骨髓间充质干细胞移植治疗对大鼠脑梗死后神经再生抑制因素的影响

目的探讨骨髓间充质干细胞(BMSCs)静脉移植对大鼠脑梗死后Nogo-A、少突胶质细胞髓磷脂糖蛋白(OMgp)和髓磷脂相关糖蛋白(MAG)蛋白的影响。方法实验动物分成假手术组、损伤对照组、溶剂对照组和移植组,各组再分为3d、7d、14d和21d组。全骨髓贴壁法分离培养大鼠BMSCs,线栓法制作大鼠脑梗死模型。移植组自大鼠尾静脉注射BMSCs悬液1ml,溶剂对照组注射磷酸盐缓冲液(PBS)。对各组动物进行神经功能缺损程度评分,免疫组化方法检测Nogo-A、OMgp和MAG的表达水平。结果移植组7、14和21d神经功能恢复优于对照组;移植组术后3、14和21d Nogo-A蛋白表达较对照组降低(P<0.05);移植组7、14和21d OMgp蛋白表达较对照组降低(P<0.05);移植组术后3、7、14和21d MAG蛋白表达较对照组降低(P<0.05)。结论 BMSCs移植可促进大鼠脑梗死后的神经功能恢复,其作用机制与下调Nogo-A、OMgp和MAG的表达有关。     

成人骨髓基质干细胞体外诱导为许旺细胞的实验研究

目的　探索成人骨髓基质干细胞 (h MSCs)诱导分化为许旺细胞 (Schwann cell,SC)的可行性 ,奠定组织工程学治疗周围神经疾病的理论基础。方法　采取 Ficoll-paque梯度离心骨髓 ,分离 h MSCs,经过纯化、扩增培养 ,并证实其细胞来源 ;之后采用 BHA、RA及 Forskolin、b FGF、PDGF、HRG顺次诱导、培养 ,经免疫组化鉴定S-10 0、GFAP的表达状况。结果　经过预诱导剂及诱导剂的先后作用 ,h MSCs的细胞形态发生明显改变 ,胞体呈长梭形 ,两极有丝状突起形成 ,经免疫组化的证实 ,S-10 0、GFAP阳性表达率分别为 (75%± 6.2 % )和 (67%± 4.5% )。结论　 h MSCs经诱导后 ,细胞形态、体积大小均发生明显改变 ,S-10 0、GFAP染色呈阳性 ,符合许旺细胞形态和功能特征 ,证实 h MSCs可以作为种子细胞转化为许旺细胞 ,促进周围神经疾病的愈合     

Initial upregulation of growth factors and inflammatory mediators during nerve regeneration in the presence of cell adhesive peptide-incorporated collagen tubes

Neurotrophic factors play an important modulatory role in axonal sprouting during nerve regeneration involving the proliferation of hematogenous and Schwann cells in damaged tissue. We have exposed lesioned sciatic nerves to a collagen prosthesis with covalently bonded small cell adhesive peptides Arg-Gly-Asp-Ser (RGDS), Lys-Arg-Asp-Ser (KRDS), and Gly-His-Lys (GHK) to study local production of growth factors and cytokines in the regenerating tissues. Western/enzyme-linked immunosorbent assay (ELISA) studies were performed after 10 days of regeneration, when the tubular prosthesis is filled with fibrous matrix infiltrated by hematogenous cells and proliferating Schwann cells with growth factors produced locally. Regeneration was also analyzed by morphometrical methods after 30 days. The quantification of growth factors and proteins by ELISA revealed that there was an enhanced expression of the neurotrophic factors nerve growth factor (NGF) and neurotrophins (NT-3 and NT-4) in the regenerating tissues. This was further established by Western blot to qualitatively analyze the presence of the antigens in the regenerating tissues. Schwann cells were localized in the regenerating tissues using antibodies against S-100 protein. Other growth factors including growth-associated protein 43 (GAP-43), apolipoprotein E (Apo E), and pro-inflammatory cytokine like interleukin-1alpha (IL-1alpha) expression in the peptide groups were evaluated by ELISA and confirmed by Western blotting. Cell adhesive integrins in the proliferating cells were localized using integrin-alpha V. The combined results suggest that the early phase of regeneration of peripheral nerves in the presence of peptide-incorporated collagen tubes results in the enhanced production of trophic factors by the recruited hematogenous cells and Schwann cells, which in turn help in the secretion of certain vital trophic and tropic factors essential for early regeneration. Furthermore, hematogenous cells recruited within the first 10 days of regeneration help in the production of inflammatory mediators like interleukins that in turn stimulate Schwann cells to produce NGF for axonal growth.     

