Heparosan-coated liposomes for drug delivery

Classification and characteristics of bacterial glycosaminoglycan lyases, and their therapeutic and experimental applications

Glycosaminoglycans (GAGs), as animal polysaccharides, are linked to proteins to form various types of proteoglycans. Bacterial GAG lyases are not only essential enzymes that spoilage bacteria use for the degradation of GAGs, but also valuable tools for investigating the biological function and potential therapeutic applications of GAGs. The ongoing discovery and characterization of novel GAG lyases has identified an increasing number of lyases suitable for functional studies and other applications involving GAGs, which include oligosaccharide sequencing, detection and removal of specific glycan chains, clinical drug development and the design of novel biomaterials and sensors, some of which have not yet been comprehensively summarized. GAG lyases can be classified into hyaluronate lyases, chondroitinases and heparinases based on their substrate spectra, and their functional applications are mainly determined by their substrates, with different lyases exhibiting differing substrate selectivity and preferences. It is thus necessary to understand the properties of the available enzymes to determine strategies for their functional application. Building on previous studies and reviews, this Review highlights small yet crucial differences among or within the various GAG lyases to aid in optimizing their use in future studies. To clarify ideas and strategies for further research, we also discuss several traditional and novel applications of GAG lyases.

Isoquercitrin Loaded PEGylated Long Circulating Liposomes Improve Bone Mass and Reduce Oxidative Stress After Osteoporosis

Osteoporosis has increasingly become a major public health concern because of its associated heightened risk of bone fragility and fractures. In order to avoid the adverse risk of hormone therapy, scientists have considered isoquercitrin (IQ) as a natural phytoestrogen to potentially prevent osteoporosis. However, IQ has poor solubility and bioavailability which culminates in rapid elimination of phytoestrogen. Herein, this study sought to solve limited applications of IQ by preparing IQ-loaded PEGylated long circulating liposomes (IQ-Lips) via thin-film hydration method. After appropriate characterization using zeta-potential, polydispersed index (PDI), particle size and entrapment efficiency (EE), IQ-Lips were applied to ovariectomized rat models to evaluate their effect on osteoporosis. The results showed that the prepared IQ-Lips exhibited smaller sized nanoparticles (125.35 ± 4.50 nm), excellent PDI (0.244 ± 0.001) and zeta-potential (-28.64 ± 0.71 mV) with stable property and higher EE (92.10 ± 0.32%). Importantly, administration of IQ-Lips through oral route increased aqueous solvability, bioavailability and circulation time of IQ. Moreover, the IQ-Lips could increase bone microstructural densities and bone mass, as well as reduce oxidative stress in ovariectomized rat models. Altogether, the IQ-Lips may serve as a novel avenue to potentially prolong the circulation of IQ in the body and improve the bioavailability of IQ for treatment of osteoporosis.

Bioengineered heparin: Advances in production technology

Heparin, a highly sulfated glycosaminoglycan, is considered an indispensable anticoagulant with diverse therapeutic applications and has been a mainstay in medical practice for nearly a century. Its potential extends beyond anticoagulation, showing promise in treating inflammation, cancer, and infectious diseases such as COVID-19. However, its current sourcing from animal tissues poses challenges due to variable structures and adulterations, impacting treatment efficacy and safety. Recent advancements in metabolic engineering and synthetic biology offer alternatives through bioengineered heparin production, albeit with challenges such as controlling molecular weight and sulfonation patterns. This review offers comprehensive insight into recent advancements, encompassing: (i) the metabolic engineering strategies in prokaryotic systems for heparin production; (ii) strides made in the development of bioengineered heparin; and (iii) groundbreaking approaches driving production enhancements in eukaryotic systems. Additionally, it explores the potential of recombinant Chinese hamster ovary cells in heparin synthesis, discussing recent progress, challenges, and future prospects, thereby opening up new avenues in biomedical research.

