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.

Effect of Human Cytomegalovirus Infection on Nerve Growth Factor Expression in Human Glioma U251 Cells

Objective To explore the change of endogenic nerve growth factor （NGF） expression in human glioma cells infected with human cytomegalovirus （HCMV）. Methods U251 cells were cultured in RPMI 1640 culture medium and infected with HCMV AD 169 strain in vitro to establish a cell model of viral infection. Morphologic changes of U251 cells were observed under inverted microscope before and after infection with HCMV. Expression of NGF gene and protein of cells was detected by RT-PCR and Western blotting before and after infection with HCMV. Results The cytopathic effects of HCMV-infected cells appeared on day 5 after infection. However, differential NGF expression was evident on day 7. NGF expression was decreased significantly in U251 cells on day 7 after infection in comparison with control group （P〈0.05）. Conclusion HCMV can down-regulate endogenous NGF levels in human glioma cell line U251.

Clinical observation of recombinant human nerve growth factor in the treatment of neurotrophic keratitis

AIM:To characterize changes of corneal nerve morphology and tear indices in patients with neurotrophic keratitis(NK)treated with recombinant human nerve growth factor(rhNGF).METHODS:In a prospective observational study,six patients(nine eyes)were locally treated with rhNGF.Visual acuity,corneal fluorescein staining score,the heights of the tear river,lipid layer thickness(LLT),tear ferning(TF)test,conjunctival impression cytology(CIC)examination,the densities of cornea subbasal nerve fibers were determined before and after treatment.RESULTS:Compared with baseline,there was a significant difference in corneal fluorescence staining scores(P<0.01);all patient corneal epithelial defects recovered completely within 8wk,but there was no significant improvement in the height of the tear river(P=0.202).LLT was significantly increased when compared with baseline(P=0.042);however,the function of conjunctival goblet cells and mucin content did not significantly improve using the TF test and CIC examination(P=0.557,P=0.539).After 8wk of treatment,the average corneal subbasal nerve fiber density increased significantly(P<0.01),as did the number of corneal nerve fiber branches(P=0.001).CONCLUSION:RhNGF can increase the density of corneal subbasal nerve fibers,promote the healing of persistent corneal epithelial defects and corneal ulcers in patients with NK,also improving tear function partially.

Fresh human amniotic membrane effectively promotes the repair of injured common peroneal nerve

Suture and autologous nerve transplantation are the primary therapeutic measures for completely severed nerves. However, imbalances in the microenvironment and adhesion of surrounding tissues can affect the quality of nerve regeneration and repair. Previous studies have shown that human amniotic membrane can promote the healing of a variety of tissues. In this study, the right common peroneal nerve underwent a 5-mm transection in rats. Epineural nerve repair was performed using 10/0 non-absorbable surgical suture. The repair site was wrapped with a two-layer amniotic membrane with α-cyanoacrylate rapid medical adhesive after suture. Hindlimb motor function was assessed using footprint analysis. Conduction velocity of the common peroneal nerve was calculated by neural electrical stimulation. The retrograde axoplasmic transport of the common peroneal nerve was observed using fast blue BB salt retrograde fluorescent staining. Hematoxylin- eosin staining was used to detect the pathological changes of the common peroneal nerve sputum. The mRNA expression of axon regeneration-related neurotrophic factors and inhibitors was measured using real-time polymerase chain reaction. The results showed that the amniotic membrane significantly improved the function of the injured nerve;the toe spread function rapidly recovered, the nerve conduction velocity was restored, and the number of fast blue BB salt particles were increased in the spinal cord. The amniotic membrane also increased the recovery rate of the tibialis anterior muscle and improved the tissue structure of the muscle. Meanwhile, mRNA expression of nerve growth factor, growth associated protein-43, collapsin response mediator protein-2, and brain-derived neurotrophic factor recovered to near-normal levels, while Lingo-1 mRNA expression decreased significantly in spinal cord tissues. mRNA expression of glial-derived neurotrophic factor did not change significantly. Changes in mRNA levels were more significant in amniotic-membrane-wrapping-treated rats compared with model and nerve sutured rats. These results demonstrate that fresh amniotic membrane wrapping can promote the functional recovery of sutured common peroneal nerve via regulation of expression levels of neurotrophic factors and inhibitors associated with axonal regeneration. The study was approved by the Committee on Animal Research and Ethics at the Affiliate Hospital of Zunyi Medical University, China (approval No. 112) on December 1, 2017.

