Nerve growth factor expression by PLG-mediated lipofection

Innovative Therapeutic Strategies in Alzheimer's Disease: A Synergistic Approach to Neurodegenerative Disorders

Alzheimer's disease (AD) remains a significant challenge in the field of neurodegenerative disorders, even nearly a century after its discovery, due to the elusive nature of its causes. The development of drugs that target multiple aspects of the disease has emerged as a promising strategy to address the complexities of AD and related conditions. The immune system's role, particularly in AD, has gained considerable interest, with nanobodies representing a new frontier in biomedical research. Advances in targeting antibodies against amyloid-β (Aβ) and using messenger RNA for genetic translation have revolutionized the production of antibodies and drug development, opening new possibilities for treatment. Despite these advancements, conventional therapies for AD, such as Cognex, Exelon, Razadyne, and Aricept, often have limited long-term effectiveness, underscoring the need for innovative solutions. This necessity has led to the incorporation advanced technologies like artificial intelligence and machine learning into the drug discovery process for neurodegenerative diseases. These technologies help identify therapeutic targets and optimize lead compounds, offering a more effective approach to addressing the challenges of AD and similar conditions.

A cationic lipid with advanced membrane fusion performance for pDNA and mRNA delivery

The success of mRNA vaccines for COVID-19 prevention raised global awareness of the importance of nucleic acid drugs. The approved systems for nucleic acid delivery were mainly formulations of different lipids, yielding lipid nanoparticles (LNPs) with complex internal structures. Due to the multiple components, the relationship between the structure of each component and the overall biological activity of LNPs is hard to study. However, ionizable lipids have been extensively explored. In contrast to former studies on the optimization of hydrophilic parts in single-component self-assemblies, we report in this study on structural alterations of the hydrophobic segment. We synthesize a library of amphiphilic cationic lipids by varying the lengths (C = 8-18), numbers (N = 2, 4), and unsaturation degrees (Ω = 0, 1) of hydrophobic tails. Notably, all self-assemblies with nucleic acid have significant differences in particle size, stability in serum, membrane fusion, and fluidity. Moreover, the novel mRNA/pDNA formulations are characterized by overall low cytotoxicity, efficient compaction, protection, and release of nucleic acids. We find that the length of hydrophobic tails dominates the formation and stability of the assembly. And at a certain length, the unsaturated hydrophobic tails enhance the membrane fusion and fluidity of assemblies and thus significantly affect the transgene expression, followed by the number of hydrophobic tails.

In-vivo time course of organ uptake and blood-brain-barrier permeation of poly(L-lactide) and poly(perfluorodecyl acrylate) nanoparticles with different surface properties in unharmed and brain-traumatized rats

Background

Traumatic brain injury (TBI) has a dramatic impact on mortality and quality of life and the development of effective treatment strategies is of great socio-economic relevance. A growing interest exists in using polymeric nanoparticles (NPs) as carriers across the blood-brain barrier (BBB) for potentially effective drugs in TBI. However, the effect of NP material and type of surfactant on their distribution within organs, the amount of the administrated dose that reaches the brain parenchyma in areas with intact and opened BBB after trauma, and a possible elicited inflammatory response are still to be clarified.

Methods

The organ distribution, BBB permeation and eventual inflammatory activation of polysorbate-80 (Tw80) and sodiumdodecylsulfate (SDS) stabilized poly(L-lactide) (PLLA) and poly(perfluorodecyl acrylate) (PFDL) nanoparticles were evaluated in rats after intravenous administration. The NP uptake into the brain was assessed under intact conditions and after controlled cortical impact (CCI).

Results

A significantly higher NP uptake at 4 and 24 h after injection was observed in the liver and spleen, followed by the brain and kidney, with minimal concentrations in the lungs and heart for all NPs. A significant increase of NP uptake at 4 and 24 h after CCI was observed within the traumatized hemisphere, especially in the perilesional area, but NPs were still found in areas away from the injury site and the contralateral hemisphere. NPs were internalized in brain capillary endothelial cells, neurons, astrocytes, and microglia. Immunohistochemical staining against GFAP, Iba1, TNFα, and IL1β demonstrated no glial activation or neuroinflammatory changes.

Conclusions

Tw80 and SDS coated biodegradable PLLA and non-biodegradable PFDL NPs reach the brain parenchyma with and without compromised BBB by TBI, even though a high amount of NPs are retained in the liver and spleen. No inflammatory reaction is elicited by these NPs within 24 h after injection. Thus, these NPs could be considered as potentially effective carriers or markers of newly developed drugs with low or even no BBB permeation.

