Predictive Model for Design of a 3D Developmental Neurotoxicity Platform

Exposure to developmental toxins during gestation have been shown to be linked to neurological disorders such as epilepsy, schizophrenia, and dyslexia [1] . In this report we describe efforts that represent the ground work to develop a predictive neurotoxicity model to test developmental toxicity on early neuronal differentiation from drugs and toxins for human consumption or exposure. Developmental toxins are toxins that prevent stem cell differentiation into neurons by impacting neural development [2] . Currency technologies used to evaluate a compound\u27s potential as a developmental toxin are centered around culturing stem cells in a two-dimensional environment or exposing animal models to the compound. The stem cells are then monitored for changes in proliferation, differentiation, and death. These classes of experiments proved not only to be expensive, but also extremely time consuming and ineffective in some cases. These technologies do not accurately mimic the in vivo environment, which uses ECM proteins and cell-cell interactions to regulate cellular functions such as migration, apoptosis, and gene expression. Our predictive model would provide a more biologically accurate alternative of the human system compared to two-dimensional cell culture and animal models. Our model would further improve the quality and relevance of developmental neurotoxicity research, reduce the number of animal experiments and overall cost to evaluate the potential for a compound to act as a developmental toxin

Role of Nanoparticle–Polymer Interactions on the Development of Double-Network Hydrogel Nanocomposites with High Mechanical Strength

Extensive experimental and theoretical research over the past several decades has pursued strategies to develop hydrogels with high mechanical strength. Our study investigated the effect of combining two approaches, addition of nanoparticles and crosslinking two different polymers (to create double-network hydrogels), on the mechanical properties of hydrogels. Our experimental analyses revealed that these orthogonal approaches may be combined to synthesize hydrogel composites with enhanced mechanical properties. However, the enhancement in double network hydrogel elastic modulus due to incorporation of nanoparticles is limited by the ability of the nanoparticles to strongly interact with the polymers in the network. Moreover, double-network hydrogel nanocomposites prepared using lower monomer concentrations showed higher enhancements in elastic moduli compared to those prepared using high monomer concentrations, thus indicating that the concentration of hydrogel monomers used for the preparation of the nanocomposites had a significant effect on the extent of nanoparticle-mediated enhancements. Collectively, these results demonstrate that the hypotheses previously developed to understand the role of nanoparticles on the mechanical properties of hydrogel nanocomposites may be extended to double-network hydrogel systems and guide the development of next-generation hydrogels with extraordinary mechanical properties through a combination of different approaches

Sodium Hyaluronate Based Drug Delivery to the Outer and Inner Ear

We have developed two projects using sodium hyaluronate (HA)-based systems for drug delivery to the ear. First, we investigated an HA-based hydrogel for use as a single use antibiotic treatment for otitis externa. Otitis externa, also known as outer ear infection, is a frequent affliction in both humans and animals. The most prevalent treatment for otitis externa is ear drops, but it is difficult to adhere properly to this treatment, causing poor patient compliance and the potential for complications. As a result, we have developed an HA-based hydrogel for use as a single application treatment for otitis externa to increase ease of use and improve patient outcomes. Herein, we studied the manufacturability, applicability, and shelf life of the hydrogels. We found that the hydrogels have a robust and scalable manufacturing process, have multiple supply chain options, and have a wide tolerance for pH adjustment and HA concentration, simplifying the manufacturing process. We also found that the hydrogels are highly appliable for use as a single application therapeutic for otitis externa. They are capable of loading and releasing a wide variety of model drugs, and alternative loading strategies can be utilized to alter the release profiles. The hydrogels are not skin irritants, and drug release from the hydrogels is not impacted by physiologically relevant factors. Finally, we investigated the shelf life of the hydrogels, and found that the shelf life of the hydrogels is impacted by both HA concentration and molecular weight. Additionally, we are currently developing topically applied treatments for hearing loss based on HA. In this work, we investigated the impact of HA molecular weight on permeation through in vitro models of the tympanic and round window membranes. We found that HA with a lower molecular weight has higher permeability through both membranes. Additionally, we found that the round window membrane has much higher HA permeability than the tympanic membrane

Multifunctional Hydrogel Nanocomposites for Biomedical Applications

Hydrogels are used for various biomedical applications due to their biocompatibility, capacity to mimic the extracellular matrix, and ability to encapsulate and deliver cells and therapeutics. However, traditional hydrogels have a few shortcomings, especially regarding their physical properties, thereby limiting their broad applicability. Recently, researchers have investigated the incorporation of nanoparticles (NPs) into hydrogels to improve and add to the physical and biochemical properties of hydrogels. This brief review focuses on papers that describe the use of nanoparticles to improve more than one property of hydrogels. Such multifunctional hydrogel nanocomposites have enhanced potential for various applications including tissue engineering, drug delivery, wound healing, bioprinting, and biowearable devices

