Soluble microneedle patch with photothermal and NO-release properties for painless and precise treatment of ischemic perforator flaps

Hybrid Hydrogels for Immunoregulation and Proangiogenesis through Mild Heat Stimulation to Accelerate Whole-Process Diabetic Wound Healing

Intense and persistent oxidative stress, excessive inflammation, and impaired angiogenesis severely hinder diabetic wound healing. Bioactive hydrogel dressings with immunoregulatory and proangiogenic properties have great promise in treating diabetic wounds. However, the therapeutic effects of dressings always depend on drugs with side effects, expensive cytokines, and cell therapies. Herein, a novel dynamic borate-bonds crosslinked hybrid multifunctional hydrogel dressings with photothermal properties are developed to regulate the microenvironment of diabetic wound sites and accelerate the whole process of its healing without additional medication. The hydrogel is composed of phenylboronic acid-modified chitosan and hyaluronic acid (HA) crosslinked by tannic acid (TA) through borate bonds and Prussian blue nanoparticles (PBNPs) with photothermal response characteristics are embedded in the polymer networks. The results indicate hydrogels show inherent broad-spectrum antioxidative activities through the integrated interaction of borate bonds, TA, and PBNPs. Meanwhile, combined with the regulation of macrophage phenotype by HA, the inflammatory microenvironment of diabetic wounds is transformed. Moreover, the angiogenesis is then enhanced by the mild photothermal effect of PBNPs, followed by promoted epithelialization and collagen deposition. In summary, this hybrid hydrogel system accelerates all stages of wound repair through antioxidative stress, immunomodulation, and proangiogenesis, showing great potential applications in diabetic wound management.

Microenvironment Remodeling Self-Healing Hydrogel for Promoting Flap Survival

Random flap grafting is a routine procedure used in plastic and reconstructive surgery to repair and reconstruct large tissue defects. Flap necrosis is primarily caused by ischemia-reperfusion injury and inadequate blood supply to the distal flap. Ischemia-reperfusion injury leads to the production of excessive reactive oxygen species, creating a pathological microenvironment that impairs cellular function and angiogenesis. In this study, we developed a microenvironment remodeling self-healing hydrogel [laminarin-chitosan-based hydrogel-loaded extracellular vesicles and ceria nanozymes (LCH@EVs&CNZs)] to improve the flap microenvironment and synergistically promote flap regeneration and survival. The natural self-healing hydrogel (LCH) was created by the oxidation laminarin and carboxymethylated chitosan via a Schiff base reaction. We loaded this hydrogel with CNZs and EVs. CNZs are a class of nanomaterials with enzymatic activity known for their strong scavenging capacity for reactive oxygen species, thus alleviating oxidative stress. EVs are cell-secreted vesicular structures containing thousands of bioactive substances that can promote cell proliferation, migration, differentiation, and angiogenesis. The constructed LCH@EVs&CNZs demonstrated a robust capacity for scavenging excess reactive oxygen species, thereby conferring cellular protection in oxidative stress environments. Moreover, these constructs notably enhance cell migration and angiogenesis. Our results demonstrate that LCH@EVs&CNZs effectively remodel the pathological skin flap microenvironment and marked improve flap survival. This approach introduces a new therapeutic strategy combining microenvironmental remodeling with EV therapy, which holds promise for promoting flap survival.

BiTiS3 bio-transducer with explosive on-demand generation of NO gas for synergetic cancer therapy

Combined photothermal therapy and nitric oxide (NO)-mediated gas therapy has shown great potential as a cancer treatment. However, the on-demand release of NO at a high concentration presents a challenge owing to the lack of an ideal bio-transducer with a high loading capacity of NO donors and sufficient energy to induce NO release. Here, we present a new 2D BiTiS3 nanosheet that is synthesized, loaded with the NO donor (BNN6), and conjugated with PEG-iRGD to produce a multifunctional bio-transducer (BNN6-BiTiS3-iRGD) for the on-demand production of NO. The BiTiS3 nanosheets not only have a high loading capacity of NO donors (750%), but also exhibit a high photothermal conversion efficiency (59.5%) after irradiation by a 1064-nm laser at 0.5 W/cm2. As a result of the above advantages, the temporal-controllable generation of NO within a large dynamic range (from 0 to 344 μM) is achieved by adjusting power densities, which is among the highest efficiency values reported for NO generators so far. Moreover, the targeted accumulation of BNN6-BiTiS3-iRGD at tumor sites leads to spatial-controllable NO release. In vitro and in vivo assessments demonstrate synergistic NO gas therapy with mild photothermal therapy based on BNN6-BiTiS3-iRGD. Our work provides insights into the design and application of other 2D nanomaterial-based therapeutic platforms.

Microneedle system for tissue engineering and regenerative medicine

Global increasing demand for high life quality and length facilitates the development of tissue engineering and regenerative medicine, which apply multidisciplinary theories and techniques to achieve the structural reconstruction and functional recovery of disordered or damaged tissues and organs. However, the clinical performances of adopted drugs, materials, and powerful cells in the laboratory are inescapably limited by the currently available technologies. To tackle the problems, versatile microneedles are developed as the new platform for local delivery of diverse cargos with minimal invasion. The efficient delivery, as well as painless and convenient procedure endow microneedles with good patient compliance in clinic. In this review, we first categorize different microneedle systems and delivery models, and then summarize their applications in tissue engineering and regenerative medicine mainly involving maintenance and rehabilitation of damaged tissues and organs. In the end, we discuss the advantages, challenges, and prospects of microneedles in depth for future clinical translations.

