Double blind, randomized, placebo controlled clinical trial for the treatment of diabetic foot ulcers, using a nitric oxide releasing patch: PATHON

Advances in Nitric Oxide-Releasing Hydrogels for Biomedical Applications

Hydrogels provide a plethora of advantages to biomedical treatments due to their highly hydrophilic nature and tissue-like mechanical properties. Additionally, the numerous and widespread endogenous roles of nitric oxide have led to an eruption in research developing biomimetic solutions to the many challenges the biomedical world faces. Though many design factors and fabrication details must be considered, utilizing hydrogels as nitric oxide delivery vehicles provides promising materials in several applications. Such applications include cardiovascular therapy, vasodilation and angiogenesis, antimicrobial treatments, wound dressings, and stem cell research. Herein, a recent update on the progress of NO-releasing hydrogels is presented in depth. In addition, considerations for the design and fabrication of hydrogels and specific biomedical applications of nitric oxide-releasing hydrogels are discussed.

Two-Pronged Microbe Delivery of Nitric Oxide and Oxygen for Diabetic Wound Healing

Chronic inflammation and hypoxia in the microenvironment of diabetic foot ulcers (DFUs) can result in sustained vascular impairment, hindering tissue regeneration. While both nitric oxide and oxygen have been shown to promote wound healing in DFUs through anti-inflammatory and neovascularization, there is currently no available therapy that delivers both. We present a novel hydrogel consisting of Weissella and Chlorella, which alternates between nitric oxide and oxygen production to reduce chronic inflammation and hypoxia. Further experiments indicate that the hydrogel accelerates wound closure, re-epithelialization, and angiogenesis in diabetic mice and improves the survival of skin grafts. This dual-gas therapy holds promise as a potential treatment option for the management of diabetic wounds.

Biodegradable Electrospun Scaffolds as an Emerging Tool for Skin Wound Regeneration: A Comprehensive Review

Skin is designed to protect various tissues, and because it is the largest and first human bodily organ to sustain damage, it has an incredible ability to regenerate. On account of extreme injuries or extensive surface loss, the normal injury recuperating interaction might be inadequate or deficient, bringing about risky and disagreeable circumstances that request the utilization of fixed adjuvants and tissue substitutes. Due to their remarkable biocompatibility, biodegradability, and bioactive abilities, such as antibacterial, immunomodulatory, cell proliferative, and wound mending properties, biodegradable polymers, both synthetic and natural, are experiencing remarkable progress. Furthermore, the ability to convert these polymers into submicrometric filaments has further enhanced their potential (e.g., by means of electrospinning) to impersonate the stringy extracellular grid and permit neo-tissue creation, which is a basic component for delivering a mending milieu. Together with natural biomaterial, synthetic polymers are used to solve stability problems and make scaffolds that can dramatically improve wound healing. Biodegradable polymers, commonly referred to as biopolymers, are increasingly used in other industrial sectors to reduce the environmental impact of material and energy usage as they are fabricated using renewable biological sources. Electrospinning is one of the best ways to fabricate nanofibers and membranes that are very thin and one of the best ways to fabricate continuous nanomaterials with a wide range of biological, chemical, and physical properties. This review paper concludes with a summary of the electrospinning (applied electric field, needle-to-collector distance, and flow rate), solution (solvent, polymer concentration, viscosity, and solution conductivity), and environmental (humidity and temperature) factors that affect the production of nanofibers and the use of bio-based natural and synthetic electrospun scaffolds in wound healing.

Nitric oxide-releasing biomaterials for promoting wound healing in impaired diabetic wounds: State of the art and recent trends

Impaired diabetic wounds are serious pathophysiological complications associated with persistent microbial infections including failure in the closure of wounds, and the cause of a high frequency of lower limb amputations. The healing of diabetic wounds is attenuated due to the lack of secretion of growth factors, prolonged inflammation, and/or inhibition of angiogenic activity. Diabetic wound healing can be enhanced by supplying nitric oxide (NO) endogenously or exogenously. NO produced inside the cells by endothelial nitric oxide synthase (eNOS) naturally aids wound healing through its beneficial vasculogenic effects. However, during hyperglycemia, the activity of eNOS is affected, and thus there becomes an utmost need for the topical supply of NO from exogenous sources. Thus, NO-donors that can release NO are loaded into wound healing patches or wound coverage matrices to treat diabetic wounds. The burst release of NO from its donors is prevented by encapsulating them in polymeric hydrogels or nanoparticles for supplying NO for an extended duration of time to the diabetic wounds. In this article, we review the etiology of diabetic wounds, wound healing strategies, and the role of NO in the wound healing process. We further discuss the challenges faced in translating NO-donors as a clinically viable nanomedicine strategy for the treatment of diabetic wounds with a focus on the use of biomaterials for the encapsulation and in vivo controlled delivery of NO-donors.