Differentiation of mesenchymal stem cells to support peripheral nerve regeneration in a rat model

Mesenchymal stem cells (MSCs) support axon regeneration across artificial nerve bridges but their differentiative capacity and ability to promote nerve regeneration remains unclear. In this study, MSCs isolated from bone marrow of Sprague–Dawley rats were characterized by plastic adherence and pluripotency towards mesodermal lineages. Isolated undifferentiated MSCs (uMSCs) were stimulated towards a Schwann cell (SC) phenotype using specific growth factors, and cell marker analysis was performed to verify SC phenotype in vitro. Differentiation resulted in temporally dependent positive immunocytochemical staining for the SC markers, glial fibrillary acidic protein (GFAP), S100, and nerve growth factor receptor (NGFR), with maximal marker expression achieved after 6 days of treatment with differentiation media. Quantitative analysis demonstrated that ~ 50% of differentiated MSCs (dMSCs) have a SC phenotype. Using an indirect co-culture system, we compared the ability of dorsal root ganglion (DRG) cells to extend neurites in indirect contact with uMSCs and dMSCs as compared to SCs. The mean values of the longest length of the DRG neurites were the same for the dMSCs and SCs and significantly higher than the uMSC and DRG mono-culture systems (p < 0.05). In vivo, compared to an empty conduit, dMSC seeded collagen nerve conduits resulted in a greater number of sciatic motoneurons regenerating axons through the conduit into the distal nerve stump. We conclude that bone marrow-derived MSCs differentiate into a SC-phenotype that expresses SC markers transiently and sufficiently to support limited neurite outgrowth in vitro and axonal regeneration equivalent to that of SCs in vitro and in vivo. The nerve autograft remains the most effective conduit for supporting regeneration across nerve gaps.     

Synergistic effects of ultrashort wave and bone marrow stromal cells on nerve regeneration with acellular nerve allografts

Acellular nerve allografts (ANA) possess bioactivity and neurite promoting factors in nerve tissue engineering. Previously we reported that low dose ultrashort wave (USW) radiation could enhance the rate and quality of peripheral nerve regeneration with ANA repairing sciatic nerve defects. Meanwhile, ANA implanted with bone marrow stromal cells (BMSCs) exhibited a similar result. Thus, it is interesting to know whether it might yield a synergistic effect when USW radiation is combined with BMSCs‐laden ANA. Here we investigated the effectiveness of ANA seeded with BMSCs, combined with USW therapy on repairing peripheral nerve injuries. Adult male Wistar rats were randomly divided into four groups: Dulbecco's modified Eagle's medium (DMEM) control group, BMSCs‐laden group, ultrashort wave (USW) group and BMSC + USW group. The regenerated nerves were assayed morphologically and functionally, and growth‐promoting factors in the regenerated tissues following USW administration or BMSCs integration were also detected. The results indicated that the combination therapy caused much better beneficial effects evidenced by increased myelinated nerve fiber number, myelin sheath thickness, axon diameter, sciatic function index, nerve conduction velocity, and restoration rate of tibialis anterior wet weight. Moreover, the mRNA levels of brain‐derived neurotrophic factor (BDNF) and vascular endothelial growth factor (VEGF) in the spinal cord and muscles were elevated significantly. In conclusion, we found a synergistic effect of USW radiation and BMSCs treatment on peripheral nerve regeneration, which may help establish novel strategies for repairing peripheral nerve defects. Synapse 67:637–647, 2013 . © 2013 Wiley Periodicals, Inc.     

