多功能复合贴片在创伤性脑损伤治疗中的应用

No abstract available

Tissue engineering using stem cells is widely used to repair damaged tissues in diverse biological systems; however, this approach has met with less success in regenerating the central nervous system (CNS). In this study we optimized and characterized the surface chemistry of chitosan‐based scaffolds for CNS repair. To maintain radial glial cell (RGC) character of primitive neural precursors, fibronectin was adsorbed to chitosan. The chitosan was further modified by covalently linking heparin using genipin, which then served as a linker to immobilize fibroblast growth factor‐2 (FGF‐2), creating a multifunctional film. Fetal rat neural precursors plated onto this multifunctional film proliferated and remained multipotent for at least 3 days without providing soluble FGF‐2. Moreover, they remained less mature and more highly proliferative than cells maintained on fibronectin‐coated substrates in culture medium supplemented with soluble FGF‐2. To create a vehicle for cell transplantation, a 3% chitosan solution was electrosprayed into a coagulation bath to generate microspheres (range 30–100 µm, mean 64 µm) that were subsequently modified. Radial glial cells seeded onto these multifunctional microspheres proliferated for at least 7 days in culture and the microspheres containing cells were small enough to be injected, using 23 Gauge Hamilton syringes, into the brains of adult rats that had previously sustained cortical contusion injuries. When analysed 3 days later, the transplanted RGCs were positive for the stem cell/progenitor marker Nestin. These results demonstrate that this multifunctional scaffold can be used as a cellular and growth factor delivery vehicle for the use in developing cell transplantation therapies for traumatic brain injuries. Copyright © 2013 John Wiley & Sons, Ltd.

Abstract Damage in neural tissues poses a significant challenge in regenerative medicine, requiring scaffolds that support both biological and electrical functions. Conductive biomaterials offer promising solutions by promoting neural repair and integration. However, the development of multifunctional scaffolds that simultaneously provide electrical conductivity, antioxidant activity, mechanical strength, and biocompatibility remains limited. This study aims to develop and characterize a biofunctional conductive neural tissue scaffold. The incorporation of polyaniline (PANI) enhanced electrical conductivity, while the addition of carvacrol (CRV) improved antioxidant activity and biological function but slightly reduced conductivity in the layered structure. In the second-layer scaffold model, cell viability reached 140% thanks to carvacrol. The electrical conductivity of the chitosan/polyaniline film was measured as 1.429 x10−2 S/m using the four-point probe method. A second layer of polycaprolactone/carvacrol was formed onto the chitosan/polyaniline conductive film using electrospinning, and the conductivity was measured as 1.052 x10−3 S/m. The values obtained for both conductive scaffolds have been shown to provide good electrical conductivity in conductive tissue scaffolds used in neural tissue engineering studies. Polycaprolactone (PCL) contributed to mechanical strength, and chitosan (CHI) improved biocompatibility. The combination of these components resulted in a scaffold with suitable properties for neural tissue repair, particularly under neurodegenerative conditions.

Developing effective platforms for neural stem cell (NSC) proliferation and transplantation remains a critical challenge in central nervous system (CNS) repair, particularly within inflammatory lesion environments. This study presents a multifunctional scaffold composed of electrospun polyurethane/carbon nanotube (PU/CNT) nanofibers functionalized with liposomal hesperidin (Hsd@lip) to enhance NSC proliferation and adhesion. Hsd@lip, fabricated via thin‐film hydration, exhibited an encapsulation efficiency of 69.6 ± 8.6%, a particle size of 105.8 ± 37.7 nm, and sustained drug release with 91% hesperidin released over 30 days. Incorporating CNTs into the PU matrix significantly improved mechanical strength (5.9 ± 1.1 MPa), electrical conductivity (0.067 S/cm), hydrophilicity (WCA: 85.2 ± 5.2°), and swelling behavior (220% after 24 h in artificial cerebrospinal fluid). FE‐SEM and TEM confirmed uniform fiber morphology and homogeneous CNT dispersion. NSCs cultured on PU/CNT/Hsd@lip scaffolds exhibited superior viability, attachment, and proliferation (covering 59 ± 9.5% of the surface after 14 days) compared with control scaffolds. Fluorescence and DAPI staining confirmed robust cell adhesion and scaffold colonization. These results demonstrate that the PU/CNT/Hsd@lip scaffold provides a favorable microenvironment that promotes NSC proliferation and adhesion, offering a promising platform for neural tissue engineering applications.

