干细胞移植治疗脊髓损伤：问题与前景

背景：目前,脊髓损伤的治疗仍然是世界性难题,采用干细胞移植的方法治疗脊髓损伤是近年来脊髓损伤修复研究的热点之一。目的：综述干细胞移植治疗脊髓损伤基础与临床的研究进展及应用前景。方法：应用计算机检索索PubMed数据库及CNKI数据库2000年以后收录文章,检索词为“脊髓损伤,干细胞,细胞移植”,“spinal cord injury,stem cel ,cel therapy”,筛选干细胞移植治疗脊髓损伤基础与临床研究,排除Meta分析等二次性文献,排除重复或较陈旧的文献,纳入52条篇归纳总结。结果与结论：文章对干细胞种类及生物学特性、干细胞移植治疗脊髓损伤的基本机制、干细胞移植技术、干细胞治疗的疗效等进行了总结,并提出干细胞移植治疗脊髓损伤所面临的问题及展望。     

神经干细胞修复脊髓损伤

背景:神经生物学和干细胞技术的发展.使通过细胞移植增加脊髓神经数量、减少胶质瘢痕和空洞的形成成为可能.目的:复习相关文献,就神经干细胞的鉴定及特性、神经干细胞修复脊髓损伤的可能机制、临床前研究及临床应用方面进行综述.方法:以 "neural stem cells,transplant,spinal cord injury"为英文检索词,以"神经干细胞,移植,脊髓损伤" 为中文检索词,由第一作者检索1997/2010 PubMed数据库及万方数据库有关神经干细胞鉴定、特性、神经干细胞修复脊髓损伤的可能机制、临床前研究及临床应用方面等方面的文章.排除发表时间较早、重复及类似研究,对29篇符合标准的文献进行归纳总结.结果与结论:神经干细胞有产生神经元、少突胶质细胞、星形胶质细胞,并替代受损的神经细胞功能等.文章从神经干细胞的鉴定及特性,神经干细胞修复脊髓损伤的可能机制,神经干细胞治疗脊髓损伤的实验研究及临床应用等方面进行了讨论.关于干细胞来源的神经元或胶质细胞移植后的长期生存及表型稳定性,以及逃脱分化及选择性程序的很少部分胚胎干细胞,可能会自在移植后的移植位点扩增并形成肿瘤等问题有待进一步解决.     

骨髓间充质干细胞与运动性脊髓损伤

背景:骨髓间充质干细胞移植对于运动性脊髓损伤是一种有效的治疗手段.但目前有关脊髓损伤的研究尚不充分,且缺乏对其机制及其良好治疗方法的探讨.目的:通过分析运动性脊髓损伤的病理特征、骨髓间充质干细胞的生理特性,及其运用于脊髓损伤的应用,为制定运动性脊髓损伤的康复治疗方案提供理论依据和科学支撑.方法:应用计算机检索Pubmed数据库(1991/2010),以"Mesenchymal stem cell,sports Knee injuries"为检索词;应用计算机检索维普数据库(1991/2010),以"骨髓间充质干细胞、运动性脊髓损伤"为检索词.结果与结论:共收集到85篇文献,排除发表时间较早、实验设计科学性较差的文献,共25篇文献符合标准被纳入.骨髓间充质干细胞能分化为神经元样细胞,反应性分泌各种营养因子及生长因子,以增强神经的保护作用和促进局部微血管再生,从而起到治疗脊髓损伤的作用.但运动性脊髓损伤后损伤部位的缺血、缺氧、运动性自由基的产生及兴奋性氨基酸等影响骨髓间充质干细胞分化及其结果的相关问题仍需要大量的实验研究予以一一证实.     

