A rat model for studying neural stem cell transplantation

Aim:

The goal of this project was to develop a rat model for neural stem cell (NSC) transplantation studies in which NSCs were modified with brain-derived neurotrophic factor (BDNF) genes that may permit extensive and reliable analysis of the transplants.

Methods:

NSCs were cultured and purified by limiting dilution assay in vitro and infected with recombinant retrovirus pLXSN-BDNF (BDNF-NSCs) and retrovirus pLXSN (p-NSCs). The expression of BDNF genes in transgenic and control NSC groups was measured by FQ-PCR and ELISA assays. NSCs were then transplanted into the subretinal space of normal rat retinas in four groups, which included NSCs alone, BDNF-NSCs, phosphate buffered saline (PBS) control, and normal control. Survival, migration, and differentiation of donor cells in host retinas were observed with optical coherence tomography (OCT), Heidelberg retina angiograph (HRA), and immunohistochemistry, respectively.

Results:

The results obtained by FQ-PCR demonstrated that the copy numbers of BDNF gene templates from BDNF-NSCs were the highest among the four groups (P<0.05). Consistent with the results of FQ-PCR, BDNF protein level from the supernatant of the BDNF-NSCs group was much higher than that of the other two groups (P<0.05) as suggested by the ELISA assays. HRA and OCT showed that graft cells could successfully survive. Immunohistochemical analysis revealed that transplanted BDNF-NSCs could migrate in the host retinas and differentiate into glial cells and neurons three months after transplantation.

Conclusion:

BDNF promotes NSCs to migrate and differentiate into neural cells in the normal host retinas.     

Click chemistry extracellular vesicle/peptide/chemokine nanocarriers for treating central nervous system injuries

Central nervous system (CNS) injuries, including stroke, traumatic brain injury, and spinal cord injury, are essential causes of death and long-term disability and are difficult to cure, mainly due to the limited neuron regeneration and the glial scar formation. Herein, we apply extracellular vesicles (EVs) secreted by M2 microglia to improve the differentiation of neural stem cells (NSCs) at the injured site, and simultaneously modify them with the injured vascular targeting peptide (DA7R) and the stem cell recruiting factor (SDF-1) on their surface via copper-free click chemistry to recruit NSCs, inducing their neuronal differentiation, and serving as the nanocarriers at the injured site (Dual-EV). Results prove that the Dual-EV could target human umbilical vascular endothelial cells (HUVECs), recruit NSCs, and promote the neuronal differentiation of NSCs in vitro. Furthermore, 10 miRNAs are found to be upregulated in Dual-M2-EVs compared to Dual-M0-EVs via bioinformatic analysis, and further NSC differentiation experiment by flow cytometry reveals that among these miRNAs, miR30b-3p, miR-222-3p, miR-129-5p, and miR-155-5p may exert effect of inducing NSC to differentiate into neurons. In vivo experiments show that Dual-EV nanocarriers achieve improved accumulation in the ischemic area of stroke model mice, potentiate NSCs recruitment, and increase neurogenesis. This work provides new insights for the treatment of neuronal regeneration after CNS injuries as well as endogenous stem cells, and the click chemistry EV/peptide/chemokine and related nanocarriers for improving human health.     

Neural stem cells: the basic biology and prospects for brain repair]

Neural stem cells (NSCs) are multipotential progenitor cells that have self-renewal activities. A single NSC is capable of generating various kinds of cells within the CNS, including neurons, astrocytes, and oligodendrocytes. Because of these characteristics, there is an increasing interest in NSCs and neural progenitor cells from the aspects of both basic developmental biology and therapeutic applications for damaged brain. By understanding the nature of NSCs present in the CNS, extracellular factors and signal transduction cascades involved in the differentiation and maintenance of NSCs, population dynamics and localization of NSCs in embryonic and adult brains, prospective identification and isolation of NSCs, and induction of NSCs into particular neuronal phenotypes, it would be possible to develop a feasible strategy to manipulate cells in situ to treat damaged brain.     

