A Fiber Alginate Co-culture Platform for the Differentiation of mESC and Modeling of the Neural Tube

Recent Advances in Alginate-Based Hydrogels for Cell Transplantation Applications

With its exceptional biocompatibility, alginate emerged as a highly promising biomaterial for a large range of applications in regenerative medicine. Whether in the form of microparticles, injectable hydrogels, rigid scaffolds, or bioinks, alginate provides a versatile platform for encapsulating cells and fostering an optimal environment to enhance cell viability. This review aims to highlight recent studies utilizing alginate in diverse formulations for cell transplantation, offering insights into its efficacy in treating various diseases and injuries within the field of regenerative medicine.

Localisation of oestrogen receptors in stem cells and in stem cell-derived neurons of the mouse

Oestrogen receptors (ER) transduce the effects of the endogenous ligand, 17β-estradiol in cells to regulate a number of important processes such as reproduction, neuroprotection, learning and memory and anxiety. The ERα or ERβ are classical intracellular nuclear hormone receptors while some of their variants or novel proteins such as the G-protein coupled receptor (GPCR), GPER1/GPR30 are reported to localise in intracellular as well as plasma membrane locations. Although the brain is an important target for oestrogen with oestrogen receptors expressed differentially in various nuclei, subcellular organisation and crosstalk between these receptors is under-explored. Using an adapted protocol that is rapid, we first generated neurons from mouse embryonic stem cells. Our immunocytochemistry approach shows that the full length ERα (ERα-66) and for the first time, that an ERα variant, ERα-36, as well as GPER1 is present in embryonic stem cells. In addition, these receptors typically decrease their nuclear localisation as neuronal maturation proceeds. Finally, although these ERs are present in many subcellular compartments such as the nucleus and plasma membrane, we show that they are specifically not colocalised with each other, suggesting that they initiate distinct signalling pathways.

Development of 3D printable graphene oxide based bio-ink for cell support and tissue engineering

Tissue engineered constructs can serve as in vitro models for research and replacement of diseased or damaged tissue. As an emerging technology, 3D bioprinting enables tissue engineering through the ability to arrange biomaterials and cells in pre-ordered structures. Hydrogels, such as alginate (Alg), can be formulated as inks for 3D bioprinting. However, Alg has limited cell affinity and lacks the functional groups needed to promote cell growth. In contrast, graphene oxide (GO) can support numerous cell types and has been purported for use in regeneration of bone, neural and cardiac tissues. Here, GO was incorporated with 2% (w/w) Alg and 3% (w/w) gelatin (Gel) to improve 3D printability for extrusion-based 3D bioprinting at room temperature (RT; 25°C) and provide a 3D cellular support platform. GO was more uniformly distributed in the ink with our developed method over a wide concentration range (0.05%–0.5%, w/w) compared to previously reported GO containing bioink. Cell support was confirmed using adipose tissue derived stem cells (ADSCs) either seeded onto 3D printed GO scaffolds or encapsulated within the GO containing ink before direct 3D printing. Added GO was shown to improve cell-affinity of bioinert biomaterials by providing more bioactive moieties on the scaffold surface. 3D cell-laden or cell-seeded constructs showed improved cell viability compared to pristine (without GO) bio-ink-based scaffolds. Our findings support the application of GO for novel bio-ink formulation, with the potential to incorporate other natural and synthetic materials such as chitosan and cellulose for advanced in situ biosensing, drug-loading and release, and with the potential for electrical stimulation of cells to further augment cell function.

Modeling Neurodegenerative Diseases Using In Vitro Compartmentalized Microfluidic Devices

The human brain is a complex organ composed of many different types of cells interconnected to create an organized system able to efficiently process information. Dysregulation of this delicately balanced system can lead to the development of neurological disorders, such as neurodegenerative diseases (NDD). To investigate the functionality of human brain physiology and pathophysiology, the scientific community has been generated various research models, from genetically modified animals to two- and three-dimensional cell culture for several decades. These models have, however, certain limitations that impede the precise study of pathophysiological features of neurodegeneration, thus hindering therapeutical research and drug development. Compartmentalized microfluidic devices provide in vitro minimalistic environments to accurately reproduce neural circuits allowing the characterization of the human central nervous system. Brain-on-chip (BoC) is allowing our capability to improve neurodegeneration models on the molecular and cellular mechanism aspects behind the progression of these troubles. This review aims to summarize and discuss the latest advancements of microfluidic models for the investigations of common neurodegenerative disorders, such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis.