Construction Strategy of Functionalized Liposomes and Multidimensional Application

Liposomes are widely used in the biological field due to their good biocompatibility and surface modification properties. With the development of biochemistry and material science, many liposome structures and their surface functional components have been modified and optimized one by one, pushing the liposome platform from traditional to functionalized and intelligent, which will better satisfy and expand the needs of scientific research. However, a main limiting factor effecting the efficiency of liposomes is the complicated environmental conditions in the living body. Currently, in order to overcome the above problem, functionalized liposomes have become a very promising strategy. In this paper, binding strategies of liposomes with four main functional elements, namely nucleic acids, antibodies, peptides, and stimuli-responsive motif have been summarized for the first time. In addition, based on the construction characteristics of functionalized liposomes, such as drug-carrying, targeting, long-circulating, and stimulus-responsive properties, a comprehensive overview of their features and respective research progress are presented. Finally, the paper critically presents the limitations of these functionalized liposomes in the current applications and also prospectively suggests the future development directions, aiming to accelerate realization of their industrialization.

Advancements in heparosan production through metabolic engineering and improved fermentation

Heparin is one of the most widely used natural drugs, and has been the preferred anticoagulant and antithrombotic agent in the clinical setting for nearly a century. Heparin also shows increasing therapeutic potential for treating inflammation, cancer, and microbial and viral diseases, including COVID-19. With advancements in synthetic biology, heparin production through microbial engineering of heparosan offers a cost-effective and scalable alternative to traditional extraction from animal tissues. Heparosan serves as the starting carbon backbone for the chemoenzymatic synthesis of bioengineered heparin, possessing a chain length that is critically important for the production of heparin-based therapeutics with specific molecular weight (MW) distributions. Recent advancements in metabolic engineering of microbial cell factories have resulted in high-yield heparosan production. This review systematically analyzes the key modules involved in microbial heparosan biosynthesis and the latest metabolic engineering strategies for enhancing production, regulating MW, and optimizing the fermentation scale-up of heparosan. It also discusses future studies, remaining challenges, and prospects in the field.

Production of different molecular weight glycosaminoglycans with microbial cell factories

Glycosaminoglycans (GAGs) are naturally occurring acidic polysaccharides with wide applications in pharmaceuticals, cosmetics, and health foods. The diverse biological activities and physiological functions of GAGs are closely associated with their molecular weights and sulfation patterns. Except for the non-sulfated hyaluronan which can be synthesized naturally by group A Streptococcus, all the other GAGs such as heparin and chondroitin sulfate are mainly acquired from animal tissues. Microbial cell factories provide a more effective platform for the production of structurally homogeneous GAGs. Enhancing the production efficiency of polysaccharides, accurately regulating the GAGs molecular weight, and effectively controlling the sulfation degree of GAGs represent the major challenges of developing GAGs microbial cell factories. Several enzymatic, metabolic engineering, and synthetic biology strategies have been developed to tackle these obstacles and push forward the industrialization of biotechnologically produced GAGs. This review summarizes the recent advances in the construction of GAGs synthesis cell factories, regulation of GAG molecular weight, and modification of GAGs chains. Furthermore, the challenges and prospects for future research in this field are also discussed.

Extending the enzymatic toolbox for heparosan polymerization, depolymerization, and detection

Heparosan is an acidic polysaccharide expressed as a capsule polymer by pathogenic and commensal bacteria, e.g. by E. coli K5. As a precursor in the biosynthesis of heparan sulfate and heparin, heparosan has a high biocompatibility and is thus of interest for pharmaceutical applications. However, due to its low immunogenicity, developing antibodies against heparosan and detecting the polymer in biological samples has been challenging. In this study, we exploited the enzyme repertoire of E. coli K5 and the E. coli K5-specific bacteriophage ΦK5B for the controlled synthesis and depolymerization of heparosan. A fluorescently labeled heparosan nonamer was used as a priming acceptor to study the elongation mechanism of the E. coli K5 heparosan polymerases KfiA and KfiC. We could demonstrate that the enzymes act in a distributive manner, producing labeled heparosan of low dispersity. The enzymatically synthesized heparosan was a useful tool to identify the tailspike protein KflB of ΦK5B as heparosan lyase and to characterize its endolytic depolymerization mechanism. Most importantly, using site-directed mutagenesis and rational construct design, we generated an inactive version of KflB for the detection of heparosan in ELISA-based assays, on blots, and on bacterial and mammalian cells.