亚低温联合载神经干细胞的纤维蛋白支架对颅脑创伤的修复作用

目的 研究大鼠颅脑创伤 （TBI） 后原位移植神经干细胞 （NSCs） 治疗的可能性, 探讨载有 NSCs 的纤维蛋白支架及与亚低温（MHT）联合对 TBI 的治疗作用。方法 从孕 14 d SD 大鼠皮质组织中分离 NSCs, 与纤维蛋白支架共培养, 应用扫描电镜观察支架及 NSCs 的形态, 并通过免疫荧光检测细胞类型。将 48 只雄性 SD 大鼠随机分成 TBI 组 （A 组）、 TBI+NSC 组 （B 组）、 TBI+MHT 组 （C 组）、 TBI+NSC+MHT 组 （D 组）, 每组 12 只。A 组通过液压损伤仪行 TBI 造模; B 组 TBI 后接受 NSCs 移植治疗; C 组 TBI 后接受 MHT 治疗; D 组 TBI 后接受 NSCs 与 MHT 联合治疗。分别在第 14、 28 天通过神经功能缺陷评分 （mNSS） 和水迷宫实验对大鼠进行神经功能评价; 28 d 后取脑组织切片, 行细胞免疫荧光检测, 观察移植后的 NSCs 在体内分化情况。结果 电镜扫描显示, NSCs 与纤维蛋白支架共培养 3 d 后形态无明显改变; 免疫荧光提示 NSCs 特异性标志物 Nestin 阳性表达, 表明神经干细胞在纤维蛋白支架上存活; D 组大鼠的 mNSS 在第 14 天和第 28 天均低于 A、 B、 C 各组; 水迷宫结果显示, D 组大鼠逃避潜伏期短于 A、 B、 C 各组; D 组 28 d 后脑组织取材可追踪到 BrdU 标记的神经干细胞分化为了神经元。结论 纤维蛋白支架与 NSCs 生物相容性良好, 具有可降解性。亚低温与载 NSCs 的纤维蛋白支架对大鼠 TBI 后的神经功能修复具有协同作用。     

共移植体对神经干细胞向神经元分化的影响

目的:探讨共移植体所构成的微环境对神经干细胞移植后向神经元分化的影响。方法:48只同一基因背景的Wistar大鼠,随机分为:NSCs移植组,共移植体移植组。在新生的同一基因背景鼠海马取神经干细胞和大脑皮质取血管内皮细胞,把单独NSCs和共移植体移植入同一基因背景大鼠MCAO造模后24h缺血半暗带区,Brdu标记其中NSCs,利用免疫荧光双标于3d,7d,14d,60d分别观察NSCs向神经元分化情况。结果:在7d,14d,60d三个时间点神经干细胞向神经元分化中,共移植体组神经元分化率高于NSCs组,差别有统计学意义(P<0.05)。结论:共移植体对移植入MCAO模型大鼠的NSCs向神经元分化有促进作用。     

PPARγ-mediated advanced glycation end products regulate neural stem cell proliferation but not neural differentiation through the BDNF-CREB pathway

Aims

To investigate the roles of PPARγ in advanced glycation end product (AGE)-mediated characteristics of neural stem cells (NSCs) and the molecular mechanisms of action.

Methods

We prepared pLentiLox3.7 lentiviral vectors expressing short hairpin RNA (shRNA) against PPARγ and transduced NSCs. MTT absorbance and cell counts were used to assay cell growth, and cell differentiation was analysed by confocal laser-scanning and western blots for the expression of MAP2/nestin. The protein and gene expression of the BDNF-CREB pathway components were examined by western blotting and real-time PCR.

Results

Immunoblot analysis indicated that shRNA delivered by lentiviral vectors silenced PPARγ expression in NSCs. The proliferation of NSCs and expression of BDNF pathway components dropped in AGE-BSA culture medium (400 mg/L and 200 mg/L) on Day 3 and Day 7, respectively (all P < 0.001). PPARγ-silenced NSCs exhibited a significant increase in cell growth and expression of BDNF pathway components compared with NSCs incubated with AGE-BSA (all P < 0.001). Immunocytochemistry and western blotting analysis showed that AGE-BSA (400 mg/L) induced a significant decrease in the expression of MAP2 both in NSCs and PPARγ-silenced NSCs, as standardised by nestin. There was no significant difference between NSCs and PPARγ-silenced NSCs in the presence of AGE-BSA.

Conclusions

PPARγ plays roles in the AGE-mediated regulation of NSC proliferation but not neural differentiation through the BDNF-CREB pathway.     

