-related macular degeneration and other diseases of the posterior segment of the eye.

Engineered therapeutic proteins for sustained-release drug delivery systems

Proteins play a vital role in diverse biological processes in the human body, and protein therapeutics have been applied to treat different diseases such as cancers, genetic disorders, autoimmunity, and inflammation. Protein therapeutics have demonstrated their advantages, such as specific pharmaceutical effects, low toxicity, and strong solubility. However, several disadvantages arise in clinical applications, including short half-life, immunogenicity, and low permeation, leading to reduced drug effectiveness. The structure of protein therapeutics can be modified to increase molecular size, leading to prolonged stability and increased plasma half-life. Notably, the controlled-release delivery systems for the sustained release of protein drugs and preserving the stability of cargo proteins are envisioned as a potential approach to overcome these challenges. In this review, we summarize recent research progress related to structural modifications (PEGylation, glycosylation, poly amino acid modification, and molecular biology-based strategies) and promising long-term delivery systems, such as polymer-based systems (injectable gel/implants, microparticles, nanoparticles, micro/nanogels, functional polymers), lipid-based systems (liposomes, solid lipid nanoparticles, nanostructured lipid carriers), and inorganic nanoparticles exploited for protein therapeutics. STATEMENT OF SIGNIFICANCE: In this review, we highlight recent advances concerning modifying proteins directly to enhance their stability and functionality and discuss state-of-the-art methods for the delivery and controlled long-term release of active protein therapeutics to their target site. In terms of drug modifications, four widely used strategies, including PEGylation, poly amino acid modification, glycosylation, and genetic, are discussed. As for drug delivery systems, we emphasize recent progress relating to polymer-based systems, lipid-based systems developed, and inorganic nanoparticles for protein sustained-release delivery. This review points out the areas requiring focused research attention before the full potential of protein therapeutics for human health and disease can be realized.

Extending the use of biologics to mucous membranes by attachment of a binding domain

Biologics are almost exclusively administered systemically, but localized delivery is preferable as it minimizes off-target exposure and allows more aggressive treatments. Topical application of biologics to epithelia is generally ineffective because most are covered with fluids and biologics are washed out too quickly to have significant therapeutic effects. Here we explore the idea that attaching a binding domain can serve as an "anchor" to extend the residency time of biologics on wet epithelia, allowing their effective use even with infrequent applications. We use topical application to the ocular surface as a challenging test since foreign substances are washed out especially efficiently by tear flow and blinking. Our results demonstrate that conjugation of antibodies to wheat germ agglutinin, which binds GlcNAc and sialic acid that are ubiquitously present in tissues, increases their half-life 350-fold upon application to the ocular surface in a mouse model of dry eye, a common and onerous disease in humans. Importantly, antibodies to IL-17A, IL-23, and IL-1β conjugated to the agglutinin reduces manifestations of dry eye, even when applied just once daily. In contrast, unconjugated antibodies are ineffective. Attaching an anchor to biologics is a simple means to overcome washout and to extend their therapeutic use.

Characteristics of Mitomycin C-Loaded Peptide Hydrogel In Vitro and Antiscarring Effects in Rat Ocular Injury Model

Purpose: To investigate the characteristics of sustained drug release systems established by an arginine-glycine-aspartic acid (RGD) peptide hydrogel and mitomycin C (MMC) in vitro, and verify their antiscar effects in rat ocular injury model. Methods: Low, medium, and high loading doses of MMC were added to 5 mL 0.25%, 0.5%, and 1% wt RGD peptide hydrogel, respectively, to prepare 9 ratios of MMC-RGD systems. Drug release characteristics of the systems in phosphate-buffered saline solution were investigated by plotting the drug release curves and fitting them with mathematical models in OriginPro8.0 software. Appropriate ratios of MMC-RGD systems were selected as treatment in rat ocular injury model. Scar formation was observed by Masson staining and immunohistochemical staining with alpha-smooth muscle actin (α-SMA) and fibronectin (FN). Results: Nine ratios of MMC-RGD systems could release drug slowly. The maximum drug release proportions of all systems were >80%, and the time to maximum release proportions statistically prolonged with the increase of drug loading. Fitting with mathematical models indicated that the mechanisms of drug release were mainly Fick diffusion at early stage and Anomalous Transport at later stage. Systems of 1% wt RGD hydrogel were evaluated in animal experiments, which could inhibit hyperplasia of collagen and expression of α-SMA and FN. Conclusions: The RGD peptide hydrogel could be used as the carrier of MMC to establish sustained drug release system, which could inhibit scar formation after rat's ocular injury.

