Micro- and nanoparticles-based immunoregulation of macrophages for tissue repair and regeneration

Current application and modification strategy of marine polysaccharides in tissue regeneration: A review

Marine polysaccharides (MPs) are exceptional bioactive materials that possess unique biochemical mechanisms and pharmacological stability, making them ideal for various tissue engineering applications. Certain MPs, including agarose, alginate, carrageenan, chitosan, and glucan have been successfully employed as biological scaffolds in animal studies. As carriers of signaling molecules, scaffolds can enhance the adhesion, growth, and differentiation of somatic cells, thereby significantly improving the tissue regeneration process. However, the biological benefits of pure MPs composite scaffold are limited. Therefore, physical, chemical, enzyme modification and other methods are employed to expand its efficacy. Chemically, the structural properties of MPs scaffolds can be altered through modifications to functional groups or molecular weight reduction, thereby enhancing their biological activities. Physically, MPs hydrogels and sponges emulate the natural extracellular matrix, creating a more conducive environment for tissue repair. The porosity and high permeability of MPs membranes and nanomaterials expedite wound healing. This review explores the distinctive properties and applications of select MPs in tissue regeneration, highlighting their structural versatility and biological applicability. Additionally, we provide a brief overview of common modification strategies employed for MP scaffolds. In conclusion, MPs have significant potential and are expected to be a novel regenerative material for tissue engineering.

Laponite Composites: In Situ Films Forming as a Possible Healing Agent

A healing material must have desirable characteristics such as maintaining a physiological environment, protective barrier-forming abilities, exudate absorption, easy handling, and non-toxicity. Laponite is a synthetic clay with properties such as swelling, physical crosslinking, rheological stability, and drug entrapment, making it an interesting alternative for developing new dressings. This study evaluated its performance in lecithin/gelatin composites (LGL) as well as with the addition of maltodextrin/sodium ascorbate mixture (LGL MAS). These materials were applied as nanoparticles, dispersed, and prepared by using the gelatin desolvation method-eventually being turned into films via the solvent-casting method. Both types of composites were also studied as dispersions and films. Dynamic Light Scattering (DLS) and rheological techniques were used to characterize the dispersions, while the films' mechanical properties and drug release were determined. Laponite in an amount of 8.8 mg developed the optimal composites, reducing the particulate size and avoiding the agglomeration by its physical crosslinker and amphoteric properties. On the films, it enhanced the swelling and provided stability below 50 °C. Moreover, the study of drug release in maltodextrin and sodium ascorbate from LGL MAS was fitted to first-order and Korsmeyer-Peppas models, respectively. The aforementioned systems represent an interesting, innovative, and promising alternative in the field of healing materials.

Red blood cell membrane-camouflaged poly(lactic-co-glycolic acid) microparticles as a potential controlled release drug delivery system for local stellate ganglion microinjection

The stellate ganglion (SG) is a part of the sympathetic nervous system that has important regulatory effects on several human tissues and organs in the upper body. SG block and intervention have been clinically and preclinically implemented to manage chronic pain in the upper extremities, neck, head, and upper chest as well as chronic heart failure. However, there has been very limited effort to develop and investigate polymer-based drug delivery systems for local delivery to the SG. In this study, we fabricated red blood cell (RBC) membrane-camouflaged poly(lactic-co-glycolic acid) (PLGA) (PLGAM) microparticles for use as a potential long-term controlled release system for local drug delivery. The structure, size, and surface zeta potential results indicated that the spherical PLGAM microparticles were successfully fabricated. Both PLGA and PLGAM microparticles exhibited biocompatibility with human adipose mesenchymal stem cells (ADMSC) and satellite glial cells and showed hemocompatibility. In addition, both PLGA and PLGAM displayed no significant effects on the secretion of proinflammatory cytokines by human monocyte derived macrophages in vitro. We microinjected microparticles into rat SGs and evaluated the retention time of microparticles and the effects of the microparticles on inflammation in vivo over 21 days. Subsequently, we fabricated drug-loaded PLGAM microparticles by using GW2580, a colony stimulating factor-1 receptor inhibitor, as a model drug and assessed its encapsulation efficiency, drug release profiles, biocompatibility, and anti-inflammatory effects in vitro. Our results demonstrated the potential of PLGAM microparticles for long-term controlled local drug release in the SG. STATEMENT OF SIGNIFICANCE: SG block by locally injecting therapeutics to inhibit the activity of the sympathetic nerves provides a valuable benefit to manage chronic pain and chronic heart failure. We describe the fabrication of RBC membrane-camouflaged PLGA microparticles with cytocompatibility, hemocompatibility, and low immunogenicity, and demonstrate that they can be successfully and safely microinjected into rat SGs. The microparticle retention time within SG is over 21 days without eliciting detectable inflammation. Furthermore, we incorporate a CSF-1R inhibitor as a model drug and demonstrate the capacities of long-term drug release and regulation of macrophage functions. The strategies demonstrate the feasibility to locally microinject therapeutics loaded microparticles into SGs and pave the way for further efficacy and disease treatment evaluation.

