Neural stem cells as delivery vehicles

The discovery of neural stem cells (NSCs) has changed our long-held view that the adult mammalian central nervous system (CNS) is postmitotic and lacks the capability for self-repair. The role of NSCs in physiological and pathological processes in the brain is slowly emerging. We are now able to isolate, expand, genetically engineer and transplant NSCs. An important characteristic of NSCs, not fully understood so far, is their migratory ability and their tropism to brain pathology. The migratory ability of NSCs and their capacity to differentiate into all neural phenotypes gives us a potentially powerful tool for the treatment of both diffuse and localised neurologic disorders. The delivery of gene products by NSCs to specific sites in the CNS can maximise the efficiency of delivery and minimise the unwanted exposure of surrounding intact tissue. Here, the recent preclinical advances in the use of NSCs for the delivery of therapeutic products are reviewed, in particular the employment of their migratory potential and the homing ability to pathology in the nervous system.     

Mesenchymal stem cells at the intersection of cell and gene therapy

Importance of the field : Mesenchymal stem cells have the ability to differentiate into osteoblasts, chondrocytes and adipocytes. Along with differentiation, MSCs can modulate inflammation, home to damaged tissues and secrete bioactive molecules. These properties can be enhanced through genetic-modification that would combine the best of both cell and gene therapy fields to treat monogenic and multigenic diseases.

Areas covered in this review: Findings demonstrating the immunomodulation, homing and paracrine activities of MSCs followed by a summary of the current research utilizing MSCs as a vector for gene therapy, focusing on skeletal disorders, but also cardiovascular disease, ischemic damage and cancer.

What the reader will gain: MSCs are a possible therapy for many diseases, especially those related to the musculoskeletal system, as a standalone treatment, or in combination with factors that enhance the abilities of these cells to migrate, survive or promote healing through anti-inflammatory and immunomodulatory effects, differentiation, angiogenesis or delivery of cytolytic or anabolic agents.

Take home message: Genetically-modified MSCs are a promising area of research that would be improved by focusing on the biology of MSCs that could lead to identification of the natural and engrafting MSC-niche and a consensus on how to isolate and expand MSCs for therapeutic purposes.     

银杏内酯B对缺氧缺血性脑损伤新生大鼠内源性神经干细胞的影响

摘要 目的：观察不同剂量银杏内酯B（GB）对缺氧缺血性脑损伤（HIBD）新生大鼠内源性神经干细胞增殖分化的影响。 方法：清洁级7d龄SD大鼠96只,随机分为假手术组、模型组、低剂量组及高剂量组,后3组采用经典Rice法制作HIBD动物模型,模型制作4h后低剂量组与高剂量组分别按5mg/kg、10mg/kg腹腔注射GB,其他两组分别注射等量生理盐水,每日1次,共5d。每组随机分别在造模后第3,7,14,28天处死,单标、双标免疫组化技术观察4组大鼠海马齿状回颗粒下层区（SGZ）溴脱氧尿嘧啶核苷（BrdU+）及皮质BrdU+/nestin+（聚蛋白）、BrdU+/NSE+（神经元特异性烯醇化酶）、BrdU+/GFAP+（胶质纤维酸性蛋白）阳性细胞的表达,并计数分析。 结果：HIBD后BrdU+、皮质BrdU+/nestin+、BrdU+/NSE+、BrdU+/GFAP+细胞数增加,低剂量组、高剂量组均高于模型组,GB高剂量组的阳性细胞数高于GB低剂量组。 结论：GB能提高HIBD新生鼠内源性神经干细胞增殖、分化的能力,提示其可以促进神经发生。     

人胎脑神经干细胞特征性标记物的分布

目的：探讨人胎脑神经干细胞特征性标记物的分布。方法：收集胎龄16-36周水囊引产胎儿90例，采用免疫组织化学和光镜技术对人胎脑不同部位神经干细胞的特征性标记物分布进行检测。结果：不同胎龄胎脑均存在神经干细胞，Nestin和CD34蛋白双阳性NSCs仅存在于28周胎龄组的海马及室下区、32周胎龄组的海马、室下区及纹状体和36周胎龄组的纹状体，且这类NSCs主要呈圆形和椭圆形，大小不一。Nestin和CD133蛋白双阳性NSCs在不同的胎龄组以及同一胎龄组的不同部位其表达不同，胎龄越小，Nestin和CD133蛋白双阳性NSCs越多，32周胎龄组仅在海马部位发现1个此类NSCs，36周胎龄组的任何部位均未发现此类NSCs。结论：Nestin是人胎脑神经干细胞特征性标记物,CD133和CD34是人胎脑部分神经干细胞特征性标记物。     