Human mesenchymal stem cells isolated from olfactory biopsies but not bone enhance CNS myelination in vitro

Spinal cord injury (SCI) is a devastating condition with limited capacity for repair. Cell transplantation is a potential strategy to promote SCI repair with cells from the olfactory system being promising candidates. Although transplants of human olfactory mucosa (OM) are already ongoing in clinical trials, the repair potential of this tissue remains unclear. Previously, we identified mesenchymal‐like stem cells that reside in the lamina propria (LP‐MSCs) of rat and human OM. Little is known about these cells or their interactions with glia such as olfactory ensheathing cells (OECs), which would be co‐transplanted with MSCs from the OM, or endogenous CNS glia such as oligodendrocytes. We have characterized, purified, and assessed the repair potential of human LP‐MSCs by investigating their effect on glial cell biology with specific emphasis on CNS myelination in vitro. Purified LP‐MSCs expressed typical bone marrow MSC (BM‐MSC) markers, formed spheres, were clonogenic and differentiated into bone and fat. LP‐MSC conditioned medium (CM) promoted oligodendrocyte precursor cell (OPC) and OEC proliferation and induced a highly branched morphology. LP‐MSC‐CM treatment caused OEC process extension. Both LP and BM‐MSCs promoted OPC proliferation and differentiation, but only myelinating cultures treated with CM from LP and not BM‐MSCs had a significant increase in myelination. Comparison with fibroblasts and contaminating OM fibroblast like‐cells showed the promyelination effect was LP‐MSC specific. Thus LP‐MSCs harvested from human OM biopsies may be an important candidate for cell transplantation by contributing to the repair of SCI. © 2012 Wiley Periodicals, Inc.     

Bone marrow stromal cells and resorbable collagen guidance tubes enhance sciatic nerve regeneration in mice

We evaluated peripheral nerve regeneration using a tubular nerve guide of resorbable collagen filled with either bone marrow-derived cells (BMDCs) in Dulbecco's cell culture medium (DMEM) or with DMEM alone (control). The control group received just the culture medium (vehicle). The left sciatic nerves of ten isogenic mice were transected and the tubular nerve guides were sutured to the end of the proximal and distal nerve stumps. Motor function was tested at 2, 4 and 6 weeks after surgery using the walking track test. The pawprints were analyzed and the print lengths (PL) were measured to evaluate functional recovery. After 6 weeks, mice were anesthetized, perfused transcardially with fixative containing aldehydes, and the sciatic nerves and tubes were dissected and processed for scanning and transmission electron microscopy. Scanning electron microscopy of the collagen tube revealed that the tube wall became progressively thinner after surgery, proving that the tube can be resorbed in vivo. Quantitative analysis of the regenerating nerves showed that the number of myelinated fibers and the myelin area were significantly increased in the experimental group. Also, motor function recovery was faster in animals that received the cell grafts. These results indicate that the collagen tube filled with BMDCs provided an adequate and favorable environment for the growth and myelination of regenerating axons compared to the collagen tube alone.     

Phenotypic and functional characteristics of mesenchymal stem cells differentiated along a Schwann cell lineage

We have investigated the phenotypic and bioassay characteristics of bone marrow mesenchymal stromal cells (MSCs) differentiated along a Schwann cell lineage using glial growth factor. Expression of the Schwann cell markers S100, P75, and GFAP was determined by immunocytochemical staining and Western blotting. The levels of the stem cell markers Stro-1 and alkaline phosphatase and the neural progenitor marker nestin were also examined throughout the differentiation process. The phenotypic properties of cells differentiated at different passages were also compared. In addition to a phenotypic characterization, the functional ability of differentiated MSCs has been investigated employing a co-culture bioassay with dissociated primary sensory neurons. Following differentiation, MSCs underwent morphological changes similar to those of cultured Schwann cells and stained positively for all three Schwann cell markers. Quantitative Western blot analysis showed that the levels of S100 and P75 protein were significantly elevated upon differentiation. Differentiated MSCs were also found to enhance neurite outgrowth in co-culture with sensory neurons to a level equivalent or superior to that produced by Schwann cells. These findings support the assertion that MSCs can be differentiated into cells that are Schwann cell-like in terms of both phenotype and function.     

