Silk-based nerve guidance conduits with macroscopic holes modulate the vascularization of regenerating rat sciatic nerve

Peripheral nerve injuries induce a severe motor and sensory deficit. Since the availability of autologous nerve transplants for nerve repair is very limited, alternative treatment strategies are sought, including the use of tubular nerve guidance conduits(tNGCs). However, the use of tNGCs results in poor functional recovery and central necrosis of the regenerating tissue, which limits their application to short nerve lesion defects(typically shorter than 3 cm). Given the importance of vascularization in nerve regeneration, we hypothesized that enabling the growth of blood vessels from the surrounding tissue into the regenerating nerve within the tNGC would help eliminate necrotic processes and lead to improved regeneration. In this study, we reported the application of macroscopic holes into the tubular walls of silk-based tNGCs and compared the various features of these improved silk^(+) tNGCs with the tubes without holes(silk^(–) tNGCs) and autologous nerve transplants in an 8-mm sciatic nerve defect in rats. Using a combination of micro-computed tomography and histological analyses, we were able to prove that the use of silk^(+) tNGCs induced the growth of blood vessels from the adjacent tissue to the intraluminal neovascular formation. A significantly higher number of blood vessels in the silk^(+) group was found compared with autologous nerve transplants and silk^(–), accompanied by improved axon regeneration at the distal coaptation point compared with the silk^(–) tNGCs at 7 weeks postoperatively. In the 15-mm(critical size) sciatic nerve defect model, we again observed a distinct ingrowth of blood vessels through the tubular walls of silk^(+) tNGCs, but without improved functional recovery at 12 weeks postoperatively. Our data proves that macroporous tNGCs increase the vascular supply of regenerating nerves and facilitate improved axonal regeneration in a short-defect model but not in a critical-size defect model. This study suggests that further optimization of the macroscopic holes silk^(+) tNGC approach containing macroscopic holes might result in improved grafting technology suitable for future clinical use.

Human umbilical cord mesenchymal stem cell-derived exosomes loaded into a composite conduit promote functional recovery after peripheral nerve injury in rats

Complete transverse injury of peripheral nerves is challenging to treat.Exosomes secreted by human umbilical cord mesenchymal stem cells are considered to play an important role in intercellular communication and regulate tissue regeneration.In previous studies,a collagen/hyaluronic acid sponge was shown to provide a suitable regeneration environment for Schwann cell proliferation and to promote axonal regeneration.This three-dimensional(3D)composite conduit contains a collagen/hyaluronic acid inner sponge enclosed in an electrospun hollow poly(lactic-co-glycolic acid)tube.However,whether there is a synergy between the 3D composite conduit and exosomes in the repair of peripheral nerve injury remains unknown.In this study,we tested a comprehensive strategy for repairing long-gap(10 mm)peripheral nerve injury that combined the 3D composite conduit with human umbilical cord mesenchymal stem cell-derived exosomes.Repair effectiveness was evaluated by sciatic functional index,sciatic nerve compound muscle action potential recording,recovery of muscle mass,measuring the cross-sectional area of the muscle fiber,Masson trichrome staining,and transmission electron microscopy of the regenerated nerve in rats.The results showed that transplantation of the 3D composite conduit loaded with human umbilical cord mesenchymal stem cell-derived exosomes promoted peripheral nerve regeneration and restoration of motor function,similar to autograft transplantation.More CD31-positive endothelial cells were observed in the regenerated nerve after transplantation of the loaded conduit than after transplantation of the conduit without exosomes,which may have contributed to the observed increase in axon regeneration and distal nerve reconnection.Therefore,the use of a 3D composite conduit loaded with human umbilical cord mesenchymal stem cell-derived exosomes represents a promising cell-free therapeutic option for the treatment of peripheral nerve injury.

