NT-3基因修饰及维甲酸预诱导的骨髓间充质干细胞在脊髓损伤处分化为神经元样细胞的研究

目的 探讨移植在脊髓损伤处的神经营养素-3(NT-3)基因修饰及维甲酸(RA)预诱导的骨髓间充质干细胞(MSCs)分化为神经元样细胞的潜能.方法 将MSCs、RA诱导的MSCs、LacZ基因修饰的MSCs、NT-3基因修饰的MSCs和NT-3基因修饰及RA预诱导的MSCs分别立即移植到脊髓全横断处(T10脊髓),术后67d取材和冷冻切片,用免疫荧光组织化学染色方法检测MSCs的分化潜能,计算各细胞移植组脊髓损伤处的MSCs分化为神经元样细胞的百分率.结果 移植的MSCs在受损伤的脊髓内可分化为神经干细胞(nestin阳性)、神经胶质样细胞(GFAP阳性)和神经元样细胞(NF和MAP2阳性),有些还可以向含有某种神经递质和有形成突触潜能的神经元样细胞分化(ChAT、5-HT和PSD95阳性).联合应用NT-3基因修饰和RA预诱导的MSCs能在受损伤的脊髓内更有效地提高MSCs向神经元样细胞分化的百分率.结论 NT-3基因修饰和RA预诱导的MSCs能在脊髓损伤处更好地分化为神经元样细胞.     

Integration of donor mesenchymal stem cell-derived neuron-like cells into host neural network after rat spinal cord transection

Functional deficits following spinal cord injury (SCI) primarily attribute to loss of neural connectivity. We therefore tested if novel tissue engineering approaches could enable neural network repair that facilitates functional recovery after spinal cord transection (SCT). Rat bone marrow-derived mesenchymal stem cells (MSCs), genetically engineered to overexpress TrkC, receptor of neurotrophin-3 (NT-3), were pre-differentiated into cells carrying neuronal features via co-culture with NT-3 overproducing Schwann cells in 3-dimensional gelatin sponge (GS) scaffold for 14 days in vitro. Intra-GS formation of MSC assemblies emulating neural network (MSC-GS) were verified morphologically via electron microscopy (EM) and functionally by whole-cell patch clamp recording of spontaneous post-synaptic currents. The differentiated MSCs still partially maintained prototypic property with the expression of some mesodermal cytokines. MSC-GS or GS was then grafted acutely into a 2 mm-wide transection gap in the T9-T10 spinal cord segments of adult rats. Eight weeks later, hindlimb function of the MSC-GS-treated SCT rats was significantly improved relative to controls receiving the GS or lesion only as indicated by BBB score. The MSC-GS transplantation also significantly recovered cortical motor evoked potential (CMEP). Histologically, MSC-derived neuron-like cells maintained their synapse-like structures in vivo; they additionally formed similar connections with host neurites (i.e., mostly serotonergic fibers plus a few corticospinal axons; validated by double-labeled immuno-EM). Moreover, motor cortex electrical stimulation triggered c-fos expression in the grafted and lumbar spinal cord cells of the treated rats only. Our data suggest that MSC-derived neuron-like cells resulting from NT-3-TrkC-induced differentiation can partially integrate into transected spinal cord and this strategy should be further investigated for reconstructing disrupted neural circuits.     

人脐血MSCs向神经元样细胞分化过程中neurogenin1的表达变化

目的: 探讨人脐血间质干细胞(MSCs)体外向神经元样细胞分化过程中neurogenin 1的表达变化。方法: 常规从人脐血中分离MSCs,采用生长因子EGF和bFGF联合诱导人脐血MSCs向神经元样细胞分化,免疫细胞化学法检测诱导前、后神经元表面标志蛋白NF-M、NSE、胶质细胞标志蛋白GFAP和neurogenin 1的表达情况;Western blotting和RT-PCR法检测诱导前、后人脐血MSCs中neurogenin 1蛋白和mRNA的表达变化。结果: 诱导前,人脐血MSCs不表达NF-M、NSE和GFAP;诱导7 d,人脐血MSCs可以分化为神经元样细胞, 同时表达NF-M、NSE和GFAP。诱导前,人脐血MSCs不表达neurogenin 1,诱导后neurogenin 1蛋白和mRNA表达显著增加。结论: Neurogenin 1可能参与了体外诱导人脐血MSCs向神经细胞分化的过程。     

