Enhancing neurological recovery and improving the prognosis of spinal cord injury have gained research attention recently. Spinal cord injury is associated with a complex molecular and cellular microenvironment. This complexity has prompted researchers to elucidate the underlying pathophysiological mechanisms and changes and to identify effective treatment strategies. Traditional approaches for spinal cord injury repair include surgery, oral or intravenous medications, and administration of neurotrophic factors; however, the efficacy of these approaches remains inconclusive, and serious adverse reactions continue to be a concern. With advancements in tissue engineering and regenerative medicine, emerging strategies for spinal cord injury repair now involve nanoparticle-based nanodelivery systems, scaffolds, and functional recovery techniques that incorporate biomaterials, bioengineering, stem cell, and growth factors as well as three-dimensional bioprinting. Ideal biomaterial scaffolds should not only provide structural support for neuron migration, adhesion, proliferation, and differentiation but also mimic the mechanical properties of natural spinal cord tissue. Additionally, these scaffolds should facilitate axon growth and neurogenesis by offering adjustable topography and a range of physical and biochemical cues. The three-dimensionally interconnected porous structure and appropriate physicochemical properties enabled by three-dimensional biomimetic printing technology can maximize the potential of biomaterials used for treating spinal cord injury. Therefore, correct selection and application of scaffolds, coupled with successful clinical translation, represent promising clinical objectives to enhance the treatment efficacy for and prognosis of spinal cord injury. This review elucidates the key mechanisms underlying the occurrence of spinal cord injury and regeneration post-injury, including neuroinflammation, oxidative stress, axon regeneration, and angiogenesis. This review also briefly discusses the critical role of nanodelivery systems used for repair and regeneration of injured spinal cord, highlighting the influence of nanoparticles and the factors that affect delivery efficiency. Finally, this review highlights tissue engineering strategies and the application of biomaterial scaffolds for the treatment of spinal cord injury. It discusses various types of scaffolds, their integrations with stem cells or growth factors, and approaches for optimization of scaffold design.

Neurological system injuries are debilitating conditions that significantly impact patients' quality of life. This study investigated using a polycaprolactone (PCL) nerve conduit loaded with anti-epidermal growth factor receptor (EGFR) hydrogel and neural stem cells (NSCs) for treating sacral nerve injury (SNI) in rats to explore its neural repair effects. The results demonstrate that the combined transplantation therapy using a 3D printed scaffold filled with crosslinked hydrogel and NSCs effectively improves SNI, with the PCL Nerve conduit showing potential promotion of neuronal differentiation. This research outcome provides a novel approach to the treatment of nerve injuries.

The development of drugs for nervous diseases poses distinctive difficulties owing to the incomplete understanding of the physiology and complex pathogenesis of the multifaceted central (CNS) and peripheral (PNS) nervous systems. Conventional animal tests and in vitro two-dimensional (2D) cell cultures fail to reproduce the sophisticated structure of natural human tissues, hindering the new drug discovery process. The emerging three-dimensional (3D) neural tissue models, including organoids, organ-on-chips and 3D-printed neural scaffolds, can provide an improved reproduction of the critical features, structural complexity, biological functions, dynamic circulation micro-environment and cell-matrix/cell interactions of the nervous systems. This review examines state-of-the-art 3D models for neural physiology/pathology, emphasizing their drug development applications. Fundamental advantages of various in vitro 3D neural models for investigating the mechanisms of nerve regeneration and disorders in both the CNS and PNS are compared in terms of the different modeling techniques. In addition, the applications of 3D neural models in drug development are summarized covering a range of areas such as disease modeling for basic research, pharmacokinetic and pharmacodynamic testing for drug screening and drug safety evaluation. Furthermore, current challenges and future outlook of biomimetic models and the existing bottlenecks hindering their successful translation into clinical use are discussed. STATEMENT OF SIGNIFICANCE: This review highlights the groundbreaking potential of 3D neural models-organoids, organ-on-chips, and 3D-printed scaffolds-to revolutionize neurological research and drug development. Unlike conventional methods, these models replicate the intricate structure and function of human nervous systems, enabling precise study of diseases like Alzheimer's, spinal injuries, and brain tumors. By synthesizing recent advancements, the review compares techniques, their applications in drug screening and personalized medicine, and addresses challenges in model accuracy and scalability. Bridging neuroscience, engineering, and pharmacology, this work provides a roadmap for researchers to innovate therapies. Its insights are critical for accelerating drug discovery and improving treatment outcomes, making it essential for scientists and clinicians tackling neurological disorders.

Motor function recovery after complete spinal cord injury remained as a challenge in medical field, while one of the key approaches is promoting the local microenvironments. In this research, we performed a conjugated therapy by transplantation of neural stem cell (NSC) scaffolds and umbilical cord mesenchymal stem cell derived exosomes (ucMSC-exos) for the treatment of complete transactional spinal cord injury (SCI). We first demonstrated the anti-inflammatory effects of ucMSC-exos in vitro and found that ucMSC-exos could regulate microglia polarization from M1 to M2, an anti-inflammatory phenotype. Besides, ucMSC-exos also promoted NSC proliferation and neural differentiation during in vitro culturing. On the other hand, core-shell hydrogel microfibers were used as transplantation scaffolds for both small and large SCI defects. The core-shell microfibers could carry large amounts of NSCs in the core portion and the shell portion is highly permeable for nutrient and metabolite transportation. In in vivo experiments, we found that conjugated transplantation of ucMSC-exos and NSC microfibers could decreased inflammatory cytokines at lesion sites, gave rise to more neurons and promoted angiogenesis, thus comprehensively improved the local microenvironment while compared with transplantation of NSC scaffolds only. These beneficial results were in accordance with those in vitro experiments and further led to better locomotor function recovery. In summary, this research has demonstrated that that conjugated transplantation of ucMSC-exos and NSC microfibers could make a potential tool for complete SCI repair.

