Scaffolds For Peripheral Nerve Regeneration Research Articles

Electrospun PCL/Alginate/Nanoclay Nerve Conduit with Olfactory Ectomesenchymal Stem Cells for Nerve Regeneration.

Biocompatible and biodegradable nerve growth conduits (NGCs) provide a promising alternative to conventional nerve grafting for peripheral nerve regeneration. Incorporating nanoclay (NC) has been shown to increase the hydrophilicity and flexibility of polymeric scaffolds. In the present study, poly caprolactone-alginate (PCL-ALG) conduits with varying percentages of NC (0.1%, 0.2%, and 0.5%) were fabricated using the electrospinning technique. The conduit containing 0.5% NC showed a greater increase in elongation (33%) and porosity, reaching 95% with the lowest contact angle (10°). For in vitro, human olfactory ectomesenchymal stem cells (OE-MSCs) were used as a favorable choice for neuronal differentiation owing to the origin from the neural crest. The viability and proliferation of OE-MSCs were maintained after 5 days on scaffolds with 0.5% NC, as confirmed by the MTT assay, cell adhesion analysis, and live/dead staining. Furthermore, the impact of 0.5% PCL-ALG-NC on the paracrine activity of OE-MSCs was studied for a period of 7 days. Our results indicated that human OE-MSCs, when cocultured with PC12 cells on NGC, have the capability to release nerve growth factor levels of up to 1392.83 pg/mL. In summary, the electrospun PCL-ALG conduit containing an optimal NC dosage (0.5%) and seeded with human OE-MSCs shows promising outcomes as NGC scaffold for peripheral nerve regeneration.

Assessing tissue mechanical properties: Development of a custom-made tensile device and application on rodents sciatic nerves

The development of biomaterials such as synthetic scaffolds for peripheral nerve regeneration requires a precise knowledge of the mechanical properties of the nerve in physiological-like conditions. Mechanical properties (Young’s modulus, maximum stress and strain at break) for peripheral nerves are scarce and large discrepancies are observed in between reports. This is due in part to the absence of a robust testing device for nerves. To overcome this limitation, a custom-made tensile device (CMTD) has been built. To evaluate its reproducibility and accuracy, the imposed speed and distance over measured speed and distance was performed, followed by a validation using poly(dimethylsiloxane) (PDMS), a commercial polymer with established mechanical properties. Finally, the mechanical characterization of rodents (mice and rats) sciatic nerves using the CMTD was performed. Mouse and rat sciatic nerves Young’s modulus were 4.57 ± 2.04 and 19.2 ± 0.86 MPa respectively. Maximum stress was 1.26 ± 0.56 MPa for mice and 3.81 ± 1.84 MPa for rats. Strain at break was 53 ± 17% for mice and 32 ± 12% for rats. The number of axons per sciatic nerve was found to be twice higher for rats. Statistical analysis of the measured mechanical properties revealed no sex-related trends, for both mice and rats (except for mouse maximum stress with p=0.03). Histological evaluation of rat sciatic nerve corroborated these findings. By developing a robust CMTD to establish the key mechanical properties (Young’s modulus, maximum stress and strain at break) values for rodents sciatic nerves, our work represent an essential step toward the development of better synthetic scaffolds for peripheral nerve regeneration.

Physical cues of scaffolds promote peripheral nerve regeneration

The effective treatment of long-gap peripheral nerve injury (PNI) remains a challenge in clinical settings. The autograft, the gold standard for the long-gap PNI therapy, has several limitations, including a limited supply of donor nerve, size mismatch between the donor and recipient sites, functional loss at the donor site, neuroma formation, and the requirement for two operations. With the increasing abundance of biocompatible materials with adjustable structures and properties, tissue engineering provides a promising avenue for bridging peripheral nerve gaps and addressing the above issues of autograft. The physical cues provided by tissue engineering scaffolds, essential for regulating the neural cell fate and microenvironments, have received considerable research attention. This review elaborates on three major physical cues of tissue engineering scaffolds for peripheral nerve regeneration: topological structure, mechanical support, and electrical stimulation. These three aspects are analogs to Lego bricks, wherein different combinations result in diverse functions. Innovative and more effective bricks, along with multi-level and all-around integration, are expected to provide new advances in tissue engineering for peripheral nerve generation.

Aligned Electroactive Electrospun Fibrous Scaffolds for Peripheral Nerve Regeneration.