Coating Materials to Increase the Stability of Liposomes

Liposomes carry various compounds with applications in pharmaceutical, food, and cosmetic fields, and the administration route is especially parenteral, oral, or transdermal. Liposomes are used to preserve and release the internal components, thus maintaining the properties of the compounds, the stability and shelf life of the encapsulated products, and their functional benefits. The main problem in obtaining liposomes at the industrial level is their low stability due to fragile phospholipid membranes. To increase the stability of liposomes, phospholipid bilayers have been modified or different coating materials have been developed and studied, both for liposomes with applications in the pharmaceutical field and liposomes in the food field. In the cosmetic field, liposomes need no additional coating because the liposomal formulation is intended to have a fast penetration into the skin. The aim of this review is to provide current knowledge regarding physical and chemical factors that influence stability, coating materials for liposomes with applications in the pharmaceutical and food fields to increase the stability of liposomes containing various sensitive compounds, and absorption of the liposomes and commercial liposomal products obtained through various technologies available on the market.

Bioimaging with Upconversion Nanoparticles

Bioimaging enables the spatiotemporal visualization of biological processes at various scales empowered by a range of different imaging modalities and contrast agents. Upconversion nanoparticles (UCNPs) represent a distinct type of such contrast agents with the potential to transform bioimaging due to their unique optical properties and functional design flexibilities. This review explores and discusses the opportunities, challenges, and limitations that UCNPs exhibit as bioimaging probes and highlights applications with spatial dimensions ranging from the single nanoparticle level to cellular, tissue, and whole animal imaging. We further summarized recent advancements in bioimaging applications enabled by UCNPs, including super-resolution techniques and multimodal imaging methods, and provide a perspective on the future potential of UCNP-based technologies in bioimaging research and clinical translation. This review may provide a valuable resource for researchers interested in exploring and applying UCNP-based bioimaging technologies.

Ultrasonic Film Rehydration Synthesis of Mixed Polylactide Micelles for Enzyme-Resistant Drug Delivery Nanovehicles

A facile technique for the preparation of mixed polylactide micelles from amorphous poly-D,L-lactide-block-polyethyleneglycol and crystalline amino-terminated poly-L-lactide is described. In comparison to the classical routine solvent substitution method, the ultrasonication assisted formation of polymer micelles allows shortening of the preparation time from several days to 15-20 min. The structure and morphology of mixed micelles were analyzed with the assistance of electron microscopy, dynamic and static light scattering and differential scanning calorimetery. The resulting polymer micelles have a hydrodynamic radius of about 150 nm and a narrow size distribution. The average molecular weight of micelles was found to be 2.1 × 107 and the aggregation number was calculated to be 6000. The obtained biocompatible particles were shown to possess low cytotoxicity, high colloid stability and high stability towards enzymatic hydrolysis. The possible application of mixed polylactide micelles as drug delivery vehicles was studied for the antitumor hydrophobic drug paclitaxel. The lethal concentration (LC50) of paclitaxel encapsulated in polylactide micelles was found to be 42 ± 4 µg/mL-a value equal to the LC50 of paclitaxel in the commercial drug Paclitaxel-Teva.

Carbohydrate anchored lipid nanoparticles

Nanotechnology has been a dynamic field for formulation scientists with multidisciplinary research being conducted worldwide. Advancements in development of functional nanosystems have led to evolution of breakthrough technologies. Lipidic nanosystems, in particular, are highly preferred owing to their non-immunogenic safety profiles along with a range of versatile intrinsic properties. Surface modification of lipid nanoparticles by anchoring carbohydrates to these systems is one such attractive drug delivery technology. Carbohydrates confer interesting properties to the nanosystems such as stealth, biostability, bioavailability, reduced toxicity due to decreased immunogenic response, targeting potential as well as ease of commercial availability. The carbohydrate anchored systems can be developed using methods such as adsorption, incorporation (nanoprecipitation or solvent displacement method), crosslinking and grafting. Current review provides a detailed overview of potential lipid based nanoparticulate systems with an emphasis on liposomes, solid lipid nanoparticles, nanostructures lipid carriers and micelles. Review further explores basics of surface modification, methods applied therein, advantages of carbohydrates as surface modifiers, their versatile applications, techniques for characterization of carbohydrate anchored systems and vital regulatory aspects concerned with these specialized systems.

