Retaining Antibodies in Tumors with a Self-Assembling Injectable System

Fibril-Guided Three-Dimensional Assembly of Human Fibroblastic Reticular Cells

Fibroblastic reticular cells (FRCs) are stromal cells (SCs) that can be isolated from lymph node (LN) biopsies. Studies have shown that these nonhematopoietic cells have the capacity to shape and regulate adaptive immunity and can become a form of personalized cell therapy. Successful translational efforts, however, require the cells to be formulated as injectable units, with their native architecture preserved. The intrinsic reticular organization of FRCs, however, is lost in the monolayer cultures. Organizing FRCs into three-dimensional (3D) clusters would recapitulate their structural and functional attributes. Herein, we report a scaffolding method based on the self-assembling peptide (SAP) EAKII biotinylated at the N-terminus (EAKbt). Cross-linking with avidin transformed the EAKbt fibrils into a dense network of coacervates. The combined forces of fibrillization and bioaffinity interactions in the cross-linked EAKbt likely drove the cells into a cohesive 3D reticula. This facile method of generating clustered FRCs (clFRCs) can be completed within 10 days. In vitro clFRCs attracted the infiltration of T cells and rendered an immunosuppressive milieu in the cocultures. These results demonstrate the potential of clFRCs as a method for stromal cell delivery.

Oncofetal reprogramming in tumor development and progression: novel insights into cancer therapy

Emerging evidence indicates that cancer cells can mimic characteristics of embryonic development, promoting their development and progression. Cancer cells share features with embryonic development, characterized by robust proliferation and differentiation regulated by signaling pathways such as Wnt, Notch, hedgehog, and Hippo signaling. In certain phase, these cells also mimic embryonic diapause and fertilized egg implantation to evade treatments or immune elimination and promote metastasis. Additionally, the upregulation of ATP-binding cassette (ABC) transporters, including multidrug resistance protein 1 (MDR1), multidrug resistance-associated protein 1 (MRP1), and breast cancer-resistant protein (BCRP), in drug-resistant cancer cells, analogous to their role in placental development, may facilitate chemotherapy efflux, further resulting in treatment resistance. In this review, we concentrate on the underlying mechanisms that contribute to tumor development and progression from the perspective of embryonic development, encompassing the dysregulation of developmental signaling pathways, the emergence of dormant cancer cells, immune microenvironment remodeling, and the hyperactivation of ABC transporters. Furthermore, we synthesize and emphasize the connections between cancer hallmarks and embryonic development, offering novel insights for the development of innovative cancer treatment strategies.

IgG Fc Affinity Ligands and Their Applications in Antibody-Involved Drug Delivery: A Brief Review

Antibodies are not only an important class of biotherapeutic drugs, but also are targeting moieties for achieving active targeting drug delivery. Meanwhile, the rapidly increasing application of antibodies and Fc-fusion proteins has inspired the emerging development of downstream processing technologies. Thus, IgG Fc affinity ligands have come into being and have been widely exploited in antibody purification strategies. Given the high binding affinity and specificity to IgGs, binding stability in physiological medium conditions, and favorable toxicity and immunogenicity profiles, Fc affinity ligands are gradually applied to antibody delivery, non-covalent antibody-drug conjugates or antibody-mediated active-targeted drug delivery systems. In this review, we will briefly introduce IgG affinity ligands that are widely used at present and summarize their diverse applications in the field of antibody-involved drug delivery. The challenges and outlook of these systems are also discussed.

Localized PD-1 Blockade in a Mouse Model of Renal Cell Carcinoma

Herein we report the impact of localized delivery of an anti-mouse PD-1-specific monoclonal antibody (aPD1) on Renca tumors in the resulting T cell responses and changes in broader immune gene expression profiles. Renca is a BALB/c mice syngeneic tumor that has been used to model human renal cell carcinoma In this study, T cell subsets were examined in tumors and draining lymph nodes of mice treated with localized PD-1 with and without the addition of adenosine deaminase (ADA), an enzyme that catabolizes adenosine (ADO), identified as an immune checkpoint in several types of human cancers. The biologics, aPD1, or aPD1 with adenosine deaminase (aPD1/ADA), were formulated with the self-assembling peptides Z15_EAK to enhance retention near the tumor inoculation site. We found that both aPD1 and aPD1/ADA skewed the local immune milieu towards an immune stimulatory phenotype by reducing Tregs, increasing CD8 T cell infiltration, and upregulating IFNɣ. Analysis of tumor specimens using bulk RNA-Seq confirmed the impact of the localized aPD1 treatment and revealed differential gene expressions elicited by the loco-regional treatment. The effects of ADA and Z15_EAK were limited to tumor growth delay and lymph node enlargement. These results support the notion of expanding the use of locoregional PD-1 blockade in solid tumors.

Emerging self-assembling peptide nanomaterial for anti-cancer therapy

Recently it is mainly focused on anti-tumor comprehensive treatments like finding target tumor cells or activating immune cells to inhibit tumor recurrence and metastasis. At present, chemotherapy and molecular-targeted drugs can inhibit tumor cell growth to a certain extent. However, multi-drug resistance and immune escape often make it difficult for new drugs to achieve expected effects. Peptide hydrogel nanoparticles is a new type of biological material with functional peptide chains as the core and self-assembling peptide (SAP) as the framework. It has a variety of significant biological functions, including effective local inflammation suppression and non-drug-resistant cell killing. Besides, it can induce immune activation more persistently in an adjuvant independent manner when compared with simple peptides. Thus, SAP nanomaterial has great potential in regulating cell physiological functions, drug delivery and sensitization, vaccine design and immunotherapy. Not only that, it is also a potential way to focus on some specific proteins and cells through peptides, which has already been examined in previous research. A full understanding of the function and application of SAP nanoparticles can provide a simple and practical strategy for the development of anti-tumor drugs and vaccine design, which contributes to the historical transition of peptide nanohydrogels from bench to bedside and brings as much survival benefits as possible to cancer patients.