Effective repair and functional recovery of large peripheral nerve deficits are urgent clinical needs. A biofunctional electroactive scaffold typically acts as a "bridge" for the repair of large nerve defects. In this study, we constructed a biomimetic piezoelectric and conductive aligned polypyrrole (PPy)/polydopamine (PDA)/poly-l-lactic acid (PLLA) electrospun fibrous scaffold to improve the hydrophilicity and cellular compatibility of PLLA and restore the weakened piezoelectric effect of PDA, which is beneficial in promoting Schwann cell differentiation and dorsal root ganglion neuronal extension and alignment. The aligned PPy/PDA/PLLA fibrous scaffold bridged the sciatic nerve of Sprague-Dawley rats with a 10 mm deficit, prevented autotomy, and promoted nerve regeneration and functional recovery, thereby activating the calcium and AMP-activated protein kinase signaling pathways. Therefore, electroactive fibrous scaffolds exhibit great potential for neural tissue regeneration.

Aminosilane Functionalized Aligned Fiber PCL Scaffolds for Peripheral Nerve Repair.

Silane modification is a simple and cost-effective tool to modify existing biomaterials for tissue engineering applications. Aminosilane layer deposition has previously been shown to control NG108-15 neuronal cell and primary Schwann cell adhesion and differentiation by controlling deposition of ─NH2 groups at the submicron scale across the entirety of a surface by varying silane chain length. This is the first study toreport depositing 11-aminoundecyltriethoxysilane (CL11) onto aligned Polycaprolactone (PCL) scaffolds for peripheral nerve regeneration. Fibers are manufactured via electrospinning and characterized using water contact angle measurements, atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). Confirmed modified fibers are investigated using in vitro cell culture of NG108-15 neuronal cells and primary Schwann cells to determine cell viability, cell differentiation, and phenotype. CL11-modified fibers significantly support NG108-15 neuronal cell and Schwann cell viability. NG108-15 neuronal cell differentiation maintains Schwann cell phenotype compared to unmodified PCL fiber scaffolds. 3D ex vivo culture of Dorsal root ganglion explants (DRGs) confirms further Schwann cell migration and longer neurite outgrowth from DRG explants cultured on CL11 fiber scaffolds compared to unmodified scaffolds. Thus, a reproducible and cost-effective tool is reported to modify biomaterials with functional amine groups that can significantly improve nerve guidance devices and enhance nerve regeneration.

Graphdiyne-loaded polycaprolactone nanofiber scaffold for peripheral nerve regeneration

Graphdiyne (GDY) is a kind of nanomaterial from the graphene carbon family with excellent physical and chemical properties. Despite some applications in medical engineering, GDY has not been used as an electroactive scaffold for tissue regeneration because of its unclear in vitro and in vivo biosafety profiles. Here, a conductive GDY nanomaterial-loaded polycaprolactone (PCL) scaffold was prepared by electrospinning technique. For the first time, the biocompatibility of GDY-based scaffold was assessed at the cellular and animal levels in a peripheral nerve injury (PNI) model. The findings indicated that the conductive three-dimensional (3D) GDY/PCL nerve guide conduits (NGCs) could significantly improve the proliferation, adhesion and glial expression of Schwann cells (SCs). The conduits were implanted into a rat 10-mm sciatic nerve defect model for 3 months in vivo. The toxicity of scaffolds to the organs was negligible, while the GDY/PCL NGCs significantly promoted myelination and axonal growth by upregulating the expression levels of SC marker (S100 β protein), Myelin basic protein (MBP), and axon regeneration marker (β3-tubulin protein (Tuj1) and neurofilament protein 200 (NF200)). In addition, upregulation of vascular factor expression in GDY/PCL NGC group suggested the potential role in angiogenesis to improve nerve repair by GDY nanomaterials. Our findings provide new perspectives on biocompatibility and effectiveness of GDY nanomaterial scaffold in peripheral nerve regeneration for preclinical application.

Schwann cell-matrix coated PCL-MWCNT multifunctional nanofibrous scaffolds for neural regeneration.