Bio-Based Electrospun Fibers for Wound Healing

Being designated to protect other tissues, skin is the first and largest human body organ to be injured and for this reason, it is accredited with a high capacity for self-repairing. However, in the case of profound lesions or large surface loss, the natural wound healing process may be ineffective or insufficient, leading to detrimental and painful conditions that require repair adjuvants and tissue substitutes. In addition to the conventional wound care options, biodegradable polymers, both synthetic and biologic origin, are gaining increased importance for their high biocompatibility, biodegradation, and bioactive properties, such as antimicrobial, immunomodulatory, cell proliferative, and angiogenic. To create a microenvironment suitable for the healing process, a key property is the ability of a polymer to be spun into submicrometric fibers (e.g., via electrospinning), since they mimic the fibrous extracellular matrix and can support neo- tissue growth. A number of biodegradable polymers used in the biomedical sector comply with the definition of bio-based polymers (known also as biopolymers), which are recently being used in other industrial sectors for reducing the material and energy impact on the environment, as they are derived from renewable biological resources. In this review, after a description of the fundamental concepts of wound healing, with emphasis on advanced wound dressings, the recent developments of bio-based natural and synthetic electrospun structures for efficient wound healing applications are highlighted and discussed. This review aims to improve awareness on the use of bio-based polymers in medical devices.

Mesenchymal stem cell cultivation in electrospun scaffolds: mechanistic modeling for tissue engineering

Tissue engineering is a multidisciplinary field of research in which the cells, biomaterials, and processes can be optimized to develop a tissue substitute. Three-dimensional (3D) architectural features from electrospun scaffolds, such as porosity, tortuosity, fiber diameter, pore size, and interconnectivity have a great impact on cell behavior. Regarding tissue development in vitro, culture conditions such as pH, osmolality, temperature, nutrient, and metabolite concentrations dictate cell viability inside the constructs. The effect of different electrospun scaffold properties, bioreactor designs, mesenchymal stem cell culture parameters, and seeding techniques on cell behavior can be studied individually or combined with phenomenological modeling techniques. This work reviews the main culture and scaffold factors that affect tissue development in vitro regarding the culture of cells inside 3D matrices. The mathematical modeling of the relationship between these factors and cell behavior inside 3D constructs has also been critically reviewed, focusing on mesenchymal stem cell culture in electrospun scaffolds.

Application of electrospun fibers for female reproductive health

Here, we present the current challenges in women's reproductive health and the current state-of-the-art treatment and prevention options for STI prevention, contraception, and treatment of infections. We discuss how the versatile platform of electrospun fibers can be applied to each challenge, and postulate at how these technologies could be improved. The void of approved electrospun fiber-based products yields the potential to apply this useful technology to a number of medical applications, many of which are relevant to women's reproductive health. Given the ability to tune drug delivery characteristics and three-dimensional geometry, there are many opportunities to pursue new product designs and routes of administration for electrospun fibers. For each application, we provide an overview of the versatility of electrospun fibers as a novel dosage form and summarize their advantages in clinical applications. We also provide a perspective on why electrospun fibers are well-suited for a variety of applications within women's reproductive health and identify areas that could greatly benefit from innovations with electrospun fiber-based approaches.

Advancements and Challenges in Multidomain Multicargo Delivery Vehicles

Reparative and regenerative processes are well-orchestrated temporal and spatial events that are governed by multiple cells, molecules, signaling pathways, and interactions thereof. Yet again, currently available implantable devices fail largely to recapitulate nature's complexity and sophistication in this regard. Herein, success stories and challenges in the field of layer-by-layer, composite, self-assembly, and core-shell technologies are discussed for the development of multidomain/multicargo delivery vehicles.