骨髓间质干细胞诱导分化为神经细胞的研究进展

骨髓间质干细胞具有较强的自我复制和多向分化能力,近几年发现在一定的条件下,能够诱导分化为神经细胞。由于其具有取材方便,回植后不会发生免疫排斥反应,体外基因转染率高并能稳定高效表达外源基因等优点,将为神经系统疾病的治疗提供新的思路。本文着重对骨髓间质干细胞向神经细胞诱导分化方面的研究进行了综述。     

The interaction of stem cells and vascularity in peripheral nerve regeneration

The degree of nerve regeneration after peripheral nerve injury can be altered by the microenvironment at the site of injury. Stem cells and vascularity are postulated to be a part of a complex pathway that enhances peripheral nerve regeneration; however, their interaction remains unexplored. This review aims to summarize current knowledge on this interaction, including various mechanisms through which trophic factors are promoted by stem cells and angiogenesis. Angiogenesis after nerve injury is stimulated by hypoxia, mediated by vascular endothelial growth factor, resulting in the growth of preexisting vessels into new areas. Modulation of distinct signaling pathways in stem cells can promote angiogenesis by the secretion of various angiogenic factors. Simultaneously, the importance of stem cells in peripheral nerve regeneration relies on their ability to promote myelin formation and their capacity to be influenced by the microenvironment to differentiate into Schwann-like cells. Stem cells can be acquired through various sources that correlate to their differentiation potential, including embryonic stem cells, neural stem cells, and mesenchymal stem cells. Each source of stem cells serves its particular differentiation potential and properties associated with the promotion of revascularization and nerve regeneration. Exosomes are a subtype of extracellular vesicles released from cell types and play an important role in cell-to-cell communication. Exosomes hold promise for future transplantation applications, as these vesicles contain fewer membrane-bound proteins, resulting in lower immunogenicity. This review presents pre-clinical and clinical studies that focus on selecting the ideal type of stem cell and optimizing stem cell delivery methods for potential translation to clinical practice. Future studies integrating stem cell-based therapies with the promotion of angiogenesis may elucidate the synergistic pathways and ultimately enhance nerve regeneration.     

脂肪干细胞诱导神经干细胞分化的体外实验研究

目的研究脂肪干细胞（ADSCs）体外诱导神经干细胞（NSCs）分化的作用。方法从新生BALB／c小鼠中分别分离获得ADSCs及NSCs,进行体外培养和传代。构建ADSCs与NSCs共培养体系,以单纯NSCs组为对照,进行ADSCs诱导分化研究。共培养4、8、12d后行神经元特异性神经丝200免疫组化鉴定,统计NSCs分化为神经元的百分率。结果共培养后8—12d,可见大量成熟神经元,大多为多极神经元,少部分为双极神经元或假单极神经元,带有较长的轴突。共培养组NSCs分化为神经元的百分率大约为21％,而单纯NSCs培养组约为4％。共培养组神经元的转化率与单纯NSCs培养组神经元的转化率之间有显著性差异（P〈0．05）。结论ADSCs在体外能够促进NSCs向神经元转化。     

5-氮胞苷体外诱导骨髓间充质干细胞向心肌样细胞分化：超顺磁性氧化铁颗粒的标记

背景：骨髓间充质干细胞体外经多种诱导剂均可成功转化为心肌样细胞,目前国内外报道中普遍采用的诱导剂为5-氮胞苷。超顺磁性氧化铁颗粒直径小,可被干细胞吞噬,加上其顺磁性可被MRI探测到信号,因而成为目前广泛应用于活体检测干细胞移植的理想示踪剂。 目的：与未经标记的干细胞相比,观察超顺磁性氧化铁颗粒标记方式对干细胞体外经5-氮胞苷诱导向心肌样细胞分化效应的影响。 方法：分离培养猪骨髓间充质干细胞,实验组采用P3代细胞经超顺磁性氧化铁颗粒标记,标记后细胞经5-氮胞苷体外诱导24 h后继续培养,对照组直接经5-氮胞苷诱导。2周后用抗结蛋白、肌球蛋白重链、心肌特异性肌钙蛋白I、连接蛋白43进行免疫细胞化学染色鉴定,经普鲁士蓝染色观察细胞内铁颗粒。 结果与结论：5-氮胞苷诱导分化后细胞表达抗结蛋白、肌球蛋白重链、心肌特异性肌钙蛋白I和连接蛋白43,且超顺磁性氧化铁颗粒标记诱导细胞内普鲁士蓝染色呈阳性。提示超顺磁性氧化铁颗粒标记骨髓间充质干细胞经5-氮胞苷体外诱导后可以分化为心肌样细胞。     

