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Reduced graphene oxide-embedded nerve conduits loaded with bone marrow mesenchymal stem cell-derived extracellular vesicles promote peripheral nerve regeneration

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Neural Regeneration Research 2023年第1期18卷 200-206页

作者： wei Zhang Xing-Xing Fang Qi-Cheng Li wei pi Na Han Department of Orthopedics and Trauma Peking University People’s HospitalBeijingChina National Center for Trauma Medicine BeijingChina Central Laboratory Peking University People’s HospitalBeijingChina

We previously combined reduced graphene oxide(rGO)with gelatin-methacryloyl(GelMA)and polycaprolactone(PCL)to create an rGO-GelMA-PCL nerve conduit and found that the conductivity and biocompatibility were ***,the rGO-GelMA-PCL nerve conduits differed greatly from autologous nerve transplants in their ability to promote the regeneration of injured peripheral nerves and axonal *** vesicles derived from bone marrow mesenchymal stem cells(BMSCs)can be loaded into rGO-GelMA-PCL nerve conduits for repair of rat sciatic nerve injury because they can promote angiogenesis at the injured *** this study,12 weeks after surgery,sciatic nerve function was measured by electrophysiology and sciatic nerve function index,and myelin sheath and axon regeneration were observed by electron microscopy,immunohistochemistry,and *** regeneration of microvessel was observed by *** results showed that rGO-GelMA-PCL nerve conduits loaded with BMSC-derived extracellular vesicles were superior to rGO-GelMA-PCL conduits alone in their ability to increase the number of newly formed vessels and axonal sprouts at the injury site as well as the recovery of neurological *** findings indicate that rGO-GelMA-PCL nerve conduits loaded with BMSC-derived extracellular vesicles can promote peripheral nerve regeneration and neurological function recovery,and provide a new direction for the curation of peripheral nerve defect in the clinic.

关键词： angiogenesis axon bone mesenchymal stem cell extracellular vesicles hybrid nanofibers myelin sheath nerve conduit neurological function peripheral nerve injury reduced graphene oxide

Myelin-associated glycoprotein combined with chitin conduit inhibits painful neuroma formation after sciatic nerve transection

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Neural Regeneration Research 2022年第6期17卷 1343-1347页

作者： wei pi Ci Li Meng Zhang wei Zhang Pei-Xun Zhang Department of Orthopedics and Trauma Peking University People’s HospitalPeking UniversityBeijingChina Key Laboratory of Trauma and Neural Regeneration Peking UniversityBeijingChina National Center for Trauma Medicine BeijingChina

Studies have shown that myelin-associated glycoprotein(MAG)can inhibit axon regeneration after nerve ***,the effects of MAG on neuroma formation after peripheral nerve injury remain poorly *** this study,local injection of MAG combined with nerve cap made of chitin conduit was used to intervene with the formation of painful neuroma after sciatic nerve transfection in *** 8 weeks of combined treatment,the autotomy behaviors were reduced in rats subjected to sciatic nerve transfection,the mRNA expression of nerve growth factor,a pain marker,in the proximal nerve stump was decreased,the density of regenerated axons was decreased,the thickness of the myelin sheath was increased,and the ratio of unmyelinated to myelinated axons was ***,the percentage of collagen fiber area and the percentage of fibrosis marker alpha-smooth muscle actin positive staining area in the proximal nerve stump were *** combined treatment exhibited superior effects in these measures to chitin conduit treatment *** findings suggest that MAG combined with chitin conduit synergistically inhibits the formation of painful neuroma after sciatic nerve transection and alleviates neuropathic *** study was approved by the Animal Ethics Committee of Peking University People’s Hospital(approval No.2019PHE027)on December 5,2019.