Nerve tissue engineering aims to create scaffolds that promote nerve regeneration in the damaged peripheral nervous system. However, there remain some challenges in the construction of scaffolds in terms of mechanical properties and cellular behaviour. The present work aims to develop multifunctional implantable nanofibrous scaffolds for nerve regeneration. Using electrospinning, nanofibrous neat polycaprolactone (PCL) and PCL/multiwalled carbon nanotubes (PCL-MWCNT) composite scaffolds were prepared in random and aligned morphology. Schwann cells and their secreted biochemical factors are responsible for neuronal survival in the peripheral nervous system. Therefore, the acellular matrix of Schwann cells was spin-coated on the PCL-MWCNT scaffolds to aid nerve regeneration. Physicochemical and mechanical properties, and the in vitro cellular response of the developed nanofibrous were investigated. We observed no significant change in fibre diameter between neat PCL and PCL-MWCNT scaffolds regardless of the morphology. However, the inclusion of MWCNT reduced the mechanical strength of nanocomposite scaffolds compared to neat PCL. In vitro study revealed biocompatibility of the developed scaffolds both with and without an acellular matrix. Gene expression study revealed a significant increase in peripheral myelin protein (PMP22) expression on acellular matrix-coated PCL-MWCNT scaffolds compared to neat PCL counterparts. Overall, the results suggested Schwann cell matrix-coated PCL-MWCNT nanofibers as a promising conduit for peripheral nerve regeneration.

Piezoelectric conduit combined with multi-channel conductive scaffold for peripheral nerve regeneration

Due to the complex structural hierarchy and regenerative microenvironment of peripheral nerves, developing a nerve guidance conduit (NGC) that can replace autografts for repairing long-distance nerve defects remains a challenge. To overcome this limitation, a multi-channel NGC with dual electrical activity of piezoelectricity and conductivity was constructed to enhance peripheral nerve regeneration. Silk fibroin (SF) was adopted to prepare a multi-channel cryogel scaffold by gradient freezing method, and then poly(3,4-ethylenedioxythiophene) (PEDOT) in situ polymerization based on the porous structure of the cryogel was carried out to achieve good conductivity. Meanwhile, a polyvinylidene fluoride (PVDF)/poly (l-lactic acid-co-caprolactone) (PLCL) film with spontaneous electrical properties and high mechanical strength was constructed and wrapped in the outer layer of SF/PEDOT cryogel to construct an NGC with spontaneous electrical stimulation properties and surgical suture resistance, providing a biomimetic electrophysiological microenvironment for peripheral nerve regeneration. In vitro cell experiments indicated that the multi-channel electroactive NGC not only promoted the proliferation, maturation and myelination of Schwann cells (SCs), but also effectively promoted neuronal differentiation and axonal regeneration of Pheochromocytoma 12 (PC12) cells. Furthermore, a rat sciatic nerve defect model was constructed to evaluate the effect of multi-channel electroactive NGC on peripheral nerve repair and the results showed that electroactive NGC could significantly promote peripheral nerve regeneration and functional recovery after 12 weeks, achieving the repair effect of autografts through the positive synergistic effect of piezoelectric and conductive properties of NGC. These results demonstrated the great potential of multi-channel electroactive NGCs in repairing peripheral nerve injury (PNI).

Apoptosis-Decellularized Peripheral Nerve Scaffold Allows Regeneration across Nerve Gap

Peripheral nerve injury results in loss of motor and sensory function distal to the nerve injury and is often permanent in nerve gaps longer than 5 cm. Autologous nerve grafts (nerve autografts) utilize patients’ own nerve tissue from another part of their body to repair the defect and are the gold standard in care. However, there is a limited autologous tissue supply, size mismatch between donor nerve and injured nerve, and morbidity at the site of nerve donation. Decellularized cadaveric nerve tissue alleviates some of these limitations and has demonstrated success clinically. We previously developed an alternative apoptosis-assisted decellularization process for nerve tissue. This new process may result in an ideal scaffold for peripheral nerve regeneration by gently removing cells and antigens while preserving delicate topographical cues. In addition, the apoptosis-assisted process requires less active processing time and is inexpensive. This study examines the utility of apoptosis-decellularized peripheral nerve scaffolds compared to detergent-decellularized peripheral nerve scaffolds and isograft controls in a rat nerve gap model. Results indicate that, at 8 weeks post-injury, apoptosis-decellularized peripheral nerve scaffolds perform similarly to detergent-decellularized and isograft controls in both functional (muscle weight recovery, gait analysis) and histological measures (neurofilament staining, macrophage infiltration). These new apoptosis-decellularized scaffolds hold great promise to provide a less expensive scaffold for nerve injury repair, with the potential to improve nerve regeneration and functional outcomes compared to current detergent-decellularized scaffolds.