Holden, Donahue ND, Green DE, Frickenstein AN, Mettenbrink EM, Schwemley TA, Francek ER, Haddad M, Hossen MN, Mukherjee S, Wu S, DeAngelis PL, Wilhelm S. Nanoparticle Surface Engineering with Heparosan Polysaccharide Reduces Serum Protein Adsorption and Enhances Cellular Uptake

Nanoparticle modification with poly(ethylene glycol) (PEG) is a widely used surface engineering strategy in nanomedicine. However, since the artificial PEG polymer may adversely impact nanomedicine safety and efficacy, alternative surface modifications are needed. Here, we explored the "self" polysaccharide heparosan (HEP) to prepare colloidally stable HEP-coated nanoparticles, including gold and silver nanoparticles and liposomes. We found that the HEP-coating reduced the nanoparticle protein corona formation as efficiently as PEG coatings upon serum incubation. Liquid chromatography-mass spectrometry revealed the protein corona profiles. Heparosan-coated nanoparticles exhibited up to 230-fold higher uptake in certain innate immune cells, but not in other tested cell types, than PEGylated nanoparticles. No noticeable cytotoxicity was observed. Serum proteins did not mediate the high cell uptake of HEP-coated nanoparticles. Our work suggests that HEP polymers may be an effective surface modification technology for nanomedicines to safely and efficiently target certain innate immune cells.

Synthetic cells in biomedical applications

Synthetic cells are engineered vesicles that can mimic one or more salient features of life. These features include directed localization, sense-and-respond behavior, gene expression, metabolism, and high stability. In nanomedicine, many of these features are desirable capabilities of drug delivery vehicles but are difficult to engineer. In this focus article, we discuss where synthetic cells offer unique advantages over nanoparticle and living cell therapies. We review progress in the engineering of the above life-like behaviors and how they are deployed in nanomedicine. Finally, we assess key challenges synthetic cells face before being deployed as drugs and suggest ways to overcome these challenges. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies Biology-Inspired Nanomaterials > Lipid-Based Structures.

Physicochemical Characterization of Hyaluronic Acid and Chitosan Liposome Coatings

Hyaluronic acid (HA) and chitosan (CH) are biopolymers that are widely used in many biomedical applications and for cosmetic purposes. Their chemical properties are fundamental to them working as drug delivery systems and improving their synergistic effects. In this work, two different protocols were used to obtain zwitterionic liposomes coated with either hyaluronic acid or chitosan. Specifically, the methodologies used to perform vesicle preparation were chosen by taking into account the specific chemical properties of these two polysaccharides. In the case of chitosan, liposomes were first synthesized and then coated, whereas the coating of hyaluronic acid was achieved through lipidic film hydration in an HA aqueous solution. The size and the zeta-potential of the polysaccharide-coated liposomes were determined by dynamic light scattering (DLS). This approach allowed coated liposomes to be obtained with hydrodynamic diameters of 264.4 ± 12.5 and 450.3 ± 16.7 nm for HA- and CH-coated liposomes, respectively. The chemical characterization of the coated liposomal systems was obtained by surface infrared (ATR-FTIR) and nuclear magnetic resonance (NMR) spectroscopies. In particular, the presence of polysaccharides was confirmed by the bands assigned to amides and saccharides being in the 1500–1700 cm−1 and 800–1100 cm−1 regions, respectively. This approach allowed confirmation of the efficiency of the coating processes, evidencing the presence of HA or CH at the liposomal surface. These data were also supported by time-of-flight secondary ion mass spectrometry (ToF-SIMS), which provided specific assessments of surface (3–5 nm deep) composition and structure of the polysaccharide-coated liposomes. In this work, the synthesis and the physical chemistry characterization of coated liposomes with HA or CH represent an important step in improving the pharmacological properties of drug delivery systems.