Recombinant protein drugs-based intra articular drug delivery systems for osteoarthritis therapy

Osteoarthritis (OA) is the most prevalent chronic degenerative joint disease. It weakens the motor function of patients and imposes a significant economic burden on society. The current medications commonly used in clinical practice do not meet the need for the treatment of OA. Recombinant protein drugs (RPDs) can treat OA by inhibiting inflammatory pathways, regulating catabolism/anabolism, and promoting cartilage repair, thereby showing promise as disease-modifying OA drugs (DMOADs). However, the rapid clearance and short half-life of them in the articular cavity limit their clinical translation. Therefore, the reliable drug delivery systems for extending drug treatment are necessary for the further development. This review introduces RPDs with therapeutic potential for OA, and summarizes their research progress on related drug delivery systems, and make proper discussion on the certain keys for optimal development of this area.

Vascular Disruptive Hydrogel Platform for Enhanced Chemotherapy and Anti-Angiogenesis through Alleviation of Immune Surveillance

Patients undergoing immunotherapy always exhibit a low-response rate due to tumor heterogeneity and immune surveillance in the tumor. Angiogenesis plays an important role in affecting the status of tumor-infiltrated lymphocytes by inducing hypoxia and acidosis microenvironment, suggesting its synergistic potential in immunotherapy. However, the antitumor efficacy of singular anti-angiogenesis therapy often suffers from failure in the clinic due to the compensatory pro-angiogenesis signaling pathway. In this work, classic injectable thermosensitive PLGA-PEG-PLGA copolymer was used to construct a platform to co-deliver CA4P (vascular disruptive agent) and EPI for inducing immunogenic cell death of cancer cells by targeting the tumor immune microenvironment. Investigation of 4T1 tumor-bearing mouse models suggests that local administration of injectable V+E@Gel could significantly inhibit the proliferation of cancer cells and prolong the survival rate of 4T1 tumor-bearing mouse models. Histological analysis further indicates that V+E@Gel could effectively inhibit tumor angiogenesis and metastasis by down-regulating the expression of CD34, CD31, MTA1 and TGF-β. Moreover, due to the sustained release kinetics of V+E@Gel, its local administration relieves the immune surveillance in tumor tissues and thus induces a robust and long-lasting specific antitumor immune response. Overall, this work provides a new treatment strategy through the mediation of the tumor immune microenvironment by vascular disruption to fulfill enhanced chemotherapy and immunotherapy.

The industrial design, translation, and development strategies for long-acting peptide delivery

INTRODUCTION

Peptides are widely recognized as therapeutic agents in the treatment of a wide range of diseases, such as cancer, diabetes etc. However, their use has been limited by their short half-life, due to significant metabolism by exo- and endo-peptidases as well as their inherent poor physical and chemical stability. Research with the aim of improving their half-life in the body, and thus improving patient compliance (by decreasing the frequency of injections) has gained significant attention.

AREAS COVERED

This review outlines the current landscape and industrial approaches to achieve extended peptide exposure and reduce dosing frequency. Emphasis is placed on identifying challenges in drug product manufacturing and desirable critical quality attributes that are essential for activity and safety, providing insights into chemistry and design aspects impacting peptide release, and summarizing important considerations for CMC developability assessments of sustained release peptide drugs.

EXPERT OPINION

Bring the patient and disease perspective early into development. Substantial advances have been made in the field of sustained delivery of peptides despite their complexity. The article will also highlight considerations for early-stage product design and development, providing an industrial perspective on risk mitigation in developing sustained release peptide drug products.

Disclosing the Potential of Fluorinated Ionic Liquids as Interferon-Alpha 2b Delivery Systems

Interferon-alpha 2b (IFN-α 2b) is a therapeutic protein used for the treatment of cancer, viral infections, and auto-immune diseases. Its application is hindered by a low bioavailability and instability in the bloodstream, and the search for new strategies for a target delivery and stabilization of IFN-α 2b to improve its therapeutic efficacy is crucial. Fluorinated ionic liquids (FILs) are promising biomaterials that: (i) can form self-assembled structures; (ii) have complete miscibility in water; and (iii) can be designed to have reduced toxicity. The influence of IFN-α 2b in the aggregation behaviour of FILs and the interactions between them were investigated through conductivity and surface tension measurements, and using electron microscopic and spectroscopy techniques to study FILs feasibility as an interferon-alpha 2b delivery system. The results show that the presence of IFN-α 2b influences the aggregation behaviour of FILs and that strong interaction between the two compounds occurs. The protein might not be fully encapsulated by FILs. However, the FIL can be tailored in the future to carry IFN-α 2b by the formation of a conjugate, which prevents the aggregation of this protein. This work constitutes a first step toward the design and development of FIL-based IFN-α 2b delivery systems.

