Nitric oxide improves regeneration and prevents calcification in bio-hybrid vascular grafts via regulation of vascular stem/progenitor cells

A photothermal responsive system accelerating nitric oxide release to enhance bone repair by promoting osteogenesis and angiogenesis

Managing bone defects remains a formidable clinical hurdle, primarily attributed to the inadequate orchestration of vascular reconstruction and osteogenic differentiation in both spatial and temporal dimensions. This challenge persists due to the constrained availability of autogenous grafts and the limited regenerative capacity of allogeneic or synthetic bone substitutes, thus necessitating continual exploration and innovation in the realm of functional and bioactive bone graft materials. While synthetic scaffolds have emerged as promising carriers for bone grafts, their efficacy is curtailed by deficiencies in vascularization and osteoinductive potential. Nitric oxide (NO) plays a key role in revascularization and bone tissue regeneration, yet studies related to the use of NO for the treatment of bone defects remain scarce. Herein, we present a pioneering approach leveraging a photothermal-responsive system to augment NO release. This system comprises macromolecular mPEG-P nanoparticles encapsulating indocyanine green (ICG) (NO-NPs@ICG) and a mPEG-PA-PP injectable thermosensitive hydrogel carrier. By harnessing the synergistic photothermal effects of near-infrared radiation and ICG, the system achieves sustained NO release, thereby activating the soluble guanylate cyclase (SGC)-cyclic guanosine monophosphate (cGMP) signaling pathway both in vitro and in vivo. This orchestrated cascade culminates in the facilitation of angiogenesis and osteogenesis, thus expediting the reparative processes in bone defects. In a nutshell, the NO release-responsive system elucidated in this study presents a pioneering avenue for refining the bone tissue microenvironment and fostering enhanced bone regeneration.

Anti-angiogenesis and anti-immunosuppression gene therapy through targeting COUP-TFII in an in situ glioblastoma mouse model

Glioblastoma (GBM) is the most common and aggressive primary brain cancer; angiogenesis and immunosuppression exacerbate GBM progression. COUP-TFII demonstrates pro-angiogenesis activity; however, its role in glioma progression remains unclear. This study revealed that COUP-TFII promotes angiogenesis in gliomas by inducing transdifferentiation of glioma cells into endothelial-like cells. Mechanistic investigation suggested that COUP-TFII as a transcription factor exerts its function via binding to the promoter of TXNIP. Interestingly, COUP-TFII knockdown attenuated tumorigenesis and tumor progression in an immunocompetent mouse model but promoted tumor progression in an immuno-deficient mouse model. As an explanation, repression of COUP-TFII induces cellular senescence and activates immune surveillance in glioma cells in vitro and in vivo. In addition, we used heparin-polyethyleneimine (HPEI) nanoparticles to deliver COUP-TFII shRNA, which regulated tumor angiogenesis and immunosuppression in an in situ GBM mouse model. This study provides a novel strategy and potential therapeutic targets to treat GBM.

Electrospun membranes of diselenide-containing poly(ester urethane)urea for in situ catalytic generation of nitric oxide

Nitric oxide (NO) plays an important role as a signalling molecule in the biological system. Organoselenium-coated or grafted biomaterials have the potential to achieve controlled NO release as they can catalyse decomposition of endogenous S-nitrosothiols to NO. However, such biomaterials are often challenged by the loss of the catalytic sites, which can affect the stability in tissue repair applications. In this work, we prepare a diselenide-containing poly(ester urethane)urea (SePEUU) polymer with Se-Se in the backbone, which is further electrospun into fibrous membranes by blending with poly(ester urethane)urea (PEUU) without diselenide bonds. The presence of catalytic sites in the main chain demonstrates stable and long-lasting NO catalytic activity, while the porous structure of the fibrous membranes ensures uniform distribution of the catalytic sites and better contact with the donor-containing solution. PEUU/SePEUU50 in 50/50 mass ratio has a physiologically adapted rate of NO release, with a sustained generation of NO after exposure to PBS at 37 °C for 30 d. PEUU/SePEUU50 has a low hemolysis and protein adsorption, with mechanical properties in the wet state matching those of natural vascular tissues. It can promote the adhesion and proliferation of human umbilical vein endothelial cells in vitro and control the proliferation of vascular smooth muscle cells in the presence of NO generation. This study exhibits the electrospun fibrous membranes have potential for utilizing as hemocompatible biomaterials for regeneration of blood-contacting tissues.