Artificial nerve graft constructed by coculture of activated Schwann cells and human hair keratin for repair of peripheral nerve defects

Studies have shown that human hair keratin(HHK) has no antigenicity and excellent mechanical properties. Schwann cells, as unique glial cells in the peripheral nervous system, can be induced by interleukin-1β to secrete nerve growth factor, which promotes neural regeneration. Therefore, HHK with Schwann cells may be a more effective approach to repair nerve defects than HHK without Schwann cells. In this study, we established an artificial nerve graft by loading an HHK skeleton with activated Schwann cells. We found that the longitudinal HHK microfilament structure provided adhesion medium, space and direction for Schwann cells, and promoted Schwann cell growth and nerve fiber regeneration. In addition, interleukin-1β not only activates Schwann cells, but also strengthens their activity and increases the expression of nerve growth factors. Activated Schwann cells activate macrophages, and activated macrophages secrete interleukin-1β, which maintains the activity of Schwann cells. Thus, a beneficial cycle forms and promotes nerve repair. Furthermore, our studies have found that the newly constructed artificial nerve graft promotes the improvements in nerve conduction function and motor function in rats with sciatic nerve injury, and increases the expression of nerve injury repair factors fibroblast growth factor 2 and human transforming growth factor B receptor 2. These findings suggest that this artificial nerve graft effectively repairs peripheral nerve injury.

Efficacy of rhNGF-loaded amniotic membrane transplantation for rabbit corneal epithelial and nerve regeneration

AIM:To evaluate the efficacy of recombinant human nerve growth factor-loaded amniotic membrane(rh NGF-AM)on corneal epithelial and nerve regeneration in rabbit model.METHODS:Freshly prepared human amniotic membrane(AM)were immersed into PBS buffer containing 100 or 500μg/mL rh NGF for 15,30,and 60 min at 4℃.The in vitro release kinetics of rh NGF was measured with ELISA.For in vivo evaluation,the AM were immersed with 500μg/mL rh NGF for 30 min.Fifty-seven rabbits were selected to establish corneal epithelial defect model.In addition to the 19 rabbits in control group,38 rabbits received AM transplantation with or without rh NGF after the removal of central epithelium.Corneal epithelial defect area,sub-epithelial nerve fiber density,corneal sensitivity,rh NGF contents in resident AM and corneas were measured after the surgery.RESULTS:rh NGF was sustained release from the AM within 14 d in vitro,with the positive correlation with initial immersion concentration.The immersion of AM in 500μg/mL rh NGF for 30 min achieved the most stable release within 14 d.After transplantation in rabbit cornea,a high concentration of rh NGF in resident rh NGF-AM and cornea was maintained within 8 d.Corneal epithelial healing,nerve fiber regeneration and the recovery of corneal sensitivity were significantly accelerated after the rh NGF-AM transplantation when compared to simple AM transplantation(all P<0.05).CONCLUSION:Simple immersion of AM achieves the sustained release of rh NGF,and promotes corneal epithelial wound healing and nerve regeneration,as well as the recovery of corneal sensitivity in rabbit.

