Hydrogen sulfide-releasing micelles for promoting angiogenesis

Recent advances in the role of hydrogen sulfide in age-related diseases

In recent years, the impact of age-related diseases on human health has become increasingly severe, and developing effective drugs to deal with these diseases has become an urgent task. Considering the essential regulatory role of hydrogen sulfide (H2S) in these diseases, it is regarded as a promising target for treatment. H2S is a novel gaseous transmitter involved in many critical physiological activities, including anti-oxidation, anti-inflammation, and angiogenesis. H2S also regulates cell activities such as cell proliferation, migration, invasion, apoptosis, and autophagy. These regulatory effects of H2S contribute to relieving and treating age-related diseases. In this review, we mainly focus on the pathogenesis and treatment prospects of H2S in regulating age-related diseases.

Manganese Porphyrin-Containing Polymeric Micelles: A Novel Approach for Intracellular Catalytic Formation of Per/Polysulfide Species from a Hydrogen Sulfide Donor

Per/polysulfide species that are generated from endogenously produced hydrogen sulfide have critical regulatory roles in a wide range of cellular processes. However, the lack of delivery systems that enable controlled and sustained release of these unstable species in biological systems hinders the advancement of sulfide biology research, as well as the translation of knowledge to therapeutic applications. Here, a novel approach is developed to generate per/polysulfide species in cells by combining an H2 S donor and manganese porphyrin-containing polymeric micelles (MnPMCs) that catalyze oxidization of H2 S to per/polysulfide species. MnPMCs serve as a catalyst for H2 S oxidation in aerobic phosphate buffer. HPLC-MS/MS analysis reveals that H2 S oxidation by MnPMCs in the presence of glutathione results in the formation of glutathione-SnH (n = 2 and 3). Furthermore, co-treatment of human umbilical vein endothelial cells with the H2 S donor anethole dithiolethione and MnPMCs increases intracellular per/polysulfide levels and induces a proangiogenic response. Co-delivery of MnPMCs and an H2 S donor is a promising approach for controlled delivery of polysulfides for therapeutic applications.

Recent advance in self-assembled polymeric nanomedicines for gaseous signaling molecule delivery

Gaseous signaling molecules such as nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H2 S) have recently been recognized as essential signal mediators that regulate diverse physiological and pathological processes in the human body. With the evolution of gaseous signaling molecule biology, their therapeutic applications have attracted growing attention. One of the challenges in translational research of gaseous signaling molecules is the lack of efficient and safe delivery systems. To tackle this issue, researchers developed a library of gas donors, which are low molecular weight compounds that can release gaseous signaling molecules upon decomposition under physiological conditions. Despite the significant efforts to control gaseous signaling molecule release from gas donors, the therapeutic potential of gaseous signaling molecules cannot be fully explored due to their unfavorable pharmacokinetics and toxic side effects. Recently, the use of nanoparticle-based gas donors, especially self-assembled polymeric gas donors, have emerged as a promising approach. In this review, we describe the development of conventional small gas donors and the challenges in their therapeutic applications. We then illustrate the concepts and critical aspects for designing self-assembled polymeric gas donors and discuss the advantages of this approach in gasotransmistter delivery. We also highlight recent efforts to develop the delivery systems for those molecules based on self-assembled polymeric nanostructures. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies.

A dual-site multifunctional fluorescent probe for selective detection of endogenous H2O2 and SO2 derivatives based on ICT process and its bioimaging application

In this paper, we reported a coumarin-based fluorescent probe for selective detection of H₂O₂/SO₂ derivatives via ICT process. To the best of our knowledge, it was few reported with the same probe to enable visual detection of H₂O₂/SO₂ derivatives in vivo and in vitro. H₂O₂ and SO₃^2- were selectively sensed over other analytes, and the probe displayed 20-fold and 220-fold relative fluorescence intensity respectively, as well as the good linear relationship and the excellent detection limits of 2.7 * 10³ nM and 19.3 nM. Furthermore, the probe was successfully used for fluorescence imaging of the HeLa cells and the mice to monitor exogenous and endogenous H₂O₂ and SO₃^2-, suggesting its potential biomedical application for investigation and detection the intermediate indicator of oxidative stress in vitro and in vivo.