Freeze-casting osteochondral scaffolds: The presence of a nutrient-permeable film between the bone and cartilage defect reduces cartilage regeneration

Microfracture treatment that is basically relied on stem cells and growth factors in bone marrow has achieved a certain progress for cartilage repair in clinic. Nevertheless, the neocartilage generated from the microfracture strategy is limited endogenous regeneration and prone to fibrosis due to the influences of cell inflammation and vascular infiltration. To explore the crucial factor for articular cartilage remodeling, here we design a trilaminar osteochondral scaffold with a selective permeable film in middle isolation layer which can prevent stem cells, immune cells, and blood vessels in the bone marrow from invading into the cartilage layer, but allow the nutrients and cytokines to penetrate. Our findings show that the trilaminar scaffold exhibits a good biocompatibility and inflammatory regulation, but the osteochondral repair is far less effective than the control of double-layer scaffold without isolation layer. These results demonstrate that it is not adequate to rely only on nutrients and cytokines to promote reconstruction of articular cartilage, and the various cells in bone marrow are indispensable. Consequently, the current study illustrates that cell infiltration involving stem cells, immune cells and other cells from bone marrow plays a crucial role in articular cartilage remodeling based on the integrated scaffold strategy. STATEMENT OF SIGNIFICANCE: Clinical microfracture treatment plays a certain role on the restoration of injured cartilage, but the regenerative cartilage is prone to be fibrocartilage due to the modulation of bone marrow cells. Herein, we design a trilaminar osteochondral scaffold with a selective permeable film in middle isolation layer. This specific film made of dense electrospun nanofiber can prevent bone marrow cells from invading into the cartilage layer, but allow the nutrients and cytokines to penetrate. Our conclusion is that the cartilage remodeling will be extremely inhibited when the bone marrow cells are blocking. Owing to the diverse cells in bone marrow, we will further explore the influence of each cell type on cartilage repair in our continuous future work.

Dynamic degradation patterns of porous polycaprolactone/β-tricalcium phosphate composites orchestrate macrophage responses and immunoregulatory bone regeneration

Biodegradable polycaprolactone/β-tricalcium phosphate (PT) composites are desirable candidates for bone tissue engineering applications. A higher β-tricalcium phosphate (TCP) ceramic content improves the mechanical, hydrophilic and osteogenic properties of PT scaffolds in vitro. Using a dynamic degradation reactor, we established a steady in vitro degradation model to investigate the changes in the physio-chemical and biological properties of PT scaffolds during degradation.PT46 and PT37 scaffolds underwent degradation more rapidly than PT scaffolds with lower TCP contents. In vivo studies revealed the rapid degradation of PT (PT46 and PT37) scaffolds disturbed macrophage responses and lead to bone healing failure. Macrophage co-culture assays and a subcutaneous implantation model indicated that the scaffold degradation process dynamically affected macrophage responses, especially polarization. RNA-Seq analysis indicated phagocytosis of the degradation products of PT37 scaffolds induces oxidative stress and inflammatory M1 polarization in macrophages. Overall, this study reveals that the dynamic patterns of biodegradation of degradable bone scaffolds highly orchestrate immune responses and thus determine the success of bone regeneration. Therefore, through evaluation of the biological effects of biomaterials during the entire process of degradation on immune responses and bone regeneration are necessary in order to develop more promising biomaterials for bone regeneration.

Catalpol modulating the crosstalking between mesenchymal stromal cells and macrophages via paracrine to enhance angiogenesis and osteogenesis

Due to the inflammatory responses associated with defect occurrence and materials implantation, immunoregulation has emerged as a promising strategy to enhance bone regeneration. It has been widely reported that a material could facilitate osteogenesis if it can guide macrophages to anti-inflammatory M2 phenotype, vice versa, a substrate will influence macrophage phenotype if it is osteoinductive. However, few studies have looked into the intercellular crosstalking directly. Herein, the compound catalpol was selected for its multiple functions to study the interactions between bone marrow mesenchymal stromal cells (BMSCs) and macrophages. This iridoid glucoside exhibits excellent anti-inflammatory and osteoinductive activities. The effects of catalpol on mediating M1/M2 polarization of macrophages, inhibiting osteoclast differentiation, promoting osteogenesis and angiogenesis were systematically investigated to correlate the biological responses of BMSCs and macrophages. To extend its in vivo application, the catalpol was then loaded onto an electrospun polylactide/gelatin composite fibrous mesh and subcutaneously implanted to evaluate the local inflammation and ectopic osteogenesis. The results revealed that the functions of catalpol displayed in modulating cellular behaviors are via cell paracrine to strengthen intercellular crosstalking, hence demonstrating that catalpol itself could serve as a promising bioactive stimulator for bone tissue engineering.

