Intracellular hydrogelation of macrophage conjugated probiotics for hitchhiking delivery and combined treatment of colitis

On the design of cell membrane-coated nanoparticles to treat inflammatory conditions

Biomimetic-based drug delivery systems (DDS) attempt to recreate the complex interactions that occur naturally between cells. Cell membrane-coated nanoparticles (CMCNPs) have been one of the main strategies in this area to prevent opsonization and clearance. Moreover, coating nanoparticles with cell membranes allows them to acquire functions and properties inherent to the mother cells. In particular, cells from bloodstream show to have specific advantages depending on the cell type to be used for that application, specifically in cases of chronic inflammation. Thus, this review focuses on the biomimetic strategies that use membranes from blood cells to target and treat inflammatory conditions.

Fabrication of cyborg bacterial cells as living cell-material hybrids using intracellular hydrogelation

The production of living therapeutics, cell-based delivery of drugs and gene-editing tools and the manufacturing of bio-commodities all share a common concept: they use either a synthetic or a living cell chassis to achieve their primary engineering or therapeutic goal. Live-cell chassis face limitations inherent to their auto-replicative nature and the complexity of the cellular context. This limitation highlights the need for a new chassis combining the engineering simplicity of synthetic materials and the functionalities of natural cells. Here, we describe a protocol to assemble a synthetic polymeric network inside bacterial cells, rendering them incapable of cell division and allowing them to resist environmental stressors such as high pH, hydrogen peroxide and cell-wall-targeting antibiotics that would otherwise kill unmodified bacteria. This cellular bioengineering protocol details how bacteria can be transformed into single-lifespan devices that are resistant to environmental stressors and possess programable functionality. We designate the modified bacteria as cyborg bacterial cells. This protocol expands the synthetic biology toolset, conferring precise control over living cells and creating a versatile cell chassis for biotechnology, biomedical engineering and living therapeutics. The protocol, including the preparation of gelation reagents and chassis strain, can be completed in 4 d. The implementation of the protocol requires expertise in microbiology techniques, hydrogel chemistry, fluorescence microscopy and flow cytometry. Further functionalization of the cyborg bacterial cells and adaptation of the protocol requires skills ranging from synthetic genetic circuit engineering to hydrogel polymerization chemistries.

Engineering Cyborg Pathogens through Intracellular Hydrogelation

Synthetic biology primarily focuses on two kinds of cell chassis: living cells and nonliving systems. Living cells are autoreplicating systems that have active metabolism. Nonliving systems, including artificial cells and nanoparticles, are nonreplicating systems typically lacking active metabolism. In recent work, Cyborg bacteria that are nonreplicating-but-metabolically active have been engineered through intracellular hydrogelation. Intracellular hydrogelation is conducted by infusing gel monomers and photoactivators into cells, followed by the activation of polymerization of the gel monomers inside the cells. However, the previous work investigated only Escherichia coli cells. Extending the Cyborg-Cell method to pathogenic bacteria could enable the exploitation of their pathogenic properties in biomedical applications. Here, we focus on different strains of Pseudomonas aeruginosa, Staphylococcus aureus, and Klebsiella pneumoniae. To synthesize the Cyborg pathogens, we first reveal the impact of different hydrogel concentrations on the metabolism, replication, and intracellular gelation of Cyborg pathogens. Next, we demonstrate that the Cyborg pathogens are taken up by macrophages in a similar magnitude as wild-type pathogens through confocal microscopy and real-time PCR. Finally, we show that the macrophage that takes up the Cyborg pathogen exhibits a similar phenotypic response to the wild-type pathogen. Our work generalizes the intracellular hydrogelation approach from lab strains of E. coli to bacterial pathogens. The new Cyborg pathogens could be applied in biomedical applications ranging from drug delivery to immunotherapy.

Bioinspired gelated cell sheet-supported lactobacillus biofilm for aerobic vaginitis diagnosis and treatment

Aerobic vaginitis (AV) is a long-standing inflammatory disease that affects female patients. The use of antibiotics is a common means for AV treatment, but it will indiscriminately kill both pathogenic bacteria and beneficial strains, which easily causes vaginal dysbacteriosis and infection recurrence. Herein, we describe a bioinspired strategy for fabricating gelated cell sheet-supported lactobacillus biofilms (GCS-LBs) for AV treatment. Compared with common planktonic probiotic formulations, probiotic biofilms forming on a robust GCS exhibit enhanced stress tolerance and better colonization capacity in the mouse vagina. Moreover, DNA nanodevices are decorated on the GCS and dynamically report the microenvironment change of biofilms for timely evaluating bacterium activity, both in vitro and in vivo. Consequently, GCS-LBs are used for treating AV in an Escherichia coli-infected mouse model, which shows enhanced therapeutic efficacy compared with conventional antibiotic or lactobacillus monotherapy. Overall, the GCS-LB shows promise as a potent multifunctional tool to combat bacterial infection.