Intelligent polymeric hydrogen sulfide delivery systems for therapeutic applications

Hydrogen sulfide (H₂S) plays an important role in regulating various pathological processes such as protecting mammalian cell from harmful injuries, promoting tissue regeneration, and regulating the process of various diseases caused by physiological disorders. Studies have revealed that the physiological effects of H₂S are highly associated with its concentrations. At relatively low concentration, H₂S shows beneficial functions. However, long-time and high-dose donation of H₂S would inhibit regular biological process, resulting in cell dysfunction and apoptosis. To regulate the dosage of H₂S delivery for precision medicine, H₂S delivery systems with intelligent characteristics were developed and a variety of biocompatibility polymers have been utilized to establish intelligent polymeric H₂S delivery systems, with the abilities to specifically target the lesions, smartly respond to pathological microenvironments, as well as real-timely monitor H₂S delivery and lesion conditions by incorporating imaging-capable moieties. In this review, we focus on the design, preparation, and therapeutic applications of intelligent polymeric H₂S delivery systems in cardiovascular therapy, inflammatory therapy, tissue regenerative therapy, cancer therapy and bacteria-associated therapy. Strategies for precise H₂S therapies especially imaging-guided H₂S theranostics are highlighted. Since H₂S donors with stimuli-responsive characters are vital components for establishing intelligent H₂S delivery systems, the development of H₂S donors is also briefly introduced.

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H₂S is an endogenous gasotransmitter that plays important role in regulating various physiological and pathological pathways.

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Controlled H₂S delivery is vital since the therapeutic effects of H₂S are highly associated with its concentrations.

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Intelligent polymeric H₂S delivery systems possess specific targeting, stimuli responsive and imaging guided capabilities, representing a strategic option for next generation of therapies.

Reactive Oxygen Species-Triggered Hydrogen Sulfide Release and Cancer-Selective Antiproliferative Effect of Anethole Dithiolethione-Containing Polymeric Micelles

Hydrogen sulfide (H2 S) is a gaseous signaling molecule in the human body and has attracted attention in cancer therapy due to its regulatory roles in cancer cell proliferation and migration. Accumulating evidence suggests that continuous delivery of H2 S to cancer cells for extended periods of time suppresses cancer progression. However, one major challenge in therapeutic applications of H2 S is its controlled delivery. To solve this problem, polymeric micelles are developed containing H2 S donating-anethole dithiolethione (ADT) groups, with H2 S release profiles optimal for suppressing cancer cell proliferation. The micelles release H2 S upon oxidation by reactive oxygens species (ROS) that are present inside the cells. The H2 S release profiles can be controlled by changing the polymer design. Furthermore, the micelles that show a moderate H2 S release rate exert the strongest anti-proliferative effect in human colon cancer cells in in vitro assays as well as the chick chorioallantoic membrane cancer model, while the micelles do not affect proliferation of human umbilical vein endothelial cells. This study shows the importance of fine-tuning H2 S release profiles using a micelle approach for realizing the full therapeutic potential of H2 S in cancer treatment.

Role of hydrogen sulphide in physiological and pathological angiogenesis

The role of hydrogen sulphide (H₂ S) in angiogenesis has been widely demonstrated. Vascular endothelial growth factor (VEGF) plays an important role in H₂ S-induced angiogenesis. H₂ S promotes angiogenesis by upregulating VEGF via pro-angiogenic signal transduction. The involved signalling pathways include the mitogen-activated protein kinase pathway, phosphoinositide-3 kinase pathway, nitric oxide (NO) synthase/NO pathway, signal transducer and activator of transcription 3 (STAT3) pathway, and adenosine triphosphate (ATP)-sensitive potassium (K_ATP ) channels. H₂ S has been shown to contribute to tumour angiogenesis, diabetic wound healing, angiogenesis in cardiac and cerebral ischaemic tissues, and physiological angiogenesis during the menstrual cycle and pregnancy. Furthermore, H₂ S can exert an anti-angiogenic effect by inactivating Wnt/β-catenin signalling or blocking the STAT3 pathway in tumours. Therefore, H₂ S plays a double-edged sword role in the process of angiogenesis. The regulation of H₂ S production is a promising therapeutic approach for angiogenesis-associated diseases. Novel H₂ S donors and/or inhibitors can be developed in the treatment of angiogenesis-dependent diseases.