Immunomodulatory neural stem cells for brain tumour therapy

Advances in the understanding of stem cells have enabled the development of novel therapies for brain tumours. Neural stem cells (NSCs) possess the ability to migrate throughout the CNS. By exploiting the tropism of NSCs to various neural pathologies (e.g., glioma, degeneration, stroke and so on) and the delivery of various immunomodulatory cytokines, new treatments for brain tumours have been investigated. These new strategies offer significantly more specificity than existing treatment regimens, such as surgery, radiation and chemotherapy. As methods in isolating and culturing NSCs are better understood, clinical applications of this therapeutic strategy may inevitably emerge. Here, the preclinical advances and the results supporting the effectiveness of stem cell therapies are reviewed. In addition, the obstacles to clinical development and methods to circumvent these caveats are discussed.     

Harnessing mesenchymal stem cell homing as an anticancer therapy

ABSTRACT

Introduction: Mesenchymal stromal cells (MSCs) are non-hematopoietic progenitor cells that have been exploited as vehicles for cell-based cancer therapy. The general approach is based on the innate potential of adoptively applied MSC to undergo facilitated recruitment to malignant tissue. MSC from different tissue sources have been engineered using a variety of therapy genes that have shown efficacy in solid tumor models.

Areas covered: In this review we will focus on the current developments of MSC-based gene therapy, in particular the diverse approaches that have been used for MSCs-targeted tumor therapy. We also discuss some outstanding issues and general prospects for their clinical application.

Expert opinion: The use of modified mesenchymal stem cells as therapy vehicles for the treatment of solid tumors has progressed to the first generation of clinical trials, but the general field is still in its infancy. There are many questions that need to be addressed if this very complex therapy approach is widely applied in clinical settings. More must be understood about the mechanisms underlying tumor tropism and we need to identify the optimal source of the cells used. Outstanding issues also include the therapy transgenes used, and which tumor types represent viable targets for this therapy.     

神经干细胞在基因治疗胶质瘤中的研究进展

神经干细胞是近几年的研究热点之一,其作为基因治疗的载体更是引起了广泛的关注和深刻研究。本文就神经干细胞在基因治疗胶质瘤方面的优点、缺点,研究现状和发展方向做一综述。     

Efficient polymer nanoparticle-mediated delivery of gene editing reagents into human hematopoietic stem and progenitor cells

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不同数量神经干细胞移植治疗颅脑外伤疗效的对比研究

目的观察脑外伤后不同数量移植神经干细胞的疗效是否存在不同,并找出受伤后进行干细胞移植的适宜量.方法 成年大鼠制成脑外伤模型在伤后24h进行神经干细胞移植,移植量分别为20万,100万,200万.伤后1 w动物运动神经功能评分后,处死取脑,行病理及免疫组化染色.结果伤后1 w,接受100万单位干细胞移植的治疗组与损伤组以及其他治疗组（20万,200万）相比呈现明显的运动功能改善.结论移植量并不是越大越好,中等量移植效果比较理想,是适宜的移植量.     

Evaluation of polyanion-coated biodegradable polymeric micelles as drug delivery vehicles

Polymeric micelles, as drug delivery vehicles, must achieve specific targeting and high stability in the body for efficient drug delivery. We recently reported the preparation of polyanion-coated biodegradable polymeric micelles by coating positively charged polymeric micelles consisting of poly(l-lysine)-block-poly(l-lactide) (PLys-b-PLLA) AB diblock copolymers with anionic hyaluronic acid (HA) by polyion complex (PIC) formation. The obtained HA-coated micelles showed significantly higher stability in aqueous solution. In this study, to evaluate the HA-coated polymeric micelles as a drug carrier, model drug release from the micelles and cytotoxicity of the micelles were investigated. The HA-coated micelles showed sustained release of model drugs and low cytotoxicity. It is known that there are receptors for HA on liver sinusoidal endothelial cells (LSEC). Specific interactions of HA-coated micelles with LSECs and Kupffer cells were investigated and compared with polymeric micelles coated with other polyanionic polysaccharides, i.e., heparin (Hep) and carboxymethyl-dextran (CMDex). Although Hep-coated micelles and CMDex-coated micelles were incorporated into both Kupffer cells and LSECs, HA-coated micelles were taken up only into LSECs. These results suggest HA-coated micelles have potential utility as drug delivery vehicles exhibiting specific accumulation into LSECs.     