The role of additive manufacturing (AM) for healthcare applications is growing, particularly in the aspiration to meet subject-specific requirements. This article reviews the application of artificial intelligence (AI) to enhance pre-, during-, and post-AM processes to meet a wider range of subject-specific requirements of healthcare interventions. This article introduces common AM processes and AI tools, such as supervised learning, unsupervised learning, deep learning, and reinforcement learning. The role of AI in pre-processing is described in the core dimensions like structural design and image reconstruction, material design and formulations, and processing parameters. The role of AI in a printing process is described based on hardware specifications, printing configurations, and core operational parameters such as temperature. Likewise, the post-processing describes the role of AI for surface finishing, dimensional accuracy, curing processes, and a relationship between AM processes and bioactivity. The later sections provide detailed scientometric studies, thematic evaluation of the subject topic, and also reflect on AI ethics in AM for biomedical applications. This review article perceives AI as a robust and powerful tool for AM of biomedical products. From tissue engineering (TE) to prosthesis, lab-on-chip to organs-on-a-chip, and additive biofabrication for range of products; AI holds a high potential to screen desired process-property-performance relationships for resource-efficient pre- to post-AM cycle to develop high-quality healthcare products with enhanced subject-specific compliance specification.

The efficient establishment of in vitro neural models that accurately mimic the structural and functional connectivity of neural networks is critical in neuroscience research. 3D bioprinting shows great potential for constructing sophisticated in vitro models with high freedom of design. However, mature neurons are delicate and susceptible to manipulation. Here, extrusion-based 3D bioprinting is employed to fabricate gelatin methacryloyl (GelMA)-based constructs containing embryonic day 18 (E18) rat cortical neurons, referred to as 3D neuMatrix. 3D neuMatrix displays favorable neuronal viability, with the progressive formation of a 3D brain-like neural network with local and long-range functional axon connections. Compared with 2D cultured neurons, 3D neuMatrix is more similar to the E18 cortex according to the bulk transcriptomic profile, with a recreation of cellular components in the cerebral cortex. The 3D neuMatrix is employed to establish a disease model of ischemic stroke, with a faithful recapitulation of the viability, function, and transcriptomic features of rats with middle cerebral artery occlusion/reperfusion (MCAO/R). These findings demonstrate the formation of multiscale neural circuits within 3D neuMatrix and its valuable potential in the study of neurodevelopment, disease modeling with drug screening, and in vitro intelligence.

Spinal cord injury (SCI) is a central nervous system (CNS) disease with a high disability rate, and reconstructing motor function after SCI remains a global challenge. Recent advancements in rehabilitation and regenerative medicine offer new approaches to SCI repair. Electrical stimulation has been shown to alter cell membrane charge distribution, generating action potentials, and affecting cell behavior. This method aids axon regeneration and neurotrophic factor upregulation, crucial for nerve repair. Biomaterials, used as scaffolds or coatings in cell culture and tissue engineering, enhance cell proliferation, migration, differentiation, and tissue regeneration. Electroactive biomaterials combined with electrical stimulation show promise in regenerating nerve, heart, and bone tissues. In this paper, different types of electrical stimulation and biomaterials applied to SCI are described, and the current application and research progress of electrical stimulation combined with biomaterials in the treatment of SCI are described, as well as the future prospects and challenges.

3D bioprinting is revolutionizing tissue engineering and regenerative medicine by enabling the precise fabrication of biologically functional constructs. At its core, the success of 3D bioprinting hinges on the development of bioinks, hydrogel-based materials that support cellular viability, proliferation, and differentiation. However, conventional bioinks face limitations in mechanical strength, biological activity, and customization. Recent advancements in genetic engineering have addressed these challenges by enhancing the properties of bioinks through genetic modifications. These innovations allow the integration of stimuli-responsive elements, bioactive molecules, and extracellular matrix (ECM) components, significantly improving the mechanical integrity, biocompatibility, and functional adaptability of bioinks. This review explores the state-of-the-art genetic approaches to bioink development, emphasizing microbial engineering, genetic functionalization, and the encapsulation of growth factors. It highlights the transformative potential of genetically modified bioinks in various applications, including bone and cartilage regeneration, cardiac and liver tissue engineering, neural tissue reconstruction, and vascularization. While these advances hold promise for personalized and adaptive therapeutic solutions, challenges in scalability, reproducibility, and integration with multi-material systems persist. By bridging genetics and bioprinting, this interdisciplinary field paves the way for sophisticated constructs and innovative therapies in tissue engineering and regenerative medicine.

Complete spinal cord injury (SCI) causes permanent locomotor, sensory and neurological dysfunctions. Targeting complex immunopathological microenvironment at SCI sites comprising inflammatory cytokines infiltration, oxidative stress and massive neuronal apoptosis, the conductive oriented nanofiber felt with efficient ROS clearance, anti-inflammatory effect and accelerating neural regeneration is constructed by step-growth addition polymerization and electrostatic spinning technique for SCI repair. The formation of innovative Fe3+-PDA-PAT chelate in nanofiber felt enhances hydrophilic, antioxidant, antibacterial, hemostatic and binding factor capacities, thereby regulating immune microenvironment of SCI. With the capabilities of up-regulating COX5A and STAT6 expressions, down-regulating the expressions of IL1β, CD36, p-ERK, NFκB2 and NFκB signaling pathway proteins, the nanofiber felt attenuates oxidative stress injury, promotes M2 macrophage polarization and down-regulates inflammatory response. After implantation into complete transection SCI rats, the nanofiber felt is revealed to recruit endogenous NSCs, induce the differentiation of NSCs into neurons while inhibit astrocytes formation and inflammation, reduces glia scar, and promotes angiogenesis, remyelination and neurological functional recovery. Overall, this innovative strategy provides a facile immune regulatory system to inhibit inflammatory response and accelerate nerve regeneration after SCI, and its targeted proteins and mechanisms are first elucidated, which holds great application promise in clinical treatment of complete SCI.