In pursuit of functional electrospun materials for clinical applications in humans

Electrospinning is a simple, low-cost and versatile approach to fabricate multifunctional materials useful in drug delivery and tissue engineering applications. Despite its emergence into other manufacturing sectors, electrospinning has not yet made a transformative impact in the clinic with a pharmaceutical product for use in humans. Why is this the current state of electrospun materials in biomedicine? Is it because electrospun materials are not yet capable of overcoming the biological safety and efficacy challenges needed in pharmaceutical products? Or, is it that technological advances in the electrospinning process are needed? This review investigates the current state of electrospun materials in medicine to identify both scientific and technological gaps that may limit clinical translation.

Advantages and challenges offered by biofunctional core-shell fiber systems for tissue engineering and drug delivery

Whereas highly porous scaffolds composed of electrospun nanofibers can mimick major features of the extracellular matrix in tissue engineering, they lack the ability to incorporate and release biocompounds (drugs, growth factors) safely in a controlled way. Here, electrospun core-shell fibers (core made from water and aqueous solutions of hydrophilic polymers and the shell from materials with well-defined release mechanisms) offer unique advantages in comparison with those that have helped make porous nanofibrillar scaffolds highly successful in tissue engineering. This review considers the preparation and biofunctionalization of such core-shell fibers as well as applications in various areas, including neural, vascular, cardiac, cartilage and bone tissue engineering, and touches on the topic of clinical trials.

The effect of nitric oxide releasing cream on healing pressure ulcers

BACKGROUND

Pressure ulcer is one of the main concerns of nurses in medical centers around the world, which, if untreated, causes irreparable problems for patients. In recent years, nitric oxide (NO) has been proposed as an effective method for wound healing. This study was conducted to determine the effect of nitric oxide on pressure ulcer healing.

MATERIALS AND METHODS

In this clinical trial, 58 patients with pressure ulcer at hospitals affiliated to Ahvaz Jundishapur University of Medical Sciences were homogenized and later divided randomly into two groups of treatment (nitric oxide cream; n = 29) and control (placebo cream; n = 29). In this research, the data collection tool was the Pressure Ulcer Scale for Healing (PUSH). At the outset of the study (before using the cream), the patients' ulcers were examined weekly in terms of size, amount of exudates, and tissue type using the PUSH tool for 3 weeks. By integrating these three factors, wound healing was determined. Data were analyzed using SPSS.

RESULTS

Although no significant difference was found in terms of the mean of score size, the amount of exudates, and the tissue type between the two groups, the mean of total score (healing) between the two groups was statistically significant (P = 0.04).

CONCLUSIONS

Nitric oxide cream seems to accelerate wound healing. Therefore, considering its easy availability and cost-effectiveness, it can be used for treating pressure ulcers in the future.

Use of a fibrin-based system for enhancing angiogenesis and modulating inflammation in the treatment of hyperglycemic wounds

The complex pathophysiology of chronic ulceration in diabetic patients is poorly understood; diabetes-related lower limb amputation is a major health issue, which has limited effective treatment regimes in the clinic. This study attempted to understand the complex pathology of hyperglycemic wound healing by showing profound changes in gene expression profiles in wounded human keratinocytes in hyperglycemic conditions compared to normal glucose conditions. In the hyper-secretory wound microenvironment of hyperglycemia, Rab18, a secretory control molecule, was found to be significantly downregulated. Using a biomaterial platform for dual therapy targeting the two distinct pathways, this study aimed to resolve the major dysregulated pathways in hyperglycemic wound healing. To complement Rab18, and promote angiogenesis eNOS was also targeted, and this novel Rab18-eNOS therapy via a dynamically controlled 'fibrin-in-fibrin' delivery system, demonstrated enhanced wound closure, by increasing functional angiogenesis and reducing inflammation, in an alloxan-induced hyperglycemic preclinical ear ulcer model of compromised wound healing.