Electrodeposition of chitosan/graphene oxide conduit to enhance peripheral nerve regeneration

Currently available commercial nerve guidance conduits have been applied in the repair of peripheral nerve defects.However,a conduit exhibiting good biocompatibility remains to be developed.In this work,a series of chitosan/graphene oxide(GO)films with concentrations of GO varying from 0-1 wt%(collectively referred to as CHGF-n)were prepared by an electrodeposition technique.The effects of CHGF-n on proliferation and adhesion abilities of Schwann cells were evaluated.The results showed that Schwann cells exhibited elongated spindle shapes and upregulated expression of nerve regeneration-related factors such as Krox20(a key myelination factor),Zeb2(essential for Schwann cell differentiation,myelination,and nerve repair),and transforming growth factorβ(a cytokine with regenerative functions).In addition,a nerve guidance conduit with a GO content of 0.25%(CHGFC-0.25)was implanted to repair a 10-mm sciatic nerve defect in rats.The results indicated improvements in sciatic functional index,electrophysiology,and sciatic nerve and gastrocnemius muscle histology compared with the CHGFC-0 group,and similar outcomes to the autograft group.In conclusion,we provide a candidate method for the repair of peripheral nerve defects using free-standing chitosan/GO nerve conduits produced by electrodeposition.

A hyaluronic acid granular hydrogel nerve guidance conduit promotes regeneration and functional recovery of injured sciatic nerves in rats

A hyaluronic acid granular hydrogel can promote neuronal and astrocyte colony formation and axonal extension in vitro,suggesting that the hydrogel can simulate an extracellular matrix structure to promote neural regeneration.However,in vivo experiments have not been conducted.In this study,we transplanted a hyaluronic acid granular hydrogel nerve guidance conduit to repair a 10-mm long sciatic nerve gap.The Basso,Beattie,and Bresnahan locomotor rating scale,sciatic nerve compound muscle action potential recording,Fluoro-Gold retrograde tracing,growth related protein 43/S100 immunofluorescence staining,transmission electron microscopy,gastrocnemius muscle dry/wet weight ratio,and Masson’s trichrome staining results showed that the nerve guidance conduit exhibited similar regeneration of sciatic nerve axons and myelin sheath,and recovery of the electrophysiological function and motor function as autologous nerve transplantation.The conduit results were superior to those of a bulk hydrogel or silicone tube transplant.These findings suggest that tissue-engineered nerve conduits containing hyaluronic acid granular hydrogels effectively promote the morphological and functional recovery of the injured sciatic nerve.The nerve conduits have the potential as a material for repairing peripheral nerve defects.

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

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 improved.However,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 sprouting.Extracellular 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 site.In 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 immunofluorescence.The regeneration of microvessel was observed by immunofluorescence.Our 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 function.These 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.

Contemporary outcomes of patients undergoing robotic-assisted radical cystectomy:A comparative analysis between intracorporeal ileal conduit and neobladder urinary diversions

Objective We aimed to compare perioperative and oncologic outcomes for patients undergoing robotic-assisted radical cystectomy(RARC)with intracorporeal ileal conduit(IC)and neobladder(NB)urinary diversion.Methods Patients undergoing RARC with intracorporeal urinary diversion between January 2017 and January 2022 at the Icahn School of Medicine at Mount Sinai,New York,NY,USA were indexed.Baseline demographics,clinical characteristics,perioperative,and oncologic outcomes were analyzed.Survival was estimated with Kaplan-Meier plots.Results Of 261 patients(206[78.9%]male),190(72.8%)received IC while 71(27.2%)received NB diversion.Median age was greater in the IC group(71[interquartile range,IQR 65-78]years vs.64[IQR 59-67]years,p<0.001)and BMI was 26.6(IQR 23.2-30.4)kg/m^(2).IC group was more likely to have prior abdominal or pelvic radiation(15.8%vs.2.8%,p=0.014).American Association of Anesthesiologists scores were comparable between groups.The IC group had a higher proportion of patients with pathological tumor stage 2(pT2)tumors(34[17.9%]vs.10[14.1%],p=0.008)and pathological node stages pN2-N3(28[14.7%]vs.3[4.2%],p<0.001).The IC group had less median operative time(272[IQR 246-306]min vs.341[IQR 303-378]min,p<0.001)and estimated blood loss(250[150-500]mL vs.325[200-575]mL,p=0.002).Thirty-and 90-day complication rates were 44.4%and 50.2%,respectively,and comparable between groups.Clavien-Dindo grades 3-5 complications occurred in 27(10.3%)and 34(13.0%)patients within 30 and 90 days,respectively,with comparable rates between groups.Median follow-up was 324(IQR 167-552)days,and comparable between groups.Kaplan-Meier estimate for overall survival at 24 months was 89%for the IC cohort and 93%for the NB cohort(hazard ratio 1.23,95%confidence interval 1.05-2.42,p=0.02).Kaplan-Meier estimate for recurrence-free survival at 24 months was 74%for IC and 87%for NB(hazard ratio 1.81,95%confidence interval 0.82-4.04,p=0.10).Conclusion Patients undergoing intracorporeal IC urinary diversion had higher postoperative cancer stage,increased nodal involvement,similar complications outcomes,decreased overall survival,and similar recurrence-free survival compared to patients undergoing RARC with intracorporeal NB urinary diversion.