Peripheral nerve injury (PNI) is a serious condition with limited surgical treatment options available. Conductive hydrogels have emerged as a promising alternative due to their ability to facilitate electrical signal exchange between cells and replicate the physiological microenvironment of electroactive tissues. Three-dimensional (3D) printing offers an innovative approach for fabricating neural scaffolds with precise structures and complex spatial architectures. In this study, we introduce a novel dual-bioink 3D printing strategy that integrates synthetic and natural materials to construct stable biomimetic neural tissue structures. The base bioink, comprising gelatin methacrylate (GelMA), chitosan (CS), and the conductive polymer polypyrrole (PPy), serves as a physical support network. It offers conductive pathways, promote cell growth, and ensures long-term structural integrity. The secondary bioink is a cell-loaded biodegradable gel-gelatin, which enables for precise cell deposition within the base network through a hybrid printing technique. The composite scaffold was evaluated for its mechanical properties, cytotoxicity, and ability to support neural differentiation. The results demonstrated that the 3D-printed neural network scaffold effectively promoted the neural differentiation and axon regeneration of PC-12 cells and HT-22 cells. These findings highlight its strong potential for facilitating neural functional recovery, positioning it as a promising candidate material for the treatment of PNI patients.

Breast cancer remains one of the leading causes of cancer-related mortality among women worldwide. Immunotherapy, a promising therapeutic approach, often faces challenges due to the immunosuppressive tumor microenvironment. This study explores the innovative use of CRISPR-Cas9 technology in conjunction with FCPCV nanoparticles to target and edit the C-C Motif Chemokine Ligand 5 (CCL5) gene, aiming to improve the efficacy of breast cancer immunotherapy. Single-cell RNA sequencing (scRNA-seq) and TCGA-BRCA data identified CCL5 as a key immune-related gene in breast cancer. Using CRISPR-Cas9, sgRNA targeting CCL5 was designed and delivered to breast cancer cells and humanized mouse models via FCPCV nanoparticles. In vitro experiments demonstrated that FCPCV nanoparticles effectively silenced CCL5, enhanced CD8+ T cell activity, and increased the production of cytokines such as IFN-γ, TNF-α, and GZMB. In vivo studies revealed significant tumor suppression, improved immune microenvironment, and increased CD8+/CD4+ ratios in treated mice, without notable toxic side effects. These findings highlight the potential of CRISPR-Cas9 nanoparticle-mediated gene editing as a novel strategy for enhancing breast cancer immunotherapy, providing a new direction for personalized and effective cancer treatment.

Biomimetic neural substitutes, constructed through the bottom-up assembly of cell-matrix modulus via 3D bioprinting, hold great promise for neural regeneration. However, achieving precise control over the fate of neural stem cells (NSCs) to ensure biological functionality remains challenging. Cell behaviors are closely linked to cellular dynamics and cell-matrix mechanotransduction within a 3D microenvironment. To address this, a dynamic bioactive bioink is designed to provide adaptable biomechanics and instructive biochemical cues, specifically tailored for the fate commitment of NSCs, through incorporating reversible Schiff-base bonds and bioactive motifs, N-cadherin-mimicking and BDNF-mimicking peptides. We demonstrate that the dynamic properties of 3D bioprinted living fibers alleviate the mechanical confinement on NSCs and significantly enhance their mechanosensing, spreading, migration, and matrix remodeling within the 3D matrix. Additionally, the inclusion of N-cadherin-mimicking and BDNF-mimicking peptides further enhances cells' ability to sense and respond to mechanical and neurotrophic cues provided by the surrounding matrix, which accelerates the self-organization of a functional neural network within the 3D bioprinted construct, leading to significant motor and sensory function recovery in a rat complete spinal cord injury model. This work underscores the critical role of precisely designing cell-instructive bioinks for the advanced functionality of 3D bioprinted living constructs in neural regeneration.

Spinal cord injury (SCI) presents a formidable challenge in clinical settings, resulting in sensory and motor function loss and imposing significant personal and societal burdens. However, owning to the adverse microenvironment and limited regenerative capacity, achieving complete functional recovery after SCI remains elusive. Additionally, traditional interventions including surgery and medication have a series of limitations that restrict the effectiveness of treatment. Recently, tissue engineering (TE) has emerged as a promising approach for promoting neural regeneration and functional recovery in SCI, which can effectively delivery drugs into injury site and delivery cells and improve the survival and differential. Here, we outline the main pathophysiology events of SCI and the adverse microenvironment post injury, further discuss the materials and common assembly strategies used for scaffolds in SCI treatment, expound on the latest advancements in treatment methods based on materials and scaffolds for drug and cell delivery in detail, and propose future directions for SCI repair with TE and highlight potential clinical applications.

Because of the evolving nature of tissue engineering scaffolds in the treatment of spinal cord injury (SCI), the current study was carried out to evaluate the research productivity of tissue engineering scaffolds in the treatment of SCI.

Studies published from 2000 to 2025 were retrieved from the Web of Science core collection with topics of spinal cord injury and tissue engineering scaffolds. The data were analyzed and visualized using the VOSviewer network analysis software.

Among 1542 articles analyzed, annual publications surged from 2000 to 2019, stabilizing thereafter. The U.S., China, and Canada led in productivity, with Northwestern University and the Biomaterials journal being top contributors. Keyword analysis revealed research hotspots such as functional recovery, axonal regeneration, stem cells, and hydrogels. Notably, hydrogels embedded with genetically engineered cells emerged as a pivotal trend, reflecting a shift toward biomimetic and combinatorial therapies. Collaboration networks highlighted intensified partnerships between Chinese and North American institutions, signaling global interdisciplinary efforts.

