Sustained Release of Immunosuppressant by Nanoparticle-anchoring Hydrogel Scaffold Improved the Survival of Transplanted Stem Cells and Tissue Regeneration

Current Status of Research on Nanomaterials Combined with Mesenchymal Stem Cells for the Treatment of Ischemic Stroke

Ischemic stroke (IS) is a disease with high mortality and disability rates worldwide and is a serious threat to patient health. Owing to the narrow therapeutic window, effective treatments during the recovery period are limited. However, in recent years, mesenchymal stem cells (MSCs) have attracted attention and have shown therapeutic potential in IS treatment because of their abilities to home and secrete multiple bioactive substances and potential for differentiation and substitution. The therapeutic mechanisms of MSCs in IS include the regulatory effects of MSCs on microglia, the dual role of MSCs in astrocytes, how MSCs connect innate and adaptive immunity, the secretion of cytokines by MSCs to counteract apoptosis and MSC apoptosis, the promotion of angiogenesis by MSCs to favor the restoration of the blood‒brain barrier (BBB), and the potential function of local neural replacement by MSCs. However, the low graft survival rate, insufficient homing, poor targeting, and inability to achieve directional differentiation of MSCs limit their wide application. As an approach to compensate for the shortcomings of MSCs, scientists have used nanomaterials to assist MSCs in homing, survival and proliferation. In addition, the unique material of nanomaterials adds tracking, imaging and real-time monitoring to stroke treatment. The identification of effective treatments for stroke is urgently needed; thus, an understanding of how MSCs treat stroke and further improvements in the use of nanomaterials are necessary.

Thermosensitive Hydrogels as Targeted and Controlled Drug Delivery Systems: Potential Applications in Transplantation

Drug delivery in transplantation plays a vital role in promoting graft survival, preventing rejection, managing complications, and contributing to positive patient outcomes. Targeted and controlled drug delivery can minimize systemic effects. Thermosensitive hydrogels, due to their unique sol-gel transition properties triggered by thermo-stimuli, have attracted significant research interest as a potential drug delivery system in transplantation. This review describes the current status, characteristics, and recent applications of thermosensitive hydrogels for drug delivery. Studies aimed at improving allotransplantation outcomes using thermosensitive hydrogels are then elaborated on. Finally, the challenges and opportunities associated with their use are discussed. Understanding the progress of research will serve as a guide for future improvements in their application as a means of targeted and controlled drug delivery in translational therapeutic applications for transplantation.

Recent Review on Biological Barriers and Host-Material Interfaces in Precision Drug Delivery: Advancement in Biomaterial Engineering for Better Treatment Therapies

Preclinical and clinical studies have demonstrated that precision therapy has a broad variety of treatment applications, making it an interesting research topic with exciting potential in numerous sectors. However, major obstacles, such as inefficient and unsafe delivery systems and severe side effects, have impeded the widespread use of precision medicine. The purpose of drug delivery systems (DDSs) is to regulate the time and place of drug release and action. They aid in enhancing the equilibrium between medicinal efficacy on target and hazardous side effects off target. One promising approach is biomaterial-assisted biotherapy, which takes advantage of biomaterials' special capabilities, such as high biocompatibility and bioactive characteristics. When administered via different routes, drug molecules deal with biological barriers; DDSs help them overcome these hurdles. With their adaptable features and ample packing capacity, biomaterial-based delivery systems allow for the targeted, localised, and prolonged release of medications. Additionally, they are being investigated more and more for the purpose of controlling the interface between the host tissue and implanted biomedical materials. This review discusses innovative nanoparticle designs for precision and non-personalised applications to improve precision therapies. We prioritised nanoparticle design trends that address heterogeneous delivery barriers, because we believe intelligent nanoparticle design can improve patient outcomes by enabling precision designs and improving general delivery efficacy. We additionally reviewed the most recent literature on biomaterials used in biotherapy and vaccine development, covering drug delivery, stem cell therapy, gene therapy, and other similar fields; we have also addressed the difficulties and future potential of biomaterial-assisted biotherapies.