Controllable Drug Delivery by Na+/K+ ATPase α1 Targeting Peptide Conjugated DSPE-PEG Nanocarriers for Breast Cancer

Although Epirubicin (EPI) is a commonly used anthracycline for the treatment of breast cancer in clinic, the serious side effects limit its long-term administration including myelosuppression and cardiomyopathy. Nanomedicines have been widely utilized as drug delivery vehicles to achieve precise targeting of breast cancer cells. Herein, we prepared a DSPE-PEG nanocarrier conjugated a peptide, which targeted the breast cancer overexpression protein Na+/K+ ATPase α1 (NKA-α1). The nanocarrier encapsulated the EPI and grafted with the NKA-α1 targeting peptide through the click reaction between maleimide and thiol groups. The EPI was slowly released from the nanocarrier after entering the breast cancer cells with the guidance of the targeting NKA-α1 peptide. The precise and controllable delivery and release of the EPI into the breast cancer cells dramatically inhibited the cells proliferation and migration in vitro and suppressed the tumor volume in vivo. These results demonstrate significant prospects for this nanocarrier as a promising platform for numerous chemotherapy drugs.

Dysregulation of MicroRNAs in Hypertrophy and Ossification of Ligamentum Flavum: New Advances, Challenges, and Potential Directions

Pathological changes in the ligamentum flavum (LF) can be defined as a process of chronic progressive aberrations in the nature and structure of ligamentous tissues characterized by increased thickness, reduced elasticity, local calcification, or aggravated ossification, which may cause severe myelopathy, radiculopathy, or both. Hypertrophy of ligamentum flavum (HLF) and ossification of ligamentum flavum (OLF) are clinically common entities. Though accumulated evidence has indicated both genetic and environmental factors could contribute to the initiation and progression of HLF/OLF, the definite pathogenesis remains fully unclear. MicroRNAs (miRNAs), one of the important epigenetic modifications, are short single-stranded RNA molecules that regulate protein-coding gene expression at posttranscriptional level, which can disclose the mechanism underlying diseases, identify valuable biomarkers, and explore potential therapeutic targets. Considering that miRNAs play a central role in regulating gene expression, we summarized current studies from the point of view of miRNA-related molecular regulation networks in HLF/OLF. Exploratory studies revealed a variety of miRNA expression profiles and identified a battery of upregulated and downregulated miRNAs in OLF/HLF patients through microarray datasets or transcriptome sequencing. Experimental studies validated the roles of specific miRNAs (e.g., miR-132-3p, miR-199b-5p in OLF, miR-155, and miR-21 in HLF) in regulating fibrosis or osteogenesis differentiation of LF cells and related target genes or molecular signaling pathways. Finally, we discussed the perspectives and challenges of miRNA-based molecular mechanism, diagnostic biomarkers, and therapeutic targets of HLF/OLF.

Application of Dual Promoter Expression System for the Enhanced Heparosan Production in Bacillus megaterium

Heparosan, a capsular polysaccharide synthesized by certain pathogenic bacteria, is a promising precursor for heparin production. Heparosan production is catalyzed by the formation of KfiC-KfiA complex and the subsequent action of KfiC and KfiA proteins. Polycistronic expression of kfiC and kfiA in Bacillus megaterium yielded an unbalanced expression of KfiC and KfiA proteins resulted in decreased heparosan production. In this study, dual promoter plasmid system was constructed to increase the expression levels of KfiC and KfiA proteins. Dual promoter plasmid system along with UDP-glucuronic acid pathway overexpression (CADuet-DB) increased the heparosan production to 203 mg/L in shake flask experiments. Batch fermentation of strain CADuet-DB under controlled conditions yielded a maximum heparosan concentration of 627 mg/L, which is 59% higher than strain CA-DB. A modified logistic model is applied to describe the kinetics of heparosan production and biomass growth. Fed batch fermentation resulted in 3-fold enhancement in heparosan concentration (1.96 g/L), compared to batch fermentation. Nuclear magnetic resonance analysis revealed that heparosan from strain CADuet-DB was similar to Escherichia coli K5 heparosan. These results suggested that dual promoter expression system is a promising alternative to polycistronic expression system to produce heparosan in B. megaterium.

