Synthesis and Characterization of Photo-Cross-Linkable Silk Fibroin Methacryloyl Hydrogel for Biomedical Applications.

Photo-cross-linkable hydrogels have recently gained increased interest in the field of biomedical applications. In this study, silk fibroin was derivatized with methacrylic anhydride (MA) to obtain silk fibroin methacryloyl (SFMA), forming hydrogel under UV light exposure in 1 min. The SFMA sol-gel transition did not involve significant structural change at the early stage. Then, the formation of the irreversible ß-sheet was confirmed after 24 h. The resulting SFMA hydrogel showed a homogeneous porous structure with pore sizes ranging from 400 to 700 µm, depending on the content. In addition, these hydrogels demonstrated a lower swelling capacity, higher rheological properties and compressive modulus, and slow degradation behavior at higher content, likely due to the higher degree of cross-linking. An experiment with cells indicated the good cell compatibility of these hydrogels, as revealed by Cell Counting Kit-8 (CCK-8) assays. As a tissue-engineered material, this photo-cross-linkable SFMA is expected to have a wide range of applications in the biomedical field.

Simulation of Cortical and Cancellous Bone to Accelerate Tissue Regeneration.

Different tissues have complex anisotropic structures to support biological functions. Mimicking these complex structures in vitro remains a challenge in biomaterials designs in support of tissue regeneration. Here, inspired by different types of silk nanofibers, a composite materials strategy was pursued towards this challenge. A combination of fabrication methods was utilized to achieve separate control of amorphous and beta-sheet rich silk nanofibers in the same solution. Aqueous solutions containing these two structural types of silk nanofibers were then simultaneously treated with an electric field and with ethylene glycol diglycidyl ether (EGDE). Under these conditions, the beta-sheet rich silk nanofibers in the mixture responded to the electric field while the amorphous nanofibers were active in the crosslinking process with the EGDE. As a result, cryogels with anisotropic structures were prepared, including mimics for cortical- and cancellous-like bone biomaterials as a complex osteoinductive niche. In vitro studies revealed that mechanical cues of the cryogels induced osteodifferentiation of stem cells while the anisotropy inside the cryogels influenced immune reactions of macrophages. These bioactive cryogels also stimulated improved bone regeneration in vivo through modulation of inflammation, angiogenesis and osteogenesis responses, suggesting an effective strategy to develop bioactive matrices with complex anisotropic structures beneficial to tissue regeneration.

Preparation of superhydrophobic sponge and its application in oil-water separation and treatment of polymer-containing wastewater.

At present, the application prospect of superhydrophobic materials in oil-water separation, an-tibacterial and other aspects have attracted more and more attention. However, preparing a simple and low-cost superhydrophobic material remains a challenge. Using acetone as solvent, candle soot, silver/silica nanoparticles and polydimethylsiloxane were uniformly mixed to form a mixed solution, and the superhydrophobic sponge was successfully prepared by spraying method. The results show that the superhydrophobic sponge has high water contact Angle (162°) and excellent oil-water separation efficiency, which can realize effective treatment of polymerized wastewater. In addition, the superhydrophobic sponge showed better antibacterial properties on the surface of Escherichia coli and Staphylococcus aureus. In this work, a simple way to prepare superhydro-phobic oil-water separation material is proposed. The preparation process is green, the material is easy to obtain, and it is expected to be widely used in practical production.

Anisotropic silk nanofiber layers as regulators of angiogenesis for optimized bone regeneration.

Osteogenesis-angiogenesis coupling processes play a crucial role in bone regeneration. Here, electric field induced aligned nanofiber layers with tunable thickness were coated on the surface of pore walls inside the deferoxamine (DFO)-laden silk fibroin (SF) and hydroxyapatite (HA) composite scaffolds to regulate the release of DFO to control vascularization dynamically. Longer electric field treatments resulted in gradually thickening layers to reduce the release rate of DFO where the released amount of DFO decreased gradually from 84% to 63% after 28 days. Besides the osteogenic capacity of HA, the changeable release of DFO brought different angiogenic behaviors in bone regeneration process, which provided a desirable niche with osteogenic and angiogenic cues. Anisotropic cues were introduced to facilitate cell migration inside the scaffolds. Changeable cytokine secretion from endothelial cells cultured in the different scaffolds revealed the regulation of cell responses related to vascularization in vitro. Peak expression of angiogenic factors appeared at days 7, 21 and 35 for endothelial cells cultured in the scaffolds with different silk nanofier layers, suggesting the dynamical regulation of angiogenesis. Although all of the scaffolds had the same silk and HA composition, in vitro cell studies indicated different osteogenic capacities for the scaffolds, suggesting that the regulation of DFO release also influenced osteogenesis outcomes in vitro. In vivo, the best bone regeneration occurred in defects treated with the composite scaffolds that exhibited the best osteogenic capacity in vitro. Using a rat bone defect model, healing was achieved within 12 weeks, superior to those treated with previous SF-HA composite matrices. Controlling angiogenic properties of bone biomaterials dynamically is an effective strategy to improve bone regeneration capacity.