关键词： autotomy axon chitin conduit fibrosis myelin-associated glycoprotein painful neuroma peripheral nerve regeneration

Cortical plasticity and nerve regeneration after peripheral nerve injury

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Neural Regeneration Research 2021年第8期16卷 1518-1523页

作者： Ci Li Song-Yang Liu wei pi Pei-Xun Zhang Department of Orthopedics and Trauma Peking University People’s HospitalBeijingChina Key Laboratory of Trauma and Neural Regeneration Peking UniversityBeijingChina National Center for Trauma Medicine BeijingChina

With the development of neuroscience, substantial advances have been achieved in peripheral nerve regeneration over the past decades. However, peripheral nerve injury remains a critical public health problem because of the subsequent impairment or absence of sensorimotor function. Uncomfortable complications of peripheral nerve injury, such as chronic pain, can also cause problems for families and society. A number of studies have demonstrated that the proper functioning of the nervous system depends not only on a complete connection from the central nervous system to the surrounding targets at an anatomical level, but also on the continuous bilateral communication between the two. After peripheral nerve injury, the interruption of afferent and efferent signals can cause complex pathophysiological changes, including neurochemical alterations, modifications in the adaptability of excitatory and inhibitory neurons, and the reorganization of somatosensory and motor regions. This review discusses the close relationship between the cerebral cortex and peripheral nerves. We also focus on common therapies for peripheral nerve injury and summarize their potential mechanisms in relation to cortical plasticity. It has been suggested that cortical plasticity may be important for improving functional recovery after peripheral nerve damage. Further understanding of the potential common mechanisms between cortical reorganization and nerve injury will help to elucidate the pathophysiological processes of nerve injury, and may allow for the reduction of adverse consequences during peripheral nerve injury recovery. We also review the role that regulating reorganization mechanisms plays in functional recovery, and conclude with a suggestion to target cortical plasticity along with therapeutic interventions to promote peripheral nerve injury recovery.

关键词： cortical plasticity injury mechanisms nerve transfer neurorrhaphy peripheral nerve phantom limb pain recovery regeneration treatment

Induced current of high temperature superconducting loops by combination of exciting coil and thermal switch

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Chinese Physics B 2022年第3期31卷 521-526页

作者： Jia-Wen Wang Yin-Shun Wang Hua Chai Ling-Feng Zhu wei pi State Key Laboratory of New Energy Renewable Power System North China Electric Power UniversityBeijing 102206China

With its commercialization, the second-generation(2G) high temperature superconducting(HTS) RE–Ba–Cu–O(REBCO, RE is rare earth) tape is extensively applied to the superconducting magnets in the high magnetic fields. However,unlike low temperature superconducting(LTS) magnets, the HTS magnet cannot operate in the persistent current mode(PCM) due to the immature superconducting soldering technique. In this paper, an exciting method for two HTS sub-loops,so-called charging and load loops, is proposed by flux pump consisting of exciting coil and controllable thermal *** HTS sub-loops are made of an REBCO tape with two slits. An exciting coil with iron core is located in one sub-loop and is supplied with a triangular waveform current so that magnetic field is generated in another sub-loop. The influence of magnetic flux on induced current in load loop is presented and verified in experiment at 77 K. The relationship between the induced magnetic flux density and the current on the sub-loops having been calibrated, magnetic flux density, and induced current are obtained. The results show that the HTS sub-loops can be excited by a coil with thermal switch and the induced current increases with magnetic flux of exciting coil increasing, which is promising for persistent current operation mode of HTS magnets.

关键词： bridge high temperature superconducting(HTS)sub-loops induced current thermal switch

Analysis of the Self-Protection Characteristics of a 1.5T Bitter-Like HTS Magnet Operated at 65K

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Chinese Physics Letters 2018年第6期35卷 79-83页

作者： Yan-Bing Hou Yin-Shun Wang Chang-Tao Kan Xi Yuan wei pi State Key Laboratory of New Energy Power System North China Electric Power University