Navigating the Immunological Crossroads: Mesenchymal Stem/Stromal Cells as Architects of Inflammatory Harmony in Tissue-Engineered Constructs

In the dynamic landscape of tissue engineering, the integration of tissue-engineered constructs (TECs) faces a dual challenge-initiating beneficial inflammation for regeneration while avoiding the perils of prolonged immune activation. As TECs encounter the immediate reaction of the immune system upon implantation, the unique immunomodulatory properties of mesenchymal stem/stromal cells (MSCs) emerge as key navigators. Harnessing the paracrine effects of MSCs, researchers aim to craft a localized microenvironment that not only enhances TEC integration but also holds therapeutic promise for inflammatory-driven pathologies. This review unravels the latest advancements, applications, obstacles, and future prospects surrounding the strategic alliance between MSCs and TECs, shedding light on the immunological symphony that guides the course of regenerative medicine.

Emerging advances in hydrogel-based therapeutic strategies for tissue regeneration

Significant developments in cell therapy and biomaterial science have broadened the therapeutic landscape of tissue regeneration. Tissue damage is a complex biological process in which different types of cells play a specific role in repairing damaged tissues and growth factors strictly regulate the activity of these cells. Hydrogels have become promising biomaterials for tissue regeneration if appropriate materials are selected and the hydrogel properties are well-regulated. Importantly, they can be used as carriers for living cells and growth factors due to the high water-holding capacity, high permeability, and good biocompatibility of hydrogels. Cell-loaded hydrogels can play an essential role in treating damaged tissues and open new avenues for cell therapy. There is ample evidence substantiating the ability of hydrogels to facilitate the delivery of cells (stem cell, macrophage, chondrocyte, and osteoblast) and growth factors (bone morphogenetic protein, transforming growth factor, vascular endothelial growth factor and fibroblast growth factor). This paper reviewed the latest advances in hydrogels loaded with cells or growth factors to promote the reconstruction of tissues. Furthermore, we discussed the shortcomings of the application of hydrogels in tissue engineering to promote their further development.

The Importance of Animal Models in Biomedical Research: Current Insights and Applications

Animal research is considered a key element in advance of biomedical science. Although its use is controversial and raises ethical challenges, the contribution of animal models in medicine is essential for understanding the physiopathology and novel treatment alternatives for several animal and human diseases. Current pandemics’ pathology, such as the 2019 Coronavirus disease, has been studied in primate, rodent, and porcine models to recognize infection routes and develop therapeutic protocols. Worldwide issues such as diabetes, obesity, neurological disorders, pain, rehabilitation medicine, and surgical techniques require studying the process in different animal species before testing them on humans. Due to their relevance, this article aims to discuss the importance of animal models in diverse lines of biomedical research by analyzing the contributions of the various species utilized in science over the past five years about key topics concerning human and animal health.

Recent advancements in design of nucleic acid nanocarriers for controlled drug delivery

Research of nanoscale nucleic acid carriers has garnered attention in recent years due to their distinctive and controllable properties. However, current knowledge is limited in how we can efficiently utilize these systems for clinical applications. Several researchers have pioneered new and innovative nanocarrier drug delivery systems, but understanding physiochemical properties and behavior in vivo is vital to implementing them as clinical drug delivery platforms. In this review, we outline the most significant innovations in the synthesis, physical properties, and utilization of nucleic acid nanocarriers in the past 5 years, addressing the crucial properties which improve nanocarrier characteristics, delivery, and drug release. The challenges of controlling the transport of nucleic acid nanocarriers and therapeutic release for biological applications are outlined. Barriers which inhibit effective transport into tissue are discussed with emphasis on the modifications needed to overcome such obstacles. The novel strategies discussed in this work summarize the pivotal features of modern nucleic nanocarriers and postulate where future developments could revolutionize the translation of these tools into a clinical setting.

Nanoceria-GO-intercalated multicellular spheroids revascularize and salvage critical ischemic limbs through anti-apoptotic and pro-angiogenic functions