EGFR Targeted Cetuximab-Valine-Citrulline (vc)-Doxorubicin Immunoconjugates- Loaded Bovine Serum Albumin (BSA) Nanoparticles for Colorectal Tumor Therapy

Background

Specific modifications to carriers to achieve targeted delivery of chemotherapeutics into malignant tissues are a critical point for efficient diagnosis and therapy. In this case, bovine serum albumin (BSA) was conjugated with cetuximab–valine–citrulline (vc)–doxorubicin (DOX) to target epidermal growth factor receptor (EGFR) and enable the release of drug in EGFR-overexpressed tumor cells.

Methods

Maleimidocaproyl–valine–citrulline–p-aminobenzylcarbonyl-p-nitrophenol (MC-Val-Cit-PAB-PNP) and DOX were used to synthesize MC-Val-Cit-PAB-DOX, which was further linked with cetuximab to prepare antibody–drug conjugates (ADCs). Then, the ADCs were adsorbed to the surface of the BSA nanoparticles (NPs), which were prepared by a desolvation method to obtain cetuximab-vc-DOX-BSA-NPs. The cetuximab-vc-DOX conjugates adsorbed on the surface of the BSA nanoparticles were determined and optimized by size exclusion chromatography. An in vitro cytotoxicity study was conducted using a colon carcinoma cell line with different EGFR-expression levels to test the selectivity of cetuximab-vc-DOX-NPs.

Results

The vc-DOX and cetuximab-vc-DOX conjugates were both synthesized successfully and their structural characteristics confirmed by ¹H-NMR and SDS-PAGE. The MTT assay showed stronger cytotoxicity of cetuximab-vc-DOX-NPs versus control IgG-vc-DOX-NPs in EGFR–overexpressing RKO cells. Cellular binding and intracellular accumulation determined by flow cytometry and confocal laser scanning microscopy revealed the strong binding ability of cetuximab-vc-DOX-NPs to RKO cells. The in vivo imaging study demonstrated that cetuximab-vc-DOX-NPs exhibited higher fluorescent intensity in tumor tissues than non-decorated nanoparticles (IgG-vc-DOX-NPs). In vivo tumor inhibition and survival tests showed that cetuximab-vc-DOX-NPs revealed higher tumor inhibition efficacy and lower systemic toxicity than control IgG-vc-DOX- NPs

Conclusion

The obtained results emphasize that cetuximab-vc-DOX-NPs, with good tumor-targeting ability and low systemic toxicity, are a promising targeting system for drug delivery.

Chemically-Induced Cross-Linking of Peptidic Fibrils for Scaffolding Polymeric Particles and Macrophages

EAK16-II (EAK) is a self-assembling peptide (SAP) that forms β-sheets and β-fibrils through ionic-complementary interactions at physiological ionic strengths. The soft materials can be injected in vivo, creating depots of drugs and cells for rendering pharmacological and biological actions. The scope of the applications of EAK is sought to extend to tissues through which the flow of extracellular fluid tends to be limited. In such anatomical locales the rate and extent of the fibrilization are limited insofar as drug delivery and cellular scaffolding would be impeded. A method is generated utilizing a carbodiimide cross-linker by which EAK fibrils are pre-assembled yet remain injectable soft materials. It is hypothesized that the resulting de novo covalent linkages enhance the stacking of the β-sheet bilayers, thereby increasing the lengths of the fibrils and the extent of their cross-linking, as evidenced in Diffuse Reflectance Infrared Fourier Transform (DRIFT) spectroscopy, scanning electron microscopy, and atomic force microscopy analyses. The cross-linked EAK (clEAK) retains polymeric microspheres with an average diameter of 1 µm. Macrophages admixed with clEAK remain viable and do not produce the inflammatory mediator interleukin-1β. These results indicate that clEAK should be investigated further as a platform for delivering particles and cells in vivo.

Molecular-level understanding of the hTAS2R1 receptor-bitter tasting tetra-peptide binding: a structural biology study based on computational approaches

Effective computational approaches for bitter-tasting peptides have been developed and analyzed in the present work.

Electrospun Nanofibers for Cancer Therapy

Lately, a remarkable progress has been recorded in the field of electrospinning for the preparation of numerous types of nanofiber scaffolds. These scaffolds present some remarkable features including high loading capacity and encapsulation efficiency, superficial area and porosity, potential for modification, structure for the co-delivery of various therapies, and cost-effectiveness. Their present and future applications for cancer diagnosis and treatment are promising and pioneering. In this chapter we provide a comprehensive overview of electrospun nanofibers (ESNFs) applications in cancer diagnosis and treatment, covering diverse types of drug-loaded electrospun nanofibers.