We present a conceptual configuration of a high-temperature superconducting（HTS）magnet made from REBCO（Re=Rare Earth,B=Barium,C=Copper,O=Oxide）annular plates,called a Bitter-like HTS magnet,which can operate in persistent current mode without joint resistance and can be excited by a flux pump and without current leads and a persistent power *** REBCO annular magnet which can generate 1.5 T corresponding to the operating current density 80%of critical current density of the magnet at an operating temperature of65 K is conceptually *** the thermal stability of the magnet is numerically simulated by Comsol *** a piece of RBCO annular plate quenches,the maximum released energy is its stored energy because each REBCO annular plate in the Bitter-like magnet is in *** calculate the stored energy in the REBCO annular plate,the inductance of every annular plate,including self-inductance and mutual inductance,is *** with the minimum quench energy（MQE）and stored energy in one REBCO annular plate,the stored energy in one REBCO annular plate is always smaller than the MQE,and the REBCO annular plate will not be damaged even though the stored energy in the REBCO annular plate is fully released,which indicates that this 1.5 T Bitter-like magnet has the property of self-protection.

关键词： REBCO Analysis of the Self-Protection Characteristics of a 1.5T Bitter-Like HTS Magnet Operated at 65K HTS

Polydopamine-modified chitin conduits with sustained release of bioactive peptides enhance peripheral nerve regeneration in rats

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Neural Regeneration Research 2022年第11期17卷 2544-2550页

作者： Ci Li Song-Yang Liu Li-ping Zhou Tian-Tian Min Meng Zhang wei pi Yong-Qiang Wen Pei-Xun Zhang Department of Orthopedics and Trauma Peking University People’s HospitalBeijingChina Key Laboratory of Trauma and Neural Regeneration Ministry of EducationBeijingChina National Center for Trauma Medicine BeijingChina Beijing Key Laboratory for Bioengineering and Sensing Technology School of Chemistry and Biological EngineeringUniversity of Science and Technology BeijingBeijingChina

The introduction of neurotrophic factors into injured peripheral nerve sites is beneficial to peripheral nerve ***,neurotrophic facto rs are rapidly degraded in vivo and obstruct axonal regeneration when used at a supraphysiological dose,which limits their clinical *** mimetic peptides have been developed to be used in place of neurotrophic factors because they have a similar mode of action to the original growth fa ctors and can activate the equivalent receptors but have simplified sequences and *** this study,we created polydopamine-modified chitin conduits loaded with brain-derived neurotrophic factor mimetic peptides and vascular endothelial growth fa ctor mimetic peptides(Chi/PDA-Ps).We found that the Chi/PDA-Ps conduits were less cytotoxic in vitro than chitin conduits alone and provided sustained release of functional *** this study,we evaluated the biocompatibility of the Chi/P DA-Ps ***-derived neurotrophic factor mimetic peptide and vascular endothelial growth fa ctor mimetic peptide synergistically promoted prolife ration of Schwann cells and secretion of neurotrophic factors by Schwann cells and attachment and migration of endothelial cells in *** Chi/P DA-Ps conduits were used to bridge a 2 mm gap between the nerve stumps in rat models of sciatic nerve *** found that the application of Chi/PDA-Ps conduits could improve the motor function of rats and reduce gastrocnemius *** electrophysiological results and the microstructure of regenerative nerves showed that the nerve conduction function and re myelination was further resto *** findings suggest that the Chi/PDA-Ps conduits have great potential in peripheral nerve injury repair.

关键词： angiogenesis bioactive peptides nerve repair neurotrophic factor peripheral nerve injury peripheral nerve regeneration polydopamine surface modification synergistic effects tissue engineering

Sustained release of exosomes loaded into polydopamine-modified chitin conduits promotes peripheral nerve regeneration in rats

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Neural Regeneration Research 2022年第9期17卷 2050-2057页

作者： Ci Li Song-Yang Liu Meng Zhang wei pi Bo Wang Qi-Cheng Li Chang-Feng Lu Pei-Xun Zhang Department of Orthopedics and Trauma Peking University People’s HospitalBeijingChina Key Laboratory of Trauma and Neural Regeneration Ministry of EducationBeijingChina National Center for Trauma Medicine BeijingChina Department of Orthopedics Beijing Jishuitan HospitalBeijingChina