No abstract available

No effective treatments are currently available for central nervous system neurotrauma although recent advances in electrical stimulation suggest some promise in neural tissue repair. It is hypothesized that structured integration of an electroconductive biomaterial into a tissue engineering scaffold can enhance electroactive signaling for neural regeneration. Electroconductive 2D Ti3C2Tx MXene nanosheets are synthesized from MAX‐phase powder, demonstrating excellent biocompatibility with neurons, astrocytes and microglia. To achieve spatially‐controlled distribution of these MXenes, melt‐electrowriting is used to 3D‐print highly‐organized PCL micro‐meshes with varying fiber spacings (low‐, medium‐, and high‐density), which are functionalized with MXenes to provide highly‐tunable electroconductive properties (0.081 ± 0.053‐18.87 ± 2.94 S/m). Embedding these electroconductive micro‐meshes within a neurotrophic, immunomodulatory hyaluronic acid‐based extracellular matrix (ECM) produced a soft, growth‐supportive MXene‐ECM composite scaffold. Electrical stimulation of neurons seeded on these scaffolds promoted neurite outgrowth, influenced by fiber spacing in the micro‐mesh. In a multicellular model of cell behavior, neurospheres stimulated for 7 days on high‐density MXene‐ECM scaffolds exhibited significantly increased axonal extension and neuronal differentiation, compared to low‐density scaffolds and MXene‐free controls. The results demonstrate that spatial‐organization of electroconductive materials in a neurotrophic scaffold can enhance repair‐critical responses to electrical stimulation and that these biomimetic MXene‐ECM scaffolds offer a promising new approach to neurotrauma repair.

The development of effective materials for neural tissue repair remains a major challenge in regenerative medicine. In this study, we present a novel MXene-reinforced composite cryogel scaffold designed for neural tissue regeneration. MXenes, a class of two-dimensional materials with high conductivity and biocompatibility, were integrated into a polyvinyl alcohol (PVA) matrix via cryopolymerization to form a macroporous, mechanically stable scaffold. The morphology, mechanical properties, and swelling behavior of the cryogel with different MXene contents have been assessed. The effects of MXene on the viability/proliferation and differentiation of neural cells (PC-12) cultured in the composite cryogel were elucidated. The MXene/PVA cryogel demonstrated excellent cell-supporting potential, with MXene not only showing no toxicity but also promoting the proliferation of cultured PC-12. Additionally, MXene induced a neuritogenesis-like process in the cells as evidenced by morphological changes and the enhanced expression of the neural marker β-III-tubulin. The neuroprotective properties of the MXene component were revealed by the alleviation of oxidative stress and reduction of intracellular ROS levels. These findings highlight the potential of MXene-embedded PVA cryogel as a promising material that can be further used in conjunction with electrostimulation therapy for advancing strategies in neural tissue engineering.

Objective. To address the limited innate regenerative capacity of neural tissues following traumatic brain injury (TBI) by developing a novel therapeutic intervention. Approach. We engineered a composite scaffold using 3D bioprinting to integrate mesenchymal stem cells (MSCs) with collagen-heparan matrices supplemented with basic fibroblast growth factor (bFGF) and nerve growth factor (NGF), creating a 3D-CH-bFGF/NGF-MSCs construct. Main results. The engineered construct demonstrated favorable biomechanical characteristics and cytocompatibility. In rat TBI models, this intervention significantly enhanced cognitive recovery and sustained sensorimotor function restoration. Histopathological analyses revealed corresponding neural network regeneration through axonal regrowth, synaptogenesis reinforcement, and myelination enhancement at injury sites. Significance. This study demonstrates the therapeutic potential of a 3D-bioprinted, growth factor-enhanced MSC-scaffold construct to promote structural and functional neural repair after TBI, offering a promising strategy for neural tissue regeneration.