Four-Octyl Itaconate Protects Chondrocytes against H2O2-Induced Oxidative Injury and Attenuates Osteoarthritis Progression by Activating Nrf2 Signaling.

Nrf2 is a critical regulator of the antioxidant defense systems in cellular protection. Emerging evidence has shown that four-octyl itaconate (OI) activates Nrf2 cascade. In this study, the chondroprotective effects of OI on H2O2-stimulated chondrocytes and DMM-induced osteoarthritis (OA) progression were investigated. In primary murine chondrocytes, OI interrupted the binding of Keap1 and Nrf2, leading to accumulation and nuclear translocation of Nrf2 protein, as well as transcription and expression of Nrf2-dependent genes, such as HO-1, NQO1, and GCLC. Furthermore, OI inhibited cell death and apoptosis, as well as H2O2-stimulated ROS generation, lipid peroxidation, superoxide accumulation, and mitochondrial depolarization in chondrocytes, which were abolished by the silence or depletion of Nrf2. In addition, in vivo experiments revealed the therapeutic effects of OI on OA progression in a DMM mouse model. Collectively, these results suggested that OI might serve as a potential treatment for OA progression.

Fabrication of Silk-Hyaluronan Composite as a Potential Scaffold for Tissue Repair.

Interest is rapidly growing in the design and preparation of bioactive scaffolds, mimicking the biochemical composition and physical microstructure for tissue repair. In this study, a biomimetic biomaterial with nanofibrous architecture composed of silk fibroin and hyaluronic acid (HA) was prepared. Silk fibroin nanofiber was firstly assembled in water and then used as the nanostructural cue; after blending with hyaluronan (silk:HA = 10:1) and the process of freeze-drying, the resulting composite scaffolds exhibited a desirable 3D porous structure and specific nanofiber features. These scaffolds were very porous with the porosity up to 99%. The mean compressive modulus of silk-HA scaffolds with HA MW of 0.6, 1.6, and 2.6 × 106 Da was about 28.3, 30.2, and 29.8 kPa, respectively, all these values were much higher than that of pure silk scaffold (27.5 kPa). This scaffold showed good biocompatibility with bone marrow mesenchymal stem cells, and it enhanced the cellular proliferation significantly when compared with the plain silk fibroin. Collectively, the silk-hyaluronan composite scaffold with a nanofibrous structure and good biocompatibility was successfully prepared, which deserved further exploration as a biomimetic platform for mesenchymal stem cell-based therapy for tissue repair.

Water-insoluble amorphous silk fibroin scaffolds from aqueous solutions.

Regenerated silk fibroin (RSF) is emerging as promising biomaterial for regeneration, drug delivery and optical devices, with continued demand for mild, all-aqueous processes to control microstructure and the performance. Here, temperature control of assembly kinetics was introduced to prepare the water-insoluble scaffolds from neutral aqueous solutions of RSF protein. Higher temperatures were used to accelerate the assembly rate of the silk fibroin protein chains in aqueous solution and during the lyophilization process, resulting in water-insoluble scaffold formation. The scaffolds were mainly composed of amorphous states of the silk fibroin chains, endowing softer mechanical properties. These scaffolds also showed nanofibrous structures, improved cell proliferation in vitro and enhanced neovascularization and tissue regeneration in vivo than previously reported silk fibroin scaffolds. These results suggest utility of silk scaffolds in soft tissue regeneration.

Fabrication of Silk Scaffolds with Nanomicroscaled Structures and Tunable Stiffness.

