骨髓移植治疗Duchenne型肌营养不良模型鼠的实验研究

目的：观察骨髓移植治疗Duchenne型肌营养不良（DMD）模型鼠（mdx鼠）后,骨骼肌中抗肌萎缩蛋白的表达，以及病理、生理和运动功能的变化情况，从而正确评价骨髓移植治疗DMD的疗效。 方法： 以正常C57鼠作为供者，以致死剂量放疗后的mdx鼠作为受者进行骨髓移植，在移植后4个月和6个月分别用荧光免疫组化法观察抗肌萎缩蛋白表达情况，用HE染色观察并计算骨骼肌细胞核中心移位纤维比例（CNF），同时进行mdx鼠腓肠肌电生理检查和运动功能检测。 结果： 骨髓移植后的mdx鼠骨骼肌细胞膜上有部分抗肌萎缩蛋白表达，CNF比例和肌肉湿重下降，mdx鼠的被动运动功能增强。 结论： 骨髓移植后，骨髓干细胞在mdx鼠体内的骨骼肌和骨髓中定居，并分化成可以表达抗肌萎缩蛋白的骨骼肌细胞，使mdx鼠病理、生理得到部分改善，最终导致了肌肉的运动功能的增强。说明骨髓移植治疗DMD是有一定价值的，为临床应用提供实验基础。     

骨髓干细胞移植治疗不同年龄mdx鼠的疗效研究

目的：研究不同年龄的Duchenne型肌营养不良鼠（mdx鼠）与骨髓干细胞移植后缺失蛋白表达的关系。 方法： 获取4-5周C57BL/6小鼠的骨髓干细胞，体外培养3 d，静脉移植到7Gy γ射线预处理的6周龄、8周龄两组各6只mdx鼠。移植12周后，对移植鼠骨骼肌dystrophin蛋白表达情况进行检测。 结果： 6周龄、8周龄两组mdx鼠，静脉移植1.2×107骨髓干细胞，3个月后，分别有16%和7%的骨骼肌纤维表达了dystrophin蛋白。 结论： 静脉移植同种、同系鼠骨髓干细胞的mdx鼠，3个月之后, 不同年龄mdx鼠骨骼肌细胞dystrophin蛋白表达的阳性率不同，幼年鼠骨髓干细胞移植有较高比率的缺失蛋白表达。     

成肌细胞移植阻止mdx鼠运动诱导的肌损害

目的:观察过量运动对肌营养不良症模型鼠(mdx鼠)骨骼肌的损害作用,以及成肌细胞移植对运动诱导损害肌纤维的保护作用。方法: 采用分离消化法对C57新生鼠的成肌细胞进行体外培养、纯化鉴定后,肌肉注射到mdx鼠左后肢,右后肢肌注DMEM作对照。成肌细胞移植后1个月,让mdx鼠作运动试验3 d后,静脉注射Evans蓝,次日取骨骼肌作冰冻切片,行dystrophin免疫荧光检测。荧光显微镜下,观察Evans蓝和dystrophin阳性纤维数,图像分析比较。 结果: 未移植肢体有26.82%±14.85%的肌纤维显示Evans蓝染色,而移植侧骨骼肌只有10.37%±2.87%的肌纤维显示Evans蓝染色。两者相比有显著差异(P＜0.05)。移植侧肢体有48.32%±6.54%的肌纤维dystrophin阳性,对照侧几乎没有dystrophin阳性肌纤维。Evans蓝染部分没有dystrophin表达。结论: 成肌细胞移植对运动诱导损害的肌纤维具有防护作用。     

In vivo fusion of circulating fluorescent cells with dystrophin-deficient myofibers results in extensive sarcoplasmic fluorescence expression but limited dystrophin sarcolemmal expression

