An in vitro study of non-aligned or aligned electrospun poly(methyl methacrylate) nanofibers as primary rat astrocytes-loading scaffold

Electrospun drug-loaded scaffolds for nervous system repair

Nervous system injuries, encompassing peripheral nerve injury (PNI), spinal cord injury (SCI), and traumatic brain injury (TBI), present significant challenges to patients' wellbeing. Traditional treatment approaches have limitations in addressing the complexity of neural tissue regeneration and require innovative solutions. Among emerging strategies, implantable materials, particularly electrospun drug-loaded scaffolds, have gained attention for their potential to simultaneously provide structural support and controlled release of therapeutic agents. This review provides a thorough exploration of recent developments in the design and application of electrospun drug-loaded scaffolds for nervous system repair. The electrospinning process offers precise control over scaffold characteristics, including mechanical properties, biocompatibility, and topography, crucial for creating a conducive environment for neural tissue regeneration. The large surface area of the resulting fibrous networks enhances biomolecule attachment, influencing cellular behaviors such as adhesion, proliferation, and migration. Polymeric electrospun materials demonstrate versatility in accommodating a spectrum of therapeutics, from small molecules to proteins. This enables tailored interventions to accelerate neuroregeneration and mitigate inflammation at the injury site. A critical aspect of this review is the examination of the interplay between structural properties and pharmacological effects, emphasizing the importance of optimizing both aspects for enhanced therapeutic outcomes. Drawing upon the latest advancements in the field, we discuss the promising outcomes of preclinical studies using electrospun drug-loaded scaffolds for nervous system repair, as well as future perspectives and considerations for their design and implementation. This article is categorized under: Implantable Materials and Surgical Technologies > Nanomaterials and Implants Implantable Materials and Surgical Technologies > Nanotechnology in Tissue Repair and Replacement Therapeutic Approaches and Drug Discovery > Emerging Technologies.

Tissue Engineering Neovagina for Vaginoplasty in Mayer-Rokitansky-Küster-Hauser Syndrome and Gender Dysphoria Patients: A Systematic Review

Background: Vaginoplasty is a surgical solution to multiple disorders, including Mayer-Rokitansky-Küster-Hauser syndrome and male-to-female gender dysphoria. Using nonvaginal tissues for these reconstructions is associated with many complications, and autologous vaginal tissue may not be sufficient. The potential of tissue engineering for vaginoplasty was studied through a systematic bibliography search. Cell types, biomaterials, and signaling factors were analyzed by investigating advantages, disadvantages, complications, and research quantity. Search Methods: A systematic search was performed in Medline, EMBASE, Web of Science, and Scopus until March 8, 2022. Term combinations for tissue engineering, guided tissue regeneration, regenerative medicine, and tissue scaffold were applied, together with vaginoplasty and neovagina. The snowball method was performed on references and a Google Scholar search on the first 200 hits. Original research articles on human and/or animal subjects that met the inclusion (reconstruction of vaginal tissue and tissue engineering method) and no exclusion criteria (not available as full text; written in foreign language; nonoriginal study article; genital surgery other than neovaginal reconstruction; and vaginal reconstruction with autologous or allogenic tissue without tissue engineering or scaffold) were assessed. The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) checklist, the Newcastle-Ottawa Scale, and the Gold Standard Publication Checklist were used to evaluate article quality and bias. Outcomes: A total of 31 out of 1569 articles were included. Data extraction was based on cell origin and type, biomaterial nature and composition, host species, number of hosts and controls, neovaginal size, replacement fraction, and signaling factors. An overview of used tissue engineering methods for neovaginal formation was created, showing high variance of cell types, biomaterials, and signaling factors and the same topics were rarely covered multiple times. Autologous vaginal cells and extracellular matrix-based biomaterials showed preferential properties, and stem cells carry potential. However, quality confirmation of orthotopic cell-seeded acellular vaginal matrix by clinical trials is needed as well as exploration of signaling factors for vaginoplasty. Impact statement General article quality was weak to sufficient due to unreported cofounders and incomplete animal study descriptions. Article quality and heterogenicity made identification of optimal cell types, biomaterials, or signaling factors unreliable. However, trends showed that autologous cells prevent complications and compatibility issues such as healthy cell destruction, whereas stem cells prevent cross talk (interference of signaling pathways by signals from other cell types) and rejection (but need confirmation testing beyond animal trials). Natural (orthotopic) extracellular matrix biomaterials have great preferential properties that encourage future research, and signaling factors for vascularization are important for tissue engineering of full-sized neovagina.