Stimulation of myelin gene expression in vitro and of sciatic nerve remyelination by interleukin-6 receptor-interleukin-6 chimera

Induction of myelin gene expression denotes the last stage of differentiation of myelinating glial cells. Following peripheral nerve transection, Schwann cells (SC) lose myelin gene expression and proliferate, resembling premyelinating embryonic SC (eSC). We show that a fusion protein of the soluble interleukin-6 receptor to interleukin-6 (IL6RIL6), a potent activator of the gp130 signaling receptor, is an inducer of MBP and Po gene products in rat E18 embryonic dorsal root ganglia (DRG) 3 day cultures. Cells whose growth is dependent on the IL6RIL6 chimera were isolated from DRG. These cells (designated CH cells) express Krox-20, as do promyelinating and myelinating SC (mSC). IL6RIL6 induces Po and MBP in CH cells and their cocultures with neurons. In addition, IL6RIL6 leads to a disappearance of Pax-3, a marker of eSC and nonmyelinating Schwann cells (nmSC). Glial fibrillary acidic protein, present in nmSC, is not significantly induced by IL6RIL6. The CH cells acquire glial morphology when exposed to IL6RIL6 and cover axons in cocultures. In a sciatic nerve-derived SC line, IL6RIL6 also induces Po and triggers a rapid attachment along axons. In vivo administration of IL6RIL6 intraperitoneally to rats after sciatic nerve transection and resuture increases 4-fold the number of myelinated nerve fibers (MF) measured on day 12, 2.5-5 mm distal to the suture. The stimulation by IL6RIL6 treatment is highest (7.1-fold) at the more distant 5 mm site, and the thickness of myelin sheaths is increased. Compared to known SC growth factors, the gp130 activator IL6RIL6 appears to combine both in vitro mitogenic effects and promotion of myelin gene expression.     

神经生长因子体外诱导人骨髓间充质干细胞分化为神经元样细胞

目的探讨神经生长因子对人骨髓间充质干细胞(hMSCs)分化成神经元样细胞的影响。方法从正常成人髂骨中获取MSCs,用碱性成纤维生长因子对MSCs进行预诱导24h后,再用浓度为50ng/mL、100ng/mL、150ng/mL、200ng/mL神经生长因子培养基诱导分化,通过形态学观察诱导后的细胞形态变化,并用免疫组织化学法观察不同浓度神经生长因子诱导hMSCs分化为神经元样细胞的阳性率。结果各种浓度的神经生长因子促进了hMSCs分化为神经元样细胞,但分化率有差别,浓度为50ng/mL、100ng/mL、150ng/mL及200ng/mL时的分化率分别为(35.6±4.4)%、(61.9±3.4)%、(57.3±5.7)%和(57.2±4.8)%,比较有显著性差异(F=338.71,P<0.05)。不同浓度的神经生长因子之间有显著性差异,其中50ng/mL组诱导的神经元样细胞数最低(P<0.01),而其他三组间比较差异无显著性意义。结论神经生长因子可以促进hMSC向神经元样细胞分化,而100ng/mL的浓度是较合适的浓度。     