To investigate the therapeutic potential of bone marrow transplantation in Duchenne muscular dystrophy, green fluorescent protein-positive (GFP+) bone marrow cells were transplanted into irradiated wild-type and dystrophin-deficient mdx mice. Tibialis anterior muscles showed fivefold to sixfold more GFP+ mononucleated cells and threefold to fourfold more GFP+ myofibers in mdx than in wild-type mice. In contrast, dystrophin expression in mdx mice remained within the level of nontransplanted mdx mice, and co-expression with GFP was rare. Longitudinal sections of 5000 myofibers showed 160 GFP+ fibers, including 9 that co-expressed dystrophin. GFP was always visualized as full-length sarcoplasmic fluorescence that exceeded the span of sample length (up to 1500 microm), whereas dystrophin expression was restricted to 11 to 28% of this length. Dystrophin expression span was much shorter in GFP+ fibers (116 +/- 46 microm) than in revertant fibers (654 +/- 409 microm). These data suggest that soluble GFP diffuses far from the fusion site with a pre-existing dystrophin(-) myofiber whereas dystrophin remains mainly expressed close to the site of fusion. Because restoration of dystrophin in whole muscle fiber length is required to expect functional improvement and clinical benefits for Duchenne muscular dystrophy, future applications of cell therapies to neuromuscular disorders could be more appropriately envisaged for replacement of defective soluble sarcoplasmic proteins.     

人骨髓胎儿间充质干细胞在小鼠体内的分化

目的：探讨人骨髓胎儿间充质干细胞（ hfMSC）的特性及其在X染色体- 连锁肌萎缩（ mdx）小鼠体内分 化的可能性。 方法：从胎儿骨髓中分离扩增hfMSC,检测hfMSC Oct-4 和Nanog-3 的表达。经DIR 标记后注射 hfMSC 到mdx小鼠腹股沟三角皮下,采用活体成像法观察小鼠离体后肢肌肉植入细胞的存活状态,观察是否出 现畸胎瘤,并采用免疫荧光染色法检测dystrophin 的表达。结果：从胎儿骨髓中分离到表达Oct-4 和Nanog-3 的 hfMSC。在注射hfMSC 的mdx小鼠离体后肢肌肉中检测到明显的荧光信号,并在肌肉组织中检测到人dystrophin 的 表达,而没有发现畸胎瘤的出现。结论： hfMSC 表达多潜能抗原标志Oct-4 和Nanog-3,hfMSC 在mdx小鼠体内可 以产生dystrophin,且不会形成畸胎瘤。     

骨髓间充质干细胞移植治疗失神经肌萎缩

背景:外科显微镜手术和一些辅助治疗方法均无法通过修复损伤的神经细胞来有效延缓或治疗失神经肌萎缩。研究发现骨髓间充质干细胞具有定向分化潜能,并且在一定环境因素下能对损伤的组织进行修复,由此推测其可以对失神经萎缩肌肉起到一定的修复作用。目的:探讨移植骨髓间充质干细胞是否能够减轻和延缓失神经肌肉组织萎缩。方法:分离培养SD大鼠骨髓间充质干细胞,取第3代骨髓间充质干细胞经BrdU标记后用于移植治疗。将30只SD大鼠分为3组,每组10只,对每只大鼠左后肢进行手术。假手术组只暴露坐骨神经主干,不钳夹神经,移植治疗组、模型对照组钳夹坐骨神经主干后,向其支配的腓肠肌注射骨髓间充质干细胞悬液和不含胎牛血清的DMEM培养液。骨髓间充质干细胞移植后1,2周,采用BBB评分评价各组大鼠左后肢运动功能;骨髓间充质干细胞移植后14 d,取腓肠肌组织进行苏木精-伊红染色和BrdU免疫组化染色。结果与结论:第3代骨髓间充质干细胞BrdU标记为阳性;标记的骨髓间充质干细胞能在移植治疗组失神经损伤的肌肉组织中存活并起修复作用;相对于模型对照组,移植治疗组失神经肌纤维由相互融合重新恢复规整。结果表明移植骨髓间充质干细胞能够减轻和延缓失神经肌肉组织萎缩。     