人脐带间充质干细胞的富集及向神经细胞的诱导分化

目的:寻找一种稳定、高效的分离人脐带间充质干细胞(MSCs)的方法,并探讨脐带MSCs向神经细胞方向分化的可能性。方法:分别采用组织块贴壁法和双酶消化法分离人脐带MSCs,对比其培养成功率;BrdU掺入实验检测脐带MSCs的增殖能力;流式细胞仪检测脐带MSCs表面分子标志;采用丹参联合生长因子的方法诱导其向神经细胞分化,免疫荧光方法检测神经元特异性烯醇化酶(NSE)、微管相关蛋白2(MAP2)、胶质纤维酸性蛋白(GFAP)的表达。结果:组织块贴壁法获得脐带MSCs成功率高;BrdU阳性标记率达90%以上;流式细胞仪检测显示细胞表达CD29、CD44和CD90,不表达CD34;脐带MSCs经诱导分化,伸出长突起,呈神经元样细胞改变,且表达神经元标志性蛋白NSE、MAP2。神经胶质细胞标志性蛋白GFAP表达较少。结论:成功建立了高效、稳定的脐带MSCs分离培养方法。脐带MSCs经诱导可向神经细胞方向分化,为临床移植治疗神经系统疾病提供了理想的细胞来源。     

Neurotrophin-3 gene-modified Schwann cells promote TrkC gene-modified mesenchymal stem cells to differentiate into neuron-like cells in poly(lactic-acid-co-glycolic acid) multiple-channel conduit

Rapid progress in the field of nerve tissue engineering has opened up the way for new therapeutic strategies for spinal cord injury (SCI). Bone marrow-derived mesenchymal stem cells (MSCs) could be differentiated into neural lineages, which can be used as a potential cell source for nerve repair. Schwann cells (SCs) have been reported to support structural and functional recovery of SCI. In this study, we co-cultured neurotrophin-3 (NT-3) gene-modified SCs and NT-3 receptor tyrosine protein kinase C (TrkC) gene-modified MSCs in a three-dimensional porous poly(lactic-acid-co-glycolic acid) (PLGA) conduit with multiple channels in vitro for 14 days. Our results showed that more than 50% of the grafted MSCs were MAP2- and β-III-tubulin-positive cells, and the MSCs expressed a high level of β-III-tubulin detected by Western blotting, indicating a high rate of neuronal differentiation. Furthermore, immunostaining of PSD95 revealed the formation of a synapse-like structure, which was confirmed under electron microscopy. In conclusion, co-culture of NT-3 gene-modified SCs and TrkC gene-modified MSCs in the PLGA multiple-channeled conduit can promote MSCs' differentiation into neuron-like cells with synaptogenesis potential. Our study provides a biological basis for future application of this artificial MSCs/SCs/PLGA complex in the SCI treatment.     

维甲酸、音猬因子对大鼠脊髓神经干细胞向运动神经元样细胞分化的影响

目的:分离大鼠胚胎的脊髓神经干细胞进行体外培养,探讨维甲酸(RA)、音猬因子(Shh)诱导其向运动神经元样细胞分化. 方法:应用无血清培养技术分离培养脊髓神经干细胞,通过5-溴-2-脱氧尿苷标记、免疫荧光显色检测细胞增殖、分化情况;培养液分组添加Shh、 RA或Shh+RA,观察神经干细胞向运动神经元样细胞的分化情况. 结果:大鼠胚胎脊髓可成功分离神经干细胞,分化后可表达神经元、星形胶质细胞的特异性抗原;诱导分化后结果显示Shh组未检测到胆碱乙酰转移酶阳性细胞,RA组为20.63%, Shh+RA组为66.84%,其差异具统计学意义.结论:从大鼠胚胎脊髓可成功分离神经干细胞,Shh、 RA可不同程度地诱导脊髓神经干细胞分化为运动神经元样细胞.     