Critical limb ischemia (CLI) is a serious form of peripheral arterial disease that involves severe blockage of blood flow in lower extremities, often leading to foot necrosis and limb loss. Lack of blood flow and high pro-inflammation with overproduced reactive oxygen species (ROS) in CLI aggravate the degenerative events. Among other therapies, cell delivery is considered potential for restoring regenerative capacity, and preservation of cell survival under high oxidative stress has been challenging and prerequisite to harness cellular functions. Here, we introduce a multicellular delivery system that is intercalated with nanoceria-decorated graphene oxide (CeGO), which is considered to have high ROS scavenging ability while providing cell-matrix interaction signals. The CeGO nano-microsheets (8-nm-nanoceria/0.9-μm-GO) incorporated in HUVEC/MSC (7/3) could form cell-material hybrid spheroids mediated by cellular contraction. Under in vitro oxidative-stress-challenge with H₂O₂, the CeGO-intercalation enhanced the survival and anti-apoptotic capacity of cellular spheroids. Pro-angiogenic events of cellular spheroids, including cell sprouting and expression of angiogenic markers (HIF1α, VEGF, FGF2, eNOS) were significantly enhanced by the CeGO-intercalation. Proteomics analysis also confirmed substantial up-regulation of a series of angiogenesis-related secretome molecules. Such pro-angiogenic events with CeGO-intercalation were proven to be mediated by the APE/Ref-1 signaling pathway. When delivered to ischemic hindlimb in mice, the CeGO-cell spheroids could inhibit the accumulation of in vivo ROS rapidly, preserving high cell survival rate (cells were more proliferative and less apoptotic vs. those in cell-only spheroids), and up-regulated angiogenic molecular expressions. Monitoring over 28 days revealed significantly enhanced blood reperfusion and tissue recovery, and an ultimate limb salvage with the CeGO-cell delivery (∼60% salvaged vs. ∼29% in cell-only delivery vs. 0% in ischemia control). Together, the CeGO intercalated in HUVEC/MSC delivery is considered a potential nano-microplatform for CLI treatment, by scavenging excessive ROS and enhancing transplanted cell survival, while stimulating angiogenic events, which collectively help revascularization and tissue recovery, salvaging critical ischemic limbs.

Locally controlled release of immunosuppressive promotes survival of transplanted adult spinal cord tissue

Transplantation of adult spinal cord tissue (aSCT) is a promising treatment for spinal cord injury (SCI) basing on various types of neural cells and matrix components inside aSCT. However, long-term systemic administration of immunosuppressors (e.g. tacrolimus, TAC) is required for the survival of allogeneic tissue, which often associated with severe side effects such as infection, liver damageand renal failure. In this study, a triglycerol monostearate (TGM)-based TAC delivery system (e.g. TAC@TGM) with high drug loading concentration was developed, which possessed injectable properties as well as sustainable and immune-responsive drug release behaviors. In complete transected SCI model, locally injected TAC@TGM could reduce the infiltration of inflammation cells, enhance the survival of transplanted aSCT (e.g. Tuj-1⁺ and NF⁺ neurons) and promote the recovery of locomotor function. Moreover, controlled release of TAC by TAC@TGM attenuated side effects of TAC on liver and kidneys compared with traditional systemic administration. More importantly, the developed TAC@TGM system provided a facile single dose of long-term immunosuppressive effect not just for aSCT transplantation, but also for other tissue/organ and cell transplantations.

Modification Strategies for Ionic Complementary Self-Assembling Peptides: Taking RADA16-I as an Example

Ion-complementary self-assembling peptides have been studied in many fields for their distinct advantages, mainly due to their self-assembly properties. However, their shortcomings, such as insufficient specific activity and poor mechanical properties, also limited their application. For the better and wider application of these promising biomaterials, ion-complementary self-assembling peptides can be modified with their self-assembly properties not being destroyed to the greatest extent. The modification strategies were reviewed by taking RADA16-I as an example. For insufficient specific activity, RADA16-I can be structurally modified with active motifs derived from the active domain of the extracellular matrix or other related active factors. For weak mechanical properties, materials with strong mechanical properties or that can undergo chemical crosslinking were used to mix with RADA16-I to enhance the mechanical properties of RADA16-I. To improve the performance of RADA16-I as drug carriers, appropriate adjustment of the RADA16-I sequence and/or modification of the RADA16-I-related delivery system with polymer materials or specific molecules can be considered to achieve sustained and controlled release of specific drugs or active factors. The modification strategies reviewed in this paper may provide some references for further basic research and clinical application of ion-complementary self-assembling peptides and their derivatives.