Detailed control of nano- and microstructures in porous biomaterial scaffold systems is important for control of interfacial and biological functions. Self-assembled silk protein nanostructured building blocks were incorporated into salt-leached scaffolds to control these features. Controllable concentration and pH were used to induce the formation of amorphous silk nanofibers in solution and also to reduce ß-sheet transformation during the more traditional salt-leaching process. These new scaffolds showed nanofibrous-microporous structures, reduced ß-sheet content, and tunable mechanical properties. Bone marrow mesenchymal stem cells grew better and showed differentiation behavior on these nanofibrous scaffolds, suggesting cytocompatibility and support for tunable differentiation via the scaffolds. These results suggested a new strategy of designing bioactive silk scaffolds by combining traditional scaffold formation processes with the controllable self-assembly of silk.

Nanoscale Silk-Hydroxyapatite Hydrogels for Injectable Bone Biomaterials.

Injectable hydrogel systems are important bone substitutes for regeneration because of their handling properties and the ability to fill irregular defects. Silk-hydroxyapatite composite materials with silk nanofibers in hydrogels were prepared and used as biomaterials for osteogenesis. These thixotropic silk nanofiber hydrogels and water-dispersible silk-HA nanoparticles were blended to form injectable nanoscale systems with a homogeneous distribution of a high HA content [60% (w/w)] to imitate bone niche. A modulus of ∼21 kPa was also achieved following the addition of HA in the systems, providing physical cues to induce osteodifferentiation. The composite hydrogels supported improved osteogenesis compared to that with silk nanofiber hydrogels. The newly formed bone tissue and bone defect healing were detected after implantation of the silk-HA composite hydrogels, suggesting utility for the regeneration of irregular bone defects.

Silk-Hydroxyapatite Nanoscale Scaffolds with Programmable Growth Factor Delivery for Bone Repair.

Osteoinductive biomaterials are attractive for repairing a variety of bone defects, and biomimetic strategies are useful toward developing bone scaffolds with such capacity. Here, a multiple biomimetic design was developed to improve the osteogenesis capacity of composite scaffolds consisting of hydroxyapatite nanoparticles (HA) and silk fibroin (SF). SF nanofibers and water-dispersible HA nanoparticles were blended to prepare the nanoscaled composite scaffolds with a uniform distribution of HA with a high HA content (40%), imitating the extracellular matrix (ECM) of bone. Bone morphogenetic protein-2 (BMP-2) was loaded in the SF scaffolds and HA to tune BMP-2 release. In vitro studies showed the preservation of BMP-2 bioactivity in the composite scaffolds, and programmable sustained release was achieved through adjusting the ratio of BMP-2 loaded on SF and HA. In vitro and in vivo osteogenesis studies demonstrated that the composite scaffolds showed improved osteogenesis capacity under suitable BMP-2 release conditions, significantly better than that of BMP-2 loaded SF-HA composite scaffolds reported previously. Therefore, these biomimetic SF-HA nanoscaled scaffolds with tunable BMP-2 delivery provide preferable microenvironments for bone regeneration.

Silk Biomaterials with Vascularization Capacity.

Functional vascularization is critical for the clinical regeneration of complex tissues such as kidney, liver or bone. The immobilization or delivery of growth factors has been explored to improve vascularization capacity of tissue engineered constructs, however, the use of growth factors has inherent problems such as the loss of signaling capability and the risk of complications such as immunological responses and cancer. Here, a new method of preparing water-insoluble silk protein scaffolds with vascularization capacity using an all aqueous process is reported. Acid was added temporally to tune the self-assembly of silk in lyophilization process, resulting in water insoluble scaffold formation directly. These biomaterials are mainly noncrystalline, offering improved cell proliferation than previously reported silk materials. These systems also have appropriate softer mechanical property that could provide physical cues to promote cell differentiation into endothelial cells, and enhance neovascularization and tissue ingrowth in vivo without the addition of growth factors. Therefore, silk-based degradable scaffolds represent an exciting biomaterial option, with vascularization capacity for soft tissue engineering and regenerative medicine.

Calcitonin gene-related peptide is a key factor in the homing of transplanted human MSCs to sites of spinal cord injury.