Extravascular administration of IGF1R antagonists protects against aortic aneurysm in rodent and porcine models

An abdominal aortic aneurysm (AAA) is a life-threatening cardiovascular disease. We identified plasma insulin-like growth factor 1 (IGF1) as an independent risk factor in patients with AAA by correlating plasma IGF1 with risk. Smooth muscle cell- or fibroblast-specific knockout of Igf1r, the gene encoding the IGF1 receptor (IGF1R), attenuated AAA formation in two mouse models of AAA induced by angiotensin II infusion or CaCl2 treatment. IGF1R was activated in aortic aneurysm samples from human patients and mice with AAA. Systemic administration of IGF1C, a peptide fragment of IGF1, 2 weeks after disease development inhibited AAA progression in mice. Decreased AAA formation was linked to competitive inhibition of IGF1 binding to its receptor by IGF1C and modulation of downstream alpha serine/threonine protein kinase (AKT)/mammalian target of rapamycin signaling. Localized application of an IGF1C-loaded hydrogel was developed to reduce the side effects observed after systemic administration of IGF1C or IGF1R antagonists in the CaCl2-induced AAA mouse model. The inhibitory effect of the IGF1C-loaded hydrogel administered at disease onset on AAA formation was further evaluated in a guinea pig-to-rat xenograft model and in a sheep-to-minipig xenograft model of AAA formation. The therapeutic efficacy of IGF1C for treating AAA was tested through extravascular delivery in the sheep-to-minipig model with AAA established for 2 weeks. Percutaneous injection of the IGF1C-loaded hydrogel around the AAA resulted in improved vessel flow dynamics in the minipig aorta. These findings suggest that extravascular administration of IGF1R antagonists may have translational potential for treating AAA.

Nitric Oxide Releasing Nanomaterials for Cardiovascular Applications

A central paradigm of cardiovascular homeostasis is that impaired nitric oxide (NO) bioavailability results in a wide array of cardiovascular dysfunction including incompetent endothelium-dependent vasodilatation, thrombosis, vascular inflammation, and proliferation of the intima. Over the course of more than a century, NO donating formulations such as organic nitrates and nitrites have remained a cornerstone of treatment for patients with cardiovascular diseases. These donors primarily produce NO in the circulation and are not targeted to specific (sub)cellular sites of action. However, safe, and therapeutic levels of NO require delivery of the right amount to a precise location at the right time. To achieve these aims, several recent strategies aimed at therapeutically generating or releasing NO in living systems have shown that polymeric and inorganic (silica, gold) nanoparticles and nanoscale metal-organic frameworks could either generate NO endogenously by the catalytic decomposition of endogenous NO substrates or can store and release therapeutically relevant amounts of NO gas. NO-releasing nanomaterials have been developed for vascular implants (such as stents and grafts) to target atherosclerosis, hypertension, myocardial ischemia-reperfusion injury, and cardiac tissue engineering. In this review, we discuss the advances in design and development of novel NO-releasing nanomaterials for cardiovascular therapeutics and critically examine the therapeutic potential of these nanoplatforms to modulate cellular metabolism, to regulate vascular tone, inhibit platelet aggregation, and limit proliferation of vascular smooth muscle with minimal toxic effects.

Trinitroglycerin-loaded chitosan nanogels: Shedding light on cytotoxicity, antioxidativity, and antibacterial activities

AIM AND BACKGROUND

Trinitroglycerin (TNG) is a remarkable NO-releasing agent. Here, we synthesized TNG based on chitosan Nanogels (Ngs) for ameliorating complications associated with high-dose TNG administration.

METHOD

TNG-Ngs fabricated through ionic-gelation technique. Fourier-transformed infrared (FT-IR), zeta-potential, dynamic light scattering (DLS), and electron microscopy techniques evaluated the physicochemical properties of TNG-Ngs. MTT was used to assess the biocompatibility of TNG-Ngs, as the antioxidative properties were determined via lactate dehydrogenase (LDH), reactive oxygen species (ROS), and lipid peroxide (LPO) assays. The antibacterial activity was evaluated against Staphylococcus aureus (S. aureus), Escherichia coli (E. coli), Methicillin-resistant Staphylococcus aureus (MRSA), and vancomycin-resistant Enterococci (VRE).