Electrospun fibers for vaginal anti-HIV drug delivery

Diversity of microbicide delivery systems is essential for future success in the prevention and treatment of HIV in order to account for the varied populations of women all over the world that may benefit from use of these products. Recently, a novel dosage form for intravaginal drug delivery has been developed using drug-eluting fibers fabricated by electrospinning. There is a strong rationale to support the idea that drug-eluting fibers can be designed to realize multiple design constraints in a single product for topical HIV prevention: fibers are able to deliver a wide range of agents, incorporate multiple agents via composites, and facilitate controlled release over relevant time frames for pericoital and sustained (coitally-independent) use. It is also technologically feasible to scale-up production of fiber-based microbicides. Electrospun fibers may allow for prioritization of physical attributes that affect user perceptions without compromising biological efficacy. Challenges with using fibers as a microbicide include issues related to vehicle deployment, spreading and retention in the vaginal vault. In addition, studies will need to address the interaction of the fibers with the mucosal environment, including unknown safety and toxicity. Sustained release fiber microbicides capable of delivering multiple antiretroviral drugs while simultaneously exhibiting tunable degradation or dissolution of the fibers is also a challenge. However, electrospun fibers are a promising new platform for vaginal delivery of anti-HIV agents and future research will inform their place in the field. This article is based on a presentation at the "Product Development Workshop 2013: HIV and Multipurpose Prevention Technologies", held in Arlington, Virginia on February 20-21, 2013. It forms part of a special supplement to Antiviral Research.

Characterization of novel nitrite-based nitric oxide generating delivery systems for topical dermal application

Topical application of nitric oxide (NO) has been shown to exert beneficial effects in the therapy of chronic wounds, impaired microcirculation, and skin infections. Nitrite acidified by ascorbic acid has been widely used in many studies as NO-donor system, unfortunately with inflammatory and toxic effects on the treated skin due to unregulated excessive NO generation, low pH and possible toxic side products. Here we describe an essentially modified nitrite based NO generating system that avoid the mentioned unwanted side effects on human skin by using a pH-stable acetate/acetic acid buffer with a skin neutral pH of 5.5 and sodium ascorbate. In order to overcome the shortcoming of lower NO yields due to the higher pH-value and low nitrite concentrations, we have determined additionally the influence of copper ions. To investigate the influence of different NO release and penetration kinetics on NO-induced toxicity, we have developed a fibroblast assay using cell culture plates with gas permeable bottoms. The results show clearly that the donor system can achieve a sustained NO generation without generating high peaks. Furthermore, the presence of Cu(2+) ions enhances manifold NO generation of pH/ascorbate-induced nitrite decomposition, a mechanism comprising the reduction of Cu(2+) ions to Cu(1+) by ascorbate. Finally, we have found that apart from the NO dose the NO release kinetics had a significant influence of cell toxicity. Thus, application of comparable NO amounts within a time interval of 600s led to the development of variable cell toxicities, which predominantly depended on the NO concentration values generated in the first 200s. In summary, we here describe a novel nitrite-based NO-donor system that can provide well defined NO concentrations at skin neutral pH-values for side effect poor topical dermal application, i.e. in the therapy of chronic wounds and impaired microcirculation.

Healing potential of Rosmarinus officinalis L. on full-thickness excision cutaneous wounds in alloxan-induced-diabetic BALB/c mice

AIM OF THE STUDY

Rosmarinus officinalis (Rosemary) used in Jordanian folk medicine for wound management and treatment. Therefore, the present study was conducted to assess the healing efficacy of both aqueous extract and essential oil of the aerial parts on alloxan-induced diabetic BALB/c mice.

MATERIALS AND METHODS

Two full-thickness round wounds were created in the dorsal area of each mouse. Animals were divided into four groups of twenty mice each: untreated normal, untreated diabetic, aqueous extract- (intraperitoneal injection of 0.2 ml at a dose of 10% for 3 days) and essential oil-treated diabetic mice (topical application of 25 microl/excision wound, twice a day for 3 days). For 15 days, the wounds were visually observed; blood glucose level, body weight, regenerated granulation tissue weight and the percentage of wound contraction were measured. On days 6 and 15 after wounding, the animals were sacrificed and the histology of wound area was examined.

RESULTS

Significant positive differences (p<0.01) between treated and control groups were observed at different aspects of diabetic wound healing process. Reduced inflammation and enhanced wound contraction, re-epithelialization, regeneration of granulation tissue, angiogenesis and collagen deposition were detected in the treated wounds.

CONCLUSIONS

Results indicated that the essential oil of Rosmarinus officinalis was the most active in healing diabetic wounds and provide a scientific evidence for the traditional use of this herb in wound treatment. However, further scientific verification is required to confirm and assess the range of wound healing potential of essential oils of Rosemary chemotypes.