Three-dimensional conductive polycaprolactone/carbon nanotubes scaffolds for peripheral nerve regeneration

Three-dimensional conductive polycaprolactone/carbon nanotubes scaffolds for peripheral nerve regeneration

Polyhydroxybutyrate (PHB) Scaffolds for Peripheral Nerve Regeneration: A Systematic Review of Animal Models.

Simple SummaryCurrently, polymeric biomaterials are the choice for the design of scaffolds for the regeneration of peripheral nerves. Polyhydroxybutyrate (PHB) is a polymer belonging to the class of polyesters that are produced naturally in nature by microorganisms. To gain a better understanding of the efficacy of therapeutic approaches involving PHB scaffolds for peripheral nerve regeneration, we conducted a systematic review of the literature with the aim of discussing the current knowledge of PHB scaffolds applied to nerve regeneration. The use of PHB as a biomaterial to prepare tubular scaffolds for nerve regeneration was shown to be promising. The incorporation of additives appears to be a trend that improves nerve regeneration.In the last two decades, artificial scaffolds for nerve regeneration have been produced using a variety of polymers. Polyhydroxybutyrate (PHB) is a natural polyester that can be easily processed and offer several advantages; hence, the purpose of this review is to provide a better understanding of the efficacy of therapeutic approaches involving PHB scaffolds in promoting peripheral nerve regeneration following nerve dissection in animal models. A systematic literature review was performed following the “Preferred Reporting Items for Systematic Reviews and Meta-Analyses” (PRISMA) criteria. The revised databases were: Pub-Med/MEDLINE, Web of Science, Science Direct, EMBASE, and SCOPUS. Sixteen studies were included in this review. Different animal models and nerves were studied. Extension of nerve gaps reconnected by PHB scaffolds and the time periods of analysis were varied. The additives included in the scaffolds, if any, were growth factors, neurotrophins, other biopolymers, and neural progenitor cells. The analysis of the quality of the studies revealed good quality in general, with some aspects that could be improved. The analysis of the risk of bias revealed several weaknesses in all studies. The use of PHB as a biomaterial to prepare tubular scaffolds for nerve regeneration was shown to be promising. The incorporation of additives appears to be a trend that improves nerve regeneration. One of the main weaknesses of the reviewed articles was the lack of standardized experimentation on animals. It is recommended to follow the currently available guidelines to improve the design, avoid the risk of bias, maximize the quality of studies, and enhance translationality.

Electrospinning porcine decellularized nerve matrix scaffold for peripheral nerve regeneration

The composition and spatial structure of bioscaffold materials are essential for constructing tissue regeneration microenvironments. In this study, by using an electrospinning technique without any other additives, we successfully developed pure porcine decellularized nerve matrix (xDNME) conduits. The developed xDNME was composed of an obvious decellularized matrix fiber structure and effectively retained the natural components in the decellularized matrix of the nerve tissue. The xDNME conduit exhibited superior biocompatibility and the ability to overcome inter-species barriers. In vivo, after 12 weeks of implantation, xDNME significantly promoted the regeneration of rat sciatic nerve. The regenerated nerve fibers completely connected the two ends of the nerve defect, which were about 8 mm apart. The xDNME and xDNME-OPC groups showed myelin structures in the regenerated nerve fibers. In the xDNME group, the average thickness of the regenerated myelin sheath was 0.640 ± 0.013 μm, which was almost comparable to that in the autologous nerve group (0.646 ± 0.017 μm). Electrophysiological experiments revealed that both of the regenerated nerve fibers in the xDNME and xDNME-OPC groups had excellent abilities to transmit electrical signals. Respectively, the average conduction velocities of xDNME and xDNME-OPC were 8.86 ± 3.57 m/s and 6.99 ± 3.43 m/s. In conclusion, the xDNME conduits have a great potential for clinical treatment of peripheral nerve injuries, which may clinically transform peripheral nerve related regenerative medicine.

Polybutylene succinate artificial scaffold for peripheral nerve regeneration.

Regeneration and recovery of nerve tissues are a great challenge for medicine, and positively affect the quality of life of patients. The development of tissue engineering offers a new approach to the problem with the creation of multifunctional artificial scaffolds that act on various levels in the damaged tissue, providing physical and biochemical support for the growth of nerve cells. In this study, the effects of the use of a tubular scaffold made of polybutylene succinate (PBS), surgically positioned at the level of a sciatic nerve injured in rat, between the proximal stump and the distal one, was investigated. Scaffolds characterization was carried out by scanning electron microscopy and X‐ray microcomputed tomography and magnetic resonance imaging, in vivo. The demonstration of the nerve regeneration was based on the evaluation of electroneurography, measuring the weight of gastrocnemius and tibialis anterior muscles, histological examination of regenerated nerves and observing the recovery of the locomotor activity of animals. The PBS tubular scaffold minimized iatrogenic trauma on the nerve, acting as a directional guide for the regenerating fibers by conveying them toward the distal stump. In this context, neurotrophic and neurotropic factors may accumulate and perform their functions, while invasion by macrophages and scar tissue is hampered.