RESULTS

Physicochemical characterization reveals that TNG-Ngs with size diameter (96.2 ± 29 nm), polydispersity index (PDI, 0.732), and negative zeta potential (-1.1 mv) were fabricated. The encapsulation efficacy (EE) and loading capacity (LC) were obtained at 71.1 % and 2.3 %, respectively, with no considerable effect on particle size and morphology. The cytotoxicity assay demonstrated that HepG2 cells exposed to TNG-Ngs showed relative cell viability (RCV) of >80 % for 70 μg/ml compared to the TNG-free drug at the same concentration (P < 0.05). TNG-Ngs showed significant differences with the TNG-free drug for LDH, LPO, and ROS formation at the same concentration (P < 0.001). The antibacterial activity of the TNG-Ngs against S. aureus, E. coli, VRE, and MRSA was higher than the TNG-free drug and Ngs (P < 0.05).

CONCLUSION

TNG-Ngs with enhanced antibacterial and antioxidative activity and no obvious cytotoxicity might be afforded as novel nanoformulation for promoting NO-dependent diseases.

Propelling Multi-Modal Therapeutics of PEEK Implants through the Power of NO evolving Covalent Organic Frameworks (COFs)

The design and fabrication of NO-evolving core-shell nanoparticles (denoted as NC@Fe), comprised of BNN6-laden COF@Fe3 O4 nanoparticles, are reported. This innovation extends to the modification of 3D printed polyetheretherketone scaffolds with NC@Fe, establishing a pioneering approach to multi-modal bone therapy tailored to address complications such as device-associated infections and osteomyelitis. This work stands out prominently from previous research, particularly those relying on the use of antibiotics, by introducing a bone implant capable of simultaneous NO gas therapy and photothermal therapy (PPT). Under NIR laser irradiation, the Fe3 O4 NP core (photothermal conversion agent) within NC@Fe absorbs photoenergy and initiates electron transfer to the loaded NO donor (BNN6), resulting in controlled NO release. The additional heat generated through photothermal conversion further propels the NC@Fe nanoparticles, amplifying the therapeutic reach. The combined effect of NO release and PPT enhances the efficacy in eradicating bacteria over a more extensive area around the implant, presenting a distinctive solution to conventional challenges. Thorough in vitro and in vivo investigations validate the robust potential of the scaffold in infection control, osteogenesis, and angiogenesis, emphasizing the timeliness of this unique solution in managing complicated bone related infectious diseases.

Intracellular delivery of nitric oxide enhances the therapeutic efficacy of mesenchymal stem cells for myocardial infarction

Cell therapy by autologous mesenchymal stem cells (MSCs) is a clinically acceptable strategy for treating various diseases. Unfortunately, the therapeutic efficacy is largely affected by the low quality of MSCs collected from patients. Here, we showed that the gene expression of MSCs from patients with diabetes was differentially regulated compared to that of MSCs from healthy controls. Then, MSCs were genetically engineered to catalyze an NO prodrug to release NO intracellularly. Compared to extracellular NO conversion, intracellular NO delivery effectively prolonged survival and enhanced the paracrine function of MSCs, as demonstrated by in vitro and in vivo assays. The enhanced therapeutic efficacy of engineered MSCs combined with intracellular NO delivery was further confirmed in mouse and rat models of myocardial infarction, and a clinically relevant cell administration paradigm through secondary thoracotomy has been attempted.

Photothermal-Ionic-Pharmacotherapy of Myocardial Infarction with Enhanced Angiogenesis and Antiapoptosis

Promoting angiogenesis is an effective therapeutic strategy to repair damaged hearts after myocardial infarction (MI). Copper ions and mild heat (41-42 °C) have been shown to promote angiogenesis, but their efficacy in MI is unknown. Here, a multicomponent hydrogel (EDR@PHCuS HG) is developed by encapsulating edaravone (EDR, a free radical scavenger) loaded porous hollow copper sulfide nanoparticles (PHCuS NPs) in a hyaluronic acid hydrogel (HG). Exposed to 808 nm near-infrared (NIR) light irradiation, the EDR@PHCuS HG exhibits controlled copper-ion release and mild photothermal effect to synergistically promote angiogenesis. In addition, released EDR inhibits cardiomyocyte apoptosis to further repair hearts. In the mouse model of MI, treatment with the EDR@PHCuS HG under an 808 nm laser significantly recovers the cardiac function and inhibits ventricular remodeling. This platform elucidates the cardioprotective effects of copper ions and mild heat and will provide a highly efficient treatment for MI.