Sono-Assembly of the [Arg-Phe]4 Octapeptide into Biofunctional Nanoparticles

High-frequency ultrasound treatment is found to be a one-pot green technique to produce peptide-based nanostructures by ultrasound assisted self-assembly of oligopeptides. [Arg-Phe]₄ octapeptides, consisting of alternating arginine (Arg/R) and phenylalanine (Phe/F) sequences, were subjected to 430 kHz ultrasound in aqueous solution in the absence of any external agents, to form [RF]₄ nanoparticles ([RF]₄-NPs), ~220 nm in diameter. A comprehensive analysis of the obtained nanoparticles demonstrated that the aromatic moieties of the oligopeptides can undergo oxidative coupling to form multiple oligomeric species, which then self-assemble into well-defined fluorescent nanoparticles. [RF]₄-NPs were functionalized with polyethylene glycol (PEGylated) to improve their colloidal stability. Unlike the parent peptide, the PEGylated [RF]₄-NPs showed limited cytotoxicity towards MDA-MB-231 cells. Furthermore, the intracellular trafficking of PEGylated [RF]₄-NPs was investigated after incubation with MDA-MB-231 cells to demonstrate their efficient endo-lysosomal escape. This work highlights that the combined use of ultrasonic technologies and peptides enables easy fabrication of nanoparticles, with potential application in drug delivery.

A drug delivery perspective on intratumoral-immunotherapy in renal cell carcinoma

In less than 5years immune checkpoint inhibitors (ICI) went from first FDA approval to become first-line options in advanced renal cell carcinoma. Despite that many patients have benefited from ICI, a significant fraction of individuals are refractory to these new immunological treatments. In this review, we discussed using intratumoral (i.t.) route of drug administration as an alternative to systemic therapy to increase the response rates and to circumvent potential drug-induced systemic adverse events. We provided a historic account of i.t. drug treatments in cancer and reviewed the contemporary experience in local drug delivery. We discussed the potential for enhancing the therapeutic impact of ICI by leveraging hydrogels as drug delivery vehicles and presented an outlook for implementing i.t. in renal cell carcinoma.

Self-assemble peptide biomaterials and their biomedical applications

Inspired by self-assembling peptides found in native proteins, deliberately designed engineered peptides have shown outstanding biocompatibility, biodegradability, and extracellular matrix-mimicking microenvironments. Assembly of the peptides can be triggered by external stimuli, such as electrolytes, temperature, and pH. The formation of nanostructures and subsequent nanocomposite materials often occur under physiological conditions. The respective properties of side chains in each amino acids provide numerous sites for chemical modification and conjugation choices of the peptides, enabling various resulting supramolecular nanostructures and hydrogels with adjustable mechanical and physicochemical properties. Moreover, additional functionalities can be easily induced into the hydrogels, including shear-thinning, bioactivity, self-healing, and shape memory. It further broaden the scope of application of self-assemble peptide materials. This review outlines designs of self-assembly peptide (β-sheet, α-helix, collagen-like peptides, elastin-like polypeptides, and peptide amphiphiles) with potential additional functionalities and their biomedical applications in bioprinting, tissue engineering, and drug delivery.

T cell immunotherapy enhanced by designer biomaterials

Cancer immunotherapy has recently burst onto the center stage of cancer treatment and research. T lymphocyte adoptive cellular transfer (ACT), a form of cancer immunotherapy, has spawned unprecedented complete remissions for terminal patients with certain leukemias and lymphomas. Unfortunately, the successes have been overshadowed by the disappointing clinical results of ACT administered to treat solid tumors, in addition to the toxicities associated with the treatment, a lack of efficacy in a significant proportion of the patient population, and cancer relapse following the treatment. Biomaterials hold the promise of addressing these shortcomings. ACT consists of two main stages - T lymphocyte ex vivo expansion followed by reinfusion into the patient - and biomaterials can improve the efficacy of ACT at both stages. In this review, we highlight recent advances in the use of biomaterials for T lymphocyte adoptive cellular cancer immunotherapy and discuss the challenges at each stage.

A genetically engineered Fc-binding amphiphilic polypeptide for congregating antibodies in vivo

We report herein an affinity-based hydrogel used in creating subcutaneous depots of antibodies in vivo. The biomaterials design centered on pG_EAK, a polypeptide we designed and expressed in E. coli. The sequence consists of a truncated protein G (pG) genetically fused with repeats of the amphiphilic sequence AEAEAKAK ("EAK"). Capture of IgG was demonstrated in vitro in gels prepared from admixing pG_EAK and EAK ("pG_EAK/EAK gel"). The binding affinities and kinetics of pG for IgG were recapitulated in the pG_EAK polypeptide. Injecting IgG antibodies formulated with pG_EAK/EAK gel into subcutaneous space resulted in retention of the antibodies at the site for at least six days, whereas only signal at background levels was detected in grafts injected with IgG formulated in saline or diffusion-driven gel. The local retention of IgG in pG_EAK/EAK gel was correlated with limited distribution of the antibody in liver, spleen and lymph nodes, in contrast to those injected with antibodies formulated in saline or non-Fc binding EAK gel. In addition, antibodies formulated with pG_EAK/EAK gel and injected in mouse footpads were found to retain at the site for 19 days. As a demonstration of potential bioengineering applications, thymic epithelial cells (TECs), the primary population of thymic stromal cells that are critical for the development of T-lymphocytes, were mixed with pG_EAK/EAK gel formulated with TEC-specific anti-EpCAM antibodies and injected subcutaneously into athymic nude mice. The injected TECs congregated into functional thymic units in vivo, supporting the development of both CD4+ and CD8+ T cells as well as Foxp3+ regulatory T cells in the mice. In conclusion, pG_EAK/EAK gel can be used to retain IgG locally in vivo, and can be tailored as scaffolds for controlling deposition of molecular and/or cellular therapeutics. STATEMENT OF SIGNIFICANCE: The unique concept of the work centers on the genetic fusion of an Fc-binding domain and a self-assembling domain into a single polypeptide. To our knowledge, such bi-functional peptide has not been reported in the literature. The impact of the work lies in the ability to display IgG antibodies and Fc-fusion proteins of any specificity. The data shown demonstrate the platform can be used to localize IgG in vivo, and can be tailored for controlling deposition of primary thymic epithelial cells (TECs). The results support a biomaterials-based strategy by which TECs can be delivered as functional units to support T-lymphocyte development in vivo. The platform described in the study may serve as an important tool for immune engineering.