MicroRNA in multiple sclerosis

Multiple sclerosis (MS) is an autoimmune disease that affects the central nervous system (CNS). Despite a complex pathogenesis, it appears that an imbalanced immune system plays an important role in the disease process. MicroRNAs (miRNAs) are comprised of short non-coding single-stranded molecules mainly involved in regulating gene expression through the inhibition of transcription and translation. miRNAs are key regulatory molecules in the nucleus and participate in the proliferation, differentiation, and apoptosis of various cells throughout the body. Recent studies, however, have found that miRNAs are also involved in MS pathogenesis, mainly affecting glial cells and peripheral immune cells. Fortunately, miRNAs are highly stable and have high specificity in peripheral body fluids. Accordingly, these molecules have become new diagnostic and therapeutic targets. The present review discusses the role of miRNAs in the pathogenesis of MS. We highlight the potential of miRNAs as new biomarkers of MS and potential therapeutic agents.

Nanoparticle Toxicology

Nanoparticles from natural and anthropogenic sources are abundant in the environment, thus human exposure to nanoparticles is inevitable. Due to this constant exposure, it is critically important to understand the potential acute and chronic adverse effects that nanoparticles may cause to humans. In this review, we explore and highlight the current state of nanotoxicology research with a focus on mechanistic understanding of nanoparticle toxicity at organ, tissue, cell, and biomolecular levels. We discuss nanotoxicity mechanisms, including generation of reactive oxygen species, nanoparticle disintegration, modulation of cell signaling pathways, protein corona formation, and poly(ethylene glycol)-mediated immunogenicity. We conclude with a perspective on potential approaches to advance current understanding of nanoparticle toxicity. Such improved understanding may lead to mitigation strategies that could enable safe application of nanoparticles in humans. Advances in nanotoxicity research will ultimately inform efforts to establish standardized regulatory frameworks with the goal of fully exploiting the potential of nanotechnology while minimizing harm to humans.

Cells and cell derivatives as drug carriers for targeted delivery

For over a century, researchers have focused on how to optimize drug delivery. Systemic administration means that the drug becomes dilute and has the potential to diffuse to all tissues, which is only until the immune system steps in and rapidly clears it from blood circulation. Drug carriers are the solution for amplifying the intended effect and diminishing side effects. With drug carriers, tissue-specific drug delivery and controlled drug release is possible. Thus far, both synthetic and non-synthetic carriers exist. However, due to the numerous limitations of synthetic carriers, science has begun to concentrate on using live cells and cell-derivatives as drug carriers. The most problematic shortcomings of synthetic carriers are their limited biocompatibility and biodegradability. Most synthetic carriers are cytotoxic or induce immune responses. Moreover, synthetic carriers typically depend on passive diffusion and risk phagocytosis, further reducing their impact. On the other hand, live-cell carriers and their derivatives usually have a targeting mechanism and drug release is controlled, increasing the efficiency with which a drug accumulates and acts on a tissue. Still, both types of carriers face similar problems, including achieving high loading capacity, maintaining drug quality, efficiently accumulating in the target tissue, and minimizing side effects. This review aims to elucidate the advantages and disadvantages of each popular cell or cell-derived carrier and to spotlight novel solutions.

Ligand Binding and Signaling of HARE/Stabilin-2

The Stabilin receptors are a two-member family in the type H class of scavenger receptors. These dynamic receptors bind and internalize multiple ligands from the cell surface for the purpose of clearing extracellular material including some synthetic drugs and for sensing the external environment of the cell. Stabilin-1 was the first receptor to be cloned, though the biological activity of Hyaluronic Acid Receptor for Endocytosis (HARE)/Stabilin-2 was observed about 10 years prior to the cloning of Stabilin-1. Stabilin-1 has a more diverse expression profile among the tissues than HARE/Stabilin-2. This review will focus on HARE/Stabilin-2 and its interactions with hyaluronan, heparin, and phosphorothioate antisense oligonucleotides and what is known about how this receptor participates in signaling upon ligand binding.