A comparative study on the transplantation of different concentrations of human umbilical mesenchymal cells into diabetic rats

AIM: To observe the effects of intravitreal injections of different concentrations of human umbilical mesenchymal stem cells on retinopathy in rats with diabetes mellitus.METHODS: Healthy and adult male Sprague-Dawley(SD) rats were randomly assigned to a normal control group(group A), a diabetic retinopathy(DR) blank control group(group B), a high-concentration transplantation group(group C), a low-concentration transplantation group(group D) and a placebo transplantation group(group E). The expression of nerve growth factor(NGF)protein in the retinal layers was detected by immunohistochemical staining at 2, 4, 6 and 8wk.RESULTS: The expression of NGF was positive in group A and most positive in the retinal ganglion cell layer. In groups B and E, the expression of NGF was positive 2wk after transplantation and showed an increase in all layers. However, the level of expression had decreased in all layers at 4wk and was significantly reduced at 8wk. In groups C and D, the expression of NGF had increased at 2wk and continued to increase up to 8wk. The level of expression in group C was much higher than that in group D.CONCLUSION: DR can be improved by intravitreal injection of human umbilical mesenchymal stem cells.High concentrations of human umbilical mesenchymal stem cells confer a better protective effect on DR than low concentrations.

Transplantation of human umbilical cord blood mesenchymal stem cells to treat a rat model of traumatic brain injury

In the present study, human umbilical cord blood mesenchymal stem cells were injected into a rat model of traumatic brain injury via the tail vein. Results showed that 5-bromodeoxyuridine-labeled cells aggregated around the injury site, surviving up to 4 weeks post-transplantation. In addition, transplantation-related death did not occur, and neurological functions significantly improved. Histological detection revealed attenuated pathological injury in rat brain tissues following human umbilical cord blood mesenchymal stem cell transplantation. In addition, the number of apoptotic cells decreased. Immunohistochemistry and in situ hybridization showed increased expression of brain-derived neurotrophic factor, nerve growth factor, basic fibroblast growth factor, and vascular endothelial growth factor, along with increased microvessel density in surrounding areas of brain injury. Results demonstrated migration of transplanted human umbilical cord blood mesenchymal stem cells into the lesioned boundary zone of rats, as well as increased angiogenesis and expression of related neurotrophic factors in the lesioned boundary zone.

Functional recovery and microenvironmental alterations in a rat model of spinal cord injury following human umbilical cord blood-derived mesenchymal stem cells transplantation

BACKGROUND： Transplantation of human umbilical cord blood-derived mesenchymal stem cells （MSCs） has been shown to benefit spinal cord injury （SCI） repair. However, mechanisms of microenvironmental regulation during differentiation of transplanted MSCs remain poorly understood. OBJECTIVE： To observe changes in nerve growth factor （NGF）, brain-derived neurotrophic factor （BDNF）, and interleukin-8 （IL-8） expression following transplantation of human umbilical cord-derived MSCs, and to explore the association between microenvironment and neural functional recovery following MSCs transplantation. DESIGN, TIME AND SETTING： A randomized, controlled, animal experiment was performed at the Department of Orthopedics, First Affiliated Hospital of Soochow University from April 2005 to March 2007. MATERIALS： Human cord blood samples were provided by the Department of Gynecology and Obstetrics, First Affiliated Hospital of Soochow University. Written informed consent was obtained. METHODS： A total of 62 Wister rats were randomly assigned to control （n = 18）, model （n = 22, SCI ＋ PBS）, and transplantation （n = 22, SCI ＋ MSCs） groups. The rat SCI model was established using the weight compression method. MSCs were isolated from human umbilical cord blood and cultured in vitro for several passages. 5-bromodeoxyuridine （BrdU）-Iabeled MSCs （24 hours before injection） were intravascularly transplanted. MAIN OUTCOME MEASURES： The rats were evaluated using the Basso, Beattie and Bresnahan （BBB） locomotor score and inclined plane tests. Transplanted cells were analyzed following immunohistochemistry. Enzyme-linked immunosorbant assay was performed to determine NGF, BDNF, and IL-8 levels prior to and after cell transplantation. RESULTS： A large number of BrdU-positive MSCs were observed in the SCI region of the transplantation group, and MSCs were evenly distributed in injured spinal cord tissue 1 week after transplantation. BBB score and inclined plane test results revealed significant functional improvement in the transplantation group compared to the model group （P 〈 0.05）, which was maintained for 2-3 weeks. Compared to the model group, NGF and BDNF levels were significantly increased in the injured region following MSCs transplantation at 3 weeks （P 〈 0.05）, but IL-8 levels remained unchanged （P 〉 0.05）. CONCLUSION： MSCs transplantation increased NGF and BDNF expression in injured spinal cord tissue. MSCs could promote neurological function recovery in SCI rats by upregulating NGF expression and improving regional microenvironments.