丹参诱导大鼠骨髓间充质干细胞向神经样细胞分化

目的:探讨骨髓间充质干细胞(marrow stromal stem cells,MSCs)向神经细胞分化中神经蛋白分子及相关基因的表达情况。方法:分离提取大鼠的MSCs,体外培养扩增。用含丹参的无血清的L-DMEM培养基进行诱导,并以不含丹参的无血清L-DMEM培养基作为对照。提取两组的MSCs总RNA,RT-PCR检测ngn-1、mash-1的表达。结果:丹参诱导90 min后,细胞发生了明显的形态学变化,大多数细胞转变为类似双极或多极神经元样形态,伸出轴突或树突样突起。免疫细胞化学显示诱导后的MSCs表现为nestin、NSE、GFAP染色阳性,对照组为阴性。未经诱导的MSCs ngn-1,mash-1 mRNA为阴性,诱导后有表达。结论:丹参可诱导大鼠MSCs向神经前体细胞和神经细胞分化。MSCs向神经元样的分化可能与ngn-1,mash-1有关。     

促红细胞生成素对小鼠诱导多能干细胞源性神经干细胞向功能性神经元样细胞分化的影响

目的:探讨促红细胞生成素体外对小鼠诱导多能干细胞(iPSCs)来源的神经干细胞神经分化的影响。方法:神经干细胞培养基培养诱导iPSCs分化为神经干细胞,设4个浓度加入含促红细胞生成素的培养基,免疫细胞化学荧光鉴定神经元标志物微管相关蛋白2(MAP-2)、神经干细胞标志物巢蛋白的表达。FM 1-43染色技术观察FM 1-43染色颗粒消失的情况。结果:iPSCs在条件培养液的诱导下形成神经干细胞克隆,15 U/ml促红细胞生成素处理后神经干细胞克隆球向神经元方向分化,呈MAP-2阳性细胞。新分化的神经元有大量FM 1-43绿色阳性颗粒。结论:iPSCs体外诱导可获得神经干细胞,促红细胞生成素浓度为15 U/ml时可促进iPSCs源性神经干细胞向功能性的神经元方向分化。     

NT-3 gene modified Schwann cells promote TrkC gene modified mesenchymal stem cells to differentiate into neuron-like cells in vitro

Reports of neuronal differentiation of bone marrow derived mesenchymal stem cells (MSCs) suggested the possibility that these cells could serve as a source of treatment for spinal cord injury. However, the percentages of neuron-like cells differentiated from the MSCs were relatively low both in vitro and in vivo. Here, we investigated whether co-culture of human neurotrophin-3 (NT-3) gene modified Schwann cells (SCs) and human NT-3 receptor tyrosine protein kinase C (TrkC) gene modified MSCs could increase differentiation of neuron-like cells from MSCs. It was shown that MSCs were significantly promoted to differentiate into neuron-like cells, as evidenced immunocytochemically by the expression of neuronal markers, including nestin, β-III-tubulin, MAP2 and PSD95, 7 days after co-culture. However, the expression of glial fibrillary acidic protein (GFAP)—an astrocyte marker in these cells—was not so obvious. These results demonstrate that the binding of overexpressed NT-3 in SCs and its receptor TrkC in MSCs can be considered to stimulate the increased rate of neuronal differentiation.     

骨髓间充质干细胞体外诱导为神经细胞的研究

本实验观察了大鼠MSCs向神经细胞方向的诱导分化情况,以期为MSCs在神经移植领域的临床应用提供理论基础。用含10 ng／ml bFGF+20％FBS的DMEM对MSCs进行预诱导24 h后,以含200μmol／L的BHA+2％DMSO的无血清DMEM对MSCs进行诱导,观察诱导后细胞的光、电镜形态学变化,通过免疫组织化学法对诱导后细胞进行神经细胞表型及神经递质合成酶鉴定。结果显示:MSCs经BHA和DMSO诱导后,80％以上的细胞表现出神经元样形态,胞浆内可见较多Nissl体,并表达nestin、NSE、NF、MAP、SYN,部分诱导后的细胞表达ChAT、TH、GAD;电镜下观察,诱导后细胞核大而圆,核仁明显,胞浆内细胞器发达,可见大量粗面内质网和游离核糖体。提示,MSCs体外可被诱导分化为神经元样细胞,诱导后的细胞有合成某些神经递质的能力并具有发育早期神经元的超微结构特点。     