Chitosan conduits enriched with fibrin-collagen hydrogel with or without adipose-derived mesenchymal stem cells for the repair of 15-mm-long sciatic nerve defect

Hollow conduits of natural or synthetic origins have shown acceptable regeneration results in short nerve gap repair;however,results are still not comparable with the current gold standard technique“autografts”.Hollow conduits do not provide a successful regeneration outcome when it comes to critical nerve gap repair.Enriching the lumen of conduits with different extracellular materials and cells could provide a better biomimicry of the natural nerve regenerating environment and is expected to ameliorate the conduit performance.In this study,we evaluated nerve regeneration in vivo using hollow chitosan conduits or conduits enriched with fibrin-collagen hydrogels alone or with the further addition of adipose-derived mesenchymal stem cells in a 15 mm rat sciatic nerve transection model.Unexpected changes in the hydrogel consistency and structural stability in vivo led to a failure of nerve regeneration after 15 weeks.Nevertheless,the molecular assessment in the early regeneration phase(7,14,and 28 days)has shown an upregulation of useful regenerative genes in hydrogel enriched conduits compared with the hollow ones.Hydrogels composed of fibrin-collagen were able to upregulate the expression of soluble NRG1,a growth factor that plays an important role in Schwann cell transdifferentiation.The further enrichment with adipose-derived mesenchymal stem cells has led to the upregulation of other important genes such as ErbB2,VEGF-A,BDNF,c-Jun,and ATF3.

Hypoxic pre-conditioned adipose-derived stem/progenitor cells embedded in fibrin conduits promote peripheral nerve regeneration in a sciatic nerve graft model

Recent results emphasize the supportive effects of adipose-derived multipotent stem/progenitor cells(ADSPCs)in peripheral nerve recovery.Cultivation under hypoxia is considered to enhance the release of the regenerative potential of ADSPCs.This study aimed to examine whether peripheral nerve regeneration in a rat model of autologous sciatic nerve graft benefits from an additional custom-made fibrin conduit seeded with hypoxic pre-conditioned(2%oxygen for 72 hours)autologous ADSPCs(n=9).This treatment mode was compared with three others:fibrin conduit seeded with ADSPCs cultivated under normoxic conditions(n=9);non-cell-carrying conduit(n=9);and nerve autograft only(n=9).A 16-week follow-up included functional testing(sciatic functional index and static sciatic index)as well as postmortem muscle mass analyses and morphometric nerve evaluations(histology,g-ratio,axon density,and diameter).At 8 weeks,the hypoxic pre-conditioned group achieved significantly higher sciatic functional index/static sciatic index scores than the other three groups,indicating faster functional regeneration.Furthermore,histologic evaluation showed significantly increased axon outgrowth/branching,axon density,remyelination,and a reduced relative connective tissue area.Hypoxic pre-conditioned ADSPCs seeded in fibrin conduits are a promising adjunct to current nerve autografts.Further studies are needed to understand the underlying cellular mechanism and to investigate a potential application in clinical practice.

