Evidence for high translational potential of mesenchymal stromal cell therapy to improve recovery from ischemic stroke

Although ischemic stroke is a major cause of morbidity and mortality, current therapies benefit only a small proportion of patients. Transplantation of mesenchymal stromal cells (MSC, also known as mesenchymal stem cells or multipotent stromal cells) has attracted attention as a regenerative therapy for numerous diseases, including stroke. Mesenchymal stromal cells may aid in reducing the long-term impact of stroke via multiple mechanisms that include induction of angiogenesis, promotion of neurogenesis, prevention of apoptosis, and immunomodulation. In this review, we discuss the clinical rationale of MSC for stroke therapy in the context of their emerging utility in other diseases, and their recent clinical approval for treatment of graft-versus-host disease. An analysis of preclinical studies examining the effects of MSC therapy after ischemic stroke indicates near-universal agreement that MSC have significant favorable effect on stroke recovery, across a range of doses and treatment time windows. These results are interpreted in the context of completed and ongoing human clinical trials, which provide support for MSC as a safe and potentially efficacious therapy for stroke recovery in humans. Finally, we consider principles of brain repair and manufacturing considerations that will be useful for effective translation of MSC from the bench to the bedside for stroke recovery.     

人脐带间充质干细胞在3种不同培养体系中的生长状况及腺病毒感染效率*☆

背景：目前所报道的脐带间充质干细胞体外培养条件及培养效率不尽相同,尚缺乏统一标准。而且由于不同来源的间充质干细胞生物学特征尚有一定差异,因此建立脐带间充质干细胞简便、高效的培养体系十分必要。 目的：观察人脐带来源的间充质干细胞在体外不同培养体系中的生长状态,以及不同腺病毒感染的效率。 方法：采用胶原酶消化法从正常足月新生儿脐带中分离出间充质干细胞,贴壁法纯化培养,细胞贴壁后利用低糖DMEM,MesenPRO RS™ Medium和STEMPRO® MSC SFM这3种培养体系进行体外扩增。取对数生长期的第3~5脐带间充质干细胞,应用腺病毒Ad5-EGFP,Ad5/11-EGFP,Ad5/35-EGFP分别以感染复数=1,10,100进行感染,分别于感染后24,56,72 h倒置荧光显微镜观察病毒感染及绿色荧光表达情况。 结果与结论：使用低糖DMEM培养的细胞初期融合时间长,STEMPRO® MSC SFM培养的细胞虽然连接紧密,但消化传代后不易贴壁,而MesenPRO RS™ Medium培养的细胞在相同时间内能达到较高的细胞密度,更适于脐带间充质干细胞的体外扩增。Ad5/35-EGFP感染脐带间充质干细胞的效率明显高于其他两种腺病毒,但可导致细胞凋亡;腺病毒Ad5/11-EGFP对脐带间充质干细胞的感染效率较佳,随着感染复数的升高,所表达的荧光强度也逐渐增大。     

Astrocytic and neuronal fate of mesenchymal stem cells expressing nestin

Classically, bone marrow mesenchymal stem cells (MSC) differentiate in vivo or in vitro into osteocytes, chondrocytes, fibroblasts and adipocytes. Recently, it was reported by several groups that MSC can also adopt a neural fate in appropriate in vivo or in vitro experimental conditions. However, it is unclear if those cells are really able to differentiate into functional neural cells and in particular into functional neurons. Some observations suggest that a cell fusion process underlies the neural fate adoption by MSC in vivo and first attempts to reproduce in vitro this neural fate decision in MSC cultures were unsuccessful. More recently, however, in several laboratories including ours, differentiation of MSC cultivated from adult rat bone marrow into astrocytes and neuron-like cells was demonstrated. More precisely, we stressed the importance of the expression by MSC of nestin, an intermediate filament protein associated with immaturity in the nervous system, as a pre-requisite to adopting an astrocytic or a neuronal fate in a co-culture paradigm. Using this approach, we have also demonstrated that the MSC-derived neuron-like cells exhibit several electrophysiological key properties classically devoted to neurons, including firing of action potentials. In this review, we will discuss the neurogenic potential of MSC, the factor(s) required for such plasticity, the molecular mechanism(s) underlying this neural plasticity, the importance of the environment of MSC to adopt this neural fate and the therapeutic potential of these observations.     

Neural induction of adult bone marrow and umbilical cord stem cells

Recent reports of neural differentiation of postnatally derived bone marrow and umbilical cord cells have transformed our understanding of the biology of cell lineages, differentiation, and plasticity. While much controversy remains, it is clear that adult tissues, and bone marrow in particular, are composed in part of cells with much more diverse lineage capacity than previously thought. Traditionally, cell-based therapies for the CNS have been derived from fetal or embryonic origin. By harnessing the neural potential of readily-available and accessible adult bone marrow and umbilical cord blood stem cells, substantial ethical and technical dilemmas may be circumvented. This review will focus on the potential of adult bone marrow derived cells and umbilical cord blood stem cells for cell replacement and repair therapies of the central nervous system. The various isolation protocols, phenotypic properties, and methods for in vivo and in vitro neural differentiation of mesenchymal stem cells/marrow stromal cells (MSC), hematopoietic stem cells (HSC), multipotent adult progenitor cells (MAPCs), and umbilical cord blood stem cells (UCBSC) will be discussed. Current progress regarding transplant paradigms in various disease models as well as in our understanding of transdifferentiation mechanisms will be presented.     