Polythionoester Vesicle: An Efficient Polymeric Platform for Tuning H2S Release

Hydrogen sulfide (H₂S) serves as a key gaseous regulator that not only directs many physiological activities, but also manifests therapeutic benefits to many diseases. Developing H₂S vehicle platforms for its local delivery and long-acting release is important to achieve target gas therapy. Most of the known H₂S-donating polymers contain labile thioester scaffolds within their structures that suffer from the issue of low gas releasing efficiency. Here we present the use of thionoester, a constitutional isomer of thioester, as the functional unit to build a structural platform of cysteine-triggered H₂S donor polymer, polythionoester. Simple exchange of the sulfur and oxygen positions in the carbonyl sulfide scaffold makes the polythionoesters undergo a distinct mechanism of H₂S production, which can largely improve the gas-releasing efficiency (>80%). Moreover, the thionoester-containing block copolymers can self-assemble into vesicles in an aqueous media. We discover that control over the size effect can adjust the vesicle disassembly rate and gas-releasing kinetics. A tunable half-life of H₂S generation (2.6-9.8 h) can be accessed by tailoring the vesicle dimension. This allows such polymersomes to be potential as a gas nanodelivery system for long-lasting gas therapeutics.

Polymeric nanoparticles—Promising carriers for cancer therapy

Polymeric nanoparticles (NPs) play an important role in controlled cancer drug delivery. Anticancer drugs can be conjugated or encapsulated by polymeric nanocarriers, which are known as polymeric nanomedicine. Polymeric nanomedicine has shown its potential in providing sustained release of drugs with reduced cytotoxicity and modified tumor retention, but until now, few delivery systems loading drugs have been able to meet clinical demands, so more efforts are needed. This research reviews the current state of the cancer drug-loading system by exhibiting a series of published articles that highlight the novelty and functions from a variety of different architectures including micelles, liposomes, dendrimers, polymersomes, hydrogels, and metal–organic frameworks. These may contribute to the development of useful polymeric NPs to achieve different therapeutic purposes.

Therapeutic gas-releasing nanomedicines with controlled release: Advances and perspectives

Nanoparticle-based drug delivery has become one of the most popular approaches for maximising drug therapeutic potentials. With the notable improvements, a greater challenge hinges on the formulation of gasotransmitters with unique challenges that are not met in liquid and solid active ingredients. Gas molecules upon release from formulations for therapeutic purposes have not really been discussed extensively. Herein, we take a critical look at four key gasotransmitters, that is, carbon monoxide (CO), nitric oxide (NO), hydrogen sulphide (H2S) and sulphur dioxide (SO2), their possible modification into prodrugs known as gas-releasing molecules (GRMs), and their release from GRMs. Different nanosystems and their mediatory roles for efficient shuttling, targeting and release of these therapeutic gases are also reviewed extensively. This review thoroughly looks at the diverse ways in which these GRM prodrugs in delivery nanosystems are designed to respond to intrinsic and extrinsic stimuli for sustained release. In this review, we seek to provide a succinct summary for the development of therapeutic gases into potent prodrugs that can be adapted in nanomedicine for potential clinical use.

Core-Cross-Linking of Polymeric Micelles by Di-para-Substituted S-Aroylthiooximes as Linkers for Controlled H2S Release

As one of the gasotransmitters, the therapeutic effects of hydrogen sulfide (H₂S) were reported widespread in recent years. Considering the short physiological half-life and significant dose-dependent effects of H₂S, it is vital to achieve controlled H₂S delivery for biomedical applications. Polymeric micelles have been explored to regulate H₂S delivery. However, the dilution-induced dissociation of micelles in physiological conditions limits their therapeutic effects. The circulation stability of polymeric micelles could be improved through core-cross-linking, but reduced H₂S releasing efficiency is usually unavoidable. To solve these problems, we developed di-para-substituted S-aroylthiooximes (p-diSATOs) as linkers, which integrated cross-linking of micelle core and conjugation of H₂S donors through one simple reaction. Compared with SATO-bearing non-cross-linked micelle, the core-cross-linked micelle (CCM) prepared through this method exhibited initial rapid H₂S release owing to the electron-withdrawing effect of p-diSATOs, and subsequently, a sustained release could last for a long period of time. Considering the characteristic H₂S releasing behavior of CCM, it may accelerate wound healing through initial efficient and subsequent prolonged pro-healing effects. As a proof of concept, we explored the therapeutic potential of CCM using a murine burn wound model, which exhibited pro-healing effect on burn wounds.