Ultra-High Packing Density Next Generation Microtube Array Membrane for Absorption Based Applications

Previously, we successfully developed an extracorporeal endotoxin removal device (EERD) that is based on the novel next generation alternating microtube array membrane (MTAM-A) that was superior to the commercial equivalent. In this article, we demonstrated multiple different parameter modifications that led to multiple different types of novel new MTAM structures, which ultimately led to the formation of the MTAM-A. Contrary to the single layered MTAM, the MTAM-A series consisted of a superior packing density fiber connected in a double layered, alternating position which allowed for the greater fiber count to be packed per unit area. The respective MTAM variants were electrospun by utilizing our internally developed tri-axial electrospinning set up to produce the novel microstructures as seen in the respective MTAM variants. A key uniqueness of this study is the ability to produce self-arranged fibers into the respective MTAM variants by utilizing a single spinneret, which has not been demonstrated before. Of the MTAM variants, we observed a change in the microstructure from a single layered MTAM to the MTAM-A series when the ratio of surfactant to shell flow rate approaches 1:1.92. MTAM-A registered the greatest surface area of 2.2 times compared to the traditional single layered MTAM, with the greatest tensile strength at 1.02 ± 0.13 MPa and a maximum elongation of 57.70 ± 9.42%. The MTAM-A was selected for downstream immobilization of polymyxin B (PMB) and assembly into our own internally developed and fabricated dialyzer housing. Subsequently, the entire setup was tested with whole blood spiked with endotoxin; and benchmarked against commercial Toraymyxin fibers of the same size. The results demonstrated that the EERD based on the MTAM-A performed superior to that of the commercial equivalent, registering a rapid reduction of 73.18% of endotoxin (vs. Toraymyxin at 38.78%) at time point 15 min and a final total endotoxin removal of 89.43% (vs. Toraymyxin at 65.03%).

A combinatorial approach to modulate microenvironment toward regeneration and repair after spinal cord injury in rats

Traumatic spinal cord injury (SCI) is a devastating condition of CNS which leads to loss of sensory as well as motor functions. Secondary damage after SCI initiates cascade of events that creates an inhibitory milieu for axonal growth and repair. Combinatorial therapies are the hope to attenuate secondary injury progression and make the microenvironment growth and repair friendly for the neurons. We fabricated gelatin- genipin hydrogel system which was impregnated with IONPs and injected at the lesion site in a clinically relevant contusion rat model of SCI. 24 h later, the rats were exposed to magnetic fields (17.96 μT, 50 Hz uniform EMF) for 2 h/day for 5 weeks. A significant (P < 0.001) improvement in Basso, Beattie and Bresnahan (BBB) locomotor score, amplitude and threshold of spinally mediated reflexes and motor and somatosensory evoked potentials (MEP & SSEP) was observed following IONPs implantation and EMF exposure. Moreover, retrograde tracing showed a higher level of neuronal connectivity and survival after the intervention. There was also a reduction in activated microglia and lesion volume which attenuate secondary damage as evident by reduction in the scaring following intervention for 5 weeks. Moreover, we observed increase in the neuronal growth cone marker, GAP-43, growth promoting neurotrophins (GDNF, BDNF & NT-3) and reduction in the inhibitory molecule (Nogo-A) after this combinatorial therapy. We obsrvered that a significant improvement in behavioral, electrophysiological and morphological parameters was due to an alteration in neurotrophin levels, reduction in activated microglia and increase in GAP-43 expression after the combinatorial therapy. We propose that implantation of IONPs embedded gelatin-genipin hydrogel system along with MF exposure modulated the microenvironment, making it conducive for neural repair and regeneration.