Human bone marrow mesenchymal stem cell transplantation attenuates axonal injury in stroke rats

Previous studies have shown that transplantation of human bone marrow mesenchymal stem cells promotes neural functional recovery after stroke, but the neurorestorative mechanisms remain largely unknown. We hypothesized that functional recovery of myelinated axons may be one of underlying mechanisms. In this study, an ischemia/reperfusion rat model was established using the middle cerebral artery occlusion method. Rats were used to test the hypothesis that intravenous transplantation of human bone marrow mesenchyrnal stem cells through the femoral vein could exert neuroprotective effects against cerebral ischemia via a mechanism associated with the ability to attenuate axonal injury. The results of behavioral tests, infarction volume analysis and immunohistochemistry showed that cerebral ischemia caused severe damage to the myelin sheath and axons. After rats were intravenously transplanted with human bone marrow mesenchymal stem cells, the levels of axon and myelin sheath-related proteins, including microtubule-associated protein 2, myelin basic protein, and growth-associated protein 43, were elevated, infarct volume was decreased and neural function was improved in cerebral ischemic rats. These findings suggest that intravenously transplanted human bone marrow mesenchymal stem cells promote neural function. Possible mechanisms underlying these beneficial effects include resistance to demyelination after cerebral ischemia, prevention of axonal degeneration, and promotion of axonal regeneration.

Expression of human nerve growth factor βgene in central nervous system mediated by recombinant adeno-associated viruses type-2 vector

Background Neurone atrophy and loss are major causes of chronic neurodegenerative disorders such as Alzheimer’s disease. Despite many pharmacotherapies for neurodegeneration, there are no accepted treatments. We investigated the feasibility of human nerve growth factor β (hNGFβ) gene expression mediated by recombinant adeno-associated viruses type-2 (rAAV-2) vector in the central nervous system (CNS) after blood brain barrier (BBB) disruption.Methods rAAV-2 containing hNGFβ gene was constructed. The ability of hNGFβ gene mediated by rAAV-2 vector (rAAV-2/hNGFβ) to transfect cells in vitro was confirmed by both ELISA and bioassay of hNGFβ in the culture supernatant of BHK-21 cells infected by rAAV-2/hNGFβ. rAAV-2/hNGFβ and rAAV-2/green fluorescence protein (GFP) were administrated separately to rat brains through internal carotid intubation after BBB disruption with hypertonic mannitol. Brain hNGFβ concentration was measured by ELISA and GFP in brain sections was examined by laser scan confocal microscope.Results After 48 hours, hNGFβ content in supernatant was up to (188.0±28.6) pg/ml when BHK-21 cells were infected by rAAV-2/hNGFβ at multiplicity of infection (MOI)1.0×106 vector genome. Neurone fibre outgrowths were obvious in dorsal root ganglion neurone assays by adding serum free culture medium harvested from BHK-21 cells exposed to rAAV-2/hNGFβ. Whole brain hNGFβ content in rAAV-2/hNGFβ transferred group was up to (636.2±140.6) pg/ml. hNGFβ content of BBB disruption in rAAV-2/hNGFβ infused group increased significantly compared to the control group (P<0.05). GFP expression was clearly observed in brain sections of rAAV-2/GFP transferred group.Conclusion rAAV-2/hNGFβ successfully expresses in the CNS after BBB disruption induced by hypertonic mannitol.