Biomedical polymers: synthesis, properties, and applications

Biomedical polymers have been extensively developed for promising applications in a lot of biomedical fields, such as therapeutic medicine delivery, disease detection and diagnosis, biosensing, regenerative medicine, and disease treatment. In this review, we summarize the most recent advances in the synthesis and application of biomedical polymers, and discuss the comprehensive understanding of their property-function relationship for corresponding biomedical applications. In particular, a few burgeoning bioactive polymers, such as peptide/biomembrane/microorganism/cell-based biomedical polymers, are also introduced and highlighted as the emerging biomaterials for cancer precision therapy. Furthermore, the foreseeable challenges and outlook of the development of more efficient, healthier and safer biomedical polymers are discussed. We wish this systemic and comprehensive review on highlighting frontier progress of biomedical polymers could inspire and promote new breakthrough in fundamental research and clinical translation.

The phagocytic receptors of β-glucan

Phagocytosis is a cellular process maintaining tissue balance and plays an essential role in initiating the innate immune response. The process of phagocytosis was triggered by the binding of pathogen-associated molecular patterns (PAMP) with their cell surface receptors on the phagocytes. These receptors not only perform phagocytic functions, but also bridge the gap between extracellular and intracellular communication, leading to signal transduction and the production of inflammatory mediators, which are crucial for clearing the invading pathogens and maintaining cell homeostasis. For the past few years, the application of β-glucan comes down to immunoregulation and anti-tumor territory. As a well-known PAMP, β-glucan is one of the most abundant polysaccharides in nature. By binding to specific receptors on immune cells and activating intracellular signal transduction pathways, it causes phagocytosis and promotes the release of cytokines. Further retrieval and straightening out literature related to β-glucan phagocytic receptors will help better elucidate their immunomodulatory functions. This review attempts to summarize physicochemical properties and specific processes involved in β-glucan induced phagocytosis, its phagocytic receptors, and cascade events triggered by β-glucan at the cellular and molecular levels.

Boron Nano-hydroxyapatite Composite Increases the Bone Regeneration of Ovariectomized Rabbit Femurs

Osteoporosis is a systemic metabolic disease defined by a decreased bone mineral density, microarchitectural deterioration, and an increased incidence of fragility fractures that may lead to morbidity and mortality. Boron may stimulate new bone formation and regeneration, when combined with nano-hydroxyapatite. We questioned whether injecting boron-containing nano-hydroxyapatite composites with hyaluronan increased the bone mineral density and new bone formation in osteoporotic rabbit femurs. The regenerative effects of injectable boron-containing nano-hydroxyapatite composites from 6 to 12 weeks, which may prevent osteoporotic femoral fractures, were assessed. Boron-containing (10 μg/ml) nano-hydroxyapatite composites were injected into the intramedullary femoral cavity with hyaluronan. These significantly increased the histomorphometric new bone surface to the total bone surface ratio at 6 and 9 weeks. The micro-tomographic bone volume to the total volume ratio and bone mineral density in osteoporotic rabbit femurs increased when compared to the hyaluronan (p = 0.004, p = 0.004, p = 0.004, p = 0.01, respectively) and the sham-control (p = 0.01, p = 0.004, p = 0.01, p = 0.037, respectively) groups. The boron-containing group had a higher bone mineralization and new bone formation compared to the nano-hydroxyapatite group, although the difference was not statistically significant. These findings reveal that intramedullary injection of boron-containing nano-hydroxyapatite with hyaluronan increases new bone formation and mineralization in ovariectomized rabbit femurs. Boron-containing nano-hydroxyapatite composites are promising tissue engineering biomaterials that may have regenerative potential in preventing primary and/or secondary femoral fractures in osteoporosis patients.

Nanotechnology: A Potential Weapon to Fight against COVID-19

The COVID-19 infections have posed an unprecedented global health emergency, with nearly three million deaths to date, and have caused substantial economic loss globally. Hence, an urgent exploration of effective and safe diagnostic/therapeutic approaches for minimizing the threat of this highly pathogenic coronavirus infection is needed. As an alternative to conventional diagnosis and antiviral agents, nanomaterials have a great potential to cope with the current or even future health emergency situation with a wide range of applications. Fundamentally, nanomaterials are physically and chemically tunable and can be employed for the next generation nanomaterial-based detection of viral antigens and host antibodies in body fluids as antiviral agents, nanovaccine, suppressant of cytokine storm, nanocarrier for efficient delivery of antiviral drugs at infection site or inside the host cells, and can also be a significant tool for better understanding of the gut microbiome and SARS-CoV-2 interaction. The applicability of nanomaterial-based therapeutic options to cope with the current and possible future pandemic is discussed here.