Extracellular matrix produced by bone marrow stromal cells and by their derivative,SB623 cells,supports neural cell growth

Several studies have shown the benefits of transplanting bone marrow‐derived multipotent mesenchymal stromal cells (MSC) into neurodegenerative lesions of the central nervous system, despite a low engraftment rate and the poor persistence of grafts. It is known that the extracellular matrix (ECM) modulates neuritogenesis and glial growth, but little is known about effects of MSC‐derived ECM on neural cells. In this study, we demonstrate in vitro that the ECM produced by MSC can support neural cell attachment and growth. We also compare the neurosupportive properties of MSC to the MSC derivative, SB623 cells, which is being developed as a cell therapy for stroke. Embryonic rat brain cortical cells cultured for 3 weeks on human MSC‐ and SB623 cell‐derived ECM exhibit about a 1.5 and 3 times higher metabolic activity, respectively, compared with the cultures grown on poly‐D‐lysine (PDL), although the initial neural cell adhesion to cell‐derived ECM and PDL is similar. The MSC‐ and SB623 cell‐derived ECM protects neural cells from nutrient and growth factor deprivation. Under the conditions used, only neurons grow on PDL. In contrast, both MSC‐ and SB623 cell‐derived ECMs support the growth of neurons, astrocytes, and oligodendrocytes, as demonstrated by immunostaining. Morphologically, neurons on cell‐derived ECM form more complex and extended neurite networks than those cultured on PDL. Together, these data indicate that the beneficial effect of MSC and SB623 cells in neurotransplantation could be explained in part by the neurosupportive properties of the ECM produced by these cells. © 2009 Wiley‐Liss, Inc.     

Mesenchymal stromal cell therapy for damaged retinal ganglion cells,is gold all that glitters?

Mesenchymal stromal cells are an excellent source of stem cells because they are isolated from adult tissues or perinatal derivatives, avoiding the ethical concerns that encumber embryonic stem cells. In preclinical models, it has been shown that mesenchymal stromal cells have neuroprotective and immunomodulatory properties, both of which are ideal for central nervous system treatment and repair. Here we will review the current literature on mesenchymal stromal cells, focusing on bone marrow mesenchymal stromal cells, adipose-derived mesenchymal stromal cells and mesenchymal stromal cells from the umbilical cord stroma, i.e.,Wharton's jelly mesenchymal stromal cells. Finally, we will discuss the use of these cells to alleviate retinal ganglion cell degeneration following axonal trauma.     

Mesenchymal stem cell therapy alleviates the neuroinflammation associated with acquired brain injury

Ischemic stroke and traumatic brain injury (TBI) comprise two particularly prevalent and costly examples of acquired brain injury (ABI). Following stroke or TBI, primary cell death and secondary cell death closely model disease progression and worsen outcomes. Mounting evidence indicates that long‐term neuroinflammation extensively exacerbates the secondary deterioration of brain structure and function. Due to their immunomodulatory and regenerative properties, mesenchymal stem cell transplants have emerged as a promising approach to treating this facet of stroke and TBI pathology. In this review, we summarize the classification of cell death in ABI and discuss the prominent role of inflammation. We then consider the efficacy of bone marrow–derived mesenchymal stem/stromal cell (BM‐MSC) transplantation as a therapy for these injuries. Finally, we examine recent laboratory and clinical studies utilizing transplanted BM‐MSCs as antiinflammatory and neurorestorative treatments for stroke and TBI. Clinical trials of BM‐MSC transplants for stroke and TBI support their promising protective and regenerative properties. Future research is needed to allow for better comparison among trials and to elaborate on the emerging area of cell‐based combination treatments.     

Reevaluation of in vitro differentiation protocols for bone marrow stromal cells: disruption of actin cytoskeleton induces rapid morphological changes and mimics neuronal phenotype

Bone marrow stromal cells (MSC), which represent a population of multipotential mesenchymal stem cells, have been reported to undergo rapid and robust transformation into neuron-like phenotypes in vitro following treatment with chemical induction medium including dimethyl sulfoxide (DMSO; Woodbury et al. [2002] J. Neurosci. Res. 96:908). In this study, we confirmed the ability of cultured rat MSC to undergo in vitro osteogenesis, chondrogenesis, and adipogenesis, demonstrating differentiation of these cells to three mesenchymal cell fates. We then evaluated the potential for in vitro neuronal differentiation of these MSC, finding that changes in morphology upon addition of the chemical induction medium were caused by rapid disruption of the actin cytoskeleton. Retraction of the cytoplasm left behind long processes, which, although strikingly resembling neurites, showed essentially no motility and no further elaboration during time-lapse studies. Similar neurite-like processes were induced by treating MSC with DMSO only or with actin filament-depolymerizing agents. Although process formation was accompanied by rapid expression of some neuronal and glial markers, the absence of other essential neuronal proteins pointed toward aberrantly induced gene expression rather than toward a sequence of gene expression as is required for neurogenesis. Moreover, rat dermal fibroblasts responded to neuronal induction by forming similar processes and expressing similar markers. These studies do not rule out the possibility that MSC can differentiate into neurons; however, we do want to caution that in vitro differentiation protocols may have unexpected, misleading effects. A dissection of molecular signaling and commitment events may be necessary to verify the ability of MSC transdifferentiation to neuronal lineages.     