Evaluation of Selected Properties of Sodium Alginate-Based Hydrogel Material—Mechanical Strength, μDIC Analysis and Degradation

The search for ideal solutions for the treatment of urethral stenosis continues. This includes developing the material, design, while maintaining its optimal and desired properties. This paper presents the results of the research conducted on sodium alginate-based hydrogel material (AHM), which may be used as a material for stents dedicated to the treatment of pathologies occurring in the genitourinary system. In order to determine the selected parameters of the AHM samples, strength and degradation tests, as well as analysis of the micro changes occurring on the surface of the material using a digital image correlation (µDIC) system, were performed. This study shows that the material possessed good mechanical strength parameters, the knowledge of which is particularly important from the point of view of the stent-tissue interaction. The degradation analysis performed showed that the AHM samples degrade in an artificial urine environment, and that the degradation time mainly depends on the chemical composition of the material. The novel µDIC method performed allowed us to characterize the homogeneity of the material structure depending on the cross-linking agent used.

Optimizing fibrin hydrogel toward effective neural progenitor cell delivery in spinal cord injury

Transplantation of neural progenitor cell (NPC) possessing the potential to differentiate into neurons may guard against spinal cord injury (SCI)- associated neuronal trauma. We propose that autologous-like NPC may reduce post-transplant immune response. The study used the rat SCI model to prove this concept. For isolation and expansion of rat NPC for cell-based SCI therapy, thein vitroprotocol standardized with human NPC seemed suitable. The primary aim of this study is to select a cell/neural tissue-compatible biomaterial for improving NPC survivalin vivo. The composition of the fibrin hydrogel is adjusted to obtain degradable, porous, and robust fibrin strands for supporting neural cell attachment, migration, and tissue regeneration. This study employed NPC culture to evaluate the cytocompatibility and suitability of the hydrogel, composed by adding graded concentrations of thrombin to a fixed fibrinogen concentration. The microstructure evaluation by scanning electron microscope guided the selection of a suitable composition for delivering the embedded cells. On adding more thrombin, fibrinogen clotted quickly but reduced porosity, pore size, and fiber strand thickness. The high activity of thrombin also affected NPC morphology and thein vitrocell survival. The selected hydrogel carried viable NPC and retained them at the injury site post-transplantation. The fibrin hydrogel played a protective role throughout the transfer process by providing cell attachment sites and survival signals. The fibrin and NPC together regulated the immune response at the SCI site reducing ED1^+ve/ED2^+vemacrophages in the early period of 8-16 d after injury. Migration ofβ-III tubulin^+veneural-like cells into the fibrin-injected control SCI is evident. The continuous use of a non-neurotoxic fibrin matrix could be a convenient strategy forin vitroNPC preparation, minimally invasive cell delivery, and better transplantation outcome.

Microencapsulated Neural Stem Cells Inhibit Sciatic Nerve Injury-Induced Pain by Reducing P2 × 4 Receptor Expression