HCMV Infection Depress NGF Expression in Human Glioma Cells

Human cytomegalovirus （HCMV） is the most common cause of congenital infection, resulting in birth defects such as microcephaly. In this study, RT-PCR and Western Blotting were performed to quantify the regulation of endogenic nerve growth factor expression in neuroglia ceils by HCMV infection. The results showed that basal, endogenous NGF expression in U251 was unchanged during early HCMV infection. NGF expression is strongly down-regulated during the latent phase of infection. These results suggest that HCMV can depress the NGF expression in U251 cells.

Effects of Recombinant Human Growth Hormone on Corneal Healing, Epithelial Nerve Regeneration and Tear Inflammatory Factors in Rabbits

Objective:The goal of this study is to investigate the effects of recombinant human growth hormone(rh GH)on corneal healing,epithelial nerve regeneration and tear inflammatory factor levels in rabbits.Methods:After corneal epithelial injury models were established,fifty adult clean New Zealand white rabbits were randomly divided into two groups,normal saline was administered to the control group,while recombinant human growth hormone was administered to the observation group.The healing rate of corneal epithelial injury,the regeneration ability of corneal epithelial nerve and the level of inflammatory factors in tears were observed and compared between the two groups of rabbits before and 24,48,72 and 96 h after modeling.Results:There were significant differences in corneal epithelial healing rate,time and interaction between the two groups(P<0.05).The experimental group exhibited a superior healing rate of corneal epithelium at 24,48,72,and 96 h compared to the control group(P<0.05).There were significant differences in central cornea sensitivity between the two groups,along with variations in time and interaction(P<0.05).There was no significant difference in the central corneal sensitivity between the two groups before modeling and at 24,72 and 96 h after modeling(P>0.05),whereas the experimental group exhibited a higher central corneal sensitivity compared to the control group at 48 h after modeling(P<0.05).There were significant differences in IL-1α,TNF-α,IL-17a and IL-21 between the two groups(P<0.05).There were significant differences in IL-17a and IL-21 between the two groups(P<0.05).The experimental group exhibited a significant decrease in IL-1αlevels compared to the control group between 24 and 72 h after modeling(P<0.05),the experimental group exhibited a substantial increase in IL-17a levels compared to the control group at 72 h after modeling(P<0.05),and the level of TNF-αin the experimental group was significantly lower than that of the control group between 24 and 96 h after modeling.Conclusion:Recombinant human growth hormone aids in expediting the healing process of the healing of rabbit corneal epithelial injury,facilitating the restoration of epithelial nerve,and mitigating the inflammatory response.

鼠神经生长因子联合低剂量重组人促红细胞生成素对早产儿脑损伤后神经发育的影响

目的:探讨鼠神经生长因子(mNGF)联合低剂量重组人促红细胞生成素(rh Epo)对早产儿脑损伤后神经发育的影响。方法:选取2021年3月~2022年3月期间某院收治的200例脑损伤早产儿作为研究对象,依据随机数字表法分为对照组和观察组,每组100例。两组患儿均给予营养支持、水电解质纠正、血糖、血压维持等常规治疗,对照组在常规治疗基础上给予注射用鼠神经生长因子,观察组在对照组治疗基础上静脉注射低剂量重组人促红素注射液(CHO细胞)。比较两组患儿脑损伤相关因子[神经元特异性烯醇化酶(NSE)、S100钙结合蛋白β(S100β)、8-羟基脱氧鸟苷(8-OHdG)、8-异前列腺素F2α(8-iso-PGF2α)]、炎症因子[肿瘤坏死因子-α(TNF-α)、白介素-18(IL-18)、Toll样受体4(TLR4)]水平、神经发育异常情况、智能等级及不良反应发生情况。结果:治疗后,两组患儿NSE、S100β、8-OHdG、8-iso-PGF2α水平均降低(P<0.05),且观察组低于对照组(P<0.05);两组患儿TNF-α、IL-18、TLR4水平均降低(P<0.05),且观察组低于对照组(P<0.05);观察组患儿神经发育异常项目≥3项及异常项目≥1项的发生率均低于对照组(P<0.05);两组患儿智能等级均呈升高趋势(P<0.05),且观察组升高趋势更明显(P<0.05);两组患儿不良反应总发生率比较无统计学差异(P>0.05)。结论:在常规治疗基础上联用m NGF、低剂量rhEpo可有效降低患儿脑损伤相关因子水平及神经发育异常率,提高智能等级,且未增加不良反应的发生风险。