Electrospun Fiber Scaffolds for Engineering Glial Cell Behavior to Promote Neural Regeneration

Electrospinning is a fabrication technique used to produce nano- or micro- diameter fibers to generate biocompatible, biodegradable scaffolds for tissue engineering applications. Electrospun fiber scaffolds are advantageous for neural regeneration because they mimic the structure of the nervous system extracellular matrix and provide contact guidance for regenerating axons. Glia are non-neuronal regulatory cells that maintain homeostasis in the healthy nervous system and regulate regeneration in the injured nervous system. Electrospun fiber scaffolds offer a wide range of characteristics, such as fiber alignment, diameter, surface nanotopography, and surface chemistry that can be engineered to achieve a desired glial cell response to injury. Further, electrospun fibers can be loaded with drugs, nucleic acids, or proteins to provide the local, sustained release of such therapeutics to alter glial cell phenotype to better support regeneration. This review provides the first comprehensive overview of how electrospun fiber alignment, diameter, surface nanotopography, surface functionalization, and therapeutic delivery affect Schwann cells in the peripheral nervous system and astrocytes, oligodendrocytes, and microglia in the central nervous system both in vitro and in vivo. The information presented can be used to design and optimize electrospun fiber scaffolds to target glial cell response to mitigate nervous system injury and improve regeneration.

Topographical and Biomechanical Guidance of Electrospun Fibers for Biomedical Applications

Electrospinning is gaining increasing interest in the biomedical field as an eco-friendly and economic technique for production of random and oriented polymeric fibers. The aim of this review was to give an overview of electrospinning potentialities in the production of fibers for biomedical applications with a focus on the possibility to combine biomechanical and topographical stimuli. In fact, selection of the polymer and the eventual surface modification of the fibers allow selection of the proper chemical/biological signal to be administered to the cells. Moreover, a proper design of fiber orientation, dimension, and topography can give the opportunity to drive cell growth also from a spatial standpoint. At this purpose, the review contains a first introduction on potentialities of electrospinning for the obtainment of random and oriented fibers both with synthetic and natural polymers. The biological phenomena which can be guided and promoted by fibers composition and topography are in depth investigated and discussed in the second section of the paper. Finally, the recent strategies developed in the scientific community for the realization of electrospun fibers and for their surface modification for biomedical application are presented and discussed in the last section.

Recent Advances in the Regenerative Approaches for Traumatic Spinal Cord Injury: Materials Perspective

Spinal cord injury (SCI) is a devastating health condition that may lead to permanent disabilities and death. Understanding the pathophysiological perspectives of traumatic SCI is essential to define mechanisms that can help in designing recovery strategies. Since central nervous system tissues are notorious for their deficient ability to heal, efforts have been made to identify solutions to aid in restoration of the spinal cord tissues and thus its function. The two main approaches proposed to address this issue are neuroprotection and neuro-regeneration. Neuroprotection involves administering drugs to restore the injured microenvironment to normal after SCI. As for the neuro-regeneration approach, it focuses on axonal sprouting for functional recovery of the injured neural tissues and damaged axons. Despite the progress made in the field, neural regeneration treatment after SCI is still unsatisfactory owing to the disorganized way of axonal growth and extension. Nanomedicine and tissue engineering are considered promising therapeutic approaches that enhance axonal growth and directionality through implanting or injecting of the biomaterial scaffolds. One of these recent approaches is nanofibrous scaffolds that are used to provide physical support to maintain directional axonal growth in the lesion site. Furthermore, these preferable tissue-engineered substrates can afford axonal regeneration by mimicking the extracellular matrix of the neural tissues in terms of biological, chemical, and architectural characteristics. In this review, we discuss the regenerative approach using nanofibrous scaffolds with a focus on their fabrication methods and their properties that define their functionality performed to heal the neural tissue efficiently.