体外诱导人脐带间充质干细胞分化为许旺细胞

背景：人脐带Wharton’s Jelly源间充质干细胞避免了伦理的限制,来源丰富,可以作为种子细胞进行组织修复。 目的：观察体外诱导脐带Wharton’s Jelly中间充质干细胞向许旺细胞分化的可行性。 方法：分离、培养脐带Wharton’s Jelly中间充质干细胞,流式细胞术鉴定细胞表面标志。利用神经细胞培养基、碱性成纤维生长因子、表皮生长因子、维甲酸、血小板源性生长因子等采用两步法将脐带间充质干细胞诱导分化为许旺细胞,倒置显微镜下观察细胞形态变化。利用免疫细胞化学染色法检测巢蛋白、S-100、纤维酸性蛋白的表达,反转录-聚合酶链反应、免疫印记技术检测许旺细胞特异性蛋白产物表达。 结果与结论：脐带细胞培养第7天形态发生变化,部分细胞变成梭形。原代细胞培养10 d左右可达80%~90%融合,细胞呈梭形。分离培养的细胞表达具有间充质干细胞表面特有标志：CD44(91.4%),CD29(91.3%),CD105(99.2%),不表达CD34(0.2%),CD45(0.9%),CD14(0.6%)。脐带Wharton’s Jelly中间充质干细胞经第一阶段诱导后,细胞由短梭形变成长梭形或纺锤形,并出现聚集现象,由形状规则、表面圆滑的球形细胞团形成。第二阶段诱导后,有长梭形细胞从球形细胞团爬出,96 h后细胞形态多为长梭形,伴有多极现象。免疫细胞化学染色结果示：长梭形多极细胞具有许旺细胞特异的纤维酸性蛋白、S100蛋白染色。结果表明脐带Wharton’s Jelly中间充质干细胞可在体外诱导分化为许旺细胞。     

体外诱导获得雪旺细胞的可靠性研究

目的 研究骨髓基质细胞(BMSCs)在体外条件下向周围神经雪旰细胞(SCs)分化的可靠性. 方法 分离提取SD大鼠股骨和胫骨部位BMSCs.利用其贴壁生长的特性.培养纯化,传代扩增.用复合诱导因子(β.巯基乙醇+全反式维甲酸+血小板凝集抑制剂+m小板源性生长因子+碱性成纤维细胞生长因子)在体外诱导BMSCs分化.免疫细胞化学方法 检测P75、S-100及胶质原纤维酸性蛋白(GFAP)的表达,荧光实时定量PCR检测P75、S100及CD104的表达. 结果诱导后的BMSCs形态类似SCs,免疫荧光染色鉴定其具有SCs性质,表达SCs的表面标志物(GFAP、S100和P75).荧光实时定量PCR结果显示诱导后BMSCs S-100、CD104的表达量达到了SCs的表达量水平,但P75的表达量与SCs的表达量水平还有较大差距. 结论 体外诱导BMSCs可部分获得SCs的特征,传代后恢复至未诱导状态,这种预诱导加复合因子诱导的方法 尚待完善.     

骨髓间充质干细胞移植治疗脑出血大鼠的实验研究

目的探讨骨髓间充质干细胞移植对脑出血大鼠的行为和血肿周围神经细胞凋亡的影响。方法全骨髓贴壁法分离培养大鼠骨髓间充质干细胞,使用立体定向纹状体注入胶原酶法制作大鼠脑出血模型。SD大鼠30只,随机分为对照组和移植组(各15只),对照组制作脑出血模型,不移植;移植组制作脑出血模型并于造模后48 h经立体定向脑内注射1×105个干细胞,并于移植后1 d、3 d、5 d、7 d、14 d进行神经功能缺损评分,对照组在相应时间点同样评分,各组再根据时间的不同随机分成五个亚组(每组3只),在相应时间点处死大鼠行免疫组织化学法检测细胞凋亡。结果在移植后1 d、3 d,两组大鼠评分及血肿周围脑组织内凋亡细胞的数量均较高,两组之间无显著性差异。在移植后第5 d、7 d,两组大鼠评分及血肿周围脑组织内凋亡细胞的数量开始下降,移植组下降幅度大于对照组,两组之间差异显著。移植后14 d,两组之间无显著性差异。结论骨髓间充质干细胞移植可明显促进大鼠脑出血后神经功能的恢复,其机制可能与下调血肿周围神经细胞凋亡有关。