细菌体内同源重组构建pAdEasy-1-hNGFβ重组体

目的采用细菌内同源重组法高效制备含神经生长因子β基因(hNGFβ)的重组腺病毒质粒。方法hNGFβ自载体pBLAST44hNGFβv02中切出,亚克隆至质粒pBluescriptⅡsk(+)中,形成pBluescriptⅡsk(+)hNGFβ,自pBluescriptⅡsk(+)hNGFβ中酶切出hNGFβDNA,亚克隆至腺病毒穿梭质粒pShuttleCMV中,形成转移质粒pShuttleCMVhNGFβ,在感受态大肠杆菌BJ5183内与腺病毒骨架质粒pAdEasy1同源重组,得到重组腺病毒载体pAdEasy1hNGFβ。结果线性化的pShuttleCMVhNGFβ转化含pAdEasy1的高效感受态大肠杆菌BJ5183,24h后获得了30%阳性重组质粒克隆,经酶切获得大于20kb的大片段和4.5kb的特征性条带,PCR反应扩增出731bp片段。结论应用细菌内同源重组能快速构建含hNGFβ基因的重组腺病毒载体pAdEasy1hNGFβ,为hNGFβ基因的研究及应用奠定了基础。

腺苷钴胺与丹红注射液联合硫辛酸对老年2型糖尿病周围神经病变患者神经传导及血清IGF-1、NGF水平的影响

目的探讨腺苷钴胺与丹红注射液联合硫辛酸对老年2型糖尿病周围神经病变患者神经传导及血清人胰岛素样生长因子-1(IGF-1)、人神经生长因子(NGF)水平的影响。方法选取79例老年2型糖尿病周围神经病变患者,按照随机数字表法分组,对照组39例予以腺苷钴胺+硫辛酸治疗,观察组40例予以硫辛酸+腺苷钴胺+丹红注射液治疗。观察比较两组正中、腓总神经感觉传导速度(SNCV)与运动传导速度(MNCV)及临床疗效各症状(灼热感、麻木、疼痛、感觉异常)评分,并统计两组血清IGF-1、NGF水平及毒副作用发生情况。结果观察组治疗1个月后正中、腓总神经SNCV及MNCV均高于对照组,差异具有统计学意义(P<0.05);观察组治疗总有效率为87.50%(35/40),高于对照组66.67%(26/39),差异具有统计学意义(P<0.05);治疗1个月后观察组灼热感、麻木及疼痛、感觉异常症状评分均低于对照组,差异有统计学意义(P<0.05);观察组治疗1个月后血清IGF‐1、NGF水平高于对照组,差异具有统计学意义(P<0.05);观察组毒副作用发生率为15.00%(6/40),对照组为10.26%(4/39),组间比较差异无统计学意义(P>0.05)。结论硫辛酸、腺苷钴胺与丹红注射液联合治疗老年2型糖尿病周围神经病变,效果显著,安全性高,可改善患者神经传导速度及神经生长相关因子水平。