Research progress and prospects of tissue engineering scaffolds for spinal cord injury repair and protection

Spinal cord injury (SCI) is one of the leading causes of global disability. However, there are currently no effective clinical treatments for SCI. Repair of SCI is essential but poses great challenges. As a comprehensive treatment program combining biological scaffolds, seed cells and drugs or biological factors, tissue engineering has gradually replaced the single transplantation approach to become a focus of research that brings new opportunities for the clinical treatment of SCI.

Nonwoven membranes for tissue engineering: an overview of cartilage, epithelium, and bone regeneration

Scaffold-type biomaterials are crucial for application in tissue engineering. Among them, the use of a nonwoven scaffold has grown in recent years and has been widely investigated for the regeneration of different types of tissues. Several polymers, whether they are synthetic, biopolymers or both, have been used to produce a scaffold that can mimic the natural tissue to which it will be applied to. The scaffolds used in tissue engineering must be biocompatible and allow cell adhesion and proliferation to be applied in tissue engineering. In addition, the scaffolds should maintain the mechanical properties and architecture of the desired tissue. Nonwoven fabrics have produced good results and are more extensively applied for the regeneration of cartilage, epithelial and bone tissues. Recent advances in tissue engineering have shown promising results, however, no ideal material or standardization parameters and characteristics of the materials were obtained. The present review provides an overview of the application of nonwoven scaffolds, including the main results obtained regarding the properties of the biomaterials and their applications in vitro and in vivo, focusing on the cartilaginous, the epithelium, and bone tissue regeneration.

Tissue-engineered solution containing cells and biomaterials-an in vitro study: A perspective as a novel therapeutic application

Some biomaterial scaffolds can positively interfere with tissue regeneration and are being developed to successfully repair the tissue function. The possibility of using epithelial cells combined with biomaterials appears to be a new option as therapeutic application. This combination emerges as a possibility for patients with Mayer-Rokitansky-Kuster-Hauser syndrome which requires vaginal repair and can be performed with tissue-engineered solution containing cells and biomaterials. It is expected that tissue-engineered solution containing cells and biomaterials would promote tissue repair in a more efficient, modern, and safe way. This study tested the efficiency of tissue-engineered solution containing human malignant melanoma cell line (HMV-II) and different biomaterials, including Cellprene^®, Membracel^®, and poly lactic-co-glycolic acid/epoxidized polyisoprene. The cells adhered better on poly lactic-co-glycolic acid/epoxidized polyisoprene, and it was found that tissue-engineered solution may also contain mesenchymal stem cells cultivated on poly lactic-co-glycolic acid/epoxidized polyisoprene. Histological, immunofluorescence, and scanning electron microscopy analyses were performed. These initial in vitro results suggest that tissue-engineered solution containing cells and poly lactic-co-glycolic acid/epoxidized polyisoprene is a potential for tissue reconstruction.

Cellular Response to Surface Morphology: Electrospinning and Computational Modeling

Surface properties of biomaterials, such as chemistry and morphology, have a major role in modulating cellular behavior and therefore impact on the development of high-performance devices for biomedical applications, such as scaffolds for tissue engineering and systems for drug delivery. Opportunely-designed micro- and nanostructures provides a unique way of controlling cell-biomaterial interaction. This mini-review discusses the current research on the use of electrospinning (extrusion of polymer nanofibers upon the application of an electric field) as effective technique to fabricate patterns of micro- and nano-scale resolution, and the corresponding biological studies. The focus is on the effect of morphological cues, including fiber alignment, porosity and surface roughness of electrospun mats, to direct cell migration and to influence cell adhesion, differentiation and proliferation. Experimental studies are combined with computational models that predict and correlate the surface composition of a biomaterial with the response of cells in contact with it. The use of predictive models can facilitate the rational design of new bio-interfaces.