A composite polymeric scaffold of gelatin/alginate /graphene is fabricated through freeze‐drying technique. Initially, a hydrogel system comprised of gelatin/alginate (1:1) is prepared, and then the effect of different amounts of graphene carboxyl nanosheets (1,1.5, 2, and 2.5 wt.%) on the resultant structural properties are thoroughly evaluated. The swelling ratio, biodegradability, electrical and mechanical properties of bio‐composite hydrogels are controlled by manipulating the concentration of graphene‐COOH. The significant increase in the electrical conductivity is observed with the addition of 2.5% graphene‐COOH, and the electrical conductivity increased from 8.525 × 10−7 ± 0.01 S cm−1 to 7.644 × 10−4 ± 0.04 S cm−1. Also, the biocomposite hydrogels exhibited compressive and tensile strength ranging from 25 to 382 KPa and 11.4 to 148 KPa with an increase in the concentration of graphene‐COOH. The simplicity, low cost, tunable mechanical properties, and optimal electrical conductivity of the hydrogel system presented in this study highlight its potential as nerve tissue replacement.

Dynamic mechanical cues are crucial for glial neuromodulation and energy metabolism in neural regeneration, yet the mechanisms underlying mechanotransduction and intracellular organelle responses in glia after neurotrauma remain vague. In this study, we develop mechano-bioactive piezoelectric hydrogel bioelectronics (BaTiO3-embedded collagen-1 hydrogel) and investigate mechanotransduction in astrocytes and Schwann cells. Ultrasound-driven piezoelectric hydrogel bioelectronics exerts electrical signals from mechanical stimulation and upregulates PIEZO1 channel in astrocytes and PIEZO2 channel in Schwann cells. This mechanoelectrical conversion increases calcium influx to activate ATP synthase subunit and promote MFN/OPA1 mediated mitochondrial fusion. Consequently, it enhances ATP synthesis by forming an efficient energy network as a central bioenergetic hub to promote glia mediated neural repair. Furthermore, this mechano-bioactive piezoelectric hydrogel bioelectronics exhibits therapeutic efficacy for treating central and peripheral nervous injuries in multiple animal models (mice, rats, Beagle dogs, and Rhesus monkeys), demonstrating its wide adaptivity and significant translational potential. The findings elucidate a multilevel mechanobiological energy transduction (mechanical-electrical-bioenergetic conversion) design in neural repair as a promising clinical treatment mode. Mechanical cues are key for modulation and metabolism in neural regeneration, yet the mechanisms remain unclear. Here, the authors developed mechano-bioactive piezoelectric hydrogel bioelectronics to achieve mechanical-electrical-bioenergetic energy conversion for neural repair

Clinical management of peripheral nerve injury (PNI) remains a significant challenge, necessitating urgent advancements in medical science. Although autologous nerve grafting is the clinical "gold standard," its broader application is severely limited by donor site morbidity, functional variability, and dimensional mismatches. Nerve guidance conduits (NGCs) have emerged as promising alternatives, offering the potential for structural and functional neural restoration through biomimetic topological designs and multimodal biophysical and chemical signaling. In particular, electroactive NGCs have attracted substantial research interest because of the remarkable regulatory effects of electroactive materials on the PNI microenvironment and their superior efficacy in promoting neural regeneration. PVDF/LM-ZnO NGCs were successfully prepared using electrospinning technology combined with hydrothermal synthesis. The addition of LM and ZnO notably improved the piezoelectric properties, raising the piezoelectric coefficient (d33) from 0.9 to 4.6 pC/N. The fabricated PVDF/LM-ZnO NGC demonstrated excellent cytocompatibility, supporting the adhesion, growth, and differentiation of PC12, RSC96 and HUVEC cells. In vivo evaluations demonstrated that the PVDF/LM-ZnO NGCs significantly improved functional recovery of sciatic nerve injuries in Sprague-Dawley (SD) rats. Western blot analyses confirmed the increased expression of the neurotrophic factor NT-3, further confirming its regenerative potential. By integrating piezoelectric-triboelectric nanogenerators (PTNGs) with PVDF/LM-ZnO NGCs, self-powered NGCs were successfully developed. Cellular experiments revealed that the electrical stimulation (ES) generated by PTNG outperformed the external ES in inducing neural cell proliferation, axonal elongation, and functional marker expression. Compared with non-self-powered counterparts, self-powered NGCs demonstrated superior capabilities in promoting cellular adhesion, proliferation, and differentiation, indicating enhanced therapeutic potential for PNI repair.