Interference With Redox Homeostasis Through a G6PD-Targeting Self-Assembled Hydrogel for the Enhancement of Sonodynamic Therapy in Breast Cancer

Sonodynamics has emerged as a new potential therapy for breast cancer in recent years. However, GSH-mediated redox systems in cancer cells make them tolerable to oxidative stress-related therapy. Herein, in this study, with G6PD, the gatekeeper enzyme of the pentose phosphate pathway, as the regulative target, a self-assembled thermosensitive chitosan-pluronic hydrogel coloaded with ICG (sono-sensitive agent) and RRx-001 (IR@CPGel) was successfully prepared to enhance SDT through interference with redox homeostasis. Both in vitro and in vivo antitumor investigations verified that when integrated with sonodynamic therapy applied in breast cancer treatment, local administration of IR@CPgel could enhance ROS generation under LIFU irradiation and trigger the intrinsic apoptotic pathway of cancer cells, thus effectively inhibiting tumor growth in a safe manner. Moreover, RRx-001 may interfere with redox homeostasis in cancer cells by downregulating G6PD expression. Due to this redox imbalance, proapoptotic signals, such as P21 and P53, were enhanced, and metastasis-related signals, including MMP-2, ZEB1 and HIF-1α, were effectively reduced. Taken together, this work aimed to enhance the efficacy of sonodynamic therapy through local administration of self-assembled IR@CPGel to interfere with redox homeostasis and thus amplify the oxidative stress microenvironment in tumor tissues. In a word, this work provides a new strategy for the SDT enhancement in breast cancer therapy.

Synthesis and functionalization of dendritic polyglycerol-based nanogels: application in T cell activation

The concept of multivalency finds various applications in the fields of chemistry and biology, relying on the principle that multiple weak interactions can lead to strong adhesive forces. Polymeric carriers are promising tools to translate these properties into the field of biomedicine, especially upon functionalization by active biomolecules, such as antibodies. In this study we report on the synthesis of dendritic polyglycerol (dPG) and dPG-based nanogels (NGs) as platforms for the multivalent display of molecules and their potential application as carrier units. Macromolecules based on dPG were synthesized and NGs were generated by strain-promoted azide-alkyne cycloaddition (SPAAC) by inverse nanoprecipitation under mild conditions. Scale-up screening rendered a reproducible method for a batch size of up to 50 mg for the formation of NGs in a size range of 150 nm with narrow dispersity. Dye-labelled bovine serum albumin (FITC-BSA) was chosen as a model protein and showed successful conjugation to the carriers, while the protein's secondary structure was not affected. Consequently, cyanine-5-amine (Cy5-NH₂) and avidin (Av) were conjugated in order to exploit the strong avidin-biotin interaction, facilitating the directed attachment of a myriad of biotinylated (bio)molecules. As a proof-of-concept, the biotinylated monoclonal antibodies (mAbs) α-CD3 and α-CD28 were attached to the platforms and their capability to activate T cells was assessed. Experiments were performed with a Jurkat reporter cell line which expresses green fluorescent protein (GFP) upon activation, providing a rapid and reliable readout by flow cytometry. Carriers clearly outperformed conventional compounds for activation (i.e. antibodies crosslinked with anti-IgG antibody) at significantly lower dosages. These findings could be confirmed by confocal laser scanning microscopy (CLSM), showing accumulation of the functional nanoplatforms at the cell surface and cytoplasmic GFP expression (>95% activation of cells for the multivalent conjugates at 10 μg mL^-1 compared to 37% activation with conventionally crosslinked mAbs at 25 μg mL^-1), whereas carriers without mAbs could not activate cells. As the attachment of biotinylated molecules to the functional nanoplatforms is straightforward, the results obtained show the great potential of our platforms for a broad range of applications.

Poly(disulfide)s: From Synthesis to Drug Delivery

Bioresponsive polymers have been widely used in drug delivery because of their degradability. For example, poly(disulfide)s with repeating disulfide bonds in the main chain have attracted considerable research attention. The characteristics of the disulfide bonds, including their dynamic and reversible properties and their responsiveness to stimuli such as reductants, light, heat, and mechanical force, make them ideal platforms for on-demand drug delivery. This review introduces the synthesis methods and applications of poly(disulfide)s. Furthermore, the synthesis methods of poly(disulfide)s are classified on the basis of the monomers used: oxidative step-growth polymerization with dithiols, ring-opening polymerization with cyclic disulfides, and polymerization with linear disulfides. In addition, recent advances in poly(disulfide)s for the delivery of small-molecule or biomacromolecular drugs are discussed. Quantum-dot-loaded poly(disulfide) delivery systems for imaging are also included. This review provides an overview of the various design strategies employed in the construction of poly(disulfide) platforms to inspire new applications in the field of drug delivery.