Fabrication of nonwoven coaxial fiber meshes by electrospinning

There is a great need for biodegradable polymer scaffolds that can regulate the delivery of bioactive factors such as drugs, plasmids, and proteins. Coaxial electrospinning is a novel technique that is currently being explored to create such polymer scaffolds by embedding within them aqueous-based biological molecules. In this study, we evaluated the influence of various processing parameters such as sheath polymer concentration, core polymer concentration and molecular weight, and salt ions within the core polymer on coaxial fiber morphology. The sheath polymer used in this study was poly(e-caprolactone) (PCL), and the core polymer was poly(ethylene glycol) (PEG). We examined the effects of the various processing parameters on core diameters, total fiber diameters, and sheath thicknesses of coaxial microfibers using a 2(4) full factorial statistical model. The maximum increase in total fiber diameter was observed with increase in sheath polymer (PCL) concentration from 9 to 11 wt% (0.49+/-0.03 microm) and salt concentration within the core from 0 to 500 mM (0.38+/-0.03 microm). The core fiber diameter was most influenced by the sheath and core polymer (PCL and PEG, respectively) concentrations, the latter of which increased from 200 to 400 mg/mL (0.40+/-0.01 microm and 0.36+/-0.01 microm, respectively). The core polymer (PEG) concentration had a maximal negative effect on sheath thickness (0.40+/-0.03 microm), while salt concentration had the maximal positive effect (0.28+/-0.03 microm). Molecular weight increases in core polymer (PEG) from 1.0 to 4.6 kDa caused moderate increases in total and sheath fiber diameters and sheath thicknesses. These experiments provide important information that lays the foundation required for the synthesis of coaxial fibers with tunable dimensions.

Nitric oxide-donating materials and their potential in pharmacological applications for site-specific nitric oxide delivery

The discovery of various regulatory, protective and deleterious effects of nitric oxide (NO) has prompted intense research activity in the design and synthesis of NO-donating drugs and materials that can be used to modulate the effective concentrations of NO at biological targets. To date, various NO-donating compounds have been incorporated or immobilized in biocompatible polymer matrices and such materials have been used as patches, wound dressings, coatings on blood-contacting medical devices and time-release NO drugs. Recently, attention has been drawn toward light-sensitive NO donors, such as S-nitrosothiols and metal nitrosyls, which can deliver NO at selected targets under the total control of light. The pharmacological potential of such NO-donating materials including those with immobilized photoactive NO donors are reviewed in this article.

Advancing tissue engineering by using electrospun nanofibers

Electrospinning is a versatile technique that enables the development of nanofiber-based scaffolds, from a variety of polymers that may have drug-release properties. Using nanofibers, it is now possible to produce biomimetic scaffolds that can mimic the extracellular matrix for tissue engineering. Interestingly, nanofibers can guide cell growth along their direction. Combining factors like fiber diameter, alignment and chemicals offers new ways to control tissue engineering. In vivo evaluation of nanomats included their degradation, tissue reactions and engineering of specific tissues. New advances made in electrospinning, especially in drug delivery, support the massive potential of these nanobiomaterials. Nevertheless, there is already at least one product based on electrospun nanofibers with drug-release properties in a Phase III clinical trial, for wound dressing. Hopefully, clinical applications in tissue engineering will follow to enhance the success of regenerative therapies.

Sustained release nitric oxide releasing nanoparticles: characterization of a novel delivery platform based on nitrite containing hydrogel/glass composites

A new platform using biocompatible materials is presented for generating powders comprised of nanoparticles that release therapeutic levels of nitric oxide (NO) in a controlled and sustained manner. The capacity of these particles to retain and gradually release NO arises from their having combined features of both glassy matrices and hydrogels. This feature allows both for the generation of NO through the thermal reduction of added nitrite by glucose and for the retention of the generated NO within the dry particles. Exposure of these robust biocompatible nanoparticles to moisture initiates the sustained release of the trapped NO over extended time periods as determined both fluorimetrically and amperometrically. The slow sustained release is in contrast to the much faster release pattern associated with the hydration-initialed NO release in powders derived from glassy matrices. These glasses are prepared using trehalose and sucrose doped with either glucose or tagatose as the source of thermal electrons needed to convert nitrite to gNO. Significantly, the release profiles for the NO in the hydrogel/glass composite materials are found to be an easily tuned parameter that is modulated through the specific additives used in preparing the hydrogel/glass composites. The presented data raise the prospect that these new NO releasing nanoparticles can be easily formulated for use under a wide range of therapeutic circumstances.