Advances for the treatment of lower extremity arterial disease associated with diabetes mellitus

Lower extremity arterial disease (LEAD) is a major vascular complication of diabetes. Vascular endothelial cells dysfunction can exacerbate local ischemia, leading to a significant increase in amputation, disability, and even mortality in patients with diabetes combined with LEAD. Therefore, it is of great clinical importance to explore proper and effective treatments. Conventional treatments of diabetic LEAD include lifestyle management, medication, open surgery, endovascular treatment, and amputation. As interdisciplinary research emerges, regenerative medicine strategies have provided new insights to treat chronic limb threatening ischemia (CLTI). Therapeutic angiogenesis strategies, such as delivering growth factors, stem cells, drugs to ischemic tissues, have also been proposed to treat LEAD by fundamentally stimulating multidimensional vascular regeneration. Recent years have seen the rapid growth of tissue engineering technology; tissue-engineered biomaterials have been used to study the treatment of LEAD, such as encapsulation of growth factors and drugs in hydrogel to facilitate the restoration of blood perfusion in ischemic tissues of animals. The primary purpose of this review is to introduce treatments and novel biomaterials development in LEAD. Firstly, the pathogenesis of LEAD is briefly described. Secondly, conventional therapies and therapeutic angiogenesis strategies of LEAD are discussed. Finally, recent research advances and future perspectives on biomaterials in LEAD are proposed.

[Advances in stem cell inner ear transplantation]

Sensorineural hearing loss has long been one of the common diseases in the field of otology. With the increasing research on stem cell therapy, the experiments and applications of stem cell inner ear transplantation are developing rapidly, with some remarkable results and some questions to be considered. The source of stem cells and the transplantation route are crucial, and the immune rejection in the post-transplantation period should not be ignored. This paper will review the issues related to stem cell source, transplantation route and immune rejection in inner ear transplantation, hoping to provide new ideas for research in the field of stem cell inner ear transplantation.

Implantable Immunosuppressant Delivery to Prevent Rejection in Transplantation

An innovative immunosuppressant with a minimally invasive delivery system has emerged in the biomedical field. The application of biodegradable and biocompatible polymer forms, such as hydrogels, scaffolds, microspheres, and nanoparticles, in transplant recipients to control the release of immunosuppressants can minimize the risk of developing unfavorable conditions. In this review, we summarized several studies that have used implantable immunosuppressant delivery to release therapeutic agents to prolong allograft survival. We also compared their applications, efficacy, efficiency, and safety/side effects with conventional therapeutic-agent administration. Finally, challenges and the future prospective were discussed. Collectively, this review will help relevant readers understand the different approaches to prevent transplant rejection in a new era of therapeutic agent delivery.

Mechanobiological Strategies to Enhance Stem Cell Functionality for Regenerative Medicine and Tissue Engineering

Stem cells have been extensively used in regenerative medicine and tissue engineering; however, they often lose their functionality because of the inflammatory microenvironment. This leads to their poor survival, retention, and engraftment at transplantation sites. Considering the rapid loss of transplanted cells due to poor cell-cell and cell-extracellular matrix (ECM) interactions during transplantation, it has been reasoned that stem cells mainly mediate reparative responses via paracrine mechanisms, including the secretion of extracellular vesicles (EVs). Ameliorating poor cell-cell and cell-ECM interactions may obviate the limitations associated with the poor retention and engraftment of transplanted cells and enable them to mediate tissue repair through the sustained and localized presentation of secreted bioactive cues. Biomaterial-mediated strategies may be leveraged to confer stem cells enhanced immunomodulatory properties, as well as better engraftment and retention at the target site. In these approaches, biomaterials have been exploited to spatiotemporally present bioactive cues to stem cell-laden platforms (e.g., aggregates, microtissues, and tissue-engineered constructs). An array of biomaterials, such as nanoparticles, hydrogels, and scaffolds, has been exploited to facilitate stem cells function at the target site. Additionally, biomaterials can be harnessed to suppress the inflammatory microenvironment to induce enhanced tissue repair. In this review, we summarize biomaterial-based platforms that impact stem cell function for better tissue repair that may have broader implications for the treatment of various diseases as well as tissue regeneration.