Gene-Modified Stem Cells for Spinal Cord Injury: a Promising Better Alternative Therapy

Stem cell therapy holds great promise for the treatment of spinal cord injury (SCI), which can reverse neurodegeneration and promote tissue regeneration via its pluripotency and ability to secrete neurotrophic factors. Although various stem cell-based approaches have shown certain therapeutic effects when applied to the treatment of SCI, their clinical efficacies have been disappointing. Thus, it is an urgent need to further enhance the neurological benefits of stem cells through bioengineering strategies including genetic engineering. In this review, we summarize the progress of stem cell therapy for SCI and the prospect of genetically modified stem cells, focusing on the genome editing tools and functional molecules involved in SCI repair, trying to provide a deeper understanding of genetically modified stem cell therapy and more applicable clinical strategies for SCI repair.

Nanoinjection system for precise direct delivery of biomolecules into single cells

Intracellular delivery of functional molecules such as proteins, transcription factors and DNA is effective and promising in cell biology. However, existing transfection methods are often unsuitable to deliver big molecules into cells or require carriers such as viruses and peptides specific to the target molecules. In addition, the nature of bulk processing does not generally provide accurate dose control of individual cells. The concept of single-cell-based material injection based on electrokinetic pumping through nanocapillaries could overcome these problems, yet the fabrication and operation of nanoscale 3-dimensional structures have remained unsolved. In this research, a hybrid (PDMS/glass) microfluidic chip with a true 3-dimensional nanoinjection structure (called "nanoinjection system") is presented. The nanoinjection structure was fabricated by femtosecond-laser (fs-laser) ablation in a single solid glass, which showed very successful delivery of red fluorescent protein (RFP) and expression of plasmid DNA in several different types of cells. This system is promising in that the amount of molecules to be delivered is controllable and the processed cells are systematically separated into a harvesting chamber, which can radically improve the purity of the processed cells. In addition, it was confirmed that the cells were healthy even after the molecule injection for a few seconds, indicating that the injection time can be significantly elongated, further improving the delivery efficiency of biomolecules without affecting the cell viability. We envision that the nanoinjection system having the major features of being carrier-free and dose-controllable, having an unlimited injection period, and ease of harvesting will greatly contribute to the next-generation research studies in the fields of cell biology and cell therapeutics.

Neuregulin 1 functionalization of organic fibers for Schwann cell guidance

The repair of peripheral nerve lesions is a clinical problem where the functional recovery is often far from being satisfactory, although peripheral nerves generally retain good potential for regeneration. Here, we develop a novel scaffold approach based on bioactive fibers of poly(ε-caprolactone) where nanotopographical guidance and neuregulin 1 (NRG1) cues are combined. We interface them with rat primary Schwann cells (SCs), the peripheral glial cells that drive initial regeneration of injured nerves, and found that the combination of NRG1 with parallel nano-fibrous topographies is effective in improving SC growth up to 72 h, alignment to fiber topography, and bipolar differentiation, opening original perspectives for nerve repair applications.

Hierarchically Ordered Porous and High-Volume Polycaprolactone Microchannel Scaffolds Enhanced Axon Growth in Transected Spinal Cords

The goal of this work was to design nerve guidance scaffolds with a unique architecture to maximize the open volume available for nerve growth. Polycaprolactone (PCL) was selected as the scaffold material based on its biocompatibility and month-long degradation. Yet, dense PCL does not exhibit suitable properties such as porosity, stiffness, strength, and cell adhesion to function as an effective nerve guidance scaffold. To address these shortcomings, PCL was processed using a modified salt-leaching technique to create uniquely controlled interconnected porosity. By controlling porosity, we demonstrated that the elastic modulus could be controlled between 2.09 and 182.1 MPa. In addition, introducing porosity and/or coating with fibronectin enhanced the PCL cell attachment properties. To produce PCL scaffolds with maximized open volume, porous PCL microtubes were fabricated and translated into scaffolds with 60 volume percent open volume. The scaffolds were tested in transected rat spinal cords. Linear axon growth within both the microtubes as well as the interstitial space between the tubes was observed, demonstrating that the entire open volume of the scaffold was available for nerve growth. Overall, a novel scaffold architecture and fabrication technique are presented. The scaffolds exhibit significantly higher volume than state-of-the-art scaffolds for promising spinal cord nerve repair.