Graphene-based hybrid materials as promising scaffolds for peripheral nerve regeneration

Peripheral nerve injury (PNI) is a serious clinical health problem caused by the damage of peripheral nerves which results in neurological deficits and permanent disability. There are several factors that may cause PNI such as localized damage (car accident, trauma, electrical injury) and outbreak of the systemic diseases (autoimmune or diabetes). While various diagnostic procedures including X-ray, magnetic resonance imaging (MRI), as well as other type of examinations such as electromyography or nerve conduction studies have been efficiently developed, a full recovery in patients with PNI is in many cases deficient or incomplete. This is the reason why additional therapeutic strategies should be explored to favor a complete rehabilitation in order to get appropriate nerve injury regeneration. The use of biomaterials acting as scaffolds opens an interesting approach in regenerative medicine and tissue engineering applications due to their ability to guide the growth of new tissues, adhesion and proliferation of cells including the expression of bioactive signals. This review discusses the preparation and therapeutic strategies describing in vitro and in vivo experiments using graphene-based materials in the context of PNI and their ability to promote nerve tissue regeneration.

Development of a Bioactive Scaffold based on NGF Containing PCL/Chitosan Nanofibers for Nerve Regeneration

Nanofibers are used in a wide range of applications, including scaffolds for tissue engineering. Electrospinning is a promising technique to fabricate nanofibrous scaffolds capable of supporting cell attachment and growth. Nanofibers with biomimetic alignment could also guide neural cell growth and orientation of cell processes necessary for peripheral nerve regeneration. This study fabricated aligned nanofibers of polycaprolactone/chitosan (PCL/CS) scaffolds and immobilized nerve growth factor (NGF) on them via dopamine coating mediated bonds to confer bioactivity to the scaffold and support attachment and growth of PC12 cells. The results showed that PCL/CS nanofibrous scaffolds revealed appropriate mechanical and surface properties. Cells remained viable on the scaffolds, and surface-modified aligned nanofibrous scaffolds interacted better with the cells, inducing neural morphology and orientation. Immobilization of NGF via polydopamine (PD) on nanofibers' surface proved to be a proper method to enhance PC12 cell attachment and proliferation. Thus, this construct could potentially be used as a scaffold for peripheral nerve regeneration.

Nanographene enfolded AuNPs sophisticatedly synchronized polycaprolactone based electrospun nanofibre scaffold for peripheral nerve regeneration.

Herein, we report the bioactivity of monodispersed nanosized reduced graphene oxide (RGO) enfolded gold nanoparticles (AuNPs) engineered polycaprolactone (PCL) based electrospun composite scaffolds. The 2D patterns of PCL based nanofibers prepared by the homogenous distribution of RGO-AuNPs exhibited unique topological and biological features such as mechanical properties, porous structure, large surface area, high electrical conductivity, biodegradability, and resemble the natural extracellular matrix (ECM) that supports the adhesion, growth, proliferation, and differentiation of stem cells. The prepared composite nanofibers based scaffolds containing RGO-AuNPs accelerated neuronal cell functions and confirmed that the optimized concentration showed cytocompatibility to PC12 and S42 cells. The 0.0005 wt% loading of RGO-AuNPs on PCL has a huge impact on neurite growth which leads to an almost one-fold increase in neurite length growth. The present study provides a new strategic design of highly efficient scaffolds that have a significant direct impact on cell activity and could be a potential bioimplant for peripheral nerve repair.