Explosion Event of Cavitation in Intact Xylem Conduit

Cavitation in plant conduits only involves two processes of air bubbles: the gradual expansion and elongation, and the explosion event. An explosion event of cavitation, which can only occur in intact conduit at water tension, trigs acoustic (or ultrasound) emission and induces air to diffuse with high speed, simultaneously. Synchrotron X-ray phase contrast microscopy (XPCM) was used to capture cavitation event in intact conduits of leaves of corn and rice. Cavitation events occur in certain areas of leaves and have a certain time frame. Before XPCM experiment, several preliminary experiments were done as follows: 1) Paraffin sections of leaves of different species were observed to select samples and to determine the occurrence area of cavitation event of leaves. 2) The time frame of cavitation occurrence was determined by ultrasonic emission. 3) The water potentials of leaves were determined, to know the water state of the leaves during cavitation. Locked the area and time frame of cavitation event in the leaves, consecutive XPCM images of cavitation process were more easily acquired. The images show that the phenomenon of gas bubble fully filling conduits for an instant took place in intact conduits of detached leaves of corn and rice more easily. It is that the gas diffusing in a moment was caused by the explosion of the air seeds which had entered in the intact conduits of the leaves. For living plants, it is suggested that the explosion event of cavitation is the most important for embolism formation.

松辽盆地深层中-基性火山岩有利相带及储层“甜点”逐级识别

松辽盆地深层下白垩统火石岭组中-基性火山岩广泛发育,岩性-岩相复杂,储层横向非均质性强,储层“甜点”识别难,制约了油气勘探和开发。以查干花地区为例,研究了松辽盆地深层中-基性火山岩岩相及储层特征,提出了火山通道、有利岩相、有利岩性及储层甜点识别方法。研究表明:①火山岩岩相主要为3相6亚相,优质储层岩性主要为粗粒、细粒凝灰岩和凝灰质砂岩,在近-中源相带中火山爆发相储层最为发育,相带控制了有利岩性凝灰岩的分布区域,物性和含气性是火山岩“甜点”的主要控制因素。②通过分析每个喷发期次的裂缝密度,结合蚂蚁体与地震数据的叠合剖面,识别出了不同喷发期次的火山通道,以判断火山近源相带,再结合火山机构厚度和能量半衰时属性划分中源与远源相带的边界,实现储层“甜点”发育区的定性刻画。③为降低地震反演定量预测中-基性火山岩储层的多解性,优选出低波阻抗表征沉凝灰岩,低密度表征高核磁孔隙度储层,低拉梅常数表征气层,基于此,在叠前反演密度预测孔隙度数据体的基础上,逐级剔除干扰沉凝灰岩、低孔隙度层及非气层,得到较为可靠的火山岩储层“甜点”空间分布预测结果。经验证,预测结果符合有利相带分布规律,且与已钻井气层解释结论吻合。应用有利相带定性认识及逐级定量刻画“甜点”空间分布,部署井取得较好效果,该方法可在深层火山岩“甜点”分布地震预测中广泛推广。

基于冲刷指数的雨水管渠冲刷淤积分析

流速、雷诺数、充满度等单因素指标虽然与雨水管渠的冲刷和淤积量有一定的关联,但是通过单因素指标不足以全面地判断雨水管道的冲刷和淤积。在起动流速和止动流速的基础上,提出了冲刷指数的概念。结合连续非恒定流不同工况下冲刷和淤积量模拟,计算了流速、雷诺数、充满度、冲刷指数4个因素与冲刷量的灰色关联度,其关联度大小依次为:冲刷指数>雷诺数>充满度>流速。根据不同工况的恒定流模型实验的结果,其关联度大小依次为:冲刷指数>>流速>雷诺数>充满度。可以认为,在恒定流与非恒定流工况下,冲刷量和冲刷指数有显著的强相关性,冲刷指数能代替具体的冲刷量计算实现对冲刷程度和趋势的合理判断。