组织工程脊髓种子细胞

目的:组织工程技术在脊髓损伤修复中前景广阔,其中组织工程支架和种子细胞是组织工程中的两项重要内容,对有关脊髓种子细胞的研究进行综述,以了解其进展。资料来源:应用计算机检索Medline1999-07/2004-06期间的相关文章,检索词为“spinalcordinjury,regeneration,celltransplantation,并限定文章语言为English。同时检索http://www.wanfangdata.com.cn/1999-07/2004-06期间相关的文章,检索词为“脊髓损伤,修复,细胞移植”,限定文章语言种类为中文。资料选择:对资料进行初审,选择较近期及对进一步试验有指导意义的文献。纳入标准:①选取对脊髓损伤后进行细胞移植治疗的文献。②随机对照实验研究。③单一样本研究。排除标准:①较陈旧的文献。②综述文献。③重复研究。资料提炼:共收集到40篇关于细胞移植的文献,其中有17篇符合纳入标准,排除的23篇文章系重复的同一研究和综述文献。资料综合:将17篇文献中分别对各个种子细胞移植后对脊髓损伤修复的促进作用进行了综合。结论:作为种子细胞,均能促进脊髓损伤的修复,但是最有应用前景的主要有:神经干细胞,骨髓基质干细胞,许旺细胞和嗅鞘细胞。     

干细胞移植治疗脊髓损伤的研究进展

背景:干细胞移植作为治疗脊髓损伤最具前景的方法,已经在大量的动物实验和临床试验中得到证实.目的:综述干细胞移植治疗脊髓损伤的相关研究进展.方法:应用计算机检索2006-01/2010-12中国知网、Medline数据库相关文章,中文检索词"干细胞,脊髓损伤,细胞移植",英文检索词"stem cells,spinal cord injury,cells transplantation",共检索到文献494篇,最终纳入符合标准的文献24篇.结果与结论:研究发现,移植的干细胞可以在脊髓内迁移、分化为神经元并分泌神经营养物质,促进神经组织的修复,改善神经功能.胚胎干细胞最早用于治疗脊髓损伤,但潜在的致瘤性等成为其临床应用的障碍;神经干细胞理论上是治疗脊髓损伤的首选干细胞,由于分离纯化技术要求严格,费用昂贵等使其在研究中进展缓慢;骨髓间充质干细胞来源丰富、取材方便,可行自体移植,避开了伦理学和移植后排斥等问题,目前被认为是一种理想的自体干细胞移植来源.随着细胞联合移植、基因修饰及组织工程支架移植治疗脊髓损伤的研究不断取得进展,许旺细胞、嗅鞘细胞的应用范围和治疗效果也得到提升.     

骨髓间充质干细胞免疫学特性及其移植治疗脊髓损伤

背景:近年来研究表明:骨髓间充质干细胞能在同种异基因,甚至异种基因的环境中长期存活,并且保持多向分化潜能.这一独特的免疫学特性,以及来源丰富、避免伦理问题等优点,可能为治疗脊髓损伤和促进神经功能修复提供了新的途径.目的:对骨髓间充质干细胞的免疫学特性、不同途径移植及其可能机制进行综述,为干细胞治疗脊髓损伤提供理论依据.方法:由第一作者应用计算机检索PubMed 2000-01/2010-09期间相关文章,检索词为"mesenchymal stem cells,bone marrow,immunological characteristics,transplantation,spinal cord injury".纳入标准:文章所述内容应与骨髓间充质干细胞的免疫学特性及其治疗相关研究进展.排除标准:重复研究或者Meta分析类文章.共收集到260篇相关文献,选取33篇文献进入结果分析.结果与结论:骨髓间充质干细胞具有独特的低免疫原性,有助于抑制移植排斥反应.通过不同的移植方法、选择合适的移植途径和时机,均可对脊髓损伤的治疗提供有益的保护作用,其机制可能是神经元替代、分泌神经营养因子、归巢效应等.随着对骨髓间充质干细胞和脊髓损伤机制研究的不断深入,预示着间充质干细胞移植在治疗脊髓损伤后神经功能修复领域,将有着广阔的临床应用前景.     