3D structured self-powered PVDF/PCL scaffolds for peripheral nerve regeneration

Piezoelectric materials providing in situ electrical stimulation (ES) without applying an external chemical or physical supporting open new frontiers for future bioelectric therapies. As a “smart” material which can promote cell differentiation and proliferation due to instantaneous ES, polyvinylidene fluoride (PVDF) holds great promise in tissue engineering. In this study, a porous PVDF/polycaprolactone (PCL) composite nerve tissue engineering scaffold was manufactured by a simple cast/annealing-solvent displacement method. It was found that the blend of PCL with PVDF could simultaneously improve mechanical properties, biocompatibility, as well as biodegradation. When Rat Schwann cells (RSCs) are cultured on top of the scaffolds, the electromechanical interactions stimulate cell proliferation and differentiation. After being implanted into the 15-mm defect rat sciatic nerve model for 4 months, the PVDF/PCL group exhibits significant electrophysiological, morphological and functional nerve restoration. Overall, our findings highlight the potential of an effective and user-friendly piezoelectric scaffold for peripheral nerve regeneration due to its inherent electroactivity and favorable biocompatibility.

Synthesis of an electrospun PHA/RGO/Au scaffold for peripheral nerve regeneration: an in vitro study

In this paper, we represented a one-pot biofabricated method for preparation of a graphene-decorated gold NPs (RGO/Au) scaffold, that is integrated into poly-3 hydroxybutyrate-co-12 mol.% (P3HB-co-12 mol.%) hydroxyhexanoate (HHx) fibers. The images of FESEM microscope displayed a permeable mat-shaped matrix assembly with a fibrous nature indicating the formation of a fibrous PHA/RGO/Au hybrid. The results of elemental mapping for PHA/RGO/Au hybrids have confirmed that the AuNPs were reliably present inside the hybrid matrix along with the elements ‘C’ and ‘O’. Additionally, we also analyzed the probability of combining the graphene’s conductive properties with electrospun nanofiber to produce electroactive biomimetic scaffold for the regeneration of nerve tissue. We also performed an in vitro study, which represented the conducting nanofibrous scaffold that prominently endorsed Schwann cell (SC) proliferation as well as migration. From these results, it is evident that the graphene-modified nanofibrous scaffold displays potential in repairing the peripheral nerve along with its regeneration.

Enhancement of Schwann Cells Function Using Graphene-Oxide-Modified Nanofiber Scaffolds for Peripheral Nerve Regeneration.

Peripheral nerve regeneration and functional recovery remain a significant clinical challenge. Biomaterials that can regulate biological behavior of Schwann cell (SC) and promote neural cell differentiation are beneficial for nerve regeneration and functional recovery. Graphene oxide (GO), as a bioactive nanomaterial, has attracted great attention in biomedical applications. In this study, the possibility of combining the excellent physicochemical properties of GO with nanofiber to develop a bioactive scaffold for nerve regeneration were explored. Briefly, GO was coated on the ApF/PLCL scaffolds. To demonstrate the potentials of this platform, in vitro and in vivo studies toward nerve regeneration were carried out. In vitro, GO-coated scaffolds could enhance SC biological behaviors including migration, proliferation, and myelination. The secretions from SCs cultured on GO-ApF/PLCL scaffolds could induce PC12 cells differentiation. Furthermore, GO-coated nanofibrous scaffolds proved to up-regulate focal adhesion kinase (FAK) expression of PC12 cell. In vivo, GO-ApF/PLCL nerve conduits could successfully repair a 10 mm sciatic nerve defect. These findings suggest that GO-based scaffolds efficiently modulate cell functions and promote nerve regeneration, indicating their potential for nerve regeneration applications.

Water-stable silk fibroin nerve conduits with tunable degradation prepared by a mild freezing-induced assembly

Silk fibroin (SF) is considered as an attractive candidate biomaterial for soft tissue regeneration. However, chemical treatments are normally required to achieve water-stability of regenerated SF materials and thus hinder its widespread applications. In this study, an all-water-based strategy was developed to prepare water-insoluble SF nerve conduits by freezing-induced structural transition. A facile freezing processing named soft freezing was used to induce the structural transition of SF from amorphous to silk I structure, consequently rendering the SF conduits water-stable. XRD and FTIR results clearly showed that the freezing-stabilized SF conduit is silk I-dominant structure. The conduit showed enhanced flexibility compared with the traditional ethanol-induced SF conduits because of reduced β-sheet content and high content of silk I structure. The reduced stiff makes SF conduit soft enough for matching peripheral nerve tissue regeneration. The fabrication process is mild, including all-aqueous, low temperature, and without the addition of any chemicals. Furthermore, the enzymatic degradation behavior of the SF conduits with silk I structure was investigated, revealing that the degradation rate could be effectively regulated by degumming-controlled molecular weight change of silks. The results offer useful options to prepare bioactive SF scaffolds for peripheral nerve regeneration.