Local delivery strategies to restore immune homeostasis in the context of inflammation

Immune homeostasis is maintained by a precise balance between effector immune cells and regulatory immune cells. Chronic deviations from immune homeostasis, driven by a greater ratio of effector to regulatory cues, can promote the development and propagation of inflammatory diseases/conditions (i.e., autoimmune diseases, transplant rejection, etc.). Current methods to treat chronic inflammation rely upon systemic administration of non-specific small molecules, resulting in broad immunosuppression with unwanted side effects. Consequently, recent studies have developed more localized and specific immunomodulatory approaches to treat inflammation through the use of local biomaterial-based delivery systems. In particular, this review focuses on (1) local biomaterial-based delivery systems, (2) common materials used for polymeric-delivery systems and (3) emerging immunomodulatory trends used to treat inflammation with increased specificity.

Combined local delivery of tacrolimus and stem cells in hydrogel for enhancing peripheral nerve regeneration

The application of scaffold-based stem cell transplantation to enhance peripheral nerve regeneration has great potential. Recently, the neuroregenerative potential of tacrolimus (a U.S. Food and Drug Administration-approved immunosuppressant) has been explored. In this study, a fibrin gel-based drug delivery system for sustained and localized tacrolimus release was combined with rat adipose-derived mesenchymal stem cells (MSC) to investigate cell viability in vitro. Tacrolimus was encapsulated in poly(lactic-co-glycolic) acid (PLGA) microspheres and suspended in fibrin hydrogel, using concentrations of 0.01 and 100 ng/ml. Drug release over time was measured. MSCs were cultured in drug-released media collected at various days to mimic systemic exposure. MSCs were combined with (i) hydrogel only, (ii) empty PLGA microspheres in the hydrogel, (iii) 0.01, and (iv) 100 ng/ml of tacrolimus PLGA microspheres in the hydrogel. Stem cell presence and viability were evaluated. A sustained release of 100 ng/ml tacrolimus microspheres was observed for up to 35 days. Stem cell presence was confirmed and cell viability was observed up to 7 days, with no significant differences between groups. This study suggests that combined delivery of 100 ng/ml tacrolimus and MSCs in fibrin hydrogel does not result in cytotoxic effects and could be used to enhance peripheral nerve regeneration.

Engineering precision nanoparticles for drug delivery

In recent years, the development of nanoparticles has expanded into a broad range of clinical applications. Nanoparticles have been developed to overcome the limitations of free therapeutics and navigate biological barriers - systemic, microenvironmental and cellular - that are heterogeneous across patient populations and diseases. Overcoming this patient heterogeneity has also been accomplished through precision therapeutics, in which personalized interventions have enhanced therapeutic efficacy. However, nanoparticle development continues to focus on optimizing delivery platforms with a one-size-fits-all solution. As lipid-based, polymeric and inorganic nanoparticles are engineered in increasingly specified ways, they can begin to be optimized for drug delivery in a more personalized manner, entering the era of precision medicine. In this Review, we discuss advanced nanoparticle designs utilized in both non-personalized and precision applications that could be applied to improve precision therapies. We focus on advances in nanoparticle design that overcome heterogeneous barriers to delivery, arguing that intelligent nanoparticle design can improve efficacy in general delivery applications while enabling tailored designs for precision applications, thereby ultimately improving patient outcome overall.

Self-assembling Peptides in Current Nanomedicine: Versatile Nanomaterials for Drug Delivery

BACKGROUND

The development of modern nanomedicine greatly depends on the involvement of novel materials as drug delivery system. In order to maximize the therapeutic effects of drugs and minimize their side effects, a number of natural or synthetic materials have been widely investigated for drug delivery. Among these materials, biomimetic self-assembling peptides (SAPs) have received more attention in recent years. Considering the rapidly growing number of SAPs designed for drug delivery, a summary of how SAPs-based drug delivery systems were designed, would be beneficial.

METHOD

We outlined research works on different SAPs that have been investigated as carriers for different drugs, focusing on the design of SAPs nanomaterials and how they were used for drug delivery in different strategies.

RESULTS

Based on the principle rules of chemical complementarity and structural compatibility, SAPs such as ionic self-complementary peptide, peptide amphiphile and surfactant-like peptide could be designed. Determined by the features of peptide materials and the drugs to be delivered, different strategies such as hydrogel embedding, hydrophobic interaction, electrostatic interaction, covalent conjugation or the combination of them could be employed to fabricate SAPs-drug complex, which could achieve slow release, targeted or environment-responsive delivery of drugs. Furthermore, some SAPs could also be combined with other types of materials for drug delivery, or even act as drug by themselves.