PEX基因修饰骨髓间质干细胞对C6胶质瘤细胞增殖和凋亡的影响

目的探讨PEX基因修饰的骨髓间质干细胞（mesenchymal stem cells,MSC）对C6胶质瘤细胞的作用及机制。方法分子克隆技术构建PEX基因真核表达载体并转染MSC,G418筛选获取稳定表达PEX基因的MSC（MSC-PEX）,将不同数量的MSC-PEX细胞与C6胶质瘤细胞进行共培养试验,用水溶性四氮唑法（WST-1）观察MSC-PEX对C6胶质瘤细胞增殖的影响,用Annexin-Ⅴ-FITC/PI双染荧光观察C6胶质瘤细胞凋亡的形态学变化,并用Annexin-Ⅴ-FITC/PI双标记法通过流式细胞仪检测胶质瘤细胞凋亡率。结果成功获得稳定表达PEX基因的MSC-PEX,MSC-PEX抑制C6胶质瘤细胞的生长作用较明显,Annexin-Ⅴ-FITC/PI双染荧光发现C6胶质瘤细胞发生凋亡形态改变;流式细胞仪检测显示：MSC-PEX转染组和DMEM对照组的凋亡率分别为16.7%和1.3%,差异有统计学意义（P〈0.05）。结论PEX基因修饰的骨髓间质干细胞抑制胶质瘤细胞增殖并诱导其凋亡,为胶质瘤的治疗奠定理论基础。     

肝细胞生长因子基因修饰的骨髓间充质干细胞移植治疗兔股骨头坏死

背景：课题利用实验室自主研制、已获国家SFDA批准临床试验的重组肝细胞生长因子腺病毒感染骨髓间充质干细胞,结合肝细胞生长因子的促血管新生和抗细胞凋亡以及间充质干细胞的成骨功能,通过细胞治疗的手段进行骨损伤修复。 目的：探讨肝细胞生长因子基因修饰的骨髓间充质干细胞移植对兔股骨头坏死骨缺损的治疗效果。 设计、时间及地点：细胞-材料学体内实验,于2007-09/12在北京放射与辐射医学研究所和解放军66400部队骨病专科医院完成。 材料：清洁级26~28周龄新西兰大白兔18只,由北京开源兔业养殖场提供。骨基质明胶为上海骁博科技发展有限公司产品。 方法：采用贴壁法分离培养兔自体骨髓间充质干细胞,体外鉴定成骨和成脂肪能力。18只兔均建立双侧股骨头坏死骨缺损模型,随机分为3组,6只/组,单纯材料组缺损区仅填塞骨基质明胶,细胞-材料组填塞复合骨髓间充质干细胞的骨基质明胶,基因修饰细胞-材料组填塞复合Ad-HGF感染的骨髓间充质干细胞的骨基质明胶,各组细胞用量为 107个/缺损,骨基质明胶用量为27 mm3/缺损,修复3个月后取材进行组织学检查。骨髓间充质干细胞和Ad-HGF感染的骨髓间充质干细胞经荧光染料二醋酸琥珀酰酯羟基荧光素标记后,氯化钴处理72 h,流式细胞学分析细胞增殖情况。 主要观察指标：骨髓间充质干细胞的诱导分化,骨髓间充质干细胞对兔股骨头坏死的修复效果,Ad-HGF感染的骨髓间充质干细胞抗低氧损伤能力。 结果：培养的细胞在适当诱导条件下可分化为成骨和成脂肪细胞。修复后3个月组织学分析显示,单纯材料组仅见疏松的纤维肉芽组织填充;细胞-材料组可见致密的纤维肉芽组织填充,其间有较多的新生血管,但未见新生骨组织;基因修饰细胞-材料组多为软骨样组织填充,周围可见新骨带形成。各组Lane-Sandhu骨组织学评分比较差异有非常显著性意义(P < 0.01),其中基因修饰细胞-材料组评分最高,即Ad-HGF感染的骨髓间充质干细胞具备最佳的骨修复能力。培养体系中加入氯化钴后,已增殖的Ad-HGF感染的骨髓间充质干细胞比例显著高于未感染骨髓间充质干细胞(P < 0.001)。 结论：在骨缺损模型中Ad-HGF感染的骨髓间充质干细胞具有更强的抗低氧损伤能力,其在体内成骨能力优于未感染的骨髓间充质干细胞,提示肝细胞生长因子基因修饰的骨髓间充质干细胞移植是应用于缺血性骨坏死的有效治疗途径。