Mesenchymal stem cells (MSCs) can be used to treat many diseases, including spinal cord injury (SCI). Treatment relies mostly on the precise navigation of cells to the injury site for rebuilding the damaged spinal cord. However, the key factors guiding MSCs to the epicenter of SCI remain unknown. Here, we demonstrated that calcitonin gene-related peptide (CGRP), a neural peptide synthesized in spinal cord, can dramatically aid the homing of human umbilical cord mesenchymal stem cells (HUMSCs) in spinal cord-transected SCI rats. First, HUMSCs exhibited chemotactic responses in vitro to CGRP. By time-lapse video analysis, increased chemotactic index (CMI), forward migration index (FMI) and speed contributed to this observed migration. Then, through enzyme immunoassay, higher CGRP concentrations at the lesion site were observed after injury. The release of CGRP directed HUMSCs to the injury site, which was suppressed by CGRP 8-37, a CGRP antagonist. We also verified that the PI3K/Akt and p38MAPK signaling pathways played a critical role in the CGRP-induced chemotactic migration of HUMSCs. Collectively, our data reveal that CGRP is a key chemokine that helps HUMSCs migrate to the lesion site and thereby can be used as a model molecule to study MSCs homing after SCI.

X-ray therapy promotes structural regeneration after spinal cord injury in a rat model.

OBJECTIVE: This study aims to investigate the therapeutic effects and mechanisms of x-ray treatment on rats following spinal cord injury (SCI). METHODS: Forty-six female Sprague-Dawley rats were subjected to spinal cord injury using the modified Allen weight-drop method. The animals were randomly divided into six groups. Two of the animal groups were irradiated with 10 Gy at the lesion site; another two groups were irradiated with 20 Gy; and the last two groups without irradiation were regarded as the sham group. One of the each of two animal groups was euthanized at different time points at 4 and 12 weeks, respectively, after irradiation. Spinal cord calluses were assessed using kinology and electrophysiology and histology methods. RESULTS: In all of the groups, the neurofilament (NF) counts at 14 weeks were found to be higher than that at 6 weeks after SCI. Both 10-Gy irradiated and 20-Gy irradiated groups were higher than those of the sham group at each time point (P < 0.05). The myelin basic protein (MBP) count decreased at 14 weeks after SCI in the irradiated groups (P < 0.05) but increased at 14 weeks in the sham group (P < 0.05). Furthermore, the MBP count of the irradiated groups was lower than that of the sham group at 14 weeks (P < 0.05). The glial fibrillary acidic protein (GFAP) and Nogo-A counts at 14 weeks were higher than those at 6 weeks in all the groups (P < 0.05), and there was no statistical significance with kinology and electrophysiology tests in all groups. CONCLUSIONS: A self-repair mechanism exists after spinal cord injury, which lasts at least 14 weeks. X-ray therapy promotes the regeneration of the spinal cord system after injury.

Effect of hyaluronan molecular weight on structure and biocompatibility of silk fibroin/hyaluronan scaffolds.

The structure of scaffolds is known to play a key role in tissue engineering as it provides structural support and physical environment allowing cells to reside and rebuild the target tissue. In this work we investigated the effects of hyaluronan (HA) molecular weight (MW: 0.6, 1.6 and 2.6×10(6) Da) on the pore structure, secondary structure, and biocompatibility of lyophilized silk fibroin (SF)/HA composite scaffolds. The results showed that HA promoted the pore structure formation and restrained the formation of separate sheet like structures in the SF/HA blend scaffolds, which was dependent on HA MW. The 3D pore structure maintained the scaffold shape during the process of 75% ethanol annealing. Structural studies indicated that HA did not induce but hinder SF conformation transition from random coil to ß-sheet before and after treatment. In addition, SF/HA scaffolds showed an increase in cell proliferation compared to pure SF scaffold. These findings demonstrated the important role of HA MW in preparing SF/HA blend scaffolds suitable for application in tissue engineering.

Control of olfactory ensheathing cell behaviors by electrospun silk fibroin fibers.

Olfactory ensheathing cells (OECs), the only glial cell type that normally penetrates the transition zone between the peripheral and central nervous systems, are one of the most promising candidates for cell transplantation in repairing spinal cord injury (SCI). However, we must manipulate and regulate OECs' behavior to make these cells effective in cell transplantation. In the present study, we assessed the response of rat OECs to different variants of nanofibrous silk fibroin mats with regard to cell morphology, adhesion, proliferation, and migration and the related gene and protein expression. Results showed that OECs adhere and spread more easily on Tussah silk fibroin (TSF) fibers than Bombyx mori silk fibroin fibers, resulting in a higher rate of cell proliferation and gene and protein expression, examined by RT-PCR and ELISA. In addition, the morphology of OECs on microfibers is mainly polygonal with short protrusions, whereas the OECs on nanofibers exhibit a bipolar shape with long protrusions that align along the fibers, especially when aligned fibers are employed. Moreover, OECs on silk fibroin nanofibers migrate more efficiently than those on poly-L-lysine (PLL). Based on the experimental results, the morphology, adhesion, spread, gene and protein expression, and migration of OECs could be modulated and regulated by adjusting the contents and structure of silk fibroin nanofibers, shedding light on the control of OECs' behavior in nerve tissue engineering and thus the future therapeutic intervention for nerve repair after injury. This manuscript is published as part of the International Association of Neurorestoratology (IANR) supplement issue of Cell Transplantation.