This study provides the first bibliometric roadmap for tissue engineering scaffolds in SCI, identifying key trends, influential entities, and underexplored areas. The rise in hydrogels and international collaborations underscores opportunities for targeted research. These findings guide researchers in prioritizing high-impact journals, fostering partnerships, and advancing novel scaffold designs to bridge translational gaps in SCI treatment.

Combinatorial treatments integrating cells and biomolecules within scaffolds have been investigated to address the multifactorial nature of spinal cord injury (SCI). Current regenerative treatments have been ineffective as they do not consider the spatial positions of various cell types to effectively form functional neural pathways. Emulating the complex heterogeneity of cells in the native spinal cord requires translating the existing biological understanding of spatial patterning in neural development, as well as the influence of biomolecule and mechanical patterning on regional specification and axonal regeneration, to engineer a scaffold for spinal cord regeneration. This review explores the potential of 3D bioprinting to precisely control material, cell and drug patterns in scaffolds, achieving spatial phenotype specification and providing axonal guidance to form appropriate connections. We also discuss the application of extrusion-based and digital light processing bioprinting in integrating mechanical, chemical and biological cues within a scaffold to advance spatially patterned 3D bioprinted scaffold, as well as current challenges and future perspectives in these bioengineering strategies.

Advancements in biomaterial-based spinal cord tissue engineering technology have profoundly influenced regenerative medicine, providing innovative solutions for both spinal cord organoid development and engineered spinal cord injury (SCI) repair. In spinal cord organoids, biomaterials offer a supportive microenvironment that mimics the natural extracellular matrix, facilitating cell differentiation and organization and advancing the understanding of spinal cord development and pathophysiology. Furthermore, biomaterials are essential in constructing engineered spinal cords for SCI repair. The incorporation of biomaterials with growth factors, fabrication of ordered scaffold structures, and artificial spinal cord assemblies are critical insights for SCI to ensure structural integrity, enhance cell viability, and promote neural regeneration in transplantation. In summary, this review summarizes the contribution of biomaterials to the spinal cord organoids progression and discusses strategies for biomaterial-based spinal cord engineering in SCI therapy. These achievements underscore the transformative potential of biomaterials to improve treatment options for SCI and accelerate future clinical applications.

Spinal cord injury (SCI) leads to acute tissue damage that disrupts the microenvironmental homeostasis of the spinal cord, inhibiting cell survival and function, and thereby undermining treatment efficacy. Traditional stem cell therapies have limited success in SCI, due to the difficulties in maintaining cell survival and inducing sustained differentiation into neural lineages. A new solution may arise from controlling the fate of stem cells by creating an appropriate mechanical microenvironment. In this study, mechanical response stem cell complex (MRSCC) is created as an innovative therapeutic strategy for SCI, utilizing 3D bioprinting technology and gelatin microcarriers (GM) loaded with mesenchymal stem cells (MSCs). GM creates an optimal microenvironment for MSCs growth and paracrine activity. Meanwhile, 3D bioprinting allows accurate control of spatial pore architecture and mechanical characteristics of the cell construct to encourage neuroregeneration. The mechanical microenvironment created by MRSCC is found to activate the Piezo1 channel and prevent excessive nuclear translocation of YAP, thereby increasing neural-related gene expression in MSCs. Transplanting MRSCC in rats with spinal cord injuries boosts sensory and motor recovery, reduces inflammation, and stimulates the regeneration of neurons and glial cells. The MRSCC offers a new tissue engineering solution that can promote spinal cord repair.

Conductive bioinks, integrated with 3D bioprinting and electrical stimulation, are essential for advancing neural tissue engineering. This study developed a SilMA/Pectin/MXene-soybean phospholipids (SP) bioink, where SilMA (silk fibroin modified with glycidyl methacrylate) provides a structural base, pectin enhances printability and shear-thinning properties, and MXene-SP improves conductivity through superior dispersibility. Increasing pectin and MXene-SP concentrations reduced the hydrogel's Young's modulus, promoting neural stem cell (NSC) differentiation into neurons. Electrochemical analyses revealed that higher MXene-SP levels decreased impedance and increased redox current, while conductivity measurements showed improved performance compared to unmodified MXene. NSCs encapsulated in the bioink achieved maximum proliferation under electrical stimulation at 300 μA for 10 min daily over 5 days. Neuronal differentiation positively correlated with MXene-SP concentration and stimulation intensity. Synaptic activity and vesicle recycling, assessed using FM1-43 dye, were significantly enhanced under electrical stimulation. This study successfully developed a biocompatible conductive bioink capable of inducing neuronal differentiation. Electrical stimulation further promoted cell proliferation, neuronal differentiation, and enhanced synaptic function. This bioink shows great potential for future applications in neural tissue engineering.

Spinal cord injury (SCI) is a very destructive disease of the central nervous system that often causes irreversible nerve damage. Unfortunately, the adult mammalian spinal cord displays little regenerative capacity after injury. In addition, the glial scars and inflammatory responses around the lesion site are another major obstacle for successful axon regeneration after SCI. However, biomaterials are highly biocompatible, and they could provide physical guidance to allow regenerating axon growth over the lesion site and restore functional neural circuits. In addition, combined or synergistic effects of spinal cord repair can be achieved by integrating different strategies, including the use of various biomaterials and microstructures, as well as combining bioactive molecules and living cells. Therefore, it is possible to use tissue engineering scaffolds to regulate the local microenvironment of the injured spinal cord, which may achieve better functional recovery in spinal cord injury repair. In this review, we summarize the latest progress in the treatment of SCI by biomaterials, and discussed its potential mechanism.