Three-dimensional printing of high-content graphene scaffolds for electronic and biomedical applications

The exceptional properties of graphene enable applications in electronics, optoelectronics, energy storage, and structural composites. Here we demonstrate a 3D printable graphene (3DG) composite consisting of majority graphene and minority polylactide-co-glycolide, a biocompatible elastomer, 3D-printed from a liquid ink. This ink can be utilized under ambient conditions via extrusion-based 3D printing to create graphene structures with features as small as 100 μm composed of as few as two layers (<300 μm thick object) or many hundreds of layers (>10 cm thick object). The resulting 3DG material is mechanically robust and flexible while retaining electrical conductivities greater than 800 S/m, an order of magnitude increase over previously reported 3D-printed carbon materials. In vitro experiments in simple growth medium, in the absence of neurogenic stimuli, reveal that 3DG supports human mesenchymal stem cell (hMSC) adhesion, viability, proliferation, and neurogenic differentiation with significant upregulation of glial and neuronal genes. This coincides with hMSCs adopting highly elongated morphologies with features similar to axons and presynaptic terminals. In vivo experiments indicate that 3DG has promising biocompatibility over the course of at least 30 days. Surgical tests using a human cadaver nerve model also illustrate that 3DG has exceptional handling characteristics and can be intraoperatively manipulated and applied to fine surgical procedures. With this unique set of properties, combined with ease of fabrication, 3DG could be applied toward the design and fabrication of a wide range of functional electronic, biological, and bioelectronic medical and nonmedical devices.

Liposomes in tissue engineering and regenerative medicine

Liposomes are vesicular structures made of lipids that are formed in aqueous solutions. Structurally, they resemble the lipid membrane of living cells. Therefore, they have been widely investigated, since the 1960s, as models to study the cell membrane, and as carriers for protection and/or delivery of bioactive agents. They have been used in different areas of research including vaccines, imaging, applications in cosmetics and tissue engineering. Tissue engineering is defined as a strategy for promoting the regeneration of tissues for the human body. This strategy may involve the coordinated application of defined cell types with structured biomaterial scaffolds to produce living structures. To create a new tissue, based on this strategy, a controlled stimulation of cultured cells is needed, through a systematic combination of bioactive agents and mechanical signals. In this review, we highlight the potential role of liposomes as a platform for the sustained and local delivery of bioactive agents for tissue engineering and regenerative medicine approaches.

Tissue engineering concept in the research of the tumor biology

Tumor is a heterogeneous complex, which lives in a three-dimensional environment flush with biopathophysiological and biomechanical signals. This signaling abundant extracellular milieu co-evolving from cell-cell and cell-host interaction guides the development and the generation of the tumor. There has been a recent surge of interest in studying the tumor biology that more closely mirror what happens in living organisms, especially in cancer research. Incorporating cancer cells in the 3D mimicking environment instead of monolayers is reasonable for maintaining in vivo cancer behaviors in spatial and temporal context. However, 3D culture for cancer still presents a challenge for researchers in this field. Tissue engineering, originally aiming at designing the artificial organs, provided a feasible approach to recreate such complex mechanical and biochemical interplay. Aside from reproducing bionic environment, tissue engineering has been routinely introduced into cancer study to build three dimensional structures not only to develop molecular therapeutics, but also to screen for toxic effects of drugs or radiotherapy sensitivity. In this article, we focused on the recent advances of the well-defined tissue-engineering biomaterials in the application in tumor biology. We also discussed the fabrications of the scaffolds from different materials, which might contribute to future cancer research.

Non-viral gene therapy for spinal cord regeneration

Spinal cord injury (SCI) normally results in life-long disabilities and a broad range of secondary complications. Advances in therapeutic delivery during the past few decades offer hope for such victims. However, the limited functional improvement shown in in vivo studies hinders effective therapeutic application in clinical practice. Recent studies showed that gene vectors can transfect cells present in the lesion of an injured spinal cord (endogenous cells) and thereby produce therapeutic molecules with long-lasting biological effects that promote neural tissue regeneration. In this article we review recent advances in non-viral gene delivery into neural cells and their use for gene therapy in SCI.