CONCLUSION

Various types of SAPs have been designed and used for drug delivery following various strategies, suggesting that SAPs as a category of versatile nanomaterials have promising potential in the field of nanomedicine.

The State of Art of Regenerative Therapy in Cardiovascular Ischemic Disease: Biology, Signaling Pathways, and Epigenetics of Endothelial Progenitor Cells

Ischemic heart disease is currently a major cause of mortality and morbidity worldwide. Nevertheless, the actual therapeutic scenario does not target myocardial cell regeneration and consequently, the progression toward the late stage of chronic heart failure is common. Endothelial progenitor cells (EPCs) are bone marrow-derived stem cells that contribute to the homeostasis of the endothelial wall in acute and chronic ischemic disease. Calcium modulation and other molecular pathways (NOTCH, VEGFR, and CXCR4) contribute to EPC proliferation and differentiation. The present review provides a summary of EPC biology with a particular focus on the regulatory pathways of EPCs and describes promising applications for cardiovascular cell therapy.

Skin-derived precursor Schwann cells protect SH-SY5Y cells against 6-OHDA-induced neurotoxicity by PI3K/AKT/Bcl-2 pathway

Skin-derived precursors (SKPs) are self-renewing and pluripotent adult stem cell sources that have been successfully obtained and cultured from adult tissues of rodents and humans. Skin-derived precursor Schwann cells (SKP-SCs), derived from SKPs when cultured in a neuro stromal medium supplemented with some appropriate neurotrophic factors, have been reported to play a neuroprotective effect in the peripheral nervous system. This proves our previous studies that SKP-SCs' function to bridge sciatic nerve gap in rats. However, the function of SKP-SCs in Parkinson disease (PD) remains unknown. This study was aimed to investigate the possible neuroprotective effects of SKP-SCs in 6-OHDA-induced Parkinson's disease (PD) model. Our results showed that the treatment with SKP-SCs prevented SH-SY5Y cells from 6-OHDA-induced apoptosis, accompanied by modulation of apoptosis-related proteins (Bcl-2 and Bax) and the decreased expression of active caspase-3. Furthermore, we confirmed that SKP-SCs might exert protective effects and increase the mitochondrial membrane potential (MMP) through PI3K/AKT/Bcl-2 pathway. Taken together, our results demonstrated that SKP-SCs protect against 6-OHDA-induced cytotoxicity through PI3K/AKT/Bcl-2 pathway in PD model in vitro, which provides a new theoretical basis for the treatment of PD.

Biomaterial and stem cell-based strategies for skeletal muscle regeneration

Adult skeletal muscle can regenerate effectively after mild physical or chemical insult. Muscle trauma or disease can overwhelm this innate capacity for regeneration and result in heightened inflammation and fibrotic tissue deposition resulting in loss of structure and function. Recent studies have focused on biomaterial and stem cell-based therapies to promote skeletal muscle regeneration following injury and disease. Many stem cell populations besides satellite cells are implicated in muscle regeneration. These stem cells include but are not limited to mesenchymal stem cells, adipose-derived stem cells, hematopoietic stem cells, pericytes, fibroadipogenic progenitors, side population cells, and CD133⁺ stem cells. However, several challenges associated with their isolation, availability, delivery, survival, engraftment, and differentiation have been reported in recent studies. While acellular scaffolds offer a relatively safe and potentially off-the-shelf solution to cell-based therapies, they are often unable to stimulate host cell migration and activity to a level that would result in clinically meaningful regeneration of traumatized muscle. Combining stem cells and biomaterials may offer a viable therapeutic strategy that may overcome the limitations associated with these therapies when they are used in isolation. In this article, we review the stem cell populations that can stimulate muscle regeneration in vitro and in vivo. We also discuss the regenerative potential of combination therapies that utilize both stem cell and biomaterials for the treatment of skeletal muscle injury and disease. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1246-1262, 2019.