骨髓间质干细胞移植治疗假肥大型肌营养不良症模型鼠后运动功能的改善

目的:观察骨髓间质干细胞(MSC)移植治疗假肥大型肌营养不良症(DMD)动物模型dko鼠后运动功能的改善情况。方法:用体外培养传代扩增纯化的第5代(P5)MSC经鼠尾静脉移植治疗dko鼠,在细胞移植治疗后15周分别对实验组与对照组dko鼠进行牵引、转棒、转轮、倒挂、翻身、走步的一系列运动功能测试观察(录像记录),并取dko鼠后肢腓肠肌组织做荧光免疫组化检测抗肌萎缩蛋白(dystrophin/utrophin)的表达,计算阳性肌纤维的平均吸光度值并进行统计学分析。 结果:传3代以上呈集落生长的MSC均一性好,静脉移植免疫反应低,移植后15周实验组dko鼠肌膜组织有dystrophin/utrophin免疫荧光表达,而对照组则无免疫荧光表达,两组有显著差异(P＜0.05);MSC移植后15周实验组dko鼠的系列运动功能测试均显著优于对照鼠(P＜0.05)。 结论:MSC移植对dko鼠肌萎缩组织有一定的修复与再生作用,并能改善DMD模型鼠的主动与被动运动功能。     

Xenotransplantation of Embryonic Precursors of Human Myogenesis for the Correction of Dystrophinopathy in Mice with Hereditary Muscular Dystrophy

Human embryonic myogenic precursors were transplanted into muscles of mdx mice with hereditary dystrophin-deficient muscular dystrophy. Transplantation induced the synthesis of human dystrophin. The number of dystrophin-positive fibers progressively decreased, however, some of them were preserved even 5 months after transplantation. Our results indicate that xenogeneic transplantation of embryonic myogenic precursors compensates the genetic defect in dystrophin-deficient mice.     

骨髓间充质干细胞移植治疗mdx鼠：3个月疗效

背景：干细胞移植治疗肌营养不良症是目前的研究热点,相对造血干细胞移植,间充质干细胞移植风险较小。 目的：观察骨髓间充质干细胞移植治疗Duchenne型肌营养不良鼠(mdx鼠)的疗效。 方法：4周龄mdx鼠16只,随机分为治疗组与对照组,每组8只,经静脉移植及肌肉局部注射C57BL/6小鼠的骨髓间充质干细胞或等量生理盐水。 结果与结论：移植3个月后,治疗组较对照组血清肌酸激酶水平下降,骨骼肌肌膜部分有dystrophin蛋白表达,而对照组检测不到dystrophin蛋白表达。但是两组的运动功能无明显改善。结果初步表明骨髓间充质干细胞移植对mdx鼠有一定的治疗作用,可能使肌细胞膜破坏减少,延缓病情发展。     

含人AGM区、胎肝及骨髓基质细胞培养体系程序化诱导小鼠胚胎干细胞向造血干细胞的分化

背景：前期已分别制备人主动脉-性腺-中肾区基质细胞系及胎肝基质细胞系,发现前者可促进小鼠胚胎干细胞定向分化为造血干细胞。 目的：模拟胚胎发育过程中永久造血发育的时空顺序,探讨人主动脉-性腺-中肾(AGM)区、胎肝(FL)及骨髓(BM)基质细胞对小鼠胚胎干细胞体外诱导分化为造血干细胞的支持作用,以寻求更佳的诱导条件。 方法：将小鼠E14胚胎干细胞诱导为拟胚体(EB),并利用Transwell非接触共培养体系依次在人主动脉-性腺-中肾区、胎肝及骨髓基质细胞饲养层上进一步诱导分化,按不同诱导阶段分为拟胚体对照、EB/AGM、EB/AGM+FL和EB/AGM+FL+BM共4组。共培养6 d后分别收获各组拟胚体来源细胞,以流式细胞仪检测Sca-1+c-Kit+细胞含量,进行各系造血细胞集落形成单位分析并观察细胞形态。 结果与结论：①EB/AGM+FL组和EB/AGM+FL+BM组收获细胞涂片均发现原始造血细胞。②拟胚体来源细胞经AGM区基质细胞诱导后Sca-1+c-Kit+ 细胞明显升高(P < 0.05)。③拟胚体对照组造血细胞集落形成单位低于其他各组(P < 0.05), 而EB/AGM+FL、EB/AGM+FL+BM组造血细胞集落形成单位计数亦较EB/AGM组明显增高。提示AGM+FL和AGM+FL+骨髓基质细胞微环境对原始造血干细胞的扩增效应均明显高于单纯主动脉-性腺-中肾饲养层。     