Thiobenzophenones: tunable hydrolysis-based donors for intracellular H2S delivery

H2S, the third gasotransmitter, is involved in many physiological and pathological processes. Compounds that can release H2S slowly under physiological conditions are useful chemical tools for studying H2S biology as...

Zwitterion-Based Hydrogen Sulfide Nanomotors Induce Multiple Acidosis in Tumor Cells by Destroying Tumor Metabolic Symbiosis

Destruction of tumor metabolism symbiosis is an attractive cancer treatment method which targets tumor cells with little harm to normal cells. Yet, a single intervention strategy and poor penetration of the drug in tumor tissue result in limited effect. Herein, we propose a zero-waste zwitterion-based hydrogen sulfide (H2 S)-driven nanomotor based on the basic principle of reaction in human body. When loaded with monocarboxylic acid transporter inhibitor α-cyano-4-hydroxycinnamic acid (α-CHCA), the nanomotor can move in tumor microenvironment and induce multiple acidosis of tumor cells and inhibit tumor growth through the synergistic effect of motion effect, driving force H2 S and α-CHCA. Given the good biosafety of the substrate and driving gas of this kind of nanomotor, as well as the limited variety of nanomotors currently available to move in the tumor microenvironment, this kind of nanomotor may provide a competitive candidate for the active drug delivery system of cancer treatment.

The Potential of Hydrogen Sulfide Donors in Treating Cardiovascular Diseases

Hydrogen sulfide (H2S) has long been considered as a toxic gas, but as research progressed, the idea has been updated and it has now been shown to have potent protective effects at reasonable concentrations. H2S is an endogenous gas signaling molecule in mammals and is produced by specific enzymes in different cell types. An increasing number of studies indicate that H2S plays an important role in cardiovascular homeostasis, and in most cases, H2S has been reported to be downregulated in cardiovascular diseases (CVDs). Similarly, in preclinical studies, H2S has been shown to prevent CVDs and improve heart function after heart failure. Recently, many H2S donors have been synthesized and tested in cellular and animal models. Moreover, numerous molecular mechanisms have been proposed to demonstrate the effects of these donors. In this review, we will provide an update on the role of H2S in cardiovascular activities and its involvement in pathological states, with a special focus on the roles of exogenous H2S in cardiac protection.

Tuning small molecule release from polymer micelles: Varying H2S release through cross linking in the micelle core

Polymer micelles, used extensively as vehicles in the delivery of active pharmaceutical ingredients, represent a versatile polymer architecture in drug delivery systems. We hypothesized that degree of crosslinking in the hydrophobic core of amphiphilic block copolymer micelles could be used to tune the rate of release of the biological signaling gas (gasotransmitter) hydrogen sulfide (H2S), a potential therapeutic. To test this hypothesis, we first synthesized amphiphilic block copolymers of the structure PEG-b-P(FBEA) (PEG = poly(ethylene glycol), FBEA = 2-(4-formylbenzoyloxy)ethyl acrylate). Using a modified arm-first approach, we then varied the crosslinking percentage in the core-forming block via addition of a 'O,O'-alkanediyl bis(hydroxylamine) crosslinking agent. We followed incorporation of the crosslinker by 1H NMR spectroscopy, monitoring the appearance of the oxime signal resulting from reaction of pendant aryl aldehydes on the block copolymer with hydroxylamines on the crosslinker, which revealed crosslinking percentages of 5, 10, and 15%. We then installed H2S-releasing S-aroylthiooxime (SATO) groups on the crosslinked polymers, yielding micelles with SATO units in their hydrophobic cores after self-assembly in water. H2S release studies in water, using cysteine (Cys) as a trigger to induce H2S release from the SATO groups in the micelle core, revealed increasing half-lives of H2S release, from 117 ± 6 min to 210 ± 30 min, with increasing crosslinking density in the micelle core. This result was consistent with our hypothesis, and we speculate that core crosslinking limits the rate of Cys diffusion into the micelle core, decreasing the release rate. This method for tuning the release of covalently linked small molecules through modulation of micelle core crosslinking density may extend beyond H2S to other drug delivery systems where precise control of release rate is needed.