The differentiation of rat adipose-derived stem cells into OEC-like cells on collagen scaffolds by co-culturing with OECs

Olfactory ensheathing cells (OECs) transplantation is a promising or potential therapy for spinal cord injury (SCI). However, their clinical use is limited because of the availability. Adipose-derived stem cells (ADSCs) have been identified as an alternative source of adult stem cells in recent years. ADSCs could be differentiated into various mesenchymal tissues cells such as chondrocytes, adipocytes, osteoblasts, and myocytes and also could be differentiated into neural lineages. In this study, we examined the feasibility of using ADSCs as a source of stem cells for the differentiation of OECs by co-culture approach. When co-cultured with OECs, the ADSCs on three-dimensional collagen scaffolds were differentiated into OEC-like cells, with similar morphology and antigenic phenotypes (p75NTR+/Nestin+/GFAP-) of OECs. Co-cultured ADSCs were positive for several important functional markers of mature OECs such as neurotrophic factor GDNF, BDNF and myelin protein PLP and the conditioned medium of OEC-like cells could significantly promote DRG neuron growth and axon sprouting without NGF supporting in contrast to that of the ADSCs. Our results showed that ADSCs had the potential to differentiate into OEC-like cells on the three-dimensional collagen scaffolds in vitro.     

大鼠MSCs体外诱导分化为神经元样细胞过程中发生细胞凋亡的机制研究

目的： 探讨体外诱导大鼠骨髓间充质干细胞(MSCs)向神经元样细胞分化过程中凋亡发生的机制。方法：分离纯化大鼠骨髓间充质干细胞,随机分为3组：对照组为单纯β-巯基乙醇诱导分化组; NEK1/2抑制剂1,4-二氨基-2,3-氰基-1,4-双［2-氨基苯基硫代］丁二烯（U0126）组为自预诱导开始在加入β-巯基乙醇的同时加入10 μmol/L U0126;蛋白激酶PKC激动剂氟波酯(PMA)组为自预诱导开始在加入β-巯基乙醇的同时分别加入30 nmol/L、120 nmol/L与300 nmol/L PMA。诱导5 h后终止反应,MTT法检测细胞活性,免疫细胞化学检测神经元特异性巢蛋白nestin及凋亡相关蛋白caspase、Bcl-2、Bax的表达情况,TUNEL法检测细胞凋亡指数。结果： 诱导后5 h与对照组相比,U0126组神经元样细胞的活性、nestin的表达、Bcl-2蛋白阳性表达率均出现增强或升高(P<0.05),细胞凋亡指数降低(P<0.05);300 nmol/L PMA组则显著抑制神经元样细胞的活性和nestin的表达(P<0.05),增强Bax并降低Bcl-2的表达(P<0.05),细胞凋亡指数明显升高(P<0.05)。结论： 大鼠MSCs诱导分化为神经元样细胞过程中发生凋亡机制涉及MAPK及PKC信号途径。     

损伤脊髓组织提取液对大鼠肌源性干细胞向神经细胞诱导分化的实验研究

目的:探讨大鼠肌源性干细胞在损伤脊髓组织提取液中向神经细胞分化的可能性,为神经再生及脊髓损伤的治疗提供一种新方法。方法:从大鼠乳鼠骨骼肌中分离培养肌源性干细胞,将正常、伤后1d,伤后1周及伤后3周脊髓提取液加入细胞培养基中,观察细胞形态的变化,并采用免疫组织化学法检测诱导后的细胞表达NSE特异性标志物。结果:加入脊髓提取液诱导后24h,部分细胞的形态已发生改变,3d后大部分细胞不仅在形态上表现为神经元样特征,而且NSE等特异性抗体呈阳性表达。结论:损伤脊髓组织液能将肌源性干细胞诱导成神经元样细胞。     