[Effect of chondroitinase ABC on axonal myelination and glial scar after spinal cord injury in rats].

OBJECTIVE: To investigate the effects of chondroitinase ABC (ChABC) on axonal myelination and glial scar after spinal cord injury (SCI) in rats. METHODS: Seventy-two adult male Sprague Dawley rats were randomly assigned into ChABC treatment group (group A), saline treatment group (group B), and sham operation group (group C), 24 rats in each group. In groups and B, the SCI model was established with modified Allen's method and then the rats of groups A and B were administrated by subarachnoid injection of 6 microL ChABC (1 U/mL) and saline respectively at 1 hour after injury and every day for 1 week; the rats of group C served as control, which canal was opened without damage to spinal cord. At 1, 7, 14, and 28 days after operation, the locomotor functions were evaluated according to the Basso-Beattie-Bresnahan (BBB) score scale; and the spinal cord samples were harvested for HE staining, Nissl staining, and immunohistochemistry analysis to detect the change of myelin basic protein (MBP), growth associated protein 43 (GAP-43), and glial fibrillary acidic protein (GFAP) of the injured spinal cord. RESULTS: At different time points, the BBB score of group C was significantly higher than those of groups A and B (P < 0.05), and the BBB score of group was significantly better than that of group B at 14 and 28 days after operation (P < 0.05). HE staining and Nissl staining showed that the morphous and the neuron number of the remainant injured spinal cord in group A were better than those in group B. The integral absorbance (IA) values of MBP and GAP-43 and the positive area of GFAP after SCI in groups A and B were significantly higher than those in group C at different time points (P < 0.05), and the IA values of MBP and GAP-43 were significantly higher in group A than those in group B at 7, 14, and 28 days after operation (P < 0.05), but the positive area of GFAP was significantly smaller in group A than that in group B (P < 0.05). CONCLUSION: The ChABC can effectively improve the microenvironment of the injured spinal cord of rats, enhance the expressions of MBP and GAP-43, and inhibit the expression of GFAP, which promotes the axonal regeneration and myelination, attenuate glial scar formation, and promote the recovery of nerve function.

Hierarchical biomineralization of calcium carbonate regulated by silk microspheres.

As an analog of the main protein contained in nacre regenerated Bombyx mori silk fibroin has a significant influence on the morphology and polymorphic nature of CaCO3 in the biomineralization process. A number of studies have implied that the self-assembling aggregate structure of silk fibroin is a key factor in controlling CaCO3 aggregation. Further insight into this role is necessary with a particular need to prepare silk fibroin aggregates with homogeneous structures to serve as templates for the mineralization process. Here we have prepared homogeneous silk microspheres to serve as templates for CaCO3 mineralization in order to provide an experimental insight into silk-regulated crystallization processes. CaCO3 particles with different nano- and microstructures, and their polymorphs, were successfully formed by controlling the mineralization process. The key function of silk aggregation in controlling the morphology and polymorphic nature of CaCO3 particles was confirmed. A regulating effect of silk on the spatial features was also observed. A two-step process for silk fibroin-regulated biomineralization was found, with different levels of heterogeneous nucleation and aggregation. A full understanding of silk fibroin-regulated biomineralization mechanisms would help in understanding the function of organic polymers in natural biomineralization, and provide a way forward in the design and synthesis of new materials in which organic-inorganic interfaces are the keys to function, biological interfaces and many related material features.

Mechanisms and control of silk-based electrospinning.