A temporal gene delivery system based on fibrin microspheres

Combining complementary nonviral gene delivery vehicles such as tissue engineering scaffolds and liposomes not only is a promising avenue for development of safe and effective gene delivery system but also provides an opportunity to design dynamic extended release systems with spatiotemporal control. However, the DNA loading capacity of scaffolds such as fibrin is limited. Fibrin microspheres carrying DNA complexes can be utilized to extend the capacity of fibrin scaffold. Here, in a proof of concept study, the feasibility of fibrin microspheres for extending gene delivery capacity is described. Toward this goal, fibrin microspheres encapsulating lipoplexes were fabricated. The structural and functional integrity of DNA was assessed respectively by gel electrophoresis and an in vivo pilot study, using endothelial nitric oxide synthase (eNOS) as a model therapeutic gene in a rabbit ear ulcer model of compromised wound healing. The results confirmed structural integrity and successful delivery and functional integrity, assessed qualitatively by angiogenic effect of eNOS. Finally, as a step toward development of a "fibrin in fibrin" temporal release system, fibrin microspheres were shown to degrade and release DNA differentially compared to fibrin scaffold. It can thus be concluded that fibrin microspheres can be utilized for gene delivery to extend the capacity of a fibrin scaffold and can form a component of a "fibrin in fibrin" temporal release system.

Lentivirus delivery by adsorption to tissue engineering scaffolds

Biomaterial scaffolds capable of localized gene delivery are being investigated for numerous regenerative medicine applications and as model systems for fundamental studies of tissue formation. In this manuscript, we investigate the delivery of lentivirus from a tissue engineering scaffold using a surface immobilization strategy. Poly(lactide-co-glycolide) (PLG) was employed as the biomaterial for delivery, which has been widely used for a number of tissue engineering applications. The virus was immobilized by freezing and subsequent lyophilization of the virus with the scaffold. The presence of sucrose during freezing and lyophilization maintained the activity of the lentivirus, and was similar to an adenovirus control. Collagen and fibronectin were investigated for their ability to enhance surface immobilization. Fibronectin modestly increased binding and transduction of the adenovirus, yet did not significantly impact the lentivirus delivery. Most of the immobilized lentivirus was released from the scaffold within 24 h. In vivo implantation of the scaffolds yielded transgene expression that persisted for at least 4 weeks. These findings indicate the potential for delivering lentivirus from tissue engineering scaffolds using a surface immobilization strategy. To our knowledge, this report is the first to investigate lentivirus delivery from porous tissue engineering scaffolds. Delivery of lentiviral vectors from PLG scaffolds could provide an efficient and versatile gene delivery system for use with in vitro and in vivo models of tissue formation, and ultimately for therapeutic applications.

Development of biomaterial scaffold for nerve tissue engineering: Biomaterial mediated neural regeneration

Neural tissue repair and regeneration strategies have received a great deal of attention because it directly affects the quality of the patient's life. There are many scientific challenges to regenerate nerve while using conventional autologous nerve grafts and from the newly developed therapeutic strategies for the reconstruction of damaged nerves. Recent advancements in nerve regeneration have involved the application of tissue engineering principles and this has evolved a new perspective to neural therapy. The success of neural tissue engineering is mainly based on the regulation of cell behavior and tissue progression through the development of a synthetic scaffold that is analogous to the natural extracellular matrix and can support three-dimensional cell cultures. As the natural extracellular matrix provides an ideal environment for topographical, electrical and chemical cues to the adhesion and proliferation of neural cells, there exists a need to develop a synthetic scaffold that would be biocompatible, immunologically inert, conducting, biodegradable, and infection-resistant biomaterial to support neurite outgrowth. This review outlines the rationale for effective neural tissue engineering through the use of suitable biomaterials and scaffolding techniques for fabrication of a construct that would allow the neurons to adhere, proliferate and eventually form nerves.

Functional protein delivery into neurons using polymeric nanoparticles

An efficient route for delivering specific proteins and peptides into neurons could greatly accelerate the development of therapies for various diseases, especially those involving intracellular defects such as Parkinson disease. Here we report the novel use of polybutylcyanoacrylate nanoparticles for delivery of intact, functional proteins into neurons and neuronal cell lines. Uptake of these particles is primarily dependent on endocytosis via the low density lipoprotein receptor. The nanoparticles are rapidly turned over and display minimal toxicity to cultured neurons. Delivery of three different functional cargo proteins is demonstrated. When primary neuronal cultures are treated with recombinant Escherichia coli beta-galactosidase as nanoparticle cargo, persistent enzyme activity is measured beyond the period of nanoparticle degradation. Delivery of the small GTPase rhoG induces neurite outgrowth and differentiation in PC12 cells. Finally, a monoclonal antibody directed against synuclein is capable of interacting with endogenous alpha-synuclein in cultured neurons following delivery via nanoparticles. Polybutylcyanoacrylate nanoparticles are thus useful for intracellular protein delivery in vitro and have potential as carriers of therapeutic proteins for treatment of neuronal disorders in vivo.