骨髓间充质干细胞分化神经元后多巴胺D2受体的表达

目的:检测骨髓间充质干细胞(mesenchymal stem cells,MSCs)分化为神经元后多巴胺D2受体(dopamine receptor D2,DRD2)的表达,探讨体外分化神经元的基本功能。方法:采用密度梯度离心法和贴壁培养的方法分离纯化MSCs,流式细胞仪检测MSCs表面标志,DMSO/BHA/FSK作为诱导剂来诱导分化;硝酸银染色法检测神经纤维丝,RT-PCR和免疫细胞化学法检测NSE、DRD2 mRNA及蛋白的表达情况。结果:分离纯化的MSCs经流式细胞仪检测显示CD34、CD45表达阴性;间充质干细胞相对特异性标志CD44强阳性表达;加入诱导剂后,MSCs形成多极神经元的形态。银染色法显示神经纤维丝阳性表达,RT-PCR显示诱导后细胞表达NSE、DRD2 mRNA,免疫组化显示NSE、DRD2蛋白表达阳性。结论:MSCs分化为神经元后可以表达神经受体DRD2。     

体外诱导大鼠骨髓间充质干细胞向神经元样细胞的分化

背景：研究表明,移植后的骨髓间充质干细胞在新的环境中能够被诱导分化为神经元样细胞,从而替代损伤细胞重建神经环路。 目的：建立大鼠骨髓间充质干细胞和神经细胞的体外共培养系统,观察共培养条件下神经细胞对骨髓间充质干细胞向神经元样细胞分化的影响。 方法：体外培养Wistar大鼠脑组织神经细胞和股骨骨髓间充质干细胞,采用Transwell小室共培养分化诱导,观察骨髓间充质干细胞的组织形态变化,在共培养第5天免疫荧光染色检测骨髓间充质干细胞中神经细胞的特异标志物;与对照组单纯骨髓间充质干细胞培养结果相比较。 结果与结论：神经细胞共培养系统中的骨髓间充质干细胞生长伸展,呈放射状,互相形成连接,特异性烯醇化酶显示阳性结果,具有神经元样细胞的特性,表达特异性烯醇化酶阳性的神经元比例可达(33.0±10.5)%。而对照组骨髓间充质干细胞未形成神经元样细胞的形态结构,免疫荧光显示特异性烯醇化酶阴性。提示神经细胞提供的微环境对骨髓间充质干细胞分化为神经元样细胞具有诱导分化作用。      

Electro-acupuncture promotes differentiation of mesenchymal stem cells,regeneration of nerve fibers and partial functional recovery after spinal cord injury

In order to improve the structure and function of acute spinal cord injury, the present study investigated the effect of electro-acupuncture (EA) on the differentiation of mesenchymal stem cells (MSCs) and the regeneration of nerve fibers in transected spinal cord of rats. The differentiation of MSCs into neuron-like cells and neuroglial cells and regeneraton of 5-hydroxytrptamine (HT) nerve fibers in the injured site of spinal cord were assessed after treatment with EA, MSCs transplantation, and EA plus MSCs transplantation. Compared with the control and MSCs groups, the content of endogenous neurotrophin-3 (NT-3) in the injured site and nearby tissues was increased in EA and EA+MSCs group. The differentiation of MSCs into neuronal-like cells and oligodendrocyte-like cells and number of 5-HT positive nerve fibers in the injured site were enhanced in the EA+MSCs group. Basso, Beattie, Bresnahan score of the paralyzed hindlimbs was highest in the EA+MSCs group. The present study demonstrates that electro-acupuncture can promote the differentiation of MSCs and regeneration of nerve fibers in injured spinal cord through induction of endogenous NT-3, and that combination of EA and MSCs transplantation can improve partial function of paralyzed hindlimbs.     

Neuroblastoma x spinal cord (NSC) hybrid cell lines resemble developing motor neurons.