Prussian blue nanosphere-embedded in situ hydrogel for photothermal therapy by peritumoral administration

To establish an injectable hydrogel containing Prussian blue (PB) nanospheres for photothermal therapy against cancer, PB nanospheres were prepared by one-pot synthesis and the thermosensitive Pluronic F127 was used as the hydrogel matrix. The PB nanospheres and the hydrogel were characterized by shape, particle size, serum stability, photothermal performance upon repeated 808 nm laser irradiation, as well as the rheological features. The effect of the PB nanospheres and the hydrogel were evaluated qualitatively and quantitatively in 4T1 mouse breast cancer cells. The retention, photothermal efficacy, therapeutic effects and systemic toxicity of the hydrogel were assessed in a tumor-bearing mouse model. The PB nanospheres had a diameter of about 150 nm and exhibited satisfactory serum stability, photo-heat convert ability and repeated laser exposure stability. The hydrogel encapsulation did not negatively influence the above features of the photothermal agent. The nanosphere-containing hydrogel showed a phase transition at body temperature and, as a result, a long retention time in vivo. The photothermal agent-embedded hydrogel displayed promising photothermal therapeutic effects in the tumor-bearing mouse model with little-to-no systemic toxicity after peritumoral administration.

Route to Rheumatoid Arthritis by Macrophage-Derived Microvesicle-Coated Nanoparticles

The targeted delivery of therapeutics to sites of rheumatoid arthritis (RA) has been a long-standing challenge. Inspired by the intrinsic inflammation-targeting capacity of macrophages, a macrophage-derived microvesicle (MMV)-coated nanoparticle (MNP) was developed for targeting RA. The MMV was efficiently produced through a novel method. Cytochalasin B (CB) was applied to relax the interaction between the cytoskeleton and membrane of macrophages, thus stimulating MMV secretion. The proteomic profile of the MMV was analyzed by iTRAQ (isobaric tags for relative and absolute quantitation). The MMV membrane proteins were similar to those of macrophages, indicating that the MMV could exhibit bioactivity similar to that of RA-targeting macrophages. A poly(lactic- co-glycolic acid) (PLGA) nanoparticle was subsequently coated with MMV, and the inflammation-mediated targeting capacity of the MNP was evaluated both in vitro and in vivo. The in vitro binding of MNP to inflamed HUVECs was significantly stronger than that of the red blood cell membrane-coated nanoparticle (RNP). Compared with bare NP and RNP, MNP showed a significantly enhanced targeting effect in vivo in a collagen-induced arthritis (CIA) mouse model. The targeting mechanism was subsequently revealed according to the proteomic analysis, indicating that Mac-1 and CD44 contributed to the outstanding targeting effect of the MNP. A model drug, tacrolimus, was encapsulated in MNP (T-RNP) and significantly suppressed the progression of RA in mice. The present study demonstrates MMV as a promising and rich material, with which to mimic macrophages, and demonstrates that MNP is an efficient biomimetic vehicle for RA targeting and treatment.

Precision-guided long-acting analgesia by Gel-immobilized bupivacaine-loaded microsphere

Peripheral nerve blockade (PNB) is a conventional strategy for the management of acute postoperative pain. However, the short duration of the associated analgesia and the potential systemic toxicity due to the low molecular weights of local anesthetics limit their application. Methods: An in situ forming injectable Gel-microsphere (Gel-MS) system consisting of PLGA-PEG-PLGA Gel (Gel) and Gel-immobilized bupivacaine-loaded microsphere (MS/BUP) was prepared for precision-guided long-acting analgesia. A series of in vitro characterizations, such as scanning electron microscopy, rheology analysis, confocal laser scanning microscopy, drug release, and erosion and degradation, were carried out. After that, the in vivo analgesia effect of the Gel-MS system, the immobilization effect of Gel on the MS, and biocompatibility of the system were evaluated using a sciatic nerve block model. Results: The BUP release from the Gel-MS system was regulated by both the inner MS and the outer Gel matrix, demonstrating sustained BUP release in vitro for several days without an initial burst release. More importantly, incorporation of the Gel immobilized the MS and hindered the diffusion of MS from the injection site because of its in situ property, which contributed to a high local drug concentration and prevented systemic side effects. In vivo, a single injection of Gel-MS/BUP allowed rats to maintain sensory and motor blockade significantly longer than treatment with MS/BUP (P < 0.01) or BUP-loaded Gel (Gel-BUP, P < 0.01). Histopathological results demonstrated the excellent biodegradability and biocompatibility of the Gel-MS system without neurotoxicity. Conclusion: This precision-guided long-acting analgesia, which provides an in situ and sustained release of BUP, is a promising strategy for long-acting analgesia, and could represent a potential alternative for clinical pain management.