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. One way to combat the complex nature of an SCI has been to create functional tissue-engineered scaffolds that replace or replenish the aspects of the CNS and tissue/ECM that are damaged following the immediate injury and subsequent immune response. This can be achieved by employing the tissue-engineering triad consisting of cells, biomaterial(s), and environmental factors. Stem cells, with their innate ability to proliferate and differentiate, are a common choice for cellular therapies. Natural or synthetic biomaterials that have tunable characteristics are normally used as the scaffold base. Environmental factors can range from drugs to growth factors (GFs) or proteins, depending on if the idea would be to stimulate exogeneous or endogenous cell populations or just simply retain cells on the scaffold for effective transplantation. For functional regeneration and integration for SCI, the scaffold must promote neuroprotection and neuroplasticity. Tissue-engineering strategies have shown benefits including neuronal differentiation, axonal regeneration, axonal outgrowth, integration into the native spinal cord, and partial functional recovery. Overall, this review focuses on the background that causes SCI to be so difficult to treat, the individual components of the tissue-engineering triad, and how combinatorial scaffolds can be beneficial toward the prospects of future SCI recovery.

Neuromuscular diseases usually manifest as abnormalities involving motor neurons, neuromuscular junctions, and skeletal muscle (SkM) in postnatal stage. Present in vitro models of neuromuscular interactions require a long time and lack neuroglia involvement. Our study aimed to construct rodent bioengineered spinal cord neural network-skeletal muscle (NN-SkM) assembloids to elucidate the interactions between spinal cord neural stem cells (SC-NSCs) and SkM cells and their biological effects on the development and maturation of postnatal spinal cord motor neural circuits. After coculture with SkM cells, SC-NSCs developed into neural networks (NNs) and exhibited a high proportion of glutamatergic and cholinergic neurons, low proportion of neuroglia and gamma-aminobutyric acidergic neurons, and increased expression of synaptic markers. In NN-SkM assembloids, the acetylcholine receptors of SkM cells were upregulated, generating neuromuscular junction-like structures with NNs. The amplitude and frequency of SkM cell contraction in NN-SkM assembloids were increased by optogenetic and glutamate stimulation and blocked by tetrodotoxin and dizocilpine, respectively, confirming the existence of multisynaptic motor NNs. The coculture process involves the secretion of neurotrophin-3 and insulin growth factor-1 by SkM cells, which activate the related ERK-MAPK and PI3K-AKT signaling pathways in NNs. Inhibition of the ERK-MAPK and PI3K-AKT pathways significantly reduces neuronal differentiation and synaptic maturation of neural cells in NN-SkM assembloids, while also decreasing acetylcholine receptor formation on SkM cells. In brief, NN-SkM assembloids simulate the composition of spinal cord motor NNs and respond to motor regulatory signals, providing an in vitro model for studying postnatal development and maturation of spinal cord motor NNs.

Addressing the urgent need for effective fracture treatments, this study investigates the efficacy of a 3D bioprinted biomimetic hydrogel, enriched with bone marrow mesenchymal stem cells (BMSCs) and targeted hypoxia-inducible factor 1 alpha (Hif1a) gene activation, in enhancing fracture healing. A photocross-linkable bioink, gelatin methacryloyl bone matrix anhydride (GBMA) is developed, and selected its 5% concentration for bioink formulation. Rat BMSCs are isolated and combined with GBMA to create the GBMA@BMSCs bioink. This bioink is then used in 3D bioprinting to fabricate a hydrogel for application in a rat femoral fracture model. Through transcriptome sequencing, WGCNA, and Venn analysis, the hypoxia-inducible factor Hif1a is identified as a critical gene in the fracture healing process. In vitro studies showed that Hif1a promoted BMSC proliferation, chondrogenic differentiation, and cartilage matrix stability. The in vivo application of the GBMA@BMSCs hydrogel with Hif1a overexpression significantly accelerated fracture healing, evidenced by early and enhanced cartilage callus formation. The study demonstrates that 3D bioprinting of GBMA@BMSCs hydrogel, particularly with Hif1a-enhanced BMSCs, offers a promising approach for rapid and effective fracture repair.

The prevalence of breast cancer (BRCA) is notable in the female population, being a commonly diagnosed malignancy, where the management of copper levels is crucial for treatment success. This research aims to explore the influence of copper homeostasis on BRCA therapy, with a specific focus on the role of Cyclin-Dependent Kinase 1 (CDK1) and its relationship to copper regulation. A novel thermosensitive hydrogel incorporating nanoparticles (NPs) was engineered to synergize with the chemotherapy drug vincristine (VCR) in inhibiting tumor growth and metastasis. Through a comprehensive approach involving bioinformatics analyses, in vitro experiments, and in vivo models, the study identified CDK1 as a significant factor in BRCA progression under copper homeostasis. MBVP-Gel, a novel thermosensitive hydrogel incorporating NPs, was developed to enhance the delivery of chemotherapy drugs and regulate copper homeostasis in breast cancer treatment. The MBVP-Gel, formulated with copper chelation and VCR NPs, effectively suppressed CDK1 expression, thereby restraining BRCA cell growth and metastasis while enhancing the therapeutic impact of VCR. This investigation offers fresh insights and experimental validation on the interaction between copper homeostasis and BRCA, providing a valuable foundation for refining future treatment strategies. These findings underscore the potential advantages of targeting copper homeostasis and CDK1 in enhancing BRCA therapy, setting the stage for individualized interventions and improved patient consequences.