Fucoidan promotes angiogenesis and accelerates wound healing through AKT/Nrf2/HIF-1α signalling pathway

After skin injury, wound repair involves a complex process in which angiogenesis plays a crucial role. Previous research has indicated that fucoidan may aid in wound healing; we therefore hypothesised that fucoidan may speed up the process by promoting angiogenesis. In this study, we investigated the potential molecular mechanism underlying fucoidan's ability to accelerate wound healing by promoting angiogenesis. Using a full-cut wound model, we observed that fucoidan significantly intensified wound closure and promoted granulation formation and collagen deposition. Immunofluorescence staining revealed that fucoidan also promoted wound angiogenesis, specifically by accelerating the migration of new blood vessels to the middle area of the wound. Furthermore, fucoidan demonstrated the ability to enhance the proliferation of human umbilical vein endothelial cells (HUVECs) damaged by hydrogen peroxide (H2 O2 ) and to improve the formation of endothelial tubes. Mechanistic studies revealed that fucoidan upregulated the protein levels of the AKT/Nrf2/HIF-1α signalling pathway, which plays a crucial role in angiogenesis. This was further confirmed using the inhibitor LY294002, which reversed the promotion of endothelial tube formation by fucoidan. Overall, our findings suggest that fucoidan can promote angiogenesis via the AKT/Nrf2/HIF-1α signalling pathway and accelerate wound healing.

Engineered exosomes reprogram Gli1+ cells in vivo to prevent calcification of vascular grafts and autologous pathological vessels

Calcification of autologous pathological vessels and tissue engineering blood vessels (TEBVs) is a thorny problem in clinic. However, there is no effective and noninvasive treatment that is available against the calcification of TEBVs and autologous pathological vessels. Gli1+ cells are progenitors of smooth muscle cells (SMCs) and can differentiate into osteoblast-like cells, leading to vascular calcification. Our results showed that the spatiotemporal distribution of Gli1+ cells in TEBVs was positively correlated with the degree of TEBV calcification. An anticalcification approach was designed consisting of exosomes derived from mesenchymal stem cells delivering lncRNA-ANCR to construct the engineered exosome-Ancr/E7-EXO. The results showed that Ancr/E7-EXO effectively targeted Gli1+ cells, promoting rapid SMC reconstruction and markedly inhibiting Gli1+ cell differentiation into osteoblast-like cells. Moreover, Ancr/E7-EXO significantly inhibited vascular calcification caused by chronic kidney disease. Therefore, Ancr/E7-EXO reprogrammed Gli1+ cells to prevent calcification of vascular graft and autologous pathological vessel, providing unique insights for an effective anticalcification.

The Inhibition Effects of Sodium Nitroprusside on the Survival of Differentiated Neural Stem Cells through the p38 Pathway

Nitric oxide (NO) is a crucial factor in regulating neuronal development. However, certain effects of NO are complex under different physiological conditions. In this study, we used differentiated neural stem cells (NSCs), which contained neural progenitor cells, neurons, astrocytes, and oligodendrocytes, to observe the physiological effects of sodium nitroprusside (SNP) on the early developmental stage of the nervous system. After SNP treatment for 24 h, the results showed that SNP at 100 μM, 200 μM, 300 μM, and 400 μM concentrations resulted in reduced cell viability and increased cleaved caspase 3 levels, while no significant changes were found at 50 μM. There were no effects on neuronal differentiation in the SNP-treated groups. The phosphorylation of p38 was also significantly upregulated with SNP concentrations of 100 μM, 200 μM, 300 μM, and 400 μM, with no changes for 50 μM concentration in comparison with the control. We also observed that the levels of phosphorylation increased with the increasing concentration of SNP. To further explore the possible role of p38 in SNP-regulated survival of differentiated NSCs, SB202190, the antagonist of p38 mitogen-activated protein kinase, at a concentration of 10 mM, was pretreated for 30 min, and the ratio of phosphorylated p38 was found to be decreased after treatment with SNP. Survival and cell viability increased in the SB202190 and SNP co-treated group. Taken together, our results suggested that p38 is involved in the cell survival of NSCs, regulated by NO.

The path to a hemocompatible cardiovascular implant: Advances and challenges of current endothelialization strategies

Cardiovascular (CV) implants are still associated with thrombogenicity due to insufficient hemocompatibility. Endothelialization of their luminal surface is a promising strategy to increase their hemocompatibility. In this review, we provide a collection of research studies and review articles aiming to summarize the recent efforts on surface modifications of CV implants, including stents, grafts, valves, and ventricular assist devises. We focus in particular on the implementation of micrometer or nanoscale surface modifications, physical characteristics of known biomaterials (such as wetness and stiffness), and surface morphological features (such as gratings, fibers, pores, and pits). We also review how biomechanical signals originating from the endothelial cell for surface interaction can be directed by topography engineering approaches toward the survival of the endothelium and its long-term adaptation. Finally, we summarize the regulatory and economic challenges that may prevent clinical implementation of endothelialized CV implants.