Two different roles of purified CD45+c-Kit+Sca-1+Lin- cells after transplantation in muscles

Recent studies have indicated that bone marrow cells can regenerate damaged muscles and that they can adopt phenotypes of other cells by cell fusion. Our direct visualization system gave evidence of massive muscle regeneration by green fluorescent protein (GFP)-labeled CD45+c-Kit+Sca-1+Lin- cells (KSL cells), and we investigated the role of KSL cells in muscle regeneration after transplantation with or without lethal irradiation. In the early phase, GFP signals were clearly observed in all the muscles of only irradiated mice. Transverse cryostat sections showed GFP+myosin+ muscle fibers, along with numerous GFP+ hematopoietic cells in damaged muscle. These phenomena were temporary, and GFP signals had dramatically reduced 30 days after transplantation. After 6 months, GFP+ fibers could hardly be detected, but GFP+c-Met+ mononuclear cells were located beneath the basal lamina where satellite cells usually exist in both conditioned mice. Immunostaining of isolated single fibers revealed GFP+PAX7+, GFP+MyoD+, and GFP+Myf5+ satellite-like cells on the fibers. Single-fiber cultures from these mice showed proliferation of GFP+ fibers. These results indicate two different roles of KSL cells: one leading to regeneration of damaged muscles in the early phase and the other to conversion into satellite cells in the late phase.     

Cardiotropic effect of extracardiac transplantation of embryonic human myoblasts to mice with bradycardia: Various effects of cell material

Animals with bradycardia were detected in reproductive colony of mdx mice. Low pulse rate was associated with poor survival and predisposition to sudden death, but did not directly depend on the presence of dystrophin mutant gene or animal age. Heart rate increased in old mice with bradycardia after extracardial, intramuscular, and intravenous injection of human embryonic myoblasts. Stable normalization of the pulse was observed 2 weeks after transplantation, but early peak of heart rate was observed as early as 24 h after cell transplantation. Cell suspensions, which could contain stem cells (blood mononuclears and CD34⁺ lymphocytes), also corrected heart rhythm. Unlike the effect of myoblasts, cardiotropic effect of mononuclears was preceded by a period of tachycardia, while the effect of CD34⁺ lymphocytes was very unstable. The cardiotropic effect of myoblasts was combined with life span prolongation and certain “rejuvenation” in some animals. Erythrocytes and supernatant obtained during blood cell fractionation did not modify the heart rhythm in mice with bradycardia. After injection of myoblasts to mice with rare and normal pulses serum creatine kinase activity decreased with different rates. These data attest to a variety of biological effects of stem cells and/or their derivatives and to ambiguous mechanisms of these effects.__________This revised version was published online in July 2005 with the addition of the issue title and article categoryTranslated from Kletochnye Tekhnologii v Biologii i Meditsine, Vol. 1, No. 1, pp. 29–33, January, 2005     

Experimental aspects of transplantation of haemopoietic cells of fetal liver

About 25% mice treated for radiation-induced bone marrow aplasia with allogeneic transplantation of histoincompatible fetal liver cells survived four months. The same survival time was observed in 80% of mice after transplantation of syngeneic fetal liver cells. Mice irradiated and not treated and those receiving transplants of allogeneic histoincompatible bone marrow died within a few weeks after transplantation. This observation confirms the reports on the therapeutic superiority of transplantation of haemopoietic fetal liver cells over transplantation of bone marrow of similar tissue incompatibility and reports on the usefulness of tissue matching, if possible. Another observation was an absence of inactivation of the haemopoietic stem cells in mixtures of genotypically different fetal liver cells. The animals receiving these cell mixtures showed survival rates similar to those of the animals receiving genetically homogenous cells. This opens theoretical possibilities for undertaking clinical trials of transplantation of cells from several fetal livers, especially in view of the accumulating reports that one human fetal liver may be too small to serve as a source of stem cells for ensuring successful transplantation.     