The incidence of nerve tissue injuries, such as peripheral nerve injury, spinal cord injury, traumatic brain injury, and various neurodegenerative diseases (NDs), is continuously increasing because of stress, physical and chemical trauma, and the aging population worldwide. Restoration of the damaged nervous system is challenging because of its structural and functional complexity and limited regenerative ability. Additionally, there is no cure available for NDs except for medications that provide symptomatic relief. Stem cells offer an alternative approach for promoting damage repair, but their efficacy is limited by a compromised survival rate and neurogenesis process. To address these challenges, neural tissue engineering has emerged as a promising strategy in which stem cells are seeded or encapsulated within a suitable biomaterial construct, increasing cell survival and neurogenesis. Numerous biomaterials are utilized to create different types of constructs for this purpose. Researchers are trying to develop ideal scaffolds that combine biomaterials, cells, and molecules that exactly mimic the biological and mechanical properties of the tissue to achieve functional recovery associated with neurological dysfunction. This review focuses on exploring the development and applications of different biomaterials for their potential use in the diagnosis, therapy, nerve tissue regeneration, and treatment of neurological disorders.

Spinal cord injury (SCI) is a profound medical condition that significantly hampers motor function, imposing substantial limitations on daily activities and exerting a considerable financial burden on patients and their families. The constrained regenerative capacity of endogenous spinal cord tissue, exacerbated by the inflammatory response following the initial trauma, poses a formidable obstacle to effective therapy. Recent advancements in the field, stem cells, biomaterials, and molecular therapy, show promising outcomes. This review provides a comprehensive analysis of tissue engineering and regenerative medicine approaches for SCI treatment, including cell transplantation, tissue-engineered construct implantation, and other potential therapeutic strategies. Additionally, it sheds light on preclinical animal studies and recent clinical trials incorporating these modalities, providing a glimpse into the evolving landscape of SCI management. STATEMENT OF SIGNIFICANCE: The investigation into spinal cord injury (SCI) treatments focuses on reducing long-term impacts by targeting scar inhibition and enhancing regeneration through stem cells, with or without growth factors. Induced pluripotent stem cells (iPSCs) show promise for autologous use, with clinical trials confirming their safety. Challenges include low cell viability and difficulty in targeted differentiation. Biomaterial scaffolds hold potential for improving cell viability and integration, and extracellular vesicles (EVs) are emerging as a novel therapy. While EV research is in its early stages, stem cell trials demonstrate safety and potential recovery. Advancing tissue engineering approaches with biomaterial scaffolds is crucial for human trials.

In recent years, there has been considerable attention devoted to flexible electronic devices within the realm of biomedical engineering. These devices demonstrate the capability to accurately capture human physiological signals, thereby facilitating efficient human-computer interaction, and providing a novel approach of flexible electronics for monitoring and treating related diseases. A notable contribution to this domain is the emergence of conductive hydrogels as a novel flexible electronic material. Renowned for their exceptional flexibility, adjustable electrical conductivity, and facile processing, conductive hydrogels have emerged as the preferred material for designing and fabricating innovative flexible electronic devices. This paper provides a comprehensive review of the recent advancements in flexible electronic devices rooted in conductive hydrogels. It offers an in-depth exploration of existing synthesis strategies for conductive hydrogels and subsequently examines the latest progress in their applications, including flexible neural electrodes, sensors, energy storage devices and soft robots. The analysis extends to the identification of technological challenges and developmental opportunities in both the synthesis of new conductive hydrogels and their application in the dynamic field of flexible electronics.

Spinal cord injury (SCI) is a debilitating condition that can result in significant functional impairment and loss of quality of life. There is a growing interest in developing new therapies for SCI, and hydrogel-based multimodal therapeutic strategies have emerged as a promising approach. They offer several advantages for SCI repair, including biocompatibility, tunable mechanical properties, low immunogenicity, and the ability to deliver therapeutic agents. This article provides an overview of the recent advances in hydrogel-based therapy strategies for SCI repair, particularly within the past three years. We summarize the SCI hydrogels with varied characteristics such as phase-change hydrogels, self-healing hydrogel, oriented fibers hydrogel, and self-assembled microspheres hydrogel, as well as different functional hydrogels such as conductive hydrogels, stimuli-responsive hydrogels, adhesive hydrogel, antioxidant hydrogel, sustained-release hydrogel, etc. The composition, preparation, and therapeutic effect of these hydrogels are briefly discussed and comprehensively evaluated. In the end, the future development of hydrogels in SCI repair is prospected to inspire more researchers to invest in this promising field.

The spalt (Sal) gene family has four members (Sall1-4) in vertebrates, all of which play pivotal roles in various biological processes and diseases. However, the expression and function of SALL2 in development are still less clear. Here, we first charted SALL2 protein expression pattern during mouse embryo development by immunofluorescence, which revealed its dominant expression in the developing nervous system. With the establishment of Sall2 deficient mouse embryonic stem cells (ESCs), the in vitro neural differentiation system was leveraged to interrogate the function of SALL2, which showed impaired neural differentiation of Sall2 knockout (KO) ESCs. Furthermore, neural stem cells (NSCs) could not be derived from Sall2 KO ESCs and the generation of neural tube organoids (NTOs) was greatly inhibited in the absence of SALL2. Meanwhile, transgenic expression of E1 isoform of SALL2 restored the defects of neural differentiation in Sall2 KO ESCs. By chromatin immunoprecipitation sequencing (ChIP-seq), Tuba1a was identified as downstream target of SALL2, whose function in neural differentiation was confirmed by rescuing neural phenotypes of Sall2 KO ESCs when overexpressed. In sum, by elucidating SALL2 expression dynamics during early mouse development and mechanistically characterizing its indispensable role in neural differentiation, this study offers insights into SALL2's function in human nervous system development, associated pathologies stemming from its mutations and relevant therapeutic strategy.

The exacerbation of extreme high-temperature events due to global climate change poses a significant challenge to public health, particularly impacting the central nervous system through heat stroke. This study aims to develop Poly(amidoamine) (PAMAM) nanoparticles loaded with curcumin (PAMAM@Cur) to enhance its therapeutic efficacy in hypothalamic neural damage in a heat stroke model and explore its potential mechanisms.