费曼式学习法在低年资护士儿童PICC维护培训中的应用

目的:探讨费曼式学习法在低年资护士儿童经外周静脉置入中心静脉导管(PICC)维护培训中的应用。方法:2022年3月—12月选取无锡市儿童医院80名低年资护士参与儿童PICC导管维护培训,采用随机数字表法将其分为观察组及对照组,每组40人。对照组行规范性培训,观察组应用费曼式学习法,比较两组护士规范化培训参与率、PICC置管知识及技能考核评分、护士自主学习能力及PICC知信行评分。结果:观察组护士第4次~第6次培训参与率明显高于对照组(P<0.05);观察组培训结束时PICC置管知识评分、技能考核评分、护士自主学习能力评分及PICC知信行评分高于对照组(P<0.05)。结论:费曼式学习法可提升低年资护士参与儿童PICC维护培训参与率,改善低年资护士自主学习能力及PICC维护知信行水平,有助于护士PICC维护知识及维护技能的提升。

岩浆通道成矿核心内涵“两深一浅一通道”及其找矿意义

岩浆通道成矿模型的建立深刻改变了岩浆铜镍硫化物矿床成因研究的范式,成为该领域的研究前沿,而且已经成功地应用于找矿勘查中。该模型揭示了硫化物熔离与聚集成矿在空间上的不一致性以及成矿与相关玄武岩铂族元素强烈亏损的成因联系,很好地解释了为什么很多含矿岩体围岩贫硫化物的现象。笔者将该模型的核心内涵概括为“两深一浅一通道”,“两深”指成矿物质来源于地幔、硫化物熔离发生在深部,“一浅”指硫化物的聚集成矿主要发生在较浅的岩浆房,“一通道”指较稳定的岩浆通道更有利于成大矿。结合对典型矿床和成矿带的分析,笔者提出侵位较浅的、规模相对较大的岩体,其成矿潜力好于深部的岩浆通道相。因此,认为地表矿化并不是唯一可靠的、甚至不能作为最重要的找矿标志,要提高找矿效率(特别是隐伏矿床),首先要全面分析成矿带岩浆通道系统在不同区域的埋藏、剥蚀和暴露状况,目标岩体地质产状及其与围岩时代差异等宏观地质要素,查明深部通道相与浅部岩体空间分布和形成深度的差异,在此基础上,判断浅部岩体的位置、合理部署重点勘查区域、选择有效的勘查技术、定位目标岩体,进行钻探验证。

完全腹腔镜膀胱根治性切除回肠膀胱术治疗膀胱癌25例疗效观察

目的探讨完全腹腔镜膀胱根治性切除回肠膀胱术的临床效果和手术技巧,以期为膀胱癌患者手术方式的选择提供参考。方法回顾性分析首都医科大学附属北京朝阳医院泌尿外科2017年3月—2022年8月收治的48例行腹腔镜膀胱根治性切除回肠膀胱术治疗膀胱癌患者的临床资料。按照手术方式分为传统腹腔镜组(腹腔镜膀胱根治性切除+脐下正中切口回肠膀胱术)患者23例,完全腹腔镜组25例。比较两组患者的手术时间、估计出血量、术后肠道功能恢复时间、引流管拔除时间及住院时间。结果48例患者手术均顺利完成,所有患者均未发生Clavien-Dindo>3级并发症。传统腹腔镜组与完全腹腔镜组的手术时间分别为(227.0±46.4)min与(253.6±58.9)min,出血量分别为(131.7±79.8)mL与(154.0±93.0)mL,两组术后肠道功能恢复时间、引流管拔除时间比较差异无统计学意义(P>0.05),而完全腹腔镜组的术后住院时间较传统腹腔镜组更短,差异有统计学意义(P=0.035)。结论完全腹腔镜膀胱根治性切除回肠膀胱术安全可行,与传统腹腔镜手术方式效果相当,而完全腹腔镜组术后住院时间更短,有利于术后快速康复。