Toward reducing biomaterial antigenic potential: a miniaturized Fc-binding domain for local deposition of antibodies

A peptide derived from staphylococcal protein A (SpA) was developed as an affinity module for antibody delivery applications. The miniaturized protein consists of the first helix of the engineered SpA Z domain fused with the self-assembling peptide (SAP) AEAEAKAKAEAEAKAK, or EAK. The resulting peptide, named Z15_EAK, was shown to possess fibrillization properties and an Fc-binding function. The peptide induced a red shift in the Congo red absorbance characteristic of peptide fibrils, also evidenced in transmission electron microscopy images. The one-site binding affinity (Kd) of a gel-like coacervate generated by admixing Z15_EAK with EAK for IgG was determined to be 1.27 ± 0.14 μM based on a microplate-based titration assay. The coacervate was found to localize IgG subcutaneously in mouse footpads for 8 to 28 days. A set of in vivo data was fit to a one-compartment model for simulating the relative fractions of IgG dissociated from the materials in the depot. The model predicted that close to 27% of the antibodies injected were available unbound for the duration of the experiment. Z15_EAK did not appear to induce innate immune responses; injecting Z15_EAK into mouse footpads elicited neither interleukin-6 (IL-6) nor tumor necrosis factor-alpha (TNF-α) from splenocytes isolated from the animals one day, seven days, or eleven days afterward. The antigenic potential of Z15 was analyzed using a bioinformatic approach in predicting sequences in SpA and Z15 dually presented by class I and class II human MHC alleles covering the majority of the population. A peptide in SpA identified as a potential T cell epitope cross reacting with a known epitope in a microbial antigen was eliminated by miniaturization. These results demonstrate that Z15_EAK is a potential platform for generating antibody depots by which the impacts of Fc-based biotherapeutics can be enhanced through spatiotemporal control.

Synthesis, physicochemical properties and ocular pharmacokinetics of thermosensitive in situ hydrogels for ganciclovir in cytomegalovirus retinitis treatment

Ganciclovir (GCV) is one of the most widely used antiviral drugs for the treatment of cytomegalovirus (CMV) retinitis. In this context, the aim of this study was to design in situ thermosensitive hydrogels for GCV ocular delivery by intravitreal injection to achieve sustained drug release behavior and improved ocular bioavailability in the treatment of CMV retinitis. A thermosensitive poly-(β-butyrolactone-co-lactic acid)-polyethylene glycol-poly (β-butyrolactone-co-lactic acid) (PBLA-PEG-PBLA) triblock copolymer was synthesized by ring-opening polymerization and characterization. The GCV-loaded PBLA-PEG-PBLA in situ hydrogels (15%, w/w) were then prepared with drug concentration at 2 mg·mL^-1 and the gelation temperatures, rheological properties, in vitro degradation and syringeability of in situ hydrogels for intravitreal injection were also investigated. Membraneless dissolution model was used to explore drug release behavior of PBLA-PEG-PBLA in situ hydrogel. The results indicated that more than 45 and 85% of GCV can be released within 24 and 96 h, respectively, which was verified by a non-Fickian diffusion mechanism. In vivo ocular pharmacokinetics study showed that area under drug-time curve (AUC) and half-life of PBLA-PEG-PBLA in situ hydrogel was higher (AUC was 61.80 μg·mL^-1·h (p < .01) and t_1/2 was 10.29 h in aqueous humor; AUC was 1008.66 μg·mL^-1·h (p < .01) and t_1/2 was 13.26 h (p < .01) in vitreous) than GCV injection with extended therapeutic activity. Based on obtained results, it was concluded that the thermosenstive PBLA-PEG-PBLA in situ hydrogel is a promising carrier of GCV for intravitreal injection.

Self-assembly of peptide amphiphiles for drug delivery: the role of peptide primary and secondary structures

Peptide amphiphiles (PAs), functionalized with alkyl chains, are capable of self-assembling into various nanostructures. Recently, PAs have been considered as ideal drug carriers due to their good biocompatibility, specific biological functions, and hypotoxicity to normal cells and tissues. Meanwhile, the nanocarriers formed by PAs are able to achieve controlled drug release and enhanced cell uptake in response to the stimulus of the physiological environment or specific biological factors in the location of the lesion. However, the underlying detailed drug delivery mechanism, especially from the aspect of primary and secondary structures of PAs, has not been systematically summarized or discussed. Focusing on the relationship between the primary and secondary structures of PAs and stimuli-responsive drug delivery applications, this review highlights the recent advances, challenges, and opportunities of PA-based functional drug nanocarriers, and their potential pharmaceutical applications are discussed.