Curcumin (Cur) was encapsulated into PAMAM nanoparticles through a hydrophobic interaction method, and various techniques were employed to characterize their physicochemical properties. A heat stroke mouse model was established to monitor body temperature and serum biochemical parameters, conduct behavioral assessments, histological examinations, and biochemical analyses. Transcriptomic and proteomic analyses were performed to investigate the therapeutic mechanisms of PAMAM@Cur, validated in an N2a cell model.

PAMAM@Cur demonstrated good stability, photostability, cell compatibility, significant blood-brain barrier (BBB) penetration capability, and effective accumulation in the brain. PAMAM@Cur markedly improved behavioral performance and neural cell structural integrity in heat stroke mice, alleviated inflammatory responses, with superior therapeutic effects compared to Cur or PAMAM alone. Multi-omics analysis revealed that PAMAM@Cur regulated antioxidant defense genes and iron death-related genes, particularly upregulating the PCBP2 protein, stabilizing SLC7A11 and GPX4 mRNA, and reducing iron-dependent cell death.

By enhancing the drug delivery properties of Cur and modulating molecular pathways relevant to disease treatment, PAMAM@Cur significantly enhances the therapeutic effects against hypothalamic neural damage induced by heat stroke, showcasing the potential of nanotechnology in improving traditional drug efficacy and providing new strategies for future clinical applications.

This study highlights the outlook of nanotechnology in treating neurological disorders caused by heat stroke, offering a novel therapeutic approach with potential clinical applications.

To assess the efficacy of a novel 3D biomimetic hydrogel scaffold with immunomodulatory properties in promoting fracture healing. Immunomodulatory scaffolds were used in cell experiments, osteotomy mice treatment, and single-cell transcriptomic sequencing. In vitro, fluorescence tracing examined macrophage mitochondrial transfer and osteogenic differentiation of bone marrow-derived mesenchymal stem cells (BMSCs). Scaffold efficacy was assessed through alkaline phosphatase (ALP), Alizarin Red S (ARS) staining, and in vivo experiments. The scaffold demonstrated excellent biocompatibility and antioxidant-immune regulation. Single-cell sequencing revealed a shift in macrophage distribution towards the M2 phenotype. In vitro experiments showed that macrophage mitochondria promoted BMSCs' osteogenic differentiation. In vivo experiments confirmed accelerated fracture healing. The GAD/Ag-pIO scaffold enhances osteogenic differentiation and fracture healing through immunomodulation and promotion of macrophage mitochondrial transfer.

Spinal cord injury (SCI) is a catastrophic condition that disrupts neurons within the spinal cord, leading to severe motor and sensory deficits. While current treatments can alleviate pain, they do not promote neural regeneration or functional recovery. Three-dimensional (3D) bioprinting offers promising solutions for SCI repair by enabling the creation of complex neural tissue constructs. This review provides a comprehensive overview of 3D bioprinting techniques, bioinks, and stem cell applications in SCI repair. Additionally, it highlights recent advancements in 3D bioprinted scaffolds, including the integration of conductive materials, the incorporation of bioactive molecules like neurotrophic factors, drugs, and exosomes, and the design of innovative structures such as multi-channel and axial scaffolds. These innovative strategies in 3D bioprinting can offer a comprehensive approach to optimizing the spinal cord microenvironment, advancing SCI repair. This review highlights a comprehensive understanding of the current state of 3D bioprinting in SCI repair, offering insights into future directions in the field of regenerative medicine.

Dysfunction of the central nervous system (CNS) following traumatic brain injuries (TBI), spinal cord injuries (SCI), or strokes remains challenging to address using existing medications and cell-based therapies. Although therapeutic cell administration, such as stem cells and neuronal progenitor cells (NPCs), have shown promise in regenerative properties, they have failed to provide substantial benefits. However, the development of living cortical tissue engineered grafts, created by encapsulating these cells within an extracellular matrix (ECM) mimetic hydrogel scaffold, presents a promising functional replacement for damaged cortex in cases of stroke, SCI, and TBI. These grafts facilitate neural network repair and regeneration following CNS injuries. Given that natural glycosaminoglycans (GAGs) are a major constituent of the CNS, GAG-based hydrogels hold potential for the next generation of CNS healing therapies and in vitro modeling of CNS diseases. Brain-specific GAGs not only offer structural and biochemical signaling support to encapsulated neural cells but also modulate the inflammatory response in lesioned brain tissue, facilitating host integration and regeneration. This review briefly discusses different roles of GAGs and their related proteoglycan counterparts in healthy and diseases brain and explores current trends and advancements in GAG-based biomaterials for treating CNS injuries and modeling diseases. Additionally, it examines injectable, 3D bioprintable, and conductive GAG-based scaffolds, highlighting their clinical potential for in vitro modeling of patient-specific neural dysfunction and their ability to enhance CNS regeneration and repair following CNS injury in vivo.

The brain and gut are sensory organs responsible for sensing, transmitting, integrating, and responding to signals from the internal and external environment. In-depth analysis of brain-gut axis interactions is important for human health and disease prevention. Current research on the brain-gut axis primarily relies on animal models. However, animal models make it difficult to study disease mechanisms due to inherent species differences, and the reproducibility of experiments is poor because of individual animal variations, which leads to a significant limitation of real-time sensory responses. Organ-on-a-chip platforms provide an innovative approach for disease treatment and personalized research by replicating brain and gut ecosystems in vitro. This enables a precise understanding of their biological functions and physiological responses. In this article, we examine the history and most current developments in brain, gut, and gut-brain chips. The importance of these systems for understanding pathophysiology and developing new drugs is emphasized throughout the review. This article also addresses future directions and present issues with the advancement and application of gut-brain-on-a-chip technologies.