移植维甲酸诱导的人胚神经干细胞在受损大鼠脊髓内的分化及作用

目的 将维甲酸(RA)诱导的人胚神经干细胞移植入受损的大鼠脊髓内，观察大鼠后肢运动功能的变化及细胞的分化情况。方法 实验大鼠30只遭受脊髓中度损伤后7天作移植治疗，实验组分两组：一组移植经维甲酸诱导后的细胞，另一组移植未诱导的细胞；对照组注射等量PBS液。每周一次观察大鼠后肢运动情况，移植后4周，应用免疫组化技术检测移植细胞在大鼠脊髓内的生存和分化情况。结果 实验组大鼠脊髓内见许多移植细胞存在，部分可分化出神经元样细胞，其后肢运动功能优于对照组。其中维甲酸诱导组能分化出神经元样细胞，其促进脊髓功能恢复的能力较另一组更强。结论 维甲酸预处理的神经干细胞在体内能替代缺失的神经细胞，促进受损的脊髓功能恢复．在脊髓损伤的临床治疗中具有潜在的应用价值。     

An Aminopropyl Carbazole Derivative Induces Neurogenesis by Increasing Final Cell Division in Neural Stem Cells

P7C3 and its derivatives, 1-(3,6-dibromo-9H-carbazol-9-yl)-3-(p-tolylamino)propan-2-ol (1) and N-(3-(3,6-dibromo-9H-carbazol-9-yl)-2-hydroxypropyl)-N-(3-methoxyphenyl)-4-methylbenzenesulfonamide (2), were previously reported to increase neurogenesis in rat neural stem cells (NSCs). Although P7C3 is known to increase neurogenesis by protecting newborn neurons, it is not known whether its derivatives also have protective effects to increase neurogenesis. In the current study, we examined how 1 induces neurogenesis. The treatment of 1 in NSCs increased numbers of cells in the absence of epidermal growth factor (EGF) and fibroblast growth factor 2 (FGF2), while not affecting those in the presence of growth factors. Compound 1 did not induce astrocytogenesis during NSC differentiation. 5-Bromo-2′-deoxyuridine (BrdU) pulsing experiments showed that 1 significantly enhanced BrdU-positive neurons. Taken together, our data suggest that 1 promotes neurogenesis by the induction of final cell division during NSC differentiation.     

依达拉奉对谷氨酸所致神经干细胞损害的保护作用

目的探讨依达拉奉对谷氨酸所致神经干细胞损害的保护作用及机制。方法取大鼠13.5 d胚胎皮质,提取神经干细胞,分为谷氨酸处理组(500μmol/L)、依达拉奉干预组(500μmol/L谷氨酸+500 ng/mL依达拉奉)和正常对照组。谷氨酸及依达拉奉处理24 h后,应用光学显微镜高倍下观察各组细胞的形态和数量;并对各组细胞作DAPI及TUNEL染色,计数阳性细胞。结果与正常对照组比较,谷氨酸处理组细胞的数量减少(P<0.05);依达拉奉组细胞的数量较谷氨酸组明显增多(P<0.05)。谷氨酸处理组的TUNEL阳性细胞明显多于正常对照组(P<0.05),依达拉奉组的TUNEL阳性细胞明显少于谷氨酸组(P<0.05)。结论依达拉奉通过拮抗谷氨酸诱导的细胞凋亡对谷氨酸所致的神经干细胞损害起到保护作用。     

Therapeutic neuronal stem cells: patents at the forefront

Background: Neural stem cells (NSCs) hold the promise to cure a broad range of neurological diseases and injuries, particularly neurodegenerative diseases and spinal cord injuries. The recent confirmation that neurogenesis occurs in the adult brain and that NSCs reside in the adult CNS opens new opportunities and avenues for cellular therapy. Objectives: To provide an overview of the current patent situation related to NSCs and to highlight the limitations and challenges of bringing NSC research to therapy. Method: Reviewing the early studies and patents in NSC research. Conclusion: NSCs are in clinical trials for Batten and Parkinson's diseases. However, clinical development and other limitations will make it difficult for pharmaceutical/biotech companies to break even with these early patents.     

不同细胞因子体外诱导神经干细胞向神经细胞分化的研究

目的观察碱性纤维母细胞生长因子、白血病抑制因子、脑源性神经营养因子及不同组合对成年SD大鼠脑神经干细胞在体外分化为神经细胞的作用。方法用含碱性纤维母细胞生长因子（bFGF）、B27的无血清细胞培养技术体外培养成年SD大鼠脑神经干细胞,单细胞克隆后行Nestin免疫细胞化学染色;根据培养液中所加营养因子的不同将单细胞克隆传代细胞分为5组培养：bFGF、LIF、BDNF、bFGF＋LIF、bFGF＋BDNF组,此5组细胞培养1周,进行NSE免疫细胞化学染色,计数阳性细胞比例后进行统计学分析。结果单细胞克隆培养后克隆球细胞表达Nestin;与bFGF组、LIF组、BDNF组相比,bFGF＋BDNF组和bFGF＋LIF组神经干细胞分化为神经细胞的比例较高（P〈0．01）,其中bFGF＋BDNF组神经细胞的比例最高。结论在bFGF培养条件下,BDNF促进成年SD大鼠脑神经干细胞向神经细胞分化的能力高于LIF。     