肢体缺血后处理促进缺血性脑损伤大鼠内源性神经干细胞的增殖

背景：远程肢体缺血预处理应用到脑缺血-再灌注损伤领域的研究已有一些报道,但肢体缺血后处理应用于该领域报道很少。目的：观察肢体缺血后处理对缺血性脑损伤大鼠侧脑室旁神经干细胞增殖的影响。方法：利用改良线栓法制作局灶性脑缺血大鼠模型,将30只造模成功的SD大鼠随机分为实验组和对照组,每组15只。实验组行远程肢体缺血后处理,对照组不做处理。2组大鼠分别于造模后5,10,15d处死取脑,处死前1d每隔8h腹腔注射50mg／kg5-嗅脱氧尿嘧啶核苷1次,共3次。应用免疫组织化学方法检测梗死灶区大鼠脑组织5嗅脱氧尿嘧啶核苷阳性细胞数。结果与结论：与对照组比较,实验组脑再灌注损伤程度呈现不同程度减轻,行为学评分降低（P〈0．05）。实验组各时间点梗死灶周边皮质的5-嗅脱氧尿嘧啶核苷阳性细胞数明显多于对照组（P〈0．05）。提示局灶性脑缺血造模后的肢体缺血后处理可以改善大鼠行为学表现,促进了内源性干细胞的激活增殖,对缺血性脑损伤有保护作用。     

Stem cells as biological heart pacemakers

Abnormalities in the pacemaker function of the heart or in cardiac impulse conduction may result in the appearance of a slow heart rate, traditionally requiring the implantation of a permanent electronic pacemaker. In recent years, a number of experimental approaches have been developed in an attempt to generate biological alternatives to implantable electronic devices. These strategies include, initially, a number of gene therapy approaches (aiming to manipulate the expression of ionic currents or their modulators and thereby convert quiescent cardiomyocytes into pacemaking cells) and, more recently, the use of cell therapy and tissue engineering. The latter approach explored the possibility of grafting pacemaking cells, either derived directly during the differentiation of human embryonic stem cells or engineered from mesenchymal stem cells, into the myocardium. This review will describe each of these approaches, focusing mainly on the stem cell strategies, their possible advantages and shortcomings, as well as the avenues required to make biological pacemaking a clinical reality.     

神经干细胞移植治疗大鼠局灶性脑缺血损伤

背景：近年来,神经干细胞移植已成为治疗神经退行性疾病和中枢神经系统损伤的研究热点。目的：探讨神经干细的定向分化调控机制和神经干细胞移植治疗大鼠局灶性脑缺血损伤的研究进展。方法：以＂neural stem cells,stem cell transplantation,ischemic brain injury＂为检索词,检索Pubmed数据库1990至2012年相关文献;以＂神经干细胞,干细胞移植,缺血性脑损伤＂为检索词,检索CNKI数据库2005至2012年相关文献。分析神经干细的定向分化调控机制和神经干细胞移植治疗大鼠局灶性脑缺血损伤的内容,排除重复研究。结果与结论：①体外分离培养的神经干细胞有胚胎来源、脐血来源和成体来源,主要采用机械分离法和胰酶消化法进行分离。②目前体外培养的神经干细胞分离鉴定的标记物有巢蛋白、波形蛋白1、5-溴脱氧尿嘧啶核苷、神经元特异性烯醇化酶等。③神经干细胞的分化调节是通过正负双重作用实现的,负性调节是通过对称性的分裂来增加神经干细胞数量,包括Notch信号途径和一些生长因子等。正性调节诱导神经干细胞分化,包括参与细胞合成的骨形态发生蛋白信号途径等。④神经干细胞移植的时间窗选择在实验动物脑缺血两三周后,时间过早和过晚均不适合细胞的存活。神经干细胞通过脑立体定位仪直接进行脑内移植治疗大鼠局灶性脑缺血损伤,移植后可见细胞在局灶性脑缺血大鼠脑室内和梗死中心均可长期存活,并可广泛迁移,移植神经干细胞后观察到其运动行为学评分有明显提高。缺血性脑卒中的神经干细胞移植治疗还存在一些问题需要解决,未来的临床应用前景广阔,是缺血性脑卒中患者的新希望。     