Objectives: The purpose of this study is to investigate the effects of transplantation of microencapsulated neural stem cells (MC-NSCs), which downregulate the P2 × 4 receptor (P2 × 4R) overexpression and relieve neuropathic pain (NPP). Methods: Neural stem cells (NSCs) and MC-NSCs were transplanted to the injured sciatic nerve. Transmission electron microscope and immunofluorescence were used to observe the changes of injured sciatic nerve. Behavioral methods were used to detect mechanical withdrawal thresholds (MWT) and thermal withdrawal latency (TWL) of rats. Expression levels of P2 × 4Rs and p-p65 in the spinal cord segment of rats were measured by using molecular biology methods. The concentrations of IL-1β and TNF-α were detected in serum of rats by ELISA. Results: After sciatic nerve injury, the sciatic nerve fibers had the myelinated lamina separated, and disintegrated fragments could be seen. The fluorescence intensity of myelin MBP was weakened. The MWT and TWL were significantly decreased, the expression of P2 × 4Rs and p-p65 were significantly increased, and the concentrations of IL-1β and TNF-α were increased. After NSC and MC-NSC transplantation, the myelin sheath of the sciatic nerve was relatively intact, some demyelination changes could be seen, and the injured sciatic nerve has been improved. The fluorescence intensity of myelin MBP was increased. The MWT and TWL were increased, expression levels of P2 × 4Rs and p-p65 were decreased, and the concentrations of IL-1β and TNF-α were significantly decreased. Compared with NSC transplantation, transplantation of MC-NSCs could better repair the damaged sciatic nerve, decrease the expression of P2 × 4Rs and p-p65, decrease the level of IL-1β and TNF-α, and relieve pain (all p-values < 0.05). Conclusion: NSCs and MC-NSCs transplantation may alleviate pain by reducing the expression of P2 × 4Rs and inhibiting the activation of NF-KB signaling, while MC-NSCs transplantation has a better effect of suppressing pain. Our experimental results provide new data support for the treatment of NPP.

Adhesion and Growth of Neuralized Mouse Embryonic Stem Cells on Parylene-C/SiO2 Substrates

Neuronal patterning on microfabricated architectures has developed rapidly over the past few years, together with the emergence of soft biocompatible materials and tissue engineering scaffolds. Previously, we introduced a patterning technique based on serum and the biopolymer parylene-C, achieving highly compliant growth of primary neurons and astrocytes on different geometries. Here, we expanded this technique and illustrated that neuralized cells derived from mouse embryonic stem cells (mESCs) followed stripes of variable widths with conformity equal to or higher than that of primary neurons and astrocytes. Our results indicate the presence of undifferentiated mESCs, which also conformed to the underlying patterns to a high degree. This is an exciting and unexpected outcome, as molecular mechanisms governing cell and ECM protein interactions are different in stem cells and primary cells. Our study enables further investigations into the development and electrophysiology of differentiating patterned neural stem cells.

Cell Tracking for Organoids: Lessons From Developmental Biology

Organoids have emerged as powerful model systems to study organ development and regeneration at the cellular level. Recently developed microscopy techniques that track individual cells through space and time hold great promise to elucidate the organizational principles of organs and organoids. Applied extensively in the past decade to embryo development and 2D cell cultures, cell tracking can reveal the cellular lineage trees, proliferation rates, and their spatial distributions, while fluorescent markers indicate differentiation events and other cellular processes. Here, we review a number of recent studies that exemplify the power of this approach, and illustrate its potential to organoid research. We will discuss promising future routes, and the key technical challenges that need to be overcome to apply cell tracking techniques to organoid biology.

Polymer Scaffolds for Biomedical Applications in Peripheral Nerve Reconstruction

The nervous system is a significant part of the human body, and peripheral nerve injury caused by trauma can cause various functional disorders. When the broken end defect is large and cannot be repaired by direct suture, small gap sutures of nerve conduits can effectively replace nerve transplantation and avoid the side effect of donor area disorders. There are many choices for nerve conduits, and natural materials and synthetic polymers have their advantages. Among them, the nerve scaffold should meet the requirements of good degradability, biocompatibility, promoting axon growth, supporting axon expansion and regeneration, and higher cell adhesion. Polymer biological scaffolds can change some shortcomings of raw materials by using electrospinning filling technology and surface modification technology to make them more suitable for nerve regeneration. Therefore, polymer scaffolds have a substantial prospect in the field of biomedicine in future. This paper reviews the application of nerve conduits in the field of repairing peripheral nerve injury, and we discuss the latest progress of materials and fabrication techniques of these polymer scaffolds.