Silk fibroin (SF) nanofibers, formed through electrospinning, have attractive utility in regenerative medicine due to the biocompatibility, mechanical properties, and tailorable degradability. The mechanism of SF electrospun nanofiber formation was studied to gain new insight into the formation and control of nanofibers. SF electrospinning solutions with different nanostructures (nanospheres or nanofilaments) were prepared by controlling the drying process during the preparation of regenerated SF films. Compared to SF nanospheres in solution, SF nanofilaments had better spinnability with lower viscosity when the concentration of silk protein was below 10%, indicating a critical role for SF morphology, and in particular, nanostructures, for the formation of electrospun fibers. More interesting, the diameter of electrospun fibers gradually increased from 50 to 300 nm as the concentration of SF nanofilaments in the solution increased from 6 to 12%, implying size control by simply adjusting SF nanostructure and concentration. Aside from process parameters investigated in previous studies, such as SF concentration, viscosity, and electrical potential, the present mechanism emphasizes significant influence of SF nanostructure on spinnability and diameter control of SF electrospun fibers, providing a controllable option for the preparation of silk-based electrospun scaffolds for biomaterials, drug delivery, and tissue engineering needs.

Pedicle screw instrumentation plus augmentation vertebroplasty using calcium sulfate for thoracolumbar burst fractures without neurologic deficits.

OBJECTIVE: To evaluate the efficacy of posterior instrumentation plus vertebroplasty and posterolateral fusion using calcium sulfate for thoracolumbar burst fractures without neurologic deficits. METHODS: Between July 2005 and January 2008, a total of 45 patients who had been diagnosed as having thoracolumbar burst fractures without neurologic deficits were treated with pedicle screw instrumentation plus vertebroplasty using calcium sulfate in our unit. The Cobb angles and loss rates of anterior-middle columns height at different time intervals were measured on lateral radiographs, and the preoperative and postoperative functional outcomes were evaluated using the Visual Analogue Scale (VAS) and Oswestry Disability Index (ODI). RESULTS: The Cobb angles and loss rates of anterior-middle columns height postoperatively period were restored significantly compared with those noted preoperatively. The angles and heights were well maintained for at least two years using this technique. The mean postoperative VAS (back pain) score was 2.1 ± 0.8, which was significantly better (P < 0.001) than the mean preoperative VAS score 7.9 ± 1.1. The average preoperative ODI was 66.6 ± 8.1% and this had improved significantly to 15.5 ± 4.5% by the latest follow-up (P < 0.001). No instrumentation failure was detected in this study. The calcium sulfate had been absorbed completely by 3-6 months postoperatively. CONCLUSION: Pedicle screw instrumentation plus augmentation vertebroplasty with calcium sulfate is an economic, efficient and reliable technique for treating unstable thoracolumbar fractures without neurologic deficits.

[Study of isolation and purification of primary Schwann cells from different parts of nerve tissue in rats].

OBJECTIVE: To establish the methods to get high activity, high purity, and adequate Schwann cells (SCs), and to provide sufficient seed cells for the peripheral nerve repair. METHODS: Six 5-day-old, male or female, Sprague Dawley rats were selected and the sciatic nerve (control group) and dorsal root ganglion (DRG) (experimental group) were harvested. Then the sciatic nerves and DRG were digested by co-enzyme and dispersed by medium containing serum to isolate SCs. Freshly isolated SCs from rats were cultured, purified and subcultured. The 1st generation of SCs were chosen to draw the growth curve of SCs by the counting method and to detect the proliferation of SCs by MTT assay at 8 days of culture, the purity of SCs by immunocytochemistry of anti-S-100 and the brain-derived neurotrophic factor (BDNF) concentration by ELISA. RESULTS: A total of 36-43 DRGs could be obtained in each rat. The number of obtained single SC in experimental group [(7.5 +/- 0.6) x 10(6)] was significantly higher than that in control group [(3.5 +/- 0.4) x 10(6)] (t = 13.175, P=0.000). SCs reached logarithm proliferation phase at 3 days. With time, the cell number and the proliferation absorbance (A) value of 2 groups all showed upward trend. The number and A value of experimental group were significantly higher than those of control group (P < 0.05). The SCs purity of experimental group (92.08% +/- 3.45%) was significantly higher than that of control group (77.50% +/- 3.57%) (t = 6.689, P = 0.001). The concentrations of BDNF at 3 days and 5 days in experimental group were significantly higher than those of control group (P < 0.05). CONCLUSION: The sufficient amount, high purity, and viability of SCs from DRGs can meet the needs of studies on peripheral nerve repairment.