Applications of Regenerative Tissue-Engineered Scaffolds for Treatment of Spinal Cord Injury.

Tissue engineering provides a path forward for emerging personalized medicine therapies as well as the ability to bring about cures for diseases or chronic injuries. Traumatic spinal cord injuries (SCIs) are an example of a chronic injury in which no cure or complete functional recovery treatment has been developed. In part, this has been due to the complex and interconnected nature of the central nervous system (CNS), the cellular makeup, its extracellular matrix (ECM), and the injury site pathophysiology.

Release of Zafirlukast from Electrospun Polyisobutylene-Based Fiber Mats to Reduce Capsular Contracture of Silicone Breast Prostheses.

Silicone rubber tissue expanders and breast implants are associated with chronic inflammation, leading to the formation of fibrous capsules. If the inflammation is left untreated, the fibrous capsules can become hard and brittle and lead to formation of capsular contracture. When capsular contracture occurs, implant failure and reoperation is unavoidable.

Chitosan-based multifunctional oxygenating antibiotic hydrogel dressings for managing chronic infection in diabetic wounds.

Current treatment strategies for infection of chronic wounds often result in compromised healing and necrosis due to antibiotic toxicity, and underlying biomarkers affected by treatments are not fully known. Here, a multifunctional dressing was developed leveraging the unique wound-healing properties of chitosan, a natural polysaccharide known for its numerous benefits in wound care. The dressing consists of an oxygenating perfluorocarbon functionalized methacrylic chitosan (MACF) hydrogel incorporated with antibacterial polyhexamethylene biguanide (PHMB).

Investigating post-traumatic syringomyelia and local fluid osmoregulation via a rat model.

Background: Syringomyelia (SM) is characterized by the development of fluid-filled cavities, referred to as syrinxes, within the spinal cord tissue. The molecular etiology of SM post-spinal cord injury (SCI) is not well understood and only invasive surgical based treatments are available to treat SM clinically. This study builds upon our previous omics studies and in vitro cellular investigations to further understand local fluid osmoregulation in post-traumatic SM (PTSM) to highlight important pathways for future molecular interventions.

Comparison of Engineered Liver 3D Models and the Role of Oxygenation for Patient-Derived Tumor Cells and Immortalized Cell Lines Cocultured with Tumor Stroma in the Detection of Hepatotoxins.

In metabolically active tumors, responses of cells to drugs are heavily influenced by oxygen availability via the surrounding vasculature alongside the extracellular matrix signaling. The objective of this study is to investigate hepatotoxicity by replicating critical features of hepatocellular carcinoma (HCC). This includes replicating 3D structures, metabolic activities, and tumor-specific markers.

Fabrication of oxygen-carrying microparticles functionalized with liver ECM-proteins to improve phenotypic three-dimensional in vitro liver assembly, function, and responses.

Oxygen and extracellular matrix (ECM)-derived biopolymers play vital roles in regulating many cellular functions in both the healthy and diseased liver. This study highlights the significance of synergistically tuning the internal microenvironment of three-dimensional (3D) cell aggregates composed of hepatocyte-like cells from the HepG2 human hepatocellular carcinoma cell line and hepatic stellate cells (HSCs) from the LX-2 cell line to enhance oxygen availability and phenotypic ECM ligand presentation for promoting the native metabolic functions of the human liver. First, fluorinated (PFC) chitosan microparticles (MPs) were generated with a microfluidic chip, then their oxygen transport properties were studied using a custom ruthenium-based oxygen sensing approach.

Advancements in bacteriophage therapies and delivery for bacterial infection.

Having co-evolved with bacteria over hundreds of millions of years, bacteriophage are effective killers of specific bacterial hosts. Therefore, phage therapies for infection are a promising treatment avenue, can provide a solution for antibiotic resistant bacterial infections, and have specified targeting of infectious bacteria while allowing the natural microbiome to survive which systemic antibiotics often wipe out. Many phages have well studied genomes that can be modified to change target, widen target range, or change mode of action of killing bacterial hosts.

Osmotic Contribution of Synthesized Betaine by Choline Dehydrogenase Using and Models of Post-traumatic Syringomyelia.