Neural stem cells (NSCs) transplantation represents a promising therapeutic strategy for spinal cord injury (SCI). However, the acquisition of functional neurons through their natural differentiation is limited and maintaining the viability of implanted NSCs poses significant challenges. In this study, based on barium titanate (BTO), polydopamine (PDA), and triphenylphosphine (TPP), mitochondria‐targeted piezoelectric nanoparticles (TPP‐PDA@BTO) are synthesized and an injectable piezoelectric nanocomposite hydrogel (BT‐Gel) is developed responsive to reactive oxygen species (ROS). The TPP‐PDA@BTO loaded within BT‐Gel effectively promotes NSCs neural differentiation under ultrasound (US) irradiation, a process confirmed by transcriptomic sequencing to be closely associated with the enhanced mitochondrial function in NSCs due to piezoelectric stimulation targeting mitochondria. Additionally, BT‐Gel under US significantly facilitates the M2 polarization of microglia and enhances myelinated axons regeneration. The bioactive hydrogel also effectively promotes the integration of transplanted NSCs with host neural circuits, supplemented damaged neurons, alleviated neuroinflammation, and inhibited glial scar formation, thereby significantly accelerating the recovery of motor function of SCI rats. Therefore, mitochondrion‐targeting piezoelectric nanocomposite hydrogel capable of delivering NSCs, based on the therapeutic concept of promoting neural differentiation of exogenous NSCs and comprehensively regulating the pathological microenvironment post‐SCI, offers a novel perspective for stem cell therapy in central nervous system injuries.

The peripheral nerve regeneration has a limited innate capacity for self-repair and thus it urgently necessitates designing a smart nerve guidance conduit. Considering the electrophysiological features of nerve tissues, a piezoelectric bilayer fibrous conduit filled with drug-encapsulated gellan was developed in this study and its ability to promote neural growth was assessed in vivo. To fabricate such conduit, bilayer fibrous mats were prepared from poly ε-caprolactone/BaTiO3 and poly-L-lactic acid -chitosan-gelatin-polyaniline/graphene via an electrospinning process. After rolling the fibrous mat, the inside of the hollow conduit was filled with gellan containing Curcumin-loaded alginate (Alg) particles. All intermediate and final products were characterized using various analytical techniques. Encapsulation of Curcumin into the Alg particles and loaded in the gellan could effectively enhance sustained release of drug during the healing process, following Higuchi model. Four weeks post-surgery, such an engineered conduit revealed much better nerve regeneration results than the control group and showed desirable outcomes in terms of sciatic function indices and formation of the perineurium as well as axon number. Such developed conduit has a high potency to repair the injured nerve tissue due to their capacity to sustain the release of drugs over a long period and transfer self-stimulated electrical signals between cells. The in vivo assay revealed the feasibility of exploiting such conduit in nerve tissue engineering.

No abstract available

Piezoelectric materials can provide in situ electrical stimulation without external chemical or physical support, opening new frontiers for future bioelectric therapies. Polyvinylidene fluoride (PVDF) possesses piezoelectricity and biocompatibility, making it an electroactive biomaterial capable of enhancing bioactivity through instantaneous electrical stimulation, which indicates significant potential in tissue engineering. In this study, we developed electroactive and biomimetic scaffolds made of electrospun PVDF and self-assembling peptides (SAPs) to enhance stem cell transplantation for spinal cord injury regeneration. We investigated the morphology and crystalline polymorphs of the electrospun scaffolds. Morphological studies demonstrated the benefit of using mixed sodium dodecyl sulfate (SDS) and SAPs as additives to form thinner, uniform, and defect-free fibers. Regarding electroactive phases, β and γ phases—evidence of electroactivity—were predominant in aligned scaffolds and scaffolds modified with SDS and SAPs. In vitro studies showed that neural stem cells (NSCs) seeded on electrospun PVDF with additives exhibited desirable proliferation and differentiation compared to the gold standard. Furthermore, the orientation of the fibers influenced scaffold topography, resulting in a higher degree of cell orientation in fiber-aligned scaffolds compared to randomly oriented ones.