干细胞移植治疗脊髓损伤研究进展

学术背景:目前治疗脊髓损伤应用比较多的方法是细胞移植治疗和神经营养因子的应用.移植的细胞可在损伤部位存活、整合入宿主组织中,分化出神经元、星形胶质细胞和少突胶质细胞,并且和宿主细胞之间可形成突触样结构,使中枢神经系统的功能得到部分恢复.目的:总结神经干细胞移植治疗大鼠脊髓损伤的研究进展.检索策略:应用计算机检索Pubmed数据库1985-01/2007-10期间的相关文献,榆索词为"Spinal Cord Inluries,Neural,Stem Cell Transplantation".并限定文章语言种类为English.吲时计算机榆索中文科技期刊数据库1989-01/2007-06期间的相关文章,检索词为"脊髓损伤,神经干细胞,神经元,干细胞移植",并限定文章语言种类为中文.对资料进行初审,并查看每篇文献后的引文.纳入标准:文章所述内容应与移植干细胞后脊髓损伤后神经轴突的再生与修复等研究进展中的应用相关.排除标准:重复研究或Meta分析类文章.共收集到66篇相关文献,31篇文献符合纳入标准,排除的35篇为内容陈旧或重复文献.文献评价:符合纳入标准的31篇文献中,23篇涉及移植后损伤脊髓神经元和轴突、髓鞘的再生及功能修复的研究,8篇涉及存在的问题与展望.资料综合:①在脊柱骨折中约有16%～40%并发脊髓损伤.脊髓损伤传统治疗仅限于脊柱骨折脱位的复位固定、解除脊髓压迫、对症及康复治疗,疗效较差.②近年来随着神经病理生理及神经发育学研究的不断深人,神经组织或非神经组织移植逐渐应用于脊髓损伤并取得了肯定的成绩.③干细胞具有自我更新能力,植入受损部位后,其释放的营养因子能促进神经元的再生,且再生轴突能快速穿越移植物与宿主组织的边界,重建轴突的连续性.④关于干细胞及营养因子在损伤脊髓修复方面的研究虽已取得较大进展,但仍存在对神经再生的不利因素,如髓鞘相关抑制分子和胶质瘢痕形成,免疫排斥等.结论:干细胞移植是治疗脊髓损伤的理想方案,可恢复损伤大鼠脊髓的部分功能.     

骨髓间充质干细胞移植治疗脊髓损伤的应用技术

背景:目前临床上对脊髓损伤患者脊神经的萎缩与坏死缺乏有效的修复方法。研究发现干细胞移植治疗脊髓损伤具有广阔的应用前景。目的:综述骨髓间充质干细胞移植治疗脊髓损伤的研究进展。方法:由第一作者检索2001/2011PubMed数据库(http://www.ncbi.nlm.nih.gov/PubMed)及万方数据库(http://g.wanfangdata.com.cn/)有关骨髓间充质干细胞、脊髓损伤、细胞移植等方面的文章,英文检索词为"bone marrow mesenchymal stem cells,spinal cord injury,cell transplantation",排除重复性研究,共保留其中的32篇文献进行归纳总结。结果与结论:骨髓间充质干细胞移植治疗脊髓损伤的研究在脊髓损伤模型制作、移植时间、移植方式、移植浓度、联合移植等多方面取得了成就,临床实验在国内外也已有所开展。但移植机制仍不十分明确,临床移植治疗的安全性和疗效需进一步研究。     