神经生长因子对人血管内皮细胞增殖作用的研究

目的:研究神经生长因子(Nerve growth factor,NGF)对人血管内皮细胞(Human vascular endothelial cell,HEVC)增殖作用的影响。方法:将NGF作用于体外培养的HEVC304,利用酶联免疫反应检测其增殖率,利用免疫组织化学的方法检测对增殖细胞核抗原(Proliferating cell nuclear antigen,PCNA)的表达和标记指数。结果:NGF作用组较对照组其细胞增殖率明显增加(P<0.001),NGF中和抗体组其细胞增殖率下降明显(P<0.05)。NGF作用组较对照组能明显增加HEVC对PCNA的表达和PCNA标记指数(P<0.05),NGF中和抗体组其PCNA表达和PCNA标记指数明显减少(P<0.05)。结论:NGF能明显促进HEVC的增殖。

神经生长导向因子Slit mRNA在人胚胎脊髓的原位杂交定位

目的 检测神经生长导向因子SlitmRNA在人胚胎脊髓中的定位表达。方法 地高辛标记的cRNA探针原位杂交技术。结果 SlitmRNA在脊髓中央管、前角和后角处表达。结论 神经生长导向因子Slit在人胚胎脊髓发育期轴突投射和神经通路形成中可能起重要作用。

人β-NGF真核表达载体的构建及其表达产物的生物活性

目的在CHO细胞中共表达二氢叶酸还原酶(DHFR)基因及人神经生长因子β亚基(-βhNGF)基因,并对表达产物进行鉴定和生物活性分析。方法克隆DHFR和-βhNGF基因,测序,酶切,连接到真核表达载体pBudCE4.1中,构建人NGF基因重组表达质粒pBudCE4.1/DHFR/-βhNGF,经电转染法导入二氢叶酸还原酶缺陷型中国仓鼠卵巢细胞(CHO-DHFR-)中,经添加Zeocin抗生素和撤除H、T(次黄嘌呤、胸腺嘧啶脱氧核苷)双筛选,获得了DHFR+细胞克隆。经MTX加压筛选高表达-βhNGF的CHO细胞株。SDS-PAGE、ELISA和Western blot对表达产物进行鉴定,并利用鸡胚背根神经节法检测表达蛋白的生物活性。结果人神经生长因子在CHO细胞中得到较高表达,表达量达0.3μg/ml,且表达产物具有良好的生物活性。结论为大规模工业化生产重组人神经生长因子奠定了基础。

人巨细胞病毒诱导分化中的神经干细胞分泌神经生长因子前体

目的研究人巨细胞病毒(human cytomegalovirus,HCMV)感染对人神经干细胞(neural stem cells,NSC)向星形胶质细胞分化过程中神经生长因子(nerve growth factor,NGF)及其受体p75NTR、trkA表达的影响,为阐明HCMV感染致NSC损伤的分子机制提供理论依据。方法体外培养人海马NSC,感染组以感染复数(multiplicity of infectin,MOI)为5的HCMVAD169株感染NSC,对照组只加入与病毒悬液等体积的培养液,在感染病毒的同时,诱导感染组和对照组NSC向星形胶质细胞分化,分别在感染后0、1、3、5、7、9 d收获细胞,用RT-PCR、免疫荧光和Western blot方法检测细胞内NGF及其受体p75NTR、trkA的转录水平和蛋白表达水平。结果对照组NSC不表达NGF及其受体P75NTR和trkA。感染组细胞在第3天开始出现NGFmRNA的表达,第5天出现P75NTRmRNA的表达,且其表达强度随时间增强;第5天出现相对分子质量为40000和100000NGF前体蛋白(ProNGF)和P75NTR蛋白,随时间延长,表达强度升高。免疫荧光检测显示,NGF前体蛋白位于细胞的细胞质;整个感染过程中未检测到trkA的表达。结论 HCMV感染可诱导向星形胶质细胞分化的海马NSC分泌NGF前体蛋白及其受体p75NTR。