Endogenous neuronal differentiation of neural stem cells (NSCs) is a promising route to restore function after traumatic brain injury (TBI), but direct transplantation of exogenous NSCs faces practical and immunological barriers and yields limited neuronal maturation. Here, a clinically relevant strategy is reported that converts a dura mater into an active piezoelectric patch to noninvasively drive endogenous NSC neurogenesis. Electrospun poly(L‑lactic acid) (PLLA) patches were subjected to surface confinement crystallization on metal substrates, producing a metastable α' crystal structure and markedly enhanced piezoelectric output. Under low‑intensity transcranial ultrasound, the treated patch generates reproducible pulsed electrical signals that remodel the local injury microenvironment. In vitro and in vivo assays show that ultrasound‑activated patches increase neuronal lineage differentiation (neurons/astrocytes ratio increased ∼9.6‑fold at 14 days) and promote greater neuronal maturation, while concomitantly modulating the immune milieu. In a rat TBI model, daily 2‑min ultrasound stimulation delivered via the patch substantially accelerated tissue repair and improved behavioral and cognitive outcomes compared with untreated controls. This work demonstrates a simple, scalable modification of clinical artificial dura mater to produce a soft, biodegradable piezoelectric implant capable of remote, noninvasive electrical modulation of endogenous NSCs, with broad implications for neural regeneration and potential clinical translation.

Stimuli‐responsive nanomaterials capable of spatiotemporal control over drug release are of nanocomposite patch (“e‐Medi‐Patch”) engineered from biodegradable polycaprolactone (PCL), graphene nanoplatelets, and a redox‐active therapeutic, niclosamide. The hierarchical composite integrates π‐π interactions between aromatic drug molecules and conductive graphene to enhance loading and retention, an Au microelectrode interface to enable wireless electrostimulation, and bluetooth‐assisted impedance sensing for real‐time monitoring of release dynamics. Under mild electrical stimulation, the nanocomposite exhibits on‐demand, unidirectional release of niclosamide with tunable kinetics, confirmed by modelling, in vitro melanoma cell studies, and in vivo xenograft tumor regression. Unlike conventional slow‐release patches that rely on passive diffusion, the e‐Medi‐Patch uniquely offers on‐demand electrostimulatory release with real‐time feedback monitoring, transforming drug delivery from a static system into an actively controlled, intelligent therapeutic platform. Beyond melanoma, the platform accommodates other redox‐active therapeutics and offers scalable melt‐blending fabrication. This work establishes an integrated materials‐electronics strategy for wearable, feedback‐controlled drug delivery, bridging multifunctional nanocomposites and precision medicine.

The distribution of electrical potentials and current in exogenous electrostimulation has significant impacts on its effectiveness in promoting tissue repair. However, there is still a lack of a flexible, implantable power source capable of generating customizable patterned electric fields for in situ electrostimulation(electrical stimulation). Herein, this study reports a fuel cell patch (FCP) that can provide in situ electrostimulation and a hypoxic microenvironment to promote tissue repair synergistically. Stable and highly efficient PtNi nanochains and PtNi nanocages electrocatalysts with anti‐interference properties catalyze glucose oxidation and oxygen reduction respectively in an encapsulation‐free fuel cell. The laser‐induced graphene (LIG) electrode loaded with PtNi electrocatalysts is transferred to the surface of a flexible chitosan hydrogel. The resulting flexible FCP can adapt to tissues with different morphologies, firmly adhere to prevent suturing, and provide potent electrostimulation (0.403 V, 51.55 µW cm−2). Additionally, it consumes oxygen in situ to create a hypoxic microenvironment, increasing the expression of hypoxia‐inducible factor‐1α (HIF‐1α). Based on the different pattern requirements of exogenous electrostimulation during the repair of various types of tissue, an axial FCP for peripheral nerves and a flower‐patterned FCP for myocardial tissue are constructed and transplanted into animals, showing significant tissue repair in both models.