Traumatic spinal cord injury (tSCI) is a severe injury to the central nervous system that is categorized into primary and secondary injuries. Among them, the local microenvironmental imbalance in the spinal cord caused by secondary spinal cord injury includes accumulation of cytokines and chemokines, reduced angiogenesis, dysregulation of cellular energy metabolism, and dysfunction of immune cells at the site of injury, which severely impedes neurological recovery from spinal cord injury (SCI). In recent years, single-cell techniques have revealed the heterogeneity of multiple immune cells at the genomic, transcriptomic, proteomic, and metabolomic levels after tSCI, further deepening our understanding of the mechanisms underlying tSCI. However, spatial information about the tSCI microenvironment, such as cell location and cell-cell interactions, is lost in these approaches. The application of spatial multi-omics technology can solve this problem by combining the data obtained from immunohistochemistry and multiparametric analysis to reveal the changes in the microenvironment at different times of secondary injury after SCI. In this review, we systematically review the progress of spatial multi-omics techniques in the study of the microenvironment after SCI, including changes in the immune microenvironment and discuss potential future therapeutic strategies.

To address lymphatic metastasis in lung cancer, we developed the Au@Gd-SiO2-HA-LyP-1 nanoprobe, assessing its diagnostic and therapeutic capabilities. This nanoprobe integrates a Au core with a Gd-SiO2 shell and dual-targeting HA-LyP-1 molecules. We evaluated its size, shape, and functional properties using various characterization techniques, alongside in vivo and in vitro toxicity tests. The spherical nanoprobes have a 50 nm diameter and contain 1.37% Gd. They specifically target lymphatic metastasis sites and tumor cells, showing enhanced MRI contrast and effective, targeted DOX delivery with reduced normal tissue toxicity. The Au@Gd-SiO2-HA-LyP-1 nanoprobe is a promising tool for diagnosing and treating lung cancer lymphatic metastasis, featuring dual-targeting and superior imaging capabilities.

The primary aim of this research was to explore the functions of Wtap and Ythdf1 in regulating neuronal Lipocalin-2 (Lcn2) through m6A modification in traumatic brain injury (TBI). By employing transcriptome sequencing and enrichment analysis, we identified the Wtap/Ythdf1-mediated Lcn2 m6A modification pathway as crucial in TBI. In our in vitro experiments using primary cortical neurons, knockout of Wtap and Ythdf1 led to the inhibition of Lcn2 m6A modification, resulting in reduced neuronal death and inflammation. Furthermore, overexpression of Lcn2 in cortical neurons induced the activation of reactive astrocytes and M1-like microglial cells, causing neuronal apoptosis. In vivo experiments confirmed the activation of reactive astrocytes and microglial cells in TBI and importantly demonstrated that Wtap knockdown improved neuroinflammation and functional impairment. These findings underscore the significance of Wtap/Ythdf1-mediated Lcn2 regulation in TBI secondary injury and suggest potential therapeutic implications for combating TBI-induced neuroinflammation and neuronal damage.

Spinal cord injury is considered one of the most difficult injuries to repair and has one of the worst prognoses for injuries to the nervous system. Following surgery, the poor regenerative capacity of nerve cells and the generation of new scars can make it very difficult for the impaired nervous system to restore its neural functionality. Traditional treatments can only alleviate secondary injuries but cannot fundamentally repair the spinal cord. Consequently, there is a critical need to develop new treatments to promote functional repair after spinal cord injury. Over recent years, there have been several developments in the use of stem cell therapy for the treatment of spinal cord injury. Alongside significant developments in the field of tissue engineering, three-dimensional bioprinting technology has become a hot research topic due to its ability to accurately print complex structures. This led to the loading of three-dimensional bioprinting scaffolds which provided precise cell localization. These three-dimensional bioprinting scaffolds could repair damaged neural circuits and had the potential to repair the damaged spinal cord. In this review, we discuss the mechanisms underlying simple stem cell therapy, the application of different types of stem cells for the treatment of spinal cord injury, and the different manufacturing methods for three-dimensional bioprinting scaffolds. In particular, we focus on the development of three-dimensional bioprinting scaffolds for the treatment of spinal cord injury.

Accurate reproduction of human intestinal structure and functionin vitrois of great significance for understanding the development and disease occurrence of the gut. However, mostin vitrostudies are often confined to 2D models, 2.5D organ chips or 3D organoids, which cannot fully recapitulate the tissue architecture, microenvironment and cell compartmentalization foundin vivo. Herein, a centimeter-scale intestine tissue that contains intestinal features, such as hollow tubular structure, capillaries and tightly connected epithelium with invivo-likering folds, crypt-villi, and microvilli is constructed by 3D embedding bioprinting. In our strategy, a novel photocurable bioink composed of methacrylated gelatin, methacrylated sodium alginate and poly (ethylene glycol) diacrylate is developed for the fabrication of intestinal model. The Caco-2 cells implanted in the lumen are induced by the topological structures of the model to derive microvilli, crypt-villi, and tight junctions, simulating the intestinal epithelial barrier. The human umbilical vein endothelial cells encapsulated within the model gradually form microvessels, mimicking the dense capillary network in the intestine. This intestine-like tissue, which closely resembles the structure and cell arrangement of the human gut, can act as a platform to predict the therapeutic and toxic side effects of new drugs on the intestine.

Spinal cord injury (SCI) is an important factor in sensory and motor disorders that affects thousands of people every year. Currently, despite successes in basic science and clinical research, there are few effective methods in the treatment of chronic and acute spinal cord injuries. In the last decade, the use of 3D printed scaffolds in the treatment of SCI had satisfactory and promising results. By providing a microenvironment around the injury site and in combination with growth factors or cells, 3D printed scaffolds help in axon regeneration as well as neural recovery after SCI. Here, we provide an overview of tissue engineering, 3D printing scaffolds, the different polymers used and their characterization methods. This review highlights the recent encouraging applications of 3D printing scaffolds in developing the novel SCI therapy.