Molecular weight determination of heparosan- and chondroitin-like capsular polysaccharides: figuring out differences between wild -type and engineered Escherichia coli strains

Heparin and chondroitin sulfate are used as anti-thrombic and anti-osteoarthritis drugs, respectively, but their pharmacological actions depend on their structural characteristics such as their sulfation grade and their molecular weight. In the last years, new fermentation-based biotechnological approaches have tried to obtain heparin and chondroitin sulfate starting from the heparosan and chondroitin-like capsular polysaccharides produced by Escherichia coli K5 and K4. The study of the microbial capsular polysaccharide molecular weight is critical to obtain nature-like or structural tailor cut glycosaminoglycan homologues. However, so far, it has been scarcely investigated. In this paper, for the first time, a new protocol was set up to determine the molecular weights of the capsular polysaccharides of three wild-type and three engineered E. coli K5 and K4 strains. The protocol includes a small-scale downstream train to purify the intact polysaccharides, directly from the fermentation broth supernatants, by using ultrafiltration membranes and anion exchange chromatography, and it couples size exclusion chromatography analyses with triple detector array. In the purification high recovery (> 85.0%) and the removal of the main contaminant, the lipopolysaccharide, were obtained. The averaged molecular weights of the wild-type capsular polysaccharides ranged from 51.3 to 90.9 kDa, while the engineered strains produced polysaccharides with higher molecular weights, ranging from 68.4 to 130.6 kDa, but with similar polydispersity values between 1.1 and 1.5.

Enhanced cytotoxic T lymphocytes recruitment targeting tumor vasculatures by endoglin aptamer and IP-10 plasmid presenting liposome-based nanocarriers

Background: Adequate recruitment of highly active tumor antigen-specific cytotoxic T lymphocytes (CTLs) remains a major challenge in cancer immunotherapy. Objective: To construct liposome (LP)-based nanocapsules with surface endoglin aptamer (ENG-Apt) encapsulating mouse interferon-inducible protein-10 (mIP-10), with the ability to target mouse tumor vascular endothelial cells (mTECs) and enhance CTLs targeting and recruitment to the tumor vasculature. Methods: ENG-Apt/mIP-10-LP nanocapsules were prepared by grafting DSPE-PEG2000-ENG-Apt on the surface of liposomes containing mIP-10 plasmids, characterized and assessed for the cell binding specificity in vitro. The tumor-targeting ability of ENG-Apt/mIP-10-LP nanocapsules was evaluated in vivo. The anti-tumor efficacy of ENG-Apt/mIP-10-LP nanocapsules treatment, as well as the combination treatment of ENG-Apt/mIP-10-LP nanocapsules and adoptive TRP2CD8+ T cells, were both tested in melanoma-bearing mice, by evaluation of the tumor volume and the mouse survival time. To discuss the anti-tumoral mechanism of ENG-Apt/mIP-10-LP nanocapsules-based therapies, IFN-γ secretion, proportion of TRP2CD8+ T cells among TILs, MDSCs in the tumor microenvironment and Tregs in the spleen, were determined after the treatments. Proliferation and apoptosis of tumor cells, and tumor angiogenesis were also assessed. Results: The prepared ENG-Apt/mIP-10-LP nanocapsules possess an adequate nanometric size, good stability, high specificity to mTECs and tumor sites, along with the ability to induce mIP-10 expression in vitro and in vivo. Treatment of ENG-Apt/mIP-10-LP nanocapsules demonstrated CTLs enrichment into the tumor site, which inhibited tumor cell proliferation and angiogenesis, as well as promoted tumor-cell apoptosis, leading to a decrease in tumor progression and prolonged survival time in melanoma tumor-bearing mice. In addition, the proportion of MDSCs and Tregs was found to decrease. The combination of ENG-Apt/mIP-10-LP nanocapsules with adoptive TRP2CD8+ T cells, showed stronger abilities in inhibiting tumor growth and increasing animal survival time, thereby displayed an enhanced anti-melanoma tumor efficacy, due to the recruitment of both endogenous CD8+ T cells and exogenous TRP2CD8+ T cells in vivo. Conclusion: ENG-Apt/mIP-10-LP nanocapsules could enhance the recruitment of both endogenous and exogenous CTLs specifically targeting melanoma tumor vasculatures and exert anti-tumoral effect, therefore provides a potentially novel strategy for tumor immunotherapy.