Photoresponsive polymeric microneedles: An innovative way to monitor and treat diseases

Microneedles (MN) technology is an emerging technology for the transdermal delivery of therapeutics. When combined with photoresponsive (PR) materials, MNs can deliver therapeutics precisely and effectively with enhanced efficacy or synergistic effects. This review systematically summarizes the therapeutic applications of PRMNs in cancer therapy, wound healing, diabetes treatment, and diagnostics. Different PR approaches to activate and control the release of therapeutic agents from MNs are also discussed. Overall, PRMNs are a powerful tool for stimuli-responsive controlled-release therapeutic delivery to treat various diseases.

Nanoparticle-based delivery of nitric oxide for therapeutic applications

Nitric oxide (NO), a low molecular weight signaling molecule, plays critical roles in both cellular health and disease. There is continued interest in new modalities for the controlled therapeutic delivery of NO to cells and tissues. The physicochemical properties of NO (including its short half-life and on-demand synthesis at the point of function), however, pose considerable challenges for its specific and efficient delivery. Recently, a number of nanoparticle (NP)-based systems are described that address some of these issues by taking advantage of the unique attributes of the NP carrier to effect efficient NO delivery. This review highlights the progress that has been made over the past 5 years in the use of various constructs for the therapeutic delivery of NO.

Microneedle Patch Delivery of Methotrexate-Loaded Albumin Nanoparticles to Immune Cells Achieves a Potent Antipsoriatic Effect

Introduction

Transdermal drug delivery provides a desirable alternative method of penetrating the skin for psoriasis treatment, by virtue of its ability to dampen the overactivation of immune cells and inflammation, while attenuating the detrimental effects of systemic administration. Lymph nodes (LNs), as a critical organ of the lymphatic and the acquired immune system, are suitable sites for drug homing to suppress the immune cells.

Methods

In this context, we developed a microneedle (MN) patch that delivers nanodrugs locally to LNs for improving the antipsoriatic treatment. In this study, human serum albumin nanoparticles carrying methotrexate (HM) were synthesized and loaded into hyaluronic acid (HA)-based microneedles (HM/MN).

Results

The patch showed an excellent ability to pierce the skin, which enhanced drug delivery. In a mouse model of psoriasis, the HM/MN patch significantly prevented the erythema with decreased skin thickness, thus inhibiting the progression of psoriasis. Further analysis for immune cells in LNs, the percent of dendritic cells (DC) and T cells reduced after the local treatment with HM/MN. Notably, the feasibility of targeted delivery of methotrexate to LNs using nanoparticles was verified by detecting increased accumulation of methotrexate in LNs. In addition, the HM/MN patch pronouncedly decreased the levels of tumor necrosis factor α and interleukin 6 in the skin.

Conclusion

The results suggested the high efficacy of using the HM/MN patch to treat psoriasis, and provided new insight into the mechanism of the transdermal drug delivery system.

Current Status of Experimental Animal Skin Flap Models: Ischemic Preconditioning and Molecular Factors

Skin flaps are necessary in plastic and reconstructive surgery for the removal of skin cancer, wounds, and ulcers. A skin flap is a portion of skin with its own blood supply that is partially separated from its original position and moved from one place to another. The use of skin flaps is often accompanied by cell necrosis or apoptosis due to ischemia-reperfusion (I/R) injury. Proinflammatory cytokines, such as nuclear factor kappa B (NF-κB), inhibitor of kappa B (IκB), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and oxygen free radicals are known causative agents of cell necrosis and apoptosis. To prevent I/R injury, many investigators have suggested the inhibition of proinflammatory cytokines, stem-cell therapies, and drug-based therapies. Ischemic preconditioning (IPC) is a strategy used to prevent I/R injury. IPC is an experimental technique that uses short-term repetition of occlusion and reperfusion to adapt the area to the loss of blood supply. IPC can prevent I/R injury by inhibiting proinflammatory cytokine activity. Various stem cell applications have been studied to facilitate flap survival and promote angiogenesis and vascularization in animal models. The possibility of constructing tissue engineered flaps has also been investigated. Although numerous animal studies have been published, clinical data with regard to IPC in flap reconstruction have never been reported. In this study, we present various experimental skin flap methods, IPC methods, and methods utilizing molecular factors associated with IPC.

Bioimaging of Dissolvable Microneedle Arrays: Challenges and Opportunities

The emergence of microneedle arrays (MNAs) as a novel, simple, and minimally invasive administration approach largely addresses the challenges of traditional drug delivery. In particular, the dissolvable MNAs act as a promising, multifarious, and well-controlled platform for micro-nanotransport in medical research and cosmetic formulation applications. The effective delivery mostly depends on the behavior of the MNAs penetrated into the body, and accurate assessment is urgently needed. Advanced imaging technologies offer high sensitivity and resolution visualization of cross-scale, multidimensional, and multiparameter information, which can be used as an important aid for the evaluation and development of new MNAs. The combination of MNA technology and imaging can generate considerable new knowledge in a cost-effective manner with regards to the pharmacokinetics and bioavailability of active substances for the treatment of various diseases. In addition, noninvasive imaging techniques allow rapid, receptive assessment of transdermal penetration and drug deposition in various tissues, which could greatly facilitate the translation of experimental MNAs into clinical application. Relying on the recent promising development of bioimaging, this review is aimed at summarizing the current status, challenges, and future perspective on in vivo assessment of MNA drug delivery by various imaging technologies.