Stimulation of wound healing using bioinspired hydrogels with basic fibroblast growth factor (bFGF)

INTRODUCTION

The objective of this study is to stimulate wound healing using bioinspired hydrogels with basic fibroblast growth factor (bFGF).

MATERIALS AND METHODS

Inspired by the crosslinking mechanism in algae-based adhesives, hydrogels were fabricated with gum arabic, pectin, and Ca2+. The physical properties of the bioinspired hydrogels were characterized, and the in vitro release of bFGF was investigated. Then, the in vitro scratch assay for wound healing and in vivo wound healing experiment in a full-thickness excision wound model were performed for the bioinspired hydrogels with bFGF. Finally, histological examinations and organ toxicity tests were conducted to investigate the wound healing applications of the bioinspired hydrogels with bFGF.

RESULTS

The in vitro and in vivo results showed that the bioinspired hydrogels with bFGF could significantly enhance cell proliferation, wound re-epithelialization, collagen deposition, and contraction without any noticeable toxicity and inflammation compared with the hydrogels without bFGF and commercial wound healing products.

CONCLUSION

These results suggest the potential application of bioinspired hydrogels with bFGF for wound healing.

Platinum(iv) prodrugs with long lipid chains for drug delivery and overcoming cisplatin resistance

Platinum(iv) prodrugs of clinically used cisplatin and oxaliplatin with two axial long lipid chains were developed for nanoparticle delivery to combat cisplatin resistance.

Multicomponent peptide assemblies

Self-assembled peptide nanostructures have been increasingly exploited as functional materials for applications in biomedicine and energy. The emergent properties of these nanomaterials determine the applications for which they can be exploited. It has recently been appreciated that nanomaterials composed of multicomponent coassembled peptides often display unique emergent properties that have the potential to dramatically expand the functional utility of peptide-based materials. This review presents recent efforts in the development of multicomponent peptide assemblies. The discussion includes multicomponent assemblies derived from short low molecular weight peptides, peptide amphiphiles, coiled coil peptides, collagen, and β-sheet peptides. The design, structure, emergent properties, and applications for these multicomponent assemblies are presented in order to illustrate the potential of these formulations as sophisticated next-generation bio-inspired materials.

Improving the clinical impact of biomaterials in cancer immunotherapy

Immunotherapies for cancer have progressed enormously over the past few decades, and hold great promise for the future. The successes of these therapies, with some patients showing durable and complete remission, demonstrate the power of harnessing the immune system to eradicate tumors. However, the effectiveness of current immunotherapies is limited by hurdles ranging from immunosuppressive strategies employed by tumors, to inadequate specificity of existing therapies, to heterogeneity of disease. Further, the vast majority of approved immunotherapies employ systemic delivery of immunomodulators or cells that make addressing some of these challenges more difficult. Natural and synthetic biomaterials–such as biocompatible polymers, self-assembled lipid particles, and implantable biodegradable devices–offer unique potential to address these hurdles by harnessing the benefits of therapeutic targeting, tissue engineering, co-delivery, controlled release, and sensing. However, despite the enormous investment in new materials and nanotechnology, translation of these ideas to the clinic is still an uncommon outcome. Here we review the major challenges facing immunotherapies and discuss how the newest biomaterials and nanotechnologies could help overcome these challenges to create new clinical options for patients.

Engineering β-sheet peptide assemblies for biomedical applications

Hydrogels have been widely studied in various biomedical applications, such as tissue engineering, cell culture, immunotherapy and vaccines, and drug delivery. Peptide-based nanofibers represent a promising new strategy for current drug delivery approaches and cell carriers for tissue engineering. This review focuses on the recent advances in the use of self-assembling engineered β-sheet peptide assemblies for biomedical applications. The applications of peptide nanofibers in biomedical fields, such as drug delivery, tissue engineering, immunotherapy, and vaccines, are highlighted. The current challenges and future perspectives for self-assembling peptide nanofibers in biomedical applications are discussed.

Strategies for transporting nanoparticles across the blood-brain barrier

The existence of blood-brain barrier (BBB) hampers the effective treatment of central nervous system (CNS) diseases. Almost all macromolecular drugs and more than 98% of small molecule drugs cannot pass the BBB. Therefore, the BBB remains a big challenge for delivery of therapeutics to the central nervous system. With the structural and mechanistic elucidation of the BBB under both physiological and pathological conditions, it is now possible to design delivery systems that could cross the BBB effectively. Because of their advantageous properties, nanoparticles have been widely deployed for brain-targeted delivery. This review paper presents the current understanding of the BBB under physiological and pathological conditions, and summarizes strategies and systems for BBB crossing with a focus on nanoparticle-based drug delivery systems. In summary, with wider applications and broader prospection the treatment of brain targeted therapy, nano-medicines have proved to be more potent, more specific and less toxic than traditional drug therapy.