嗅鞘细胞移植修复脊髓损伤的新思考

目的:针对嗅鞘细胞移植在脊髓损伤修复中的作用进行综述,并对可能导致最佳细胞移植干预脊髓损伤效果的特定因素进行深入探讨。资料来源:应用计算机检索Medline 1994-01/2007-03期间关于嗅鞘细胞移植与脊髓损伤的文章,检索词“olfactory ensheathing cells,spinal cord injury”,并限定语言种类为English。同时计算机检索万方数据资源系统与中国期刊全文数据库1994-01/2007-03关于嗅鞘细胞移植与脊髓损伤的文章,限定文章语言种类为中文,检索词“嗅鞘细胞,脊髓损伤”。资料选择:对资料进行初审,选取包括实验组和对照组的文献,筛除非随机实验,对剩余的文献开始查找全文,进一步判断为随机对照实验。纳入标准:①随机对照实验,采用单盲,双盲或非盲法。②实验包含平行对照组。排除标准:重复性实验研究及综述类文章。资料提炼:共收集到45篇关于嗅鞘细胞干预脊髓损伤的随机实验文章,30篇符合纳入标准,排除的13篇为重复的同一研究和综述。资料综合:综述神经干细胞、胚胎干细胞移植以及基因修饰的嗅鞘细胞治疗脊髓损伤的方法,并对各方法给予评价。细胞联合移植治疗各有特色,但所有的实验结果主要以啮齿类动物-大鼠的脊髓损伤模型为基础而获得的,选择的模型包括脊髓完全横断模型、挫裂伤模型、脱髓鞘模型等,目前还不能获得完全模拟人的脊髓损伤的动物模型。如何选择适当的细胞类型联合应用,并使之实现从实验室走向应用研究是不同细胞移植策略中应重点考虑的问题。结论:尚无充分证据证明目前的嗅鞘细胞联合干预策略对人类脊髓损伤后的功能恢复有十分确切的作用,但单一、纯化的嗅鞘细胞移植可能不是干预脊髓损伤的最佳选择。     

神经干细胞在脊髓损伤中的应用与进展

背景:神经干细胞来源广泛,取材方便,分离培养容易,且神经干细胞易于外源基因的导入和表达,可为基因治疗神经系统的疾病提供良好的载体.目的:对神经干细胞在脊髓损伤中的应用进行回顾性研究.方法:由通讯作者检索2006/2009 PubMed数据(http://www.ncbi.nlm.nih.gov/PubMed)及万方数据库(http://www.wanfangdata.com.cn)有关神经干细胞的培养,鉴定,分化,及其应用于脊髓损伤的组织工程修复等方面的文献,英文检索词为"neural stem cells,spinal cord injury,cellular transplantation",中文检索词为"神经干细胞,脊髓损伤,细胞移植".排除重复性研究.计算机初检得到82篇文献,根据纳入标准保留23篇进一步归纳总结.结果与结论:神经干细胞移植的动物实验已广泛开展.目前神经干细胞在修复脊髓损伤中的应用主要集中以下几方面:一是直接细胞移植进行替代治疗,通过神经干细胞的移植或激活体内的神经干细胞,使其分化为神经元和胶质细胞,并与已经存在的神经细胞结构整合到一起而达到治疗疾病的目的;二是以神经干细胞作为基因载体,携带治疗作用的目的基因进行移植,从而达到细胞替代和基因治疗的双重作用;三是通过对生长因子和细胞因子的研究,诱导自身的神经干细胞分化进行神经自我修复.     

T cell receptor alpha-, beta-, and gamma-genes in T cell and pre-B cell acute lymphoblastic leukemia

We examined alpha-, beta-, and gamma-T cell receptor (TCR) gene activation within acute lymphoblastic leukemias (ALLs) that represent early stages of B and T cell development. We wished to determine if TCR rearrangement and expression was lineage restricted, showed any developmental hierarchy, or could identify new subsets of T cells. Rearrangement of gamma and beta TCR genes occurred early in development but in no set order, and most T-ALLs (22/26) were of sufficient maturity to have rearranged both genes. T-ALLs preferentially rearranged C gamma 2 versus the C gamma 1 complex; no preference within the beta locus was apparent. Once rearranged, the beta TCR continued to be expressed (11/13), whereas the gamma TCR was rarely expressed (3/14). The alpha TCR was expressed only in more mature T-ALLs (8/14) that usually displayed T3. The 3A-1 T cell associated antigen appeared earliest in development followed by T11 and T3. Within pre-B cell ALL a higher incidence of lineage spillover was noted for gamma TCR rearrangements (8/17) than for beta rearrangements (3/17). This also contrasts with the only occasional rearrangement of immunoglobulin (Ig) heavy chains (3/25) in T-ALL. However, in pre-B ALL the pattern of gamma TCR usage was distinct from that of T cells, with the C gamma 1 complex utilized more frequently. Almost all ALLs could be classified as pre-B or T cell in type by combining Ig and TCR genes with monoclonal antibodies recognizing surface antigens, although examples of lineage duality were noted. Unique subpopulations of cells were discovered including two genetically uncommitted ALLs that failed to rearrange either Ig or TCR loci. Moreover, two T lymphoblasts were identified that possessed the T3 molecule but failed to express alpha plus beta TCR genes. These T-ALLs may represent a fortuitous transformation of T cell subsets with alternative T3-Ti complexes.     