甲泼尼龙抑制神经干细胞并诱导其凋亡的研究

目的：研究甲泼尼龙对体外培养的神经干细胞的直接作用，为有效的结合这两种治疗方法提供依据和指导。方法：体外培养神经干细胞，加入MP培养12h、24h和48h后，用细胞活性检测试剂CCK-8，检测其对神经干细胞活性的影响，用Hoeehst 33258染色观察细胞凋亡，用Annexin V／PI双染色法检测神经干细胞凋亡比率。结果：甲泼尼龙对体外培养的活性有抑制作用，而且可以诱导体外培养的神经干细胞的发生凋亡。结论：甲泼尼龙不利于神经干细胞的生长，不宜在进行甲泼尼龙冲击疗法的同时进行神经干细胞移植。     

神经干细胞移植治疗外伤性颅内血肿后遗症20例临床疗效分析

目的探讨应用神经干细胞移植治疗外伤性颅内血肿后遗症的临床疗效。方法对20例外伤性颅内血肿后遗症患者行腰椎穿刺蛛网膜下腔注入神经干细胞,并于第1次术前和第4次术后半年进行功能独立性评定（FIM）。结果患者自我料理、括约肌控制、活动和转移、运动、交流、社会认知都有明显改善（P〈0.01）。结论神经干细胞移植可以改善外伤性颅内血肿患者损伤的症状和体征,提高患者生活质量。     

Human JC virus-like particles as a gene delivery vector

Introduction: As a viral gene delivery vector, the recombinant JC virus-like particles (VLPs) can be easily generated in large quantities and at low cost. Exogenous genes of interest can be packaged by the VLP without the involvement of viral genetic material and then delivered into any tissue susceptible to JC virus (JCV) to allow gene transduction. Therefore, it should be possible in the future to develop a gene delivery vector using the human JC VLPs that will allow gene therapy.

Areas covered: Development of a gene delivery vector using the polyomavirus VLPs is reviewed in this article. The advantages and disadvantages of using JC VLP for gene delivery are discussed.

Expert opinion: Human JC VLPs are readily produced and can be engineered with ease; they allow specific targeting without the presence of any viral genetic material. For therapeutic purposes, gene(s) of interest or other compounds can be packaged into the VLP and delivered to JCV-susceptible cells at high efficiency.     

脑脊液途径移植神经干细胞治疗中枢神经系统疾病的研究现状简

背景：目前报道的用于神经干细胞移植的途径主要有经局部病变部位途径、经血液循环途径及经脑脊液循环途径3种目的：综述经脑脊液途径移植神经干细胞或神经前体细胞的方式及其在治疗中枢神经系统疾病中的应用。 方法：检索Pubmed数据库和CHKD全文数据库2000至2009年相关文献,叙述脑脊液途径移植神经干细胞的方法、在动物实验和临床方面治疗中枢神经系统疾病的应用及治疗机制。结果与结论：脑脊液适宜神经干细胞的存活、增殖、分化,经脑脊液途径移植神经干细胞治疗中枢神经系统疾病是一种有效可行的方法。但因神经干细胞的来源问题及治疗的机制、最佳时间窗和数量、安全性等诸多问题,仍需更深更广的研究,从而为蛛网膜下腔注射神经干细胞治疗中枢神经系统疾病奠定坚实的基础。     

海人酸对神经干细胞增殖及分化的影响

背景：神经干细胞对脑组织的修复作用非常有限,约80％新增殖的内源性神经干细胞在6周内死亡,仅0．2％的细胞继续增殖、分化,参与修复。目的：分析不同剂量海人酸在对神经干细胞增殖及分化的影响。方法：体外分离并培养新生Wistar大鼠神经干细胞,将神经干细胞分为空白对照组和加入不同浓度梯度的海人酸组,通过免疫组化法和免疫荧光法进行鉴定,MTT比色法测定海人酸对神经干细胞分化的影响,计算分化后神经元和星形胶质细胞比例。结果与结论：海人酸组贴壁的神经球分化速度较空白对照组快,在同一时间点进行观察,神经细胞的迁移距离较未处理组远。分化5d后,海人酸组所分化的细胞中,星状细胞较空白对照组多,而神经元样细胞相对较少,培养的细胞具有自我更新和向神经元、少突胶质细胞和星形胶质细胞分化的潜能。兴奋性氨基酸海人酸可使部分神经干细胞死亡,但可促进幸存的神经干细胞增殖及分化,并诱导其向星形胶质细胞分化。