Tumor-targeted delivery of sunitinib base enhances vaccine therapy for advanced melanoma by remodeling the tumor microenvironment

Development of an effective treatment against advanced tumors remains a major challenge for cancer immunotherapy. We have previously developed a potent mannose-modified lipid calcium phosphate (LCP) nanoparticle (NP)-based Trp2 vaccine for melanoma therapy, but because this vaccine can induce a potent anti-tumor immune response only during the early stages of melanoma, poor tumor growth inhibition has been observed in more advanced melanoma models, likely due to the development of an immune-suppressive tumor microenvironment (TME). To effectively treat this aggressive tumor, a multi-target receptor tyrosine kinase inhibitor, sunitinib base, was efficiently encapsulated into a targeted polymeric micelle nano-delivery system (SUNb-PM), working in a synergistic manner with vaccine therapy in an advanced mouse melanoma model. SUNb-PM not only increased cytotoxic T-cell infiltration and decreased the number and percentage of MDSCs and Tregs in the TME, but also induced a shift in cytokine expression from Th2 to Th1 type while remodeling the tumor-associated fibroblasts, collagen, and blood vessels in the tumor. Additionally, inhibition of the Stat3 and AKT signaling pathways by SUNb-PM may induce tumor cell apoptosis or decrease tumor immune evasion. Our findings indicated that targeted delivery of a tyrosine kinase inhibitor to tumors can be used in a novel synergistic way to enhance the therapeutic efficacy of existing immune-based therapies for advanced melanoma.

Switching the Immunogenicity of Peptide Assemblies Using Surface Properties

Biomaterials created from supramolecular peptides, proteins, and their derivatives have been receiving increasing interest for both immunological applications, such as vaccines and immunotherapies, as well as ostensibly nonimmunological applications, such as therapeutic delivery or tissue engineering. However, simple rules for either maximizing immunogenicity or abolishing it have yet to be elucidated, even though immunogenicity is a prime consideration for the design of any supramolecular biomaterial intended for use in vivo. Here, we investigated a range of physicochemical properties of fibrillized peptide biomaterials, identifying negative surface charge as a means for completely abolishing antibody and T cell responses against them in mice, even when they display a competent epitope. The work was facilitated by the modularity of the materials, which enabled the generation of a set of co-assembled fibrillar peptide materials with broad ranges of surface properties. It was found that negative surface charge, provided via negatively charged amino acid residues, prevented T cell and antibody responses to antigen-carrying assemblies because it prevented uptake of the materials by antigen-presenting cells (APCs), which in turn prevented presentation of the epitope peptide in the APCs' major histocompatibility class II molecules. Conversely, positive surface charge augmented the uptake of fibrillized peptides by APCs. These findings suggest that some surface characteristics, such as extensive negative charge, should be avoided in vaccine design using supramolecular peptide assemblies. More importantly, it provides a strategy to switch off potentially problematic immunogenicity for using these materials in nonimmunological applications.

Nanoparticle delivery of sterically hindered platinum(IV) prodrugs shows 100 times higher potency than that of cisplatin upon light activation

The introduction of a sterically hindered pyridine ligand to a photosensitive platinum(iv) drug for drug delivery resulted in a >100 fold increase in effectiveness compared to the gold standard, cisplatin.

Development of a reactive oxygen species (ROS)-responsive nanoplatform for targeted oral cancer therapy

In this study, for effective oral cancer therapy, a new targeted and ROS-triggered drug delivery nanoplatform was developed from the RGD-PEG-TK-PLGA polymer, in which the ROS-responsive TK containing linker was connected with PEG and PLGA. RGD in the drug delivery system (DDS) presented here was used to target cancer cells. This new nanoplatform shows high stability, good targeting ability, excellent ROS sensitivity and excellent biocompatibility. Loaded with DOX and alpha-TOS, the formulated nanoparticles (NPs) demonstrate much better cellular uptake efficiency and higher inhibition performance towards the oral tongue Cal27 cancer cell line. In vivo anticancer evaluation indicates that DOX and alpha-TOS loaded RGD-PEG-TK-PLGA NPs have no toxicity to mice and showed significantly improved therapeutic efficacy against tumors. Therefore, this polymeric NP platform presents great potential as a new DDS for oral cancer chemotherapy.

Antitumor and Antimetastasis Activities of Heparin-based Micelle Served As Both Carrier and Drug

Effective treatments for tumors are not easy to achieve due to the existence of metastases, which are responsible for most tumor death. Hence, a new drug delivery system is a pressing need, which should be biocompatible, stimuli-responsive, and multifunctional, including antitumor, antimetastasis, and antiangiogenesis effects. However, it is challenging to achieve all of these properties in one drug delivery system. Here, we developed a system of drug DOX and heparin into one self-assemble nanoparticle via pH-sensitive hydrazone bond and hydrophobic groups, deoxycholate. In the process, heparin itself was not only as the hydrophilic segments of the carrier, but also processed multiple biological functions such as antiangiogenesis and antimetastasis effect. The micelle nanoparticle HD-DOX processed good stability and acidic pH-triggered drug release property. After systemic administration, heparin-based micelle nanoparticle showed longer half-time and enhanced accumulation of DOX in tumors through the enhanced permeability and retention effect, leading to more efficient antitumor effects. In addition, heparin could hinder platelet-induced tumor cells epithelial-mesenchymal transition (EMT) and partially affect cell actin cytoskeletal arrangement, resulting in the disorganization of the actin cytoskeleton. Therefore, HD-DOX exhibited significant inhibitory effect on the metastasis in melanoma animal model in C57BL/6 mouse. Meanwhile, benefited from the antiangiogenesis effect of heparin, tube formations in endothelial cells were effectively inhibited and tumor vascular density was decreased by HD-DOX. Taken together, our study developed a self-assembly nanoplatform that both the drug and carrier had therapeutic effects with ideal antitumor efficacy.