Angiogenesis after Transplantation of Auto- and Allogenic Cells

Neoangiogenesis after transplantation of auto- and allogenic mononuclears and multipotent stromal cells from the bone marrow was studied on the model of inflammatory angiogenesis. Transplanted auto- and allogenic cells stimulate the formation of new blood vessels in the granulation tissue, this manifesting in an increase in the quantity and volume density of blood vessels. The most pronounced angiogenesis was observed after transplantation of allogenic mononuclears and multipotent stromal cells. It was associated with intense inflammatory infiltration, with less numerous and mature collagen fibers in the granulation tissue. Injection of allogenic cells led to stimulation and chronization of inflammation, infiltration with inflammatory and poorly differentiated cells, and more pronounced and lasting angiogenesis. However, neither auto-, nor allogenic transplanted labeled cells were detected in the walls of new blood vessels. Hence, it seems that bone marrow mononuclears and multipotent stromal cells stimulated angiogenesis mainly at the expense of production of angiogenic factors, and after transplantation of allogenic cells also by stimulating the inflammation.     

脂肪干细胞移植对Duchenne型肌营养不良症鼠神经肌肉再生单位的影响

背景：目前,Duchenne型肌营养不良症尚无有效治疗方法,之前的研究表明基因治疗和干细胞移植治疗是可能的“治愈”方法。实验拟将两者结合起来,在动物模型上观察其疗效,并验证之前提出的神经肌肉再生单位的假说。 目的：探讨脂肪干细胞移植治疗Duchenne型肌营养不良症的有效性和可行性,观察细胞移植对肌纤维、新生血管及神经末梢的影响。 方法：体外分离培养mdx鼠脂肪干细胞,经杆状病毒基因载体进行基因修饰,用于移植治疗Duchenne型肌营养不良症模型鼠。移植后检测实验动物的血清肌酸激酶水平、肌肉病理改变及肌肉内dystrophin表达;免疫荧光检测细胞移植后血管、肌肉和神经再生情况。 结果与结论：细胞移植后,能够重建模型鼠的dystrophin表达,一定程度上减轻并逆转肌肉的病理损害,进而降低血清激酸激酶水平;此外,细胞移植后能够形成干细胞来源的肌纤维、血管内皮细胞和神经末梢。这些证据表明,脂肪干细胞移植是有希望治疗Duchenne型肌营养不良症的方法之一。     

Dystrophin is expressed in mdx skeletal muscle fibers after normal myoblast implantation.

In mdx mice, the dystrophin gene of the X chromosome is defective and, as a result, immunoreactive dystrophin is undetectable in all muscle fibers of all animals of this highly inbred strain. This study showed that implantation of suspensions of clonal cultures of normal human myoblasts into different regions of quadriceps muscles of 6-to-10-day-old mdx mice or 60-day-old mdx mice (whose muscles have been crushed 4 days before implantation) results in the appearance of scattered fiber segments containing microscopically demonstrable immunoreactive dystrophin. In the animals that received the normal myoblast implantation in the prenecrotic stage of the disease (6 to 10 days of age), the dystrophin-positive fiber segments (demonstrated at ages 35, 45, and 60 days) escaped necrosis. This was determined by the absence of the characteristic chains of central nuclei, a reliable marker of prior necrosis in mdx muscle fibers. By heavy labeling of the nuclear DNA of the transplantable human myoblasts with H3-thymidine during culturing, and by sequential performance of an immunocytochemical staining for dystrophin and autoradiography on the same sections, some dystrophin-positive fiber segments were shown to contain radiolabeled myonuclei. It was concluded that nondystrophic myoblasts fused with host muscle fibers to form mosaic muscle fibers in which the normal dystrophin gene of the implanted myoblasts was expressed. This approach may be employed for the mitigation of the deleterious consequences of a gene defect in recessively inherited human muscle diseases such as Duchenne dystrophy.     

Pro- and anti-apoptotic members of the Bcl-2 family in skeletal muscle: a distinct role for Bcl-2 in later stages of myogenesis.