Traumatic brain injury (TBI) is a sudden injury to the brain, accompanied by the production of large amounts of reactive oxygen and nitrogen species (RONS) and acute neuroinflammation responses. Although traditional pharmacotherapy can effectively decrease the immune response of neuron cells via scavenging free radicals, it always involves in short reaction time as well as rigorous clinical trial. Therefore, a noninvasive topical treatment method that effectively eliminates free radicals still needs further investigation.

Three-dimensional (3D) bioprinting has emerged as a promising approach to fabricate living neural constructs with anatomically accurate complex geometries and spatial distributions of neural stem cells (NSCs) for spinal cord injury (SCI) repair. The NSC-laden 3D bioprinting, however, still faces some big challenges, such as cumbersome printing process, poor cell viability, and minimal cell-material interaction. To address these issues, we have fabricated NSC-laden scaffolds by 3D bioprinting and explore for the first time their application for in vivo SCI repair. In our strategy, we have developed a novel biocompatible bioink consisting of functional chitosan, hyaluronic acid derivatives, and matrigel. This bioink shows fast gelation (within 20 s) and spontaneous covalent crosslinking capability, facilitating convenient one-step bioprinting of spinal cord-like constructs. Thus-fabricated scaffolds maintain high NSC viability (about 95%), and offer a benign microenvironment that facilitates cell-material interactions and neuronal differentiation for optimal formation of neural network. The in vivo experiment has further demonstrated that the bioprinted scaffolds promoted the axon regeneration and decreased glial scar deposition, leading to significant locomotor recovery of the SCI model rats, which may represent a general and versatile strategy for precise engineering of central nervous system and other neural organs/tissues for regenerative medicine application.

Neural interfaces using biocompatible scaffolds provide crucial properties, such as cell adhesion, structural support, and mass transport, for the functional repair of nerve injuries and neurodegenerative diseases. Neural stimulation has also been found to be effective in promoting neural regeneration. This work provides a generalized strategy to integrate photoacoustic (PA) neural stimulation into hydrogel scaffolds using a nanocomposite hydrogel approach. Specifically, polyethylene glycol (PEG)-functionalized carbon nanotubes (CNT), highly efficient photoacoustic agents, are embedded into silk fibroin to form biocompatible and soft photoacoustic materials. We show that these photoacoustic functional scaffolds enable nongenetic activation of neurons with a spatial precision defined by the area of light illumination, promoting neuron regeneration. These CNT/silk scaffolds offered reliable and repeatable photoacoustic neural stimulation, and 94% of photoacoustic-stimulated neurons exhibit a fluorescence change larger than 10% in calcium imaging in the light-illuminated area. The on-demand photoacoustic stimulation increased neurite outgrowth by 1.74-fold in a rat dorsal root ganglion model, when compared to the unstimulated group. We also confirmed that promoted neurite outgrowth by photoacoustic stimulation is associated with an increased concentration of neurotrophic factor (BDNF). As a multifunctional neural scaffold, CNT/silk scaffolds demonstrated nongenetic PA neural stimulation functions and promoted neurite outgrowth, providing an additional method for nonpharmacological neural regeneration.

There is intense interest and effort toward regenerating the brain after severe injury. Stem cell transplantation after insult to the central nervous system has been regarded as the most promising approach for repair; however, engrafting cells alone might not be sufficient for effective regeneration. In this study, we have compared neural progenitors (NPs) from the fetal ventricular zone (VZ), the postnatal subventricular zone, and an immortalized radial glia (RG) cell line engineered to conditionally secrete the trophic factor insulin-like growth factor 1 (IGF-1). Upon differentiation in vitro, the VZ cells were able to generate a greater number of neurons than subventricular zone cells. Furthermore, differentiated VZ cells generated pyramidal neurons . In vitro, doxycycline-driven secretion of IGF-1 strongly promoted neuronal differentiation of cells with hippocampal, interneuron and cortical specificity. Accordingly, VZ and engineered RG-IGF-1-hemagglutinin (HA) cells were selected for subsequent in vivo experiments. To increase cell survival, we delivered the NPs attached to a multifunctional chitosan-based scaffold. The microspheres containing adherent NPs were injected subacutely into the lesion cavity of adult rat brains that had sustained controlled cortical impact injury. At 2 weeks posttransplantation, the exogenously introduced cells showed a reduction in stem cell or progenitor markers and acquired mature neuronal and glial markers. In beam walking tests assessing sensorimotor recovery, transplanted RG cells secreting IGF-1 contributed significantly to functional improvement while native VZ or RG cells did not promote significant recovery. Altogether, these results support the therapeutic potential of chitosan-based multifunctional microsphere scaffolds seeded with genetically modified NPs expressing IGF-1 to promote repair and functional recovery after traumatic brain injuries.