Introduction: Syringomyelia (SM) is a debilitating spinal cord disorder in which a cyst, or syrinx, forms in the spinal cord parenchyma due to congenital and acquired causes. Over time syrinxes expand and elongate, which leads to compressing the neural tissues and a mild to severe range of symptoms. In prior omics studies, significant upregulation of betaine and its synthesis enzyme choline dehydrogenase (CHDH) were reported during syrinx formation/expansion in SM injured spinal cords, but the role of betaine regulation in SM etiology remains unclear.

Modulatory Contribution of Oxygenating Hydrogels and Polyhexamethylene Biguanide on the Antimicrobial Potency of Neutrophil-like Cells.

Neutrophils are a first line of host defense against infection and utilize a series of oxygen-dependent processes to eliminate pathogens. Research suggests that oxygen availability can improve anti-infective mechanisms by promoting the formation of reactive oxygen species. Also, oxygen can synergistically upregulate the antibacterial properties of certain antibiotics against bacteria by altering their metabolism and causing an increase in the antibiotic uptake of bacteria.

Investigating Mechanisms of Subcutaneous Preconditioning Incubation for Neural Stem Cell Embedded Hydrogels.

Stem cells are a vital component of regenerative medicine therapies, however, only a fraction of stem cells delivered to the central nervous system following injury survive the inflammatory environment. Previously, we showed that subcutaneous preconditioning of neural stem cell (NSC) embedded hydrogels for 28 days improved spinal cord injury (SCI) functional outcomes over controls. Here, we investigated the mechanism of subcutaneous preconditioning of NSC-embedded hydrogels, with and without the known neurogenic cue, interferon gamma (IFN-γ), for 3, 14, or 28 days to refine and identify subcutaneous preconditioning conditions by measurement of neurogenic markers and cytokines.

Therapeutic Targeting of Stromal-Tumor HGF-MET Signaling in an Organotypic Triple-Negative Breast Tumor Model.

Unlabelled: The tumor microenvironment (TME) promotes proliferation, drug resistance, and invasiveness of cancer cells. Therapeutic targeting of the TME is an attractive strategy to improve outcomes for patients, particularly in aggressive cancers such as triple-negative breast cancer (TNBC) that have a rich stroma and limited targeted therapies. However, lack of preclinical human tumor models for mechanistic understanding of tumor-stromal interactions has been an impediment to identify effective treatments against the TME.

Generation of Oxygenating Fluorinated Methacrylamide Chitosan Microparticles to Increase Cell Survival and Function in Large Liver Spheroids.

Despite advances in the development of complex culture technologies, the utility, survival, and function of large 3D cell aggregates, or spheroids, are impeded by mass transport limitations. The incorporation of engineered microparticles into these cell aggregates offers a promising approach to increase spheroid integrity through the creation of extracellular spaces to improve mass transport. In this study, we describe the formation of uniform oxygenating fluorinated methacrylamide chitosan (MACF) microparticles via a T-shaped microfluidic device, which when incorporated into spheroids increased extracellular spacing and enhanced oxygen transport via perfluorocarbon substitutions.

Osmoregulatory Role of Betaine and Betaine/γ-Aminobutyric Acid Transporter 1 in Post-Traumatic Syringomyelia.

Syringomyelia (SM) is primarily characterized by the formation of a fluid-filled cyst that forms in the parenchyma of the spinal cord following injury or other pathology. Recent omics studies in animal models have identified dysregulation of solute carriers, channels, transporters, and small molecules associated with osmolyte regulation during syrinx formation/expansion in the spinal cord. However, their connections to syringomyelia etiology are poorly understood.

Advances in removing mass transport limitations for more physiologically relevant 3D cell constructs.

Spheroids and organoids are promising models for biomedical applications ranging from human disease modeling to drug discovery. A main goal of these 3D cell-based platforms is to recapitulate important physiological parameters of their organ counterparts. One way to achieve improved biomimetic architectures and functions is to culture cells at higher density and larger total numbers.

Softening of the chronic hemi-section spinal cord injury scar parallels dysregulation of cellular and extracellular matrix content.

Regeneration following spinal cord injury (SCI) is challenging in part due to the modified tissue composition and organization of the resulting glial and fibrotic scar regions. Inhibitory cell types and biochemical cues present in the scar have received attention as therapeutic targets to promote regeneration. However, altered Young's modulus of the scar as a readout for potential impeding factors for regeneration are not as well-defined, especially in vivo.

Thread Size and Polymer Composition of 3D Printed and Electrospun Wound Dressings Affect Wound Healing Outcomes in an Excisional Wound Rat Model.