Gene therapy used for tissue engineering applications

This review highlights the advances at the interface between tissue engineering and gene therapy. There are a large number of reports on gene therapy in tissue engineering, and these cover a huge range of different engineered tissues, different vectors, scaffolds and methodology. The review considers separately in-vitro and in-vivo gene transfer methods. The in-vivo gene transfer method is described first, using either viral or non-viral vectors to repair various tissues with and without the use of scaffolds. The use of a scaffold can overcome some of the challenges associated with delivery by direct injection. The ex-vivo method is described in the second half of the review. Attempts have been made to use this therapy for bone, cartilage, wound, urothelial, nerve tissue regeneration and for treating diabetes using viral or non-viral vectors. Again porous polymers can be used as scaffolds for cell transplantation. There are as yet few comparisons between these many different variables to show which is the best for any particular application. With few exceptions, all of the results were positive in showing some gene expression and some consequent effect on tissue growth and remodelling. Some of the principal advantages and disadvantages of various methods are discussed.

Spatially patterned gene delivery for localized neuron survival and neurite extension

Natural tissues can have complex architectures, which arise in part from spatial patterns in gene expression. Regenerative strategies for damaged tissue must recreate these architectures to restore function. In this article, we demonstrate spatially controlled gene delivery from a substrate for directing cellular processes. Non-viral vectors were immobilized to substrates in linear patterns using microfluidic techniques, and cells cultured on the surface had localized gene expression within the cell population. Transfection was achieved in pattern widths as low as 100 mum, with efficiencies dependent on the microchannel treatment and vector concentration. The ability of patterned expression to localize cellular processes was investigated using a neuronal co-culture model. Patterned expression of the diffusible neurotrophic factor nerve growth factor initiated neuron survival and neurite out-growth primarily within the pattern, which decreased significantly in regions directly adjacent to the pattern. Primary neurite density was significantly greater on patterned substrates than on surfaces without patterns. This approach demonstrates the basic technology to create patterns of gene expression that can direct tissue formation and could be employed in regenerative strategies to recreate the complex cellular architectures observed in tissues.

Spatially patterned gene delivery for localized neuron survival and neurite extension

Natural tissues can have complex architectures, which arise in part from spatial patterns in gene expression. Regenerative strategies for damaged tissue must recreate these architectures to restore function. In this article, we demonstrate spatially controlled gene delivery from a substrate for directing cellular processes. Non-viral vectors were immobilized to substrates in linear patterns using microfluidic techniques, and cells cultured on the surface had localized gene expression within the cell population. Transfection was achieved in pattern widths as low as 100 mum, with efficiencies dependent on the microchannel treatment and vector concentration. The ability of patterned expression to localize cellular processes was investigated using a neuronal co-culture model. Patterned expression of the diffusible neurotrophic factor nerve growth factor initiated neuron survival and neurite out-growth primarily within the pattern, which decreased significantly in regions directly adjacent to the pattern. Primary neurite density was significantly greater on patterned substrates than on surfaces without patterns. This approach demonstrates the basic technology to create patterns of gene expression that can direct tissue formation and could be employed in regenerative strategies to recreate the complex cellular architectures observed in tissues.

Patterned PLG substrates for localized DNA delivery and directed neurite extension

Tissue engineering strategies that enable nerve regeneration will require methods that can promote and direct neurite extension across the lesion. In this report, we investigate an in vitro combinatorial approach to directed neurite outgrowth using gene delivery from topographically patterned substrates, which can induce expression of neurotrophic factors to promote neurite extension and direct the extending neurites. Poly(lactide-co-glycolide) (PLG), which has been used to fabricate conduits or bridges for regeneration, was compression molded to create channels with 100, 150, and 250 microm widths. DNA complexes were immobilized to the PLG, and cells cultured on the substrate were transfected with efficiencies dependent on channel width and DNA amount. A co-culture model consisting of primary neurons and accessory cells was employed to investigate neurite outgrowth within the channels. Localized secretion of nerve growth factor (NGF) by the accessory cells promoted neuron survival and neurite extension. Neurons cultured in channels with NGF expression exhibited longer primary neurites than in the absence of channels. Neurons cultured in smaller width PLG microchannels exhibited a greater degree of directionality and less secondary sprouting than larger channels. Finally, surface immobilization allowed for the delivery of distinct plasmids from each channel, which may enable channels to be tailored for specific nerve tracts. This approach demonstrates the ability to combine gene delivery with physical guidance, and can be tailored to target specific axonal populations with varying neurotrophic factor requirements.