岩溶管道构造影响下浅部地层温度数值模拟研究

当含水岩溶构造体存在时,浅部地层温度场会产生变化。浅层测温法可以简单快速地获得浅层地温数据,通过温度差异反演出岩溶构造的分布。为了研究以贵州省盘州市某场地及其周围场地为对象时,浅层测温技术探测岩溶管道构造体的可行性,笔者采用数值模拟方法。结果表明:构造体不同的埋深会显著改变浅部地层的温度,对于单个岩溶构造体(等效直径为0.5 m,水温12℃),可探测深度极限约为66 m;在管道内流体的温度为12℃时,岩溶管道构造体有效流动截面积的增大会降低浅部地层温度,等效直径在0.1~1.0 m区间内改变时,2.0 m处地层温度的变化在0.02℃以内,这使得利用浅层测温法识别岩溶构造体的有效流动截面积变得困难;流体温度在一定范围内(12~18℃)的变化会改变浅部地层温度,尤其是低温流体的影响更为明显。

耐高压PICC在肿瘤患者腹部CT增强中的应用研究

目的分析耐高压经外周静脉置入中心静脉导管(PICC)在肿瘤患者腹部CT增强中的应用情况。方法随机选取我院2021年1月至2023年6月期间实施腹部CT增强扫描的肿瘤患者300例,按随机数字表法分为例数相同的3组,其中对照组100例实施常规静脉留置针予以对比剂团注;观察1组(n=100)、观察2组(n=100)均用耐高压PICC导管予以对比剂团注,根据对比剂说明书参照剂量以及患者实际特点、医院常规使用情况,将对比剂用量分别设置为1.3、1.1 mL/kg;对比三组CT增强扫描并发症、图像质量等。结果总的增强扫描不良事件发生率方面,观察1组、2组明显低于对照组(P<0.05),而1、2组相比差异无统计学意义(P>0.05)。观察1组、2组从进入检查室至CT扫描的时间、CT扫描结束至按压无出血的时间、整体耗时均短于对照组,图像质量、噪声及锐利度评分均高于对照组(P<0.05),而观察1、2组相比差异无统计学意义(P>0.05)。三组患者CT增强扫描结束后未出现导管高压注射损坏及导管堵塞的情况。观察2组的对比剂用量低于观察1组、对照组(P<0.05)。结论肿瘤患者应用耐高压PICC导管并联合低对比剂注射用量行腹部CT增强,优化了CT增强的检查流程,提高了患者的检查舒适度,减少不良事件的发生,值得临床推广。

新旗下营隧道塌方段治理措施优化设计

为了在隧道塌方地段能够保证施工安全进行,需要采取超前支护手段来保证围岩稳定。以新旗下营隧道塌方段为依托,研究不同支护措施对隧道塌方段的影响,根据现场塌方情况比选出合适的支护方式——超前小导管,采用Midas GTS NX(迈达斯)有限元软件,分别建立了无超前支护和超前小导管支护方案进行比选分析。在此基础上,对超前小导管长度和注浆加固区厚度参数进行优化比选。结果表明:超前小导管支护效果明显,能有效改善断层破碎带和地形偏压对隧道的影响,并且当超前小导管长度为4 m,注浆加固区厚度为1 m时,可有效控制围岩变形,保证围岩稳定。研究验证了参数选取的可行性,可为类似隧道塌方的预防与治理提供工程借鉴。