We have developed a series of mouse-mouse neural hybrid cell lines by fusing the aminopterin-sensitive neuroblastoma N18TG2 with motor neuron-enriched embryonic day 12-14 spinal cord cells. Of 30 neuroblastoma-spinal cord (NSC) hybrids displaying a multipolar neuron-like phenotype, 10 express choline acetyltransferase, and 4 induce twitching in cocultured mouse myotubules. NSC-19, NSC-34, and their subclones express additional properties expected of motor neurons, including generation of action potentials, expression of neurofilament triplet proteins, and acetylcholine synthesis, storage, and release. In addition, NSC-34 cells induce acetylcholine receptor clusters on cocultured myotubes, and undergo a vimentin-neurofilament switch with maturation in culture, similar to that occurring in neuronal development. NSC cell lines appear to model selected aspects of motor neuron development in an immortalized clonal system.     

Protein aggregate-containing neuron-like cells are differentiated from bone marrow mesenchymal stem cells from mice with neurofilament light subunit gene deficiency

Autologous bone marrow mesenchymal stem cell (MSC) transplantation has great potential in cell therapy used for the treatment of neurodegenerative disorders. Since many genetic deficiencies have been reported in pathogenesis of the diseases, genetic backgrounds of donor stem cells should be concerned. In this study, effects of neurofilament light subunit (NFL) gene deficiency on proliferation and neuronal differentiation of MSCs were studied in vitro. Lower proliferation rate was observed in NFL-/- MSCs. When exposed to retinoic acid (RA), both NFL-/- and normal MSCs could express several markers of neuronal lineage, such as Nestin, MAP-2, NeuN, O4 and GFAP. However, the NFL expression at mRNA and protein levels was observed only in normal MSCs but absent in NFL-/- MSCs. Significant reductions in amount of neurofilament heavy subunit (NFH) protein and number of neuron-like cells were detected in differentiated NFL-/- MSCs. Interestingly, NFH positive protein accumulations were observed in the neuron-like cells derived from NFL-/- MSCs. These accumulations were perinuclear and morphologically similar to protein aggregations in motoneurons of the spinal cord in NFL-/- mice. The results suggest that NFL gene deficiency could retard MSCs proliferation and neuronal generation, even though the capability of neuronal lineage differentiation of MSCs may not be deterred. Moreover, the NFL-/- MSCs differentiated neuron-like cells carried on the genetic and pathologic deficiency, suggesting that the genetic quality of donor cells must not only be tested, but also modified before transplantation. This also points towards the possibility of creating a stem cell-derived cell model for pathogenesis study.     

Combined transplantation of neural stem cells and olfactory ensheathing cells for the repair of spinal cord injuries

Spinal cord repair is a problem that has long puzzled neuroscientists. The failure of the spinal cord to regenerate and undergo reconstruction after spinal cord injury (SCI) can be attributed to secondary axonal demyelination and neuronal death followed by cyst formation and infarction as well as to the nature of the injury environment, which promotes glial scar formation. Cellular replacement and axon guidance are both necessary for SCI repair. Multipotent neural stem cells (NSCs) have the potential to differentiate into both neuronal and glial cells and are, therefore, likely candidates for cell replacement therapy following SCI. However, NSC transplantation alone is not sufficient for spinal cord repair because the majority of the NSCs engrafted into the spinal cord have been shown to differentiate with a phenotype which is restricted to glial lineages, further promoting glial scaring. Olfactory ensheathing cells (OECs) are a unique type of glial cell that occur both peripherally and centrally along the olfactory nerve. The ability of olfactory neurons to grow axons in the mature central nervous system (CNS) milieu has been attributed to the presence of OECs. It has been shown that transplanted OECs are capable of migrating into and through astrocytic scars and thereby facilitating axonal regrowth through an injury barrier. Given the complementary properties of NSCs and OECs, we predict that the co-transplantation of NSCs and OECs into an injured spinal cord would have a synergistic effect, promoting neural regeneration and functional reconstruction. The lost neurocytes would be replaced by NSCs, while the OECs would build "bridges" crossing the glial scaring that conduct axon elongation and promote myelinization simultaneously. Furthermore, the two types of cells could first be seeded into a bioactive scaffold and then the cell seeded construct could be implanted into the defect site. We believe that this type of treatment would lead to improved neural regeneration and functional reconstruction after SCI.