After spinal cord injury (SCI), endogenous neural stem cells (NSCs) near the damaged site are activated, but few NSCs migrate to the injury epicenter and differentiate into neurons because of the harsh microenvironment. It has demonstrated that implantation of hydrogel scaffold loaded with multiple cues can enhance the function of endogenous NSCs. However, programming different cues on request remains a great challenge. Herein, a time-programmed linear hierarchical structure scaffold is developed for spinal cord injury recovery. The scaffold is obtained through coaxial 3D printing by encapsulating a dual-network hydrogel (composed of hyaluronic acid derivatives and N-cadherin modified sodium alginate, inner layer) into a temperature responsive gelatin/cellulose nanofiber hydrogel (Gel/CNF, outer layer). The reactive species scavenger, metalloporphyrin, loaded in the outer layer is released rapidly by the degradation of Gel/CNF, inhibiting the initial oxidative stress at lesion site to protect endogenous NSCs; while the inner hydrogel with appropriate mechanical support, linear topology structure and bioactive cues facilitates the migration and neuronal differentiation of NSCs at the later stage of SCI treatment, thereby promoting motor functional restorations in SCI rats. This study offers an innovative strategy for fabrication of multifunctional nerve regeneration scaffold, which has potential for clinical treatment of SCI. STATEMENT OF SIGNIFICANCE: Two major challenges facing the recovery from spinal cord injury (SCI) are the low viability of endogenous neural stem cells (NSCs) within the damaged microenvironment, as well as the difficulty of neuronal regeneration at the injured site. To address these issues, a spinal cord-like coaxial scaffold was fabricated with free radical scavenging agent metalloporphyrin Mn (III) tetrakis (4-benzoic acid) porphyrin and chemokine N-cadherin. The scaffold was constructed by 3D bioprinting for time-programmed protection and modulation of NSCs to effectively repair SCI. This 3D coaxially bioprinted biomimetic construct enables multi-factor on-demand repair and may be a promising therapeutic strategy for SCI.

An effective paradigm for transplanting large numbers of neural stem cells after central nervous system (CNS) injury has yet to be established. Biomaterial scaffolds have shown promise in cell transplantation and in regenerative medicine, but improved scaffolds are needed. In this study we designed and optimized multifunctional and biocompatible chitosan-based films and microspheres for the delivery of neural stem cells and growth factors for CNS injuries. The chitosan microspheres were fabricated by coaxial airflow techniques, with the sphere size controlled by varying the syringe needle gauge and the airflow rate. When applying a coaxial airflow at 30 standard cubic feet per hour, ∼300μm diameter spheres were reproducibly generated that were physically stable yet susceptible to enzymatic degradation. Heparin was covalently crosslinked to the chitosan scaffolds using genipin, which bound fibroblast growth factor-2 (FGF-2) with high affinity while retaining its biological activity. At 1μgml(-1) approximately 80% of the FGF-2 bound to the scaffold. A neural stem cell line, GFP+RG3.6 derived from embryonic rat cortex, was used to evaluate cytocompatibility, attachment and survival on the crosslinked chitosan-heparin complex surfaces. The MTT assay and microscopic analysis revealed that the scaffold containing tethered FGF-2 was superior in sustaining survival and growth of neural stem cells compared to standard culture conditions. Altogether, our results demonstrate that this multifunctional scaffold possesses good cytocompatibility and can be used as a growth factor delivery vehicle while supporting neural stem cell attachment and survival.