Heparosan as a potential alternative to hyaluronic acid for the design of biopolymer-based nanovectors for anticancer therapy

Glycosaminoglycans (GAGs) are important components of the extracellular matrix that have attracted great interest for drug delivery and pharmaceutical applications due to their diverse biological functions. Among GAGs, heparosan (Hep), a biosynthetic precursor of heparin, has recently emerged as a promising building block for the design of nanoparticles with stealth properties. Though this non-sulfated polysaccharide has a chemical structure very close to that of hyaluronic acid (HA), it distinguishes from HA in that it is biologically inert in the extracellular spaces in the body. In this study, we designed Hep- and HA-based nanogels (NGs) that differ only in the chemical nature of the hydrophilic shell. The nanogels were prepared in a very straightforward way from Hep and HA modified with a thermoresponsive copolymer properly designed to induce self-assembly below room temperature. This versatile synthetic approach also enabled further shell-crosslinking allowing an increase in the colloidal stability. After careful characterization of the un-crosslinked and crosslinked Hep and HA NGs in terms of size (Z-average diameters of un-crosslinked and crosslinked NGs ∼110 and 150 nm) and morphology, they were injected intravenously into tumor-bearing mice for biodistribution experiments. Interestingly, these show that the liver uptake of Hep nanogels is remarkably reduced and tumor accumulation significantly improved as compared to HA nanogels (intensity ratios of tumor-to-liver of 2.2 and 1.4 for the un-crosslinked and crosslinked Hep NGs versus 0.11 for the un-crosslinked and crosslinked HA ones). These results highlight the key role played by the shell-forming GAGs on the in vivo fate of nanogels, which correlates with the specific biological properties of Hep and HA.

Synthesis and characterization of heparosan-granulocyte-colony stimulating factor conjugates: a natural sugar-based drug delivery system to treat neutropenia

Many injectable drugs require delivery strategies for enhancing their pharmacokinetics due to rapid loss via renal filtration if possess low molecular weight (<60-70 kDa) and/or clearance by the body's components (e.g., proteases, antibodies, high-efficiency receptors) in their native form. FDA-approved polyethylene glycol (PEG) is a vehicle for improving therapeutics, but artificial polymers have potential biocompatibility and immunogenicity liabilities. Here, we utilized a natural vertebrate carbohydrate, heparosan (HEP), the biosynthetic precursor of heparan sulfate and heparin, to enhance performance of a biologic drug. The HEP polysaccharide was stable with a long half-life (~8 days for 99-kDa chain) in the nonhuman primate bloodstream, but was efficiently degraded to very short oligosaccharides when internalized by cells, and then excreted into urine and feces. Several HEP-modified human granulocyte-colony stimulating factor (G-CSF) conjugates were synthesized with defined quasi-monodisperse HEP polysaccharide chains. Single dosing of 55- or 99-kDa HEP-G-CSF in rats increased blood neutrophil levels comparable to PEG-G-CSF conjugates. Repeated dosing of HEP-G-CSF or HEP alone for 2 weeks did not cause HEP-specific toxic effects in rats. HEP did not possess the anticoagulant behavior of its daughter, heparin, based on testing in rats or clinical diagnostic assays with human plasma. Neither anti-HEP IgG nor IgM antibodies were detected in a long-term (9 doses over 7 months) immunogenicity study of the HEP-drug conjugate with rats. These proof-of-concept experiments with HEP-G-CSF indicate that it is a valid drug candidate for neutropenia and suggest the potential of this HEP-based platform as a safe alternative delivery vehicle for other therapeutics.

‘One-pot’ sequential enzymatic modification of synthetic glycolipids in vesicle membranes

To create vesicles with cell-targeting coatings, two soluble enzymes were used to directly glycosylate vesicle surfaces in a ‘one-pot’ procedure.