神经干细胞移植对Alzheimer病大鼠脑形态及动物行为学影响

目的 :观察移植入 Alzheimer病 (AD)大鼠脑内的神经干细胞存活、分化及功能。方法 :由新生大鼠海马分离培养神经干细胞 ,采用切断穹窿海马伞的方法制作 AD大鼠模型 ,模型建立 8～ 10 d后行神经干细胞移植。移植 1个月后 ,通过暗回避试验检测大鼠的学习记忆能力 ,应用尼氏染色 ,乙酰胆碱酯酶 (Ach E)染色观察体内移植神经干细胞的存活 ,分化以及 AD大鼠 Ach E纤维密度的变化。结果 :神经干细胞在额叶和海马都能够存活 ,分化成神经元 ,可与宿主建立突触联系 ,在海马区移植神经干细胞的生长优于额叶。与对照组相比 ,接受神经干细胞移植鼠的暗回避潜伏期变长 (P <0 .0 5 ) ,探索次数减少(P<0 .0 5 ) ,海马 Ach E纤维密度增加 (P <0 .0 5 )。结论 :神经干细胞能够在 AD大鼠额叶、海马存活、分化 ,并可导致 Ach E纤维密度增加 ,AD大鼠学习、记忆能力改善     

胶质瘤细胞诱导神经干细胞迁移作用的实验研究

目的观察胶质瘤细胞在体外培养条件下对神经干细胞是否有诱导迁移的作用。方法①从新生1～2dSD大鼠脑皮层分离培养神经干细胞,进行神经干细胞及其增殖能力鉴定。②胶质瘤细胞与神经干细胞限定区域联合培养,观察神经干细胞的生长及其形态学变化。结果①所获得神经细胞球Nestin染色阳性,传代神经细胞球抗BrdU染色阳性。②可观察到神经干细胞球周围长出细胞突起,在靠近胶质瘤细胞的一侧,细胞突起的密度及长度均大于其他方向上的突起并且可见部分干细胞向胶质瘤细胞方向的移动。结论胶质瘤细胞在体外对神经干细胞有诱导迁移作用。     

大鼠胚胎神经干细胞的培养及体外基因转染研究

目的探讨大鼠胚胎神经干细胞的培养方法和经脂质体介导转染VEGF121基因的大鼠胚胎神经干细胞体外基因表达特点。方法选取孕14天SD大鼠胚胎海马,机械消化后在神经干细胞培养液中悬浮培养,并传代。脂质体介导法将VEGF121基因转染到大鼠神经干细胞中,经RT-PCR检测转基因神经干细胞体外基因表达时间窗;免疫荧光染色观察神经干细胞及其分化细胞的基因表达情况。结果培养获得高纯度神经干细胞、转基因神经干细胞及其分化的子代细胞均有VEGF121的表达并持续两周左右。结论经脂质体介导转染VEGF121基因的大鼠胚胎神经干细胞在体外良好表达基因产物。     

Neural stem cell niches in health and diseases

Presence of neural stem cells in adult mammalian brains, including human, has been clearly demonstrated by several studies. The functional significance of adult neurogenesis is slowly emerging as new data indicate the sensitivity of this event to several "every day" external stimuli such as physical activity, learning, enriched environment, aging, stress and drugs. In addition, neurogenesis appears to be instrumental for task performance involving complex cognitive functions. Despite the growing body of evidence on the functional significance of NSC and despite the bulk of data concerning the molecular and cellular properties of NSCs and their niches, several critical questions are still open. In this work we review the literature describing i) old and new sites where NSC niche have been found in the CNS; ii) the intrinsic factors regulating the NSC potential; iii) the extrinsic factors that form the niche microenvironment. Moreover, we analyse NSC niche activation in iv) physiological and v) pathological conditions. Given the not static nature of NSCs that continuously change phenotype in response to environmental clues, a unique "identity card" for NSC identification is still lacking. Moreover, the multiple location of NSC niches that increase in diseases, leaves open the question of whether and how these structures communicate throughout long distance. We propose a model where all the NSC niches in the CNS may be connected in a functional network using the threads of the meningeal net as tracks.     