Intracellularly Gelated Macrophages Loaded with Probiotics for Therapy of Colitis

Probiotics therapy has garnered significant attention in the treatment of inflammatory bowel disease (IBD). However, a large number of oral administrated probiotics are inactivated after passing through the gastric acid environment, and their ability to colonize in the intestine is also weak. Herein, this study develops a novel probiotics formulation (GM-EcN) by incorporating Escherichia coli Nissle 1917 (EcN) into intracellularly gelated macrophages (GM). Intracellular hydrogel is designed to load and prevent EcN from digestion in gastric juice, and GM acts as a macrophage-like carrier to carry the attached probiotics to colonize in the inflammatory intestine. In addition, hydrogel serves as an ideal cytoskeletal structure to maintain the intact cell morphology and membrane structure of GM, comparable to source macrophages. Due to the receptor-ligand interaction, inflammation-related membrane proteins enable GM as a cell sponge to sequestrate and neutralize multiple inflammatory cytokines. In vivo treatment demonstrates that GM-EcN efficiently alleviates IBD symptoms and enhances gut microbiota recovery.

Advanced Bioinspired Multifunctional Platforms Focusing on Gut Microbiota Regulation

Gut microbiota plays a crucial role in maintaining host homeostasis, impacting the progression and therapeutic outcomes of diseases, including inflammatory bowel disease, cancer, hepatic conditions, obesity, cardiovascular pathologies, and neurologic disorders, via immune, neural, and metabolic mechanisms. Hence, the gut microbiota is a promising target for disease therapy. The safety and precision of traditional microbiota regulation methods remain a challenge, which limits their widespread clinical application. This limitation has catalyzed a shift toward the development of multifunctional delivery systems that are predicated on microbiota modulation. Guided by bioinspired strategies, an extensive variety of naturally occurring materials and mechanisms have been emulated and harnessed for the construction of platforms aimed at the monitoring and modulation of gut microbiota. This review outlines the strategies and advantages of utilizing bioinspired principles in the design of gut microbiota intervention systems based on traditional regulation methods. Representative studies on the development of bioinspired therapeutic platforms are summarized, which are based on gut microbiota modulation to confer multiple pharmacological benefits for the synergistic management of diseases. The prospective avenues and inherent challenges associated with the adoption of bioinspired strategies in the refinement of gut microbiota modulation platforms are proposed to augment the efficacy of disease treatment.

Melanin Nanoparticle-Modified Probiotics for Targeted Synergistic Therapy of Ulcerative Colitis

Ulcerative colitis (UC) is a recurrent chronic mucosal inflammation disease whose most significant pathological characteristics are intestinal inflammation and damaged mucosal barrier induced by reactive oxygen/nitrogen species, abnormal immune microenvironment, and intestinal microecological imbalance. Oral probiotics are a living therapy for intestinal diseases, but their clinical application is hindered by poor bacterial biological activity and insufficient intestinal retention. Here, we developed a targeted oral formulation, functionalized probiotic Lf@MPB, with Lactobacillus fermentum (Lf) as the core and modified melanin nanoparticles (MNPs) on its surface through a click reaction of tricarboxyphenylboronic acid for synergistic therapy of UC. In vitro experiments showed that Lf@MPB not only possessed strong free radical scavenging ability, reduced cellular mitochondrial polarization, and inhibited apoptosis but also significantly enhanced the viability of Lf probiotics in simulated gastrointestinal fluid. Fluorescence imaging in vivo revealed the high accumulation of Lf@MPB at the site of intestinal inflammation in dextran sulfate sodium-induced UC mice. Moreover, in vivo results demonstrated that Lf@MPB effectively alleviated oxidative stress and inflammatory response and restored the intestinal barrier. In addition, 16S rRNA gene sequencing verified that Lf@MPB could increase the abundance and diversity of intestinal microbial communities and optimize microbial composition to inhibit the progression of UC. This work combines effective antioxidant and anti-inflammatory strategies with the oral administration of functionalized probiotics to provide a promising alternative for UC treatment.