碳纳米材料在周围神经再生领域的研究与应用

背景:虽然神经导管为周围神经修复提供了潜在的治疗手段,但传统神经导管只能为修复过程提供机械通道支持,治疗效果仍有待提高。碳纳米材料具有良好的理化性质,在电化学及组织工程等领域有着广阔的应用前景。负载碳纳米材料的神经导管,在经过适宜的功能化修饰后,有望进一步提升神经修复质量。目的:对近年来负载碳纳米材料的神经导管/支架应用于周围神经修复的研究进展作一综述。方法:在PubMed、Web of Science、中国知网和万方数据库中检索在周围神经再生方面应用碳纳米材料导管的相关文献,英文检索词为“carbon nanomaterials,carbon-based nanomaterials,nerve conduit,nerve guidance conduit,scaffold,nerve regeneration,peripheral nerve repair,peripheral nerve injury”,中文检索词为“碳纳米材料,碳材料,石墨烯,碳纳米管,神经导管,神经支架,神经修复,神经再生,周围神经损伤”,最终纳入69篇文章进行综述。结果与结论:①碳纳米材料主要通过激活钙离子通道及诱导胞内钙活动发生的方式恢复受损神经生物电信号传导,不同神经导管设计策略的应用提高了神经修复的效果。②神经内血管化是修复周围神经损伤的前提,碳纳米材料生成的活性氧及活性氮触发了后续相关信号通路,促进神经内新生血管形成。③M1和M2型巨噬细胞的比例变化会影响周围神经损伤的修复,碳纳米材料在损伤早期通过促进巨噬细胞向M2型极化以发挥抗炎和促神经再生作用。④部分碳纳米材料在胞内诱导过量活性氧生成,可能具有不利于神经修复的细胞毒性,但合适的功能化修饰能够改善碳纳米材料产生的不良作用。⑤碳纳米材料虽然能够恢复周围神经损伤微环境,发挥促进周围神经再生的积极作用,但由于固有的细胞毒性及不明确的体内转归降解途径,碳纳米材料距离临床应用仍有距离。未来研究可以通过如功能化改性等方法提高碳纳米材料的生物相容性,而经过改良的碳纳米材料在神经组织工程领域有着较好的应用前景。

1%富血小板血浆联合骨髓间充质干细胞促进周围神经损伤的修复

背景:富血小板血浆已被证明能够增强间充质干细胞活性并具有促血管再生能力。细胞外囊泡是间充质干细胞发挥作用的关键介质之一,但目前还不清楚富血小板血浆是否能影响细胞外囊泡的功能。目的:探索富血小板血浆对骨髓间充质干细胞分泌的细胞外囊泡功能的影响,验证是否能够将富血小板血浆用作一种刺激剂来改善骨髓间充质干细胞修复周围神经损伤的效果。方法:体外实验方面,在一般条件下和含有1%富血小板血浆的条件下培养骨髓间充质干细胞,用超速离心法分离骨髓间充质干细胞分泌的细胞外囊泡,前者命名为EVs-nor,后者命名为EVs-prp。将细胞外囊泡用于干预施万细胞,通过EdU、蛋白印迹、qPCR、光学显微镜拍照等分析施万细胞修复性重编程相关特征,包括细胞增殖、c-Jun蛋白表达、重编程相关基因表达、细胞形态等。体内实验方面,构建大鼠坐骨神经断伤模型,然后利用甲壳素神经套管将骨髓间充质干细胞单独或连同1%富血小板血浆植入损伤神经,术后8周评估组织学和功能学恢复情况,评估指标包括再生神经纤维密度、腓肠肌肌肉湿质量、坐骨神经功能指数等。结果与结论:(1)相比于EVs-nor,EVs-prp刺激后的施万细胞增殖能力更强,c-Jun基因表达水平更高,GDNF表达上调,细胞形态更长,表明EVs-prp比EVs-nor有更强的刺激施万细胞重编程的能力;(2)坐骨神经损伤动物实验结果显示,相比于单独植入骨髓间充质干细胞或单独植入富血小板血浆,将骨髓间充质干细胞联合富血小板血浆一起植入的修复效果最好,具体体现在该组的再生神经纤维密度、腓肠肌肌肉湿质量、坐骨神经功能指数等指标均显著优于其他组;(3)这些实验结果显示,富血小板血浆可以改善骨髓间充质干细胞来源细胞外囊泡的功能,并且可以作为一种实用、易得的制剂与骨髓间充质干细胞协同促进周围神经损伤修复。

轴流泵装置进水流道出口速度及脉动特性分析

为研究不同流量工况时进水流道出口速度及压力脉动特性,基于CFD软件对轴流泵装置整体进行三维非定常数值计算,分别分析了各测线的速度及监测点的压力脉动的时频特性。结果表明:在进水流道出口面,速度从导水帽外壁面到流道出口内壁面的分布大体呈现出先减再增后减的规律、压力脉动幅值与速度脉动幅值从轮缘到轮毂方向呈逐渐减小趋势;进水流道出口处各监测点的压力脉动和速度脉动最大幅值都位于4倍转频处。