Endogenous Neural Stem Cells in the Adult Brain

Despite progress in our understanding molecular mechanisms of neuronal cell death in many central nervous system (CNS) diseases, widely effective treatments remain elusive. Recent studies have shown that neural stem cells (NSCs) are present in the subventricular zone (SVZ) lining the lateral ventricles and the subgranular zone (SGZ) of the hippocampal dentate gyrus (DG) in adult mouse, rat, nonhuman primate, and human brain. Newly generated cells in the SGZ can differentiate into mature, functional neurons and integrate into the DG as granule cells, which are involved in memory formation. In addition, many CNS diseases can stimulate the proliferation of neuronal stem/progenitor cells located in the SVZ and SGZ of the adult rodent brain, and the resulting newborn cells migrate into damaged brain regions, where they express mature neuronal markers. Therefore, it might be possible for damaged cells to be replaced from endogenous neural stem cell pools. However, the capacity of self-repair is obviously not enough. Proliferation, migration, and neuronal differentiation of endogenous NSCs could be manipulated by pharmaceutical tools to reach the adequate benefits for the treatment of CNS diseases. This work is supported in part by National Institute of Health (NIH) grant AG21980 (K.J.).     

Neuron stem cell NLRP6 sustains hippocampal neurogenesis to resist stress-induced depression

Neurogenesis decline in hippocampal dentate gyrus (DG) participates in stress-induced depressive-like behaviors, but the underlying mechanism remains poorly understood. Here, we observed low-expression of NOD-like receptor family pyrin domain containing 6 (NLRP6) in hippocampus of stress-stimulated mice, being consistent with high corticosterone level. NLRP6 was found to be abundantly expressed in neural stem cells (NSCs) of DG. Both Nlrp6 knockout (Nlrp6^−/−) and NSC-conditional Nlrp6 knockout (Nlrp6CKO) mice were susceptible to stress, being more likely to develop depressive-like behaviors. Interestingly, NLRP6 was required for NSC proliferation in sustaining hippocampal neurogenesis and reinforcing stress resilience during growing up. Nlrp6 deficiency promoted esophageal cancer-related gene 4 (ECRG4) expression and caused mitochondrial dysfunction. Corticosterone as a stress factor significantly down-regulated NLRP6 expression, damaged mitochondrial function and suppressed cell proliferation in NSCs, which were blocked by Nlrp6 overexpression. ECRG4 knockdown reversed corticosterone-induced NSC mitochondrial function and cell proliferation disorders. Pioglitazone, a well-known clinical drug, up-regulated NLRP6 expression to inhibit ECRG4 expression in its protection against corticosterone-induced NSC mitochondrial dysfunction and proliferation restriction. In conclusion, this study demonstrates that NLRP6 is essential to maintain mitochondrial homeostasis and proliferation in NSCs, and identifies NLRP6 as a promising therapeutic target for hippocampal neurogenesis decline linked to depression.     

Neural stem cells and neurodegeneration

Neurodegenerative diseases, such as Parkinson's disease, are characterized by a continuous loss of specific populations of neurons. Possible regenerative interventions include transplanting developing neural tissue or neural stem cells into the host brain, and inducing proliferation of endogenous stem cells by pharmacological manipulations. Neural stem cells (NSC), with the capacity to self-renew and produce the major cell types of the brain, exist in the developing and adult central nervous system (CNS). These cells can be grown in vitro while retaining the potential to differentiate into nervous tissue. This review focuses on regenerative therapy in neurodegenerative diseases using NSC.     

Effect of lead on proliferation and neural differentiation of mouse bone marrow-mesenchymal stem cells

Bone marrow-mesenchymal stem cells (MSCs) are considered to be an ideal source of stem cells for assessing the effects of environmental toxins on the proliferation, multipotency and differentiation of adult stem cells. The aim of this study was to investigate the effect of lead on the proliferation and neuronal differentiation of murine MSCs. MTT assay used in this study revealed that while the proliferation of MSCs is sensitive to higher than 10 μM lead, a 50% reduction in the rate of their proliferation can be achieved in the presence of 60 μM lead. The results of immunocytochemistry and RT–PCR showed that β-mercaptoethanol induced-neuronal differentiation is also reduced after the treatment of MSCs by 60 μM lead. Furthermore, the comet assay analysis of MSCs showed a substantial increase in DNA damage in the lead treated cells compared to the control. In conclusion our results revealed for the first time that lead is not only cytotoxic to the survival and proliferation of MSCs but also inhibits their differentiation to neurons in a dose-dependant manner. Therefore, MSCs appear to be an alternative method for assessing the cytotoxic effects of such environmental hazards.