The Role Of Iron-Based Materials In Neural Differentiation Of Stem Cells

With the aging of society,neurodegenerative diseases threaten human living quality and health with increased morbidity.Stem cell therapy for neurological disorders has received increasing attention and research in recent years,and the basic idea is to stimulate tissue repair by using stem cells for immunomodulation,paracrine secretion,and directed differentiation into functional cells.However,there are many problems in the application of stem cell therapy in the reconstruction of spinal cord and other nerve tissues,including unsatisfactory therapeutic effect and large individual differences.One of the main reasons for the above problems is that it is difficult to regulate the directional differentiation of stem cells into functional neurons,and neural differentiation is time-consuming and inefficient.Therefore,in order to efficiently obtain high-quality neurons and to accelerate neural regeneration,we focus on neural tissue engineering,which mainly integrates seed cells,biomaterials,and factors that induce and promote nerve growth to repair damaged neural tissue.Suitable seed cells are also a key factor in tissue engineering.Mesenchymal stem cells（MSCs）have the potential for self-renewal and multidirectional differentiation,and are easy to isolate and expand in vitro.MSCs are increasingly used in the treatment of diseases and are the best choice for seed cells in tissue engineering.In addition,biomaterials are one of the core elements of neural tissue engineering,and it is of great significance for the treatment of nerve injuries to design and synthesize biomaterials that can accelerate nerve regeneration and improve the quality of regenerated nerves.FeOOH has excellent physicochemical properties,such as magnetism,strong adsorption capacity,large specific surface area,and redox properties.These characteristics make FeOOH an effective functional material for biomedical applications.For example,FeOOH can be used as a magnetic material for biological imaging and targeted therapy,and can achieve localization and control of the targeted area through the application of an external magnetic field.Additionally,FeOOH can be used as a redox material for drug transport and biocatalysis.In addition,it has been reported that FeOOH can synergistically promote neural differentiation of MSCs mediated by electrical signals of piezoelectric materials.However,it’s unclear whether the positive effect of FeOOH on neural differentiation can be displayed by itself or other nanomaterials.It is well-known that nanomaterial-based cell scaffolds and internalized nanoparticles can both influence stem cell differentiation and effectively regulate stem cells determination by enhancing the intercellular or intracellular interaction with materials,respectively.Based on this,this paper uses a research method combining materials science and cell biology to design and prepare FeOOH nanoparticles and rGO/FeOOH composite scaffolds to study their effects on and regulation of MSCs differentiation into neurons.The specific work and conclusions are summarized as follows:1.rGO/FeOOH composite scaffold can induce mesenchymal stem cell differentiation into neuronsGraphene is a new type of material with many excellent physical and chemical properties,such as high specific surface area,excellent conductivity and chemical stability.As a biological material,these excellent characteristics make it very potential for development in the field of tissue engineering.The research have shown that FeOOH-released Fe³⁺can enhance the effect of ultrasound-driven piezoelectric materials to induce MSCs differentiation into neurons.In order to explore whether FeOOH can synergistically promote the role of graphene materials in regulating stem cell fate,this study used an improved Hummers’method to prepare oxygenated graphene（GO）with excellent physicochemical properties and good biocompatibility,and used ferrous chloride as a safe and non-toxic green reducing agent to in situ reduce GO into rGO/FeOOH materials.Using rat bone marrow mesenchymal stem cells（r BMSCs）as seed cells,we studied the cell behaviors of MSCs on rGO/FeOOH composite scaffolds,such as adhesion,growth,proliferation,and neuronal differentiation.The results showed that the rGO/FeOOH composite scaffold had good biocompatibility and could support MSCs adhesion and growth well.The effect of the scaffold material on MSCs differentiation into neurons was analyzed at the protein and gene levels by immunofluorescence staining and q-PCR,and the results showed that the rGO/FeOOH composite scaffold could not only promote MSCs differentiation into neuron cells,but also produce multiple functional neurons,such as acetylcholine,dopamine,gamma-aminobutyric acid,and glutamate neurons,as detected by calcium spark detection.This system completely eliminates the effect of other neural inducing factors,and only relies on the rGO/FeOOH scaffold material to stimulate MSCs neuronal differentiation,and can obtain multiple functional neurons,providing a new idea and approach for the treatment of neurological disorders,and it is hoped that this study can bring new breakthroughs and progress to the field of neuroscience.2.FeOOH nanorods induce mesenchymal stem cell differentiation into neuronsIn the previous system,we found that the rGO/FeOOH scaffold material could induce MSCs differentiation into functional neurons,while the FeOOH film alone also showed weak neuronal differentiation ability.However,considering that the FeOOH particles in the film cannot efficiently enter the cells,their ability to promote neuronal differentiation is not significant.In addition,considering the poor degradation performance of the rGO/FeOOH scaffold material,using a large amount of scaffold material to regulate stem cell differentiation and repair neural tissue faces the problem of subsequent transformation and application.Therefore,using nano or micron-sized materials to induce stem cell differentiation is a breakthrough for solving this problem.Based on this,the authors used a simple and efficient method to prepare FeOOH nanorods with uniform size and good stability,and SEM,XRD,and FTIR proved the successful preparation of FeOOH nanorods.Transmission electron microscopy showed that FeOOH nanorods were engulfed by MSCs,and the nanorods were located in the cytoplasm,indicating that the nanorods had good internalization efficiency.Then,the effects of FeOOH nanorods on MSCs differentiation into neurons were studied.The results showed that FeOOH nanorods could promote MSCs differentiation into neurons,and the effect was better than that of the FeOOH film,which was consistent with the previous results.The mechanism may be related to the physical and chemical properties of the FeOOH nanorods,such as their large specific surface area,high adsorption capacity,and redox properties,which can provide a favorable microenvironment for MSCs to differentiate into neurons.Therefore,FeOOH nanorods have potential applications in the field of neural tissue engineering,and can be used as a new type of stimulant to promote stem cell differentiation and repair neural tissue.This study utilized the physical properties of nanomaterials to successfully induce mesenchymal stem cells to differentiate into functional neurons,overcoming issues such as the short half-life of biological factors or chemical inducers and easily dispersed signals.A simple and more localized induction system was established.This method provides a new approach for nanomaterial-mediated physical signal regulation of stem cell fate,laying the theoretical foundation for nanomaterials to participate in neural injury repair and exhibiting broad application prospects.