A cell-free ROS-responsive hydrogel/oriented poly(lactide-co-glycolide) hybrid scaffold for reducing inflammation and restoring full-thickness cartilage defectsin vivo

The modulation of inflammation in tissue microenvironment takes an important role in cartilage repair and regeneration. In this study, a novel hybrid scaffold was designed and fabricated by filling a reactive oxygen species (ROS)-scavenging hydrogel (RS Gel) into a radially oriented poly(lactide-co-glycolide) (PLGA) scaffold. The radially oriented PLGA scaffolds were fabricated through a temperature gradient-guided phase separation and freeze-drying method. The RS Gel was formed by crosslinking the mixture of ROS-responsive hyperbranched polymers and biocompatible methacrylated hyaluronic acid (HA-MA). The hybrid scaffolds exhibited a proper compressive modulus, good ROS-scavenging capability, and cell compatibility.In vivotests showed that the hybrid scaffolds significantly regulated inflammation and promoted regeneration of hyaline cartilage after they were implanted into full-thickness cartilage defects in rabbits for 12 w. In comparison with the PLGA scaffolds, the neo-cartilage in the hybrid scaffolds group possessed more deposition of glycosaminoglycans and collagen type II, and were well integrated with the surrounding tissue.

Nanoparticles to Target and Treat Macrophages: The Ockham's Concept?

Nanoparticles are nanomaterials with three external nanoscale dimensions and an average size ranging from 1 to 1000 nm. Nanoparticles have gained notoriety in technological advances due to their tunable physical, chemical, and biological characteristics. However, the administration of functionalized nanoparticles to living beings is still challenging due to the rapid detection and blood and tissue clearance by the mononuclear phagocytic system. The major exponent of this system is the macrophage. Regardless the nanomaterial composition, macrophages can detect and incorporate foreign bodies by phagocytosis. Therefore, the simplest explanation is that any injected nanoparticle will be probably taken up by macrophages. This explains, in part, the natural accumulation of most nanoparticles in the spleen, lymph nodes, and liver (the main organs of the mononuclear phagocytic system). For this reason, recent investigations are devoted to design nanoparticles for specific macrophage targeting in diseased tissues. The aim of this review is to describe current strategies for the design of nanoparticles to target macrophages and to modulate their immunological function involved in different diseases with special emphasis on chronic inflammation, tissue regeneration, and cancer.

The Dynamic Inflammatory Tissue Microenvironment: Signality and Disease Therapy by Biomaterials

Tissue regeneration is an active multiplex process involving the dynamic inflammatory microenvironment. Under a normal physiological framework, inflammation is necessary for the systematic immunity including tissue repair and regeneration as well as returning to homeostasis. Inflammatory cellular response and metabolic mechanisms play key roles in the well-orchestrated tissue regeneration. If this response is dysregulated, it becomes chronic, which in turn causes progressive fibrosis, improper repair, and autoimmune disorders, ultimately leading to organ failure and death. Therefore, understanding of the complex inflammatory multiple player responses and their cellular metabolisms facilitates the latest insights and brings novel therapeutic methods for early diseases and modern health challenges. This review discusses the recent advances in molecular interactions of immune cells, controlled shift of pro- to anti-inflammation, reparative inflammatory metabolisms in tissue regeneration, controlling of an unfavorable microenvironment, dysregulated inflammatory diseases, and emerging therapeutic strategies including the use of biomaterials, which expand therapeutic views and briefly denote important gaps that are still prevailing.

Antiviral Activity of Nanomaterials against Coronaviruses

One of the challenges facing by world nowadays is the generation of new pathogens that cause public health issues. Coronavirus (CoV) is one of the severe pathogens that possess the RNA (ribonucleic acid) envelop, and extensively infect humans, birds, and other mammals. The novel strain "SARS-CoV-2" (severe acute respiratory syndrome coronavirus-2) causes deadly infection all over the world and presents a pandemic situation nowadays. The SARS-CoV-2 has 40 different strains that create a worrying situation for health authorities. The virus develops serious pneumonia in infected persons and causes severe damage to the lungs. There is no vaccine available for this virus up to present. To cure this type of infections by making vaccines and antiviral drugs is still a major challenge for researchers. Nanotechnology covering a multidisciplinary field may find the solution to this lethal infection. The interaction of nanomaterials and microorganisms is considered as a potential treatment method because the nanomaterials owe unique physicochemical properties. The aim of this review is to present an overview of previous and recent studies of nanomaterials against coronaviruses and to provide possible new strategies for upcoming research using the nanotechnology platform.

Unique cellular interaction of macrophage-targeted liposomes potentiates anti-inflammatory activity

The small-sized (<100 nm) PSLs served as a long-lasting immunosuppressive agent through preferential association with CD300a receptor, unlike larger PSLs.