Recent progress on engineered micro/nanomaterials mediated modulation of gut microbiota for treating inflammatory bowel disease

Inflammatory bowel disease (IBD) is a type of chronic recurrent inflammation disease that mainly includes Crohn's disease and ulcerative colitis. Currently, the treatments for IBD remain highly challenging, with clinical treatment drugs showing limited efficacy and adverse side effects. Thus, developing drug candidates with comprehensive therapeutic effects, high efficiency, and low toxicity is urgently needed. Recently, micro/nanomaterials have attracted considerable interest because of their bioavailability, multitarget and efficient effects on IBD. In addition, gut modulation plays a substantial role in restoring intestinal homeostasis. Therefore, efficient microbiota-based strategies modulating gut microenvironment have great potential in remarkably treating IBD. With the development of micro- and nanomaterials for the treatment of IBD and more in-depth studies of their therapeutic mechanisms, it has been found that these treatments also have a tendency to positively regulate the intestinal flora, resulting in an increase in the beneficial flora and a decrease in the level of pathogenic bacteria, thus regulating the composition of the intestinal flora to a normal state. In this review, we first present the interactions among the immune system, intestinal barrier, and gut microbiome. In addition, recent advances in administration routes and methods that positively arouse the regulation of intestinal flora for IBD using probiotics, prebiotics, and redox-active micro/nanomaterials have been reviewed. Finally, the key challenges and critical perspectives of gut microbiota-based micro/nanomaterial treatment are also discussed.

Advancements in hydrogel-based drug delivery systems for the treatment of inflammatory bowel disease: a review

Inflammatory bowel disease (IBD) is a chronic disorder that affects millions of individuals worldwide. However, current drug therapies for IBD are plagued by significant side effects, low efficacy, and poor patient compliance. Consequently, there is an urgent need for novel therapeutic approaches to alleviate IBD. Hydrogels, three-dimensional networks of hydrophilic polymers with the ability to swell and retain water, have emerged as promising materials for drug delivery in the treatment of IBD due to their biocompatibility, tunability, and responsiveness to various stimuli. In this review, we summarize recent advancements in hydrogel-based drug delivery systems for the treatment of IBD. We first identify three pathophysiological alterations that need to be addressed in the current treatment of IBD: damage to the intestinal mucosal barrier, dysbiosis of intestinal flora, and activation of inflammatory signaling pathways leading to disequilibrium within the intestines. Subsequently, we discuss in depth the processes required to prepare hydrogel drug delivery systems, from the selection of hydrogel materials, types of drugs to be loaded, methods of drug loading and drug release mechanisms to key points in the preparation of hydrogel drug delivery systems. Additionally, we highlight the progress and impact of the hydrogel-based drug delivery system in IBD treatment through regulation of physical barrier immune responses, promotion of mucosal repair, and improvement of gut microbiota. In conclusion, we analyze the challenges of hydrogel-based drug delivery systems in clinical applications for IBD treatment, and propose potential solutions from our perspective.

Macrophage-Based Microrobots for Anticancer Therapy: Recent Progress and Future Perspectives

Macrophages, which are part of the mononuclear phagocytic system, possess sensory receptors that enable them to target cancer cells. In addition, they are able to engulf large amounts of particles through phagocytosis, suggesting a potential "Trojan horse" drug delivery approach to tumors by facilitating the engulfment of drug-hidden particles by macrophages. Recent research has focused on the development of macrophage-based microrobots for anticancer therapy, showing promising results and potential for clinical applications. In this review, we summarize the recent development of macrophage-based microrobot research for anticancer therapy. First, we discuss the types of macrophage cells used in the development of these microrobots, the common payloads they carry, and various targeting strategies utilized to guide the microrobots to cancer sites, such as biological, chemical, acoustic, and magnetic actuations. Subsequently, we analyze the applications of these microrobots in different cancer treatment modalities, including photothermal therapy, chemotherapy, immunotherapy, and various synergistic combination therapies. Finally, we present future outlooks for the development of macrophage-based microrobots.

Carbohydrate polymer-based carriers for colon targeted delivery of probiotics

Probiotics (PRO) have been recognized for their significant role in promoting human health, particularly in relation to colon-related diseases. The effective delivery of PRO to the colon is a fascinating area of research. Among various delivery materials, carbohydrates have shown great potential as colon-targeted delivery (CTD) carriers for PRO. This review explores the connection between probiotics and colonic diseases, delving into their underlying mechanisms of action. Furthermore, it discusses current strategies for the targeted delivery of active substances to the colon. Unlike other reviews, this work specifically focuses on the utilization of carbohydrates, such as alginate, chitosan, pectin, and other carbohydrates, for probiotic colon-targeted delivery applications. Carbohydrates can undergo hydrolysis at the colonic site, allowing their oligosaccharides to function as prebiotics or as direct functional polysaccharides with beneficial effects. Furthermore, the development of multilayer self-assembled coatings using different carbohydrates enables the creation of enhanced delivery systems. Additionally, chemical modifications of carbohydrates, such as for adhesion and sensitivity, can be implemented to achieve more customized delivery of PRO.