Novel walnut peptide-selenium hybrids with enhanced anticancer synergism: facile synthesis and mechanistic investigation of anticancer activity

This contribution reports a facile synthesis of degreased walnut peptides (WP1)-functionalized selenium nanoparticles (SeNPs) hybrids with enhanced anticancer activity and a detailed mechanistic evaluation of its superior anticancer activity. Structural and chemical characterizations proved that SeNPs are effectively capped with WP1 via physical absorption, resulting in a stable hybrid structure with an average diameter of 89.22 nm. A panel of selected human cancer cell lines demonstrated high susceptibility toward WP1-SeNPs and displayed significantly reduced proliferative behavior. The as-synthesized WP1-SeNPs exhibited excellent selectivity between cancer cells and normal cells. The targeted induction of apoptosis in human breast adenocarcinoma cells (MCF-7) was confirmed by the accumulation of arrested S-phase cells, nuclear condensation, and DNA breakage. Careful investigations revealed that an extrinsic apoptotic pathway can be attributed to the cell apoptosis and the same was confirmed by activation of the Fas-associated with death domain protein and caspases 3, 8, and 9. In addition, it was also understood that intrinsic apoptotic pathways including reactive oxygen species generation, as well as the reduction in mitochondrial membrane potential, are also involved in the WP1-SeNP-induced apoptosis. This suggested the involvement of multiple apoptosis pathways in the anticancer activity. Our results indicated that WP1-SeNP hybrids with Se core encapsulated in a WP1 shell could be a highly effective method to achieve anticancer synergism. Moreover, the great potential exhibited by WP1-SeNPs could make them an ideal candidate as a chemotherapeutic agent for human cancers, especially for breast cancer.

Local retention of antibodies in vivo with an injectable film embedded with a fluorogen-activating protein

Herein we report an injectable film by which antibodies can be localized in vivo. The system builds upon a bifunctional polypeptide consisting of a fluorogen-activating protein (FAP) and a β-fibrillizing peptide (βFP). The FAP domain generates fluorescence that reflects IgG binding sites conferred by Protein A/G (pAG) conjugated with the fluorogen malachite green (MG). A film is generated by mixing these proteins with molar excess of EAK16-II, a βFP that forms β-sheet fibrils at high salt concentrations. The IgG-binding, fluorogenic film can be injected in vivo through conventional needled syringes. Confocal microscopic images and dose-response titration experiments showed that loading of IgG into the film was mediated by pAG(MG) bound to the FAP. Release of IgG in vitro was significantly delayed by the bioaffinity mechanism; 26% of the IgG were released from films embedded with pAG(MG) after five days, compared to close to 90% in films without pAG(MG). Computational simulations indicated that the release rate of IgG is governed by positive cooperativity due to pAG(MG). When injected into the subcutaneous space of mouse footpads, film-embedded IgG were retained locally, with distribution through the lymphatics impeded. The ability to track IgG binding sites and distribution simultaneously will aid the optimization of local antibody delivery systems.

Salt-Dependent Aggregation and Assembly of E coli-Expressed Ferritin

Ferritin, with the primary function of iron storage, is a nearly ubiquitous protein found in most living organisms. Our recent investigations suggest that ferritin can assemble nanoparticles. So we use ferritin as a novel type of delivery vehicle for recombinant epitope vaccines. And, we found that ferritin form nonnative aggregates depended sensitively on NaCl concentrations. Here, we report that ferritin is an ion-sensitive protein and has the attribute of salt-dependent aggregation. Our results indicate that recombinant ferritin can be released as a soluble form from Escherichia coli at low NaCl concentrations (≤50 mmol/L). Moreover, this result affords us to confirm a proper self-assembling solution for soluble ferritin or other ferritin-based fusion proteins to assemble nanoparticles.

Cell growth stimulating effect of Ganoderma lucidum spores and their potential application for Chinese hamster ovary K1 cell cultivation

In this work, water-soluble extracts of Ganoderma lucidum spores (Gls), a Chinese medicinal herb that possesses cell growth stimulating function, were found to be an effective growth factor for Chinese hamster ovary (CHO) cell cultivation. The Gls extract was prepared and supplemented to CHO K1 cell culture media with various serum levels. Our results obtained from both the static culture and the spinner-flask suspension culture showed that use of small-amount Gls extract effectively promoted cell growth and suppressed cell apoptosis induced by serum deprivation with normal cell cycle maintained in a low-serum medium. The low-serum medium containing 1 % (v/v) fetal bovine serum (FBS) and 0.01 % (w/v) Gls extract showed a comparable performance on both cell growth and fusion protein productivity with the conventional CHO culture medium containing 10 % (v/v) FBS and a commercial serum-free medium. This is the first study of the potential of Gls extracts for use as an alternative cell growth factor and nutrient for CHO cells. The findings have presented a new approach to economic cultivation of CHO cells for therapeutic protein production.