T cell receptor gene recombination patterns and mechanisms: cell death, rescue, and T cell production

The antigen-specific receptors of T and B lymphocytes are generated by somatic recombination between noncontiguous gene segments encoding the variable portions of these molecules. The semirandom nature of this process, while desirable for the generation of diversity, has been thought to exact a high price in terms of sterile (out-of-frame) products. Historically, the majority of T lymphocytes generated in mammals were thought to be useless, either because they generated such sterile rearrangements or because the receptors generated did not appropriately recognize self-molecules (i.e., positive and negative selection). In the studies described here, we characterize the onset of T cell receptor (TCR) alpha and beta chain gene rearrangements and quantitate their progression throughout T cell development. The results show that T cell production efficiency is enhanced through (a) rearrangement of TCR-beta chain genes early during T cell development, with selective expansion of those cells possessing in-frame rearrangements; (b) deletion of sterile rearrangements at the TCR-alpha chain locus through ordered (proximal to distal) sequential recombination; and (c) modification of nonselectable alpha/beta heterodimer specificities through generation and expression of new TCR- alpha chains. In addition, we demonstrate strict correlations between successful TCR-beta gene rearrangement, the onset of TCR-alpha gene rearrangement, rapid cell division, and programmed cell death, which together serve to maintain cell turnover and homeostasis during T cell development.     

Relationship between systemic lupus erythematosus T cell subsets, anti-T cell antibodies, and T cell functions.

Previous studies have shown that patients with systemic lupus erythematosus (SLE) had differing T cell T4+/T8+ ratios and that the ratio correlated with clinical features of the disease. In the present study, we wished to determine whether the peripheral blood T cell subsets in these patients were related to the specificity of anti-T cell antibodies found in their plasma. Plasma from 24 SLE patients that reacted with greater than 20% of normal T cells were analyzed for their effect on in vitro pokeweed mitogen-stimulated immunoglobulin synthesis and for their reactivity with human T4+ and T8+ cells. Anti-T cell antibodies found in SLE patients have a spectrum of reactivities. We concentrated upon antibodies that interfere with suppressor function. One group of SLE anti-T cell antibodies reacts preferentially with the T8+ suppressor effector cell whereas another is reactive with T4+ suppressor inducer subsets. SLE patients with high T4+/T8+ ratios had anti-T cell antibodies predominantly reactive with the T8+ suppressor effector cells. Patients with low T4+/T8+ ratios, on the other hand, had anti-T cell antibodies reactive with either the T4+ suppressor inducer or with both the T4+ suppressor inducer and T8+ suppressor effector cells. In addition, a fourth group was defined whose anti-T cell antibodies were neither reactive with a functional T4+ suppressor inducer nor a functional T8+ suppressor effector cells. There was a significant correlation between the circulating T4+/T8+ ratio of peripheral T cells in these patients and the relative ability of their anti-T cell antibodies to kill T8+ cells vs. T4+ cells (gamma = 0.666, P less than 0.001). These results support the notion that in SLE different cellular defects in the immunoregulatory circuit underlie the development of autoimmune reactions and that the anti-T cell antibodies may cause numerical and functional deficiencies in T cell subsets.     