Thread size and polymer composition are critical properties to consider for achieving a positive healing outcome with a wound dressing. Three-dimensional (3D) printed scaffolds and electrospun mats both offer distinct advantages as replaceable wound dressings. This research aims to determine if the thread size and polymer compositions of the scaffolds affect skin wound healing outcomes, an aspect that has not been adequately explored.

Metabolomic and Signaling Programs Induced by Immobilized versus Soluble IFN γ in Neural Stem Cells.

Neural stem cells (NSCs) provide a strategy to replace damaged neurons following traumatic central nervous system injuries. A major hurdle to translation of this therapy is that direct application of NSCs to CNS injury does not support sufficient neurogenesis due to lack of proper cues. To provide prolonged spatial cues to NSCs IFN-γ was immobilized to biomimetic hydrogel substrate to supply physical and biochemical signals to instruct the encapsulated NSCs to be neurogenic.

Fluorinated Chitosan Microgels to Overcome Internal Oxygen Transport Deficiencies in Microtissue Culture Systems.

Poor oxygen transport is a major obstacle currently for 3D microtissue culture platforms, which at this time cannot be grown large enough to be truly physiologically relevant and replicate adult human organ functions. To overcome internal oxygen transport deficiencies, oxygenating microgels are formed utilizing perfluorocarbon (PFC) modified chitosan and a highly scalable water-in-oil miniemulsion method. Microgels that are on the order of a cell diameter (≈10 µm) are formed allowing them to directly associate with cells when included in 3D spheroid culture, while not being internalized.

Covalently Immobilizing Interferon-γ Drives Filopodia Production through Specific Receptor-Ligand Interactions Independently of Canonical Downstream Signaling.

Immobilizing a signaling protein to guide cell behavior has been employed in a wide variety of studies. This approach draws inspiration from biology, where specific, affinity-based interactions between membrane receptors and immobilized proteins in the extracellular matrix guide many developmental and homeostatic processes. Synthetic immobilization approaches, however, do not necessarily recapitulate the signaling system and potentially lead to artificial receptor-ligand interactions.

Subcutaneous priming of protein-functionalized chitosan scaffolds improves function following spinal cord injury.

Strategies using neural stem cells (NSCs) to aid regeneration following spinal cord injury (SCI) show much promise, but challenges remain regarding implementation and efficacy. In this work, we explored the use of an NSC-seeded scaffold consisting of covalently immobilized interferon-γ and rat NSCs within a hydrogel matrix (methacrylamide chitosan). We placed the scaffolds within the subcutaneous environment of rats, allowing them to incubate for 4 weeks in order to prime them for regeneration prior to being transplanted into a right lateral hemisection SCI model in the same animal.

Subcutaneous priming of protein-functionalized chitosan scaffolds improves function following spinal cord injury.

Strategies using neural stem cells (NSCs) to aid regeneration following spinal cord injury (SCI) show much promise, but challenges remain regarding implementation and efficacy. In this work, we explored the use of an NSC-seeded scaffold consisting of covalently immobilized interferon- and rat NSCs within a hydrogel matrix (methacrylamide chitosan). We placed the scaffolds within the subcutaneous environment of rats, allowing them to incubate for 4 weeks in order to prime them for regeneration prior to being transplanted into a right lateral hemisection SCI model in the same animal.

pH-dependent RNA isolation from cells encapsulated in chitosan-based biomaterials.

Chitosan has emerged as a useful biomaterial employed in tissue engineering and drug delivery applications due to its tunable and interesting properties. However, chitosan is protonated at biological pH and thus carries positive charges, which renders chitosan incompatible with conventional methods of RNA extraction. RNA extraction is an important step in investigating cell responses and behavior through studying their gene expression transcriptional profiles.

Polyionic Complexed Antibacterial Heparin-Chitosan Particles for Antibiotic Delivery.

Efficient delivery of antibacterial agents directly to sites of tissue injury faces challenges such as poor drug stability and fast degradation by biological mechanisms. Biocompatible nanocarrier systems can help sustain and control the delivery of antibacterial compounds while reducing the chances of antibacterial resistance or accumulation in unwanted tissues. In this study, we report the application of tailored polyionic particles via ionic interactions between negatively charged heparin and positively charge chitosan for efficient encapsulation of polyhexamethylene biguanide (PHMB) antibiotic.