Apoptotic myonuclei appear during myogenesis and in diseased muscles. To investigate cell death regulation in skeletal muscle, we examined how members of the Bcl-2 family of apoptosis regulators are expressed and function in the C2C12 muscle cell line and in primary muscle cells at different stages of development. Both anti-apoptotic (Bcl-W, Bcl-X(L)) and pro-apoptotic (Bad, Bak, Bax) members of the Bcl-2 family were expressed in developing skeletal muscle in vivo. Each was also expressed in embryonic (E11-12), fetal (E15-16), and neonatal muscle stem cells, myoblasts, and myotubes in vitro. In contrast, Bcl-2 expression was limited to a small group of mononucleate, desmin-positive, myogenin-negative muscle cells that were seen in fetal and neonatal, but not embryonic, muscle cell cultures. The cell surface protein Sca-1, which is associated with muscle and blood stem cells, was found on approximately 1/2 of these Bcl-2-positive cells. Loss of Bcl-2 did not affect expression of other family members, because neonatal muscles of wild-type and Bcl-2-null mice had similar amounts of Bcl-X(L), Bcl-W, Bad, Bak, and Bax mRNAs. Loss of Bcl-2 did have functional consequences; however, because neonatal muscles of Bcl-2-null mice had only approximately 2/3 as many fast muscle fibers as muscles in wild-type mice. Thus, Bcl-2 function is required for particular stages of fetal and postnatal myogenesis.     

Acceleration of Immune Reconstitution after Bone Marrow Transplantation in Mice by Bone Marrow Stromal

To observe potential effect of the engineered bone marrow stromal cell line QXMSC1 secreting IL-6 (QXMSCIL-6) on accelerating immnune reconstitution in syngeneic bone marrow transplantation in mice, QXMSC1 was transfected with the eukaryocytic expression vector pcDNAIL-6, which contained hIL-6 cDNA by liposome-mediated gene transfecting technique. G418-resistance clone was selected by limiting dilution. The highest secreting clone was selected by ELISA assay and used in animal experiments. The recipient mice (BALB/c) were lethally irradiated and cotransplanted syngeneic bone marrow (10^7/mice) and the QXMSCIIL-6 (5&#215;10^5/mice). Lymphocyte proliferation induced by ConA and LPS, helper T lymphocyte precursor (HTLp), cytotoxic T lymphocyte precursor (CTLp), plaque-forming cell (PFC), delayed type hypersensitivity (DTH) were examined 30, 60 days in post transplantation respectively. The results showed that lymphocytes proliferation to ConA and LPS, HTLp, CTLp increased, DTH and PFC were improved by cografted stromal cells QXMSCIIL-6 on 30, 60 days after BMT. These results demonstrated that the bone marrow stromal cell line QXMSC1 IL-6 transfected with IL-6 (QXMSC11L-6) accelerated immnune reconstitution in syngeneic bone marrow transplantation.     

Mesenchymal Bone Marrow Stem Cells More Effectively Stimulate Regeneration of Deep Burn Wounds than Embryonic Fibroblasts

Regeneration of deep burn wounds after transplantation of allogenic and autogenic fibroblast-like bone marrow mesenchymal stem cells and embryonic fibroblasts on burn surface was studied in 40 Wistar rats. Transplantation of allogenic and autogenic fibroblast-like bone marrow mesenchymal stem cells and transplantation of embryonic fibroblasts decreased cell infiltration of the wound and accelerated the formation of new vessels and granulation tissue in the wound in comparison with the control (burn wounds without cell transplantation). Regeneration processes were most active after transplantation of fibroblast-like bone marrow mesenchymal stem cells, in particular, autogenic cells, which was confirmed by more rapid decrease in burn surface area. Wound healing after transplantation of fibroblast-like bone marrow mesenchymal cells and embryonic fibroblasts was associated with long functioning of transplanted cells (as was shown by staining for -galactosidase, the cells were transfected with an adenovirus vector carrying the marker gene). It is hypothesized that more rapid regeneration of burn wounds after transplantation of fibroblast-like bone marrow mesenchymal stem cells was due to low differentiation of these cells in comparison with embryonic fibroblasts.