Human T cell hybridomas secreting factors for IgA-specific help, polyclonal B cell activation, and B cell proliferation

Human T-T hybridomas were established by fusion of concanavalin A- activated OKT-4+ T cells with hypoxanthine guanine phosphoribosyl transferase-deficient as well as nondeficient T cell lines. Four hybrids were selected for further study. Supernatant from hybrid clone J1.3 specifically enhanced IgA production and secretion by isolated human B cells, with increases in IgA plaque-forming cells approaching those seen with addition of autologous T cells and pokeweed mitogen. A monoclonal lymphocytic leukemia with membrane IgA also differentiated to IgA plasma cells by this supernatant. Evidence suggests that this hybrid supernatant acts on post-switch IgA-committed B cells. The other hybrids were not isotype specific; hybrid J2S1 enhanced polyclonal Ig secretion and hybrids K1 and K8 induced B cell proliferation without induction of Ig secretion.     

Functionally restricted, allospecific, human helper T cell lines that amplify either B cell or cytolytic T cell responses

Using a panel of partially cloned, OKT4+, DRw-1-specific, alloproliferative human T cell lines, we have identified two functionally restricted and reciprocating types of helper T cells. One provides major histocompatibility complex-restricted help for plaque-forming cell responses by DRw 1+ allogeneic B cells; the other preferentially amplifies the generation of allospecific cytotoxic T lymphocytes (CTL) from CTL precursors that have been suboptimally triggered by alloantigen.     

v-rasH induces non-small cell phenotype, with associated growth factors and receptors, in a small cell lung cancer cell line

Small cell lung cancer (SCLC) tumor progression can involve partial or complete conversion to a more treatment-resistant non-small cell (NSCLC) phenotype. In a cell culture model of this phenomenon, we have previously demonstrated that insertion of the viral Harvey ras gene (v-Ha-ras) into SCLC cell lines with amplification and overexpression of the c-myc gene induced many NSCLC phenotypic features. We now report that the v-Ha-ras gene can also induce morphologic, biochemical, and growth characteristics consistent with the NSCLC phenotype in an N-myc amplified SCLC cell line, NCI-H249. We show that v-Ha-ras has novel effects on these cells, abrogating an SCLC-specific growth requirement for gastrin-releasing peptide, and inducing mRNA expression of three NSCLC-associated growth factors and receptors, platelet-derived growth factor B chain, transforming growth factor-alpha (TGF-alpha), and epidermal growth factor receptor (EGF-R). TGF-alpha secretion and EGF-R also appear, consistent with the induction of an autocrine loop previously shown to be growth stimulatory for NSCLC in culture. These data suggest that N-myc and v-Ha-ras represent functional classes of genes that may complement each other in bringing about the phenotypic alterations seen during SCLC tumor progression, and suggest that such alterations might include the appearance of growth factors and receptors of potential importance for the growth of the tumor and its surrounding stroma.     

Preexisting pancreatic acinar cells contribute to acinar cell, but not islet beta cell, regeneration

It has been suggested that pancreatic acinar cells can serve as progenitors for pancreatic islets, a concept with substantial implications for therapeutic efforts to increase insulin-producing beta cell mass in patients with diabetes. We report what we believe to be the first in vivo lineage tracing approach to determine the plasticity potential of pancreatic acinar cells. We developed an acinar cell-specific inducible Cre recombinase transgenic mouse, which, when mated with a reporter strain and pulsed with tamoxifen, resulted in permanent and specific labeling of acinar cells and their progeny. During various time periods of observation and using several models to provoke injury, we failed to observe any chase of the labeled cells into the endocrine compartment, indicating that acinar cells do not normally transdifferentiate into islet beta cells in vivo in adult mice. In contrast, we observed a substantial role for replication of preexisting acinar cells in the regeneration of new acinar cells after partial pancreatectomy. These results indicate that mature acinar cells harbor a facultative acinar but not endocrine progenitor capacity.