Exosomes derived from mesenchymal stem cells are of therapeutic interest because of their important role in intracellular communication and biological *** the basis of previously studied nerve conduits,we designed a polydopamine-modified chitin conduit loaded with mesenchymal stem cell-derived exosomes that release the exosomes in a sustained and stable *** vitro experiments revealed that rat mesenchymal stem cell-derived exosomes enhanced Schwann cell proliferation and secretion of neurotrophic and growth factors,increased the expression of Jun and Sox2 genes,decreased the expression of Mbp and Krox20 genes in Schwann cells,and reprogrammed Schwann cells to a repair ***,mesenchymal stem cell-derived exosomes promoted neurite growth of dorsal root *** polydopamine-modified chitin conduits loaded with mesenchymal stem cell-derived exosomes were used to bridge 2 mm rat sciatic nerve *** release of exosomes greatly accelerated nerve healing and improved nerve *** findings confirm that sustained release of mesenchymal stem cell-derived exosomes loaded into polydopamine-modified chitin conduits promotes the functional recovery of injured peripheral nerves.

关键词： exosome mesenchymal stem cells modification strategy nerve conduits peripheral nerve injury peripheral nerve regeneration polydopamine reprogramming state Schwann cells sustained release

Chitin scaffold combined with autologous small nerve repairs sciatic nerve defects

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Neural Regeneration Research 2022年第5期17卷 1106-1114页

作者： Bo Wang Chang-Feng Lu Zhong-Yang Liu Shuai Han pi wei Dian-Ying Zhang Yu-Hui Kou Bao-Guo Jiang Department of Orthopedics and Trauma Key Laboratory of Trauma and Neural Regeneration(Ministry of Education/Peking University)Peking University People’s HospitalBeijingChina Department of Orthopedics Chinese PLA General HospitalBeijingChina National Clinical Research Center for Orthopedics Sports Medicine&RehabilitationBeijingChina

Although autologous nerve transplantation is the gold standard for treating peripheral nerve defects,it has many clinical *** an alternative,various tissue-engineered nerve grafts have been developed to substitute for autologous *** this study,a novel nerve graft composed of chitin scaffolds and a small autologous nerve was used to repair sciatic nerve defects in *** novel nerve graft greatly facilitated regeneration of the sciatic nerve and myelin sheath,reduced atrophy of the target muscle,and effectively restored neurological *** the epineurium of the small autogenous nerve was removed,the degree of nerve regeneration was similar to that which occurs after autogenous nerve *** findings suggest that our novel nerve graft might eventually be a new option for the construction of tissue-engineered nerve *** study was approved by the Research Ethics Committee of Peking University People's Hospital(approval No.2019 PHE27)on October 18,2019.

关键词： autologous small nerve chitin scaffold nerve defect nervous system peripheral nerve injury peripheral nerve regeneration sciatic nerve trauma

Mechanical characterization of a 10-MJ HTS SMES magnet wound by quasiisotropic strands and directly stacked tape conductors

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Superconductivity 2023年第1期5卷 69-74页

作者： ZiKun Zhao Yinshun Wang Yubo Gao Zhao Yang ZhuYong Li wei pi State Key Lab.of New Energy Renewable Power System North China Electric Power UniversityBeijing 102206China Key Lab.of HV and EMC Beijing North China Electric Power UniversityBeijing 102206China Energy Singularity Energy Technolo-gy(shanghai)Co. LtdShangHai 200000China

A 10‐MJ‐class superconducting magnetic energy storage(SMES)magnet is designed and optimized in this study using quasi‐isotropic strands and stacked‐tape *** order to ensure the stable operation of SMES systems,it is necessary to evaluate the mechanical properties risk caused by the Lorentz ***,in this study,the magnetic stress caused by the Lorentz force is analyzed using the finite element *** results show that the tapes near the inner diameter of the magnet are subjected to a higher stress and require considerable *** the maximum stress is increased by two times due to the presence of the screening current,it is within the safety *** screening current does not vanish after the discharge *** discharge,the coil is still subjected to a stress on the other of a few MPa.

关键词： Lorentz force Quasi‐isotropic strand Superconducting magnetic energy storage Screening current weibull distribution