Synthesis and Characterization of a Walnut Peptides-Zinc Complex and Its Antiproliferative Activity against Human Breast Carcinoma Cells through the Induction of Apoptosis

The walnut peptides and zinc ions were combined to generate a walnut peptides-zinc complex (WP1-Zn) with enhanced antiproliferative ability as well as reduced toxicity. The result indicated that Zn ions were successfully combined with WP1 through Zn-N and Zn-O covalent bonds. WP1-Zn compounds exhibited strong antiproliferative ability against the selected human cell lines, especially MCF-7 cells, whose survival rate reduced to 20.02% after exposure to 300 μg/mL of WP1-Zn for 48 h. WP1-Zn inhibited MCF-7 cell proliferation through inducing cell apoptosis and cell cycle arrest. The results indicated that WP1-Zn induced MCF-7 cell apoptosis via the ROS triggered mitochondrial-mediated pathway and cell surface receptor-mediated pathway. Our work is the first attempt to elucidate the synergic effect of novel walnut peptides and Zn and with the hope of better understanding the antiproliferative action of bioactive peptides and a zinc complex and support the potential application of WP1-Zn as a functional food ingredient or complementary medicine.

Design of nanomaterial based systems for novel vaccine development

With lower cell toxicity and higher specificity, novel vaccines have been greatly developed and applied to emerging infectious and chronic diseases. However, due to problems associated with low immunogenicity and complicated processing steps, the development of novel vaccines has been limited. With the rapid development of bio-technologies and material sciences, nanomaterials are playing essential roles in novel vaccine design. Incorporation of nanomaterials is expected to improve delivery efficiency, to increase immunogenicity, and to reduce the administration dosage. The purpose of this review is to discuss the employment of nanomaterials, including polymeric nanoparticles, liposomes, virus-like particles, peptide amphiphiles micelles, peptide nanofibers and microneedle arrays, in vaccine design. Compared to traditional methods, vaccines made from nanomaterials display many appealing benefits, including precise stimulation of immune responses, effective targeting to certain tissue or cells, and desirable biocompatibility. Current research suggests that nanomaterials may improve our approach to the design and delivery of novel vaccines.

Sundew-Inspired Adhesive Hydrogels Combined with Adipose-Derived Stem Cells for Wound Healing

The potential to harness the unique physical, chemical, and biological properties of the sundew (Drosera) plant's adhesive hydrogels has long intrigued researchers searching for novel wound-healing applications. However, the ability to collect sufficient quantities of the sundew plant's adhesive hydrogels is problematic and has eclipsed their therapeutic promise. Inspired by these natural hydrogels, we asked if sundew-inspired adhesive hydrogels could overcome the drawbacks associated with natural sundew hydrogels and be used in combination with stem-cell-based therapy to enhance wound-healing therapeutics. Using a bioinspired approach, we synthesized adhesive hydrogels comprised of sodium alginate, gum arabic, and calcium ions to mimic the properties of the natural sundew-derived adhesive hydrogels. We then characterized and showed that these sundew-inspired hydrogels promote wound healing through their superior adhesive strength, nanostructure, and resistance to shearing when compared to other hydrogels in vitro. In vivo, sundew-inspired hydrogels promoted a "suturing" effect to wound sites, which was demonstrated by enhanced wound closure following topical application of the hydrogels. In combination with mouse adipose-derived stem cells (ADSCs) and compared to other therapeutic biomaterials, the sundew-inspired hydrogels demonstrated superior wound-healing capabilities. Collectively, our studies show that sundew-inspired hydrogels contain ideal properties that promote wound healing and suggest that sundew-inspired-ADSCs combination therapy is an efficacious approach for treating wounds without eliciting noticeable toxicity or inflammation.

Delivery System of CpG Oligodeoxynucleotides through Eliciting an Effective T cell Immune Response against Melanoma in Mice

Purpose: In order to improve the immunogenicity of whole tumor cell lysate for tumor vaccine, we have designed a series of CpG ODNs to study their transport and to evaluate their anti-tumor activity in B16 melanoma mouse models.

Methods: In this study, we investigated whether C-class CpG ODN (CpG ODN-685) could facilitate tumor cell lysate to induce vigorous anti-tumor activity against tumors in mice both prophylactically and therapeutically.

Results: It was found that the combination of tumor cell lysate and CpG ODN-685 could inhibit the growth of B16 melanoma and prolong the survival of tumor-bearing mice. Moreover CpG ODN-685 with the addition of tumor cell lysate can also cause the generation of tumor specific immune memory by inducing specific cytotoxic T lymphocytes and helper T lymphocytes in mice.

Conclusion: The results suggest that CpG ODN-685 could be developed as an efficient adjuvant for tumor vaccines against melanoma.

Polylactic Acid Based Nanocomposites: Promising Safe and Biodegradable Materials in Biomedical Field

Polylactic acid (PLA) is widely used in biological areas due to its excellent compatibility, bioabsorbability, and degradation behavior in human bodies. Pure polylactic acid has difficulty in meeting all the requirements that specific field may demand. Therefore, PLA based nanocomposites are extensively investigated over the past few decades. PLA based nanocomposites include PLA based copolymers in nanometer size and nanocomposites with PLA or PLA copolymers as matrix and nanofillers as annexing agent. The small scale effect and surface effect of nanomaterials help improve the properties of PLA and make PLA based nanocomposites more popular compared with pure PLA materials. This review mainly introduces different kinds of PLA based nanocomposites in recent researches that have great potential to be used in biomedical fields including bone substitute and repair, tissue engineering, and drug delivery system.

Exenatide loaded PLGA microspheres for long-acting antidiabetic therapy: preparation, characterization, pharmacokinetics and pharmacodynamics

We herein fabricated the exenatide-loaded microspheres by a water in oil in oil (W/O/O) method, which presented great effect on glycemic control with low initial burst release and reduced risk of gastrointestinal intolerance and hypoglycemia.