Tetraethyl Orthosilicate-Based Hydrogels for Drug Delivery—Effects of Their Nanoparticulate Structure on Release Properties

Tetraethyl orthosilicate (TEOS)-based hydrogels, with shear stress response and drug releasing properties, can be formulated simply by TEOS hydrolysis followed by volume corrections with aqueous solvents and pH adjustments. Such basic thixotropic hydrogels (thixogels) form via the colloidal aggregation of nanoparticulate silica. Herein, we investigated the effects of the nanoparticulate building blocks on the drug release properties of these materials. Our data indicate that the age of the hydrolyzed TEOS used for the formulation impacts the nanoparticulate structure and stiffness of thixogels. Moreover, the mechanism of formation or the disturbance of the nanoparticulate network significantly affects the release profiles of the incorporated drug. Collectively, our results underline the versatility of these basic, TEOS-only hydrogels for drug delivery applications

In vitro characterization of novel hyaluronan-antioxidant conjugates as potential topical therapeutics against hearing loss

Noise-induced hearing loss affects roughly 430 million people worldwide. Current treatment options often require invasive medical procedures, and to date, there are no FDA-approved drug therapies. While the causes can be diverse, noise induced hearing loss is unequivocally associated with oxidative stress and inflammation, and subsequent damage to the inner ear structures. Several studies have shown that various antioxidants such as glutathione, cysteine, and methionine can be used to mitigate oxidative damage from reactive oxygen species; however, these studies relied on invasive or systemic drug delivery methods. This study focused on the development and characterization of a novel series of antioxidant compounds that would be suitable for non or minimally invasive topical inner ear delivery and could mitigate reactive oxygen species associated cellular damage. Specifically, a series of covalent conjugates were synthesized by using hyaluronan as a drug carrier, and methionine, cysteine or glutathione as antioxidant drugs. The conjugates were tested for their ability to readily permeate though in vitro round window membrane and tympanic membrane permeation models, as well as their in vitro internalization into cochlear cells. Our data revealed interdependence between the molecular weight of the hyaluronan carrier, and the tissue and cellular membrane permeation capacity. Subsequent screening of the adequately sized conjugates in in vitro acellular assays revealed the strongest antioxidant activity for the cysteine and glutathione conjugates. These oxidative stress protective effects were further confirmed in cellular in vitro assays. Collectively, the data herein showcase the potential value of these conjugates as therapeutics against oxidative-stress-mediated cellular damage specific to noise-induced hearing loss

DataSheet1_Hyaluronic acid-ibuprofen conjugation: a novel ototherapeutic approach protecting inner ear cells from inflammation-mediated damage.PDF

There is a substantial need of effective drugs for the treatment of hearing loss, which affects nearly 500 million individuals globally. Hearing loss can be the result of intense or prolonged noise exposure, ototoxic drugs, infections, and trauma, which trigger inflammatory signaling cascades that lead to irreversible damage to cochlear structures. To address this, we developed and characterized a series of covalent conjugates of anti-inflammatory drugs to hyaluronic acid (HA), for potential use as topical ototherapeutics. These conjugates were tested in in vitro assays designed to mirror physiological processes typically observed with acoustic trauma. Intense noise exposure leads to macrophage recruitment to the cochlea and subsequent inflammatory damage to sensory cells. We therefore first tested our conjugates’ ability to reduce the release of inflammatory cytokines in macrophages. This anti-inflammatory effect on macrophages also translated to increased cochlear cell viability. In our initial screening, one conjugate, ibuprofen-HA, demonstrated significantly higher anti-inflammatory potential than its counterparts. Subsequent cytokine release profiling of ibuprofen-HA further confirmed its ability to reduce a wider range of inflammatory markers, to a greater extent than its equivalent unconjugated drug. The conjugate’s potential as a topical therapeutic was then assessed in previously developed tympanic and round window membrane tissue permeation models. As expected, our data indicate that the conjugate has limited tympanic membrane model permeability; however, it readily permeated the round window membrane model and to a greater extent than the unconjugated drug. Interestingly, our data also revealed that ibuprofen-HA was well tolerated in cellular and tissue cytocompatibility assays, whereas the unconjugated drug displayed significant cytotoxicity at equivalent concentrations. Moreover, our data highlighted the importance of chemical conjugation of ibuprofen to HA; the conjugate had improved anti-inflammatory effects, significantly reduced cytotoxicity, and is more suitable for therapeutic formulation. Overall, this work suggests that ibuprofen-HA could be a promising safe and effective topical ototherapeutic for inflammation-mediated cochlear damage.</p