骨骼肌卫星细胞移植到大鼠体内生长发育的初步研究

目的探讨胶体金标记方法的可行性以及卫星细胞移植到正常大鼠左心室心肌后的生长分化情况.方法将胶体金标记的骨骼肌卫星细胞移植到正常大鼠心肌中,用免疫组化、共聚焦免疫荧光双标染色及透射电镜多种方法观察卫星细胞的增殖分化情况.结果移植细胞可以在宿主心肌中生长分化.在移植后1月,有多核的肌管和骨骼肌纤维形成,但移植细胞与心肌细胞之间未见连接.结论胶体金标记方法适用于光镜、电镜研究.卫星细胞移植到正常大鼠左心室心肌后能够增殖分化为骨骼肌纤维,但没有与宿主心肌产生连接.     

bFGF基因修饰骨骼肌卫星细胞移植对心肌梗死兔心功能的影响

目的:观察bFGF基因修饰骨骼肌卫星细胞在心肌梗死区存活情况以及对心功能的影响。方法:分离培养兔骨骼肌卫星细胞,构建bFGF基因修饰骨骼肌卫星细胞。建立急性心肌梗死兔模型,随机分为骨骼肌卫星细胞组、bFGF基因修饰骨骼肌卫星细胞组和对照组,每组6只,在各组动物梗死心肌内分别注射骨骼肌卫星细胞、bFGF基因修饰骨骼肌卫星细胞及等量的细胞培养液。造模前及细胞移植4周后,心脏超声测定兔左室舒张末期内径(LVEDD)、左室收缩末期内径(LVESD)、短轴缩短率(FS)和射血分数(EF),观察移植4周后心脏病理切片中心肌梗死边缘区骨骼肌卫星细胞存活情况、bFGF表达情况及新生血管形成情况。结果:细胞移植4周后病理学检查提示骨骼肌卫星细胞在心肌梗死边缘区存活,bFGF基因修饰骨骼肌卫星细胞组可见大量EGFPbFGF融合蛋白表达。与对照组相比,骨骼肌卫星细胞组和bFGF基因修饰骨骼肌卫星细胞组心肌梗死边缘区微血管密度均有增加(78.3±5.2和98.5±8.6对25.2±4.6,P均0.05),且bFGF基因修饰骨骼肌卫星细胞组微血管密度较骨骼肌卫星细胞组明显增加(P0.05)。与造模前相比,移植4周后对照组和骨骼肌卫星细胞组均出现LVESD和LVEDD增大,FS和EF降低(P均0.05),bFGF基因修饰骨骼肌卫星细胞组各指标与造模前相比差异无统计学意义。移植4周后,骨骼肌卫星细胞组和bFGF基因修饰骨骼肌卫星细胞组LVESD及LVEDD均小于对照组,FS和EF均高于对照组(P均0.05);与骨骼肌卫星细胞组相比,bFGF基因修饰骨骼肌卫星细胞组LVESD及LVEDD减小,FS和EF升高(P均0.05)。结论:bFGF基因修饰骨骼肌卫星细胞自体移植可增加急性心肌梗死兔心肌梗死边缘区新生血管形成,改善心功能。     

小鼠骨髓基质细胞参与缺血组织血管再生及时相关系

目的探讨体外培养的骨髓基质细胞体内移植后在缺血区新血管生成中的作用及其时相关系.方法分离5～6周龄的小鼠胫骨、股骨,用预冷的DMEM/F12培养基冲洗出骨髓,经密度梯度离心分离出骨髓单个核细胞体外培养.体外成内皮细胞诱导分化鉴定分离的细胞,建立下肢缺血模型,荧光标记的体外扩增的骨髓基质细胞移植入左侧缺血组织,右侧注射等量培养介质作为对照组,分为7d、14d、28d 3个观察期(n=6),冰冻切片荧光显微镜观察,毗邻切片HE及vWF染色,检查荧光阳性细胞与染色阳性细胞的时空关系,并计算移植前后毛细血管密度的变化.结果体外分离培养的骨髓基质细胞在成内皮细胞供及物存在条件下表达vWF,并分泌NO.移植后7d,观察到大量分散开来的DAPI标记细胞存活(蓝色荧光),毗邻切片HE染色显示了高密度HE染色阳性区和荧光阳性区的一致性,MSC来源的供体细胞核浆比大,提示是较幼稚细胞,移植区未见明显炎症反应.移植后14d,组织切片可见大量荧光标记细胞存活,呈与骨骼肌直径大小相似的网状散在分布,对照组未见荧光,在毗邻的切片,大部分荧光阳性细胞vwF因子染色阳性,毗邻切片的HE染色,细胞移植组骨骼肌纤维未见明显异常,而对照组骨骼肌可见部分肌纤维变性.移植的28d,移植组毛细胞血管数量为(57±18)mm2,对照组为(36±12)mm2,移植组高于对照组(P＜0.05).结论体外培养的骨髓基质细胞在体外能够定向分化为血管内皮细胞,移植入体内缺血区能促进缺血区新血管生成,可望用作组织缺血细胞治疗的种子细胞.     

骨髓基质细胞的血管新生作用及对心功能的影响

目的　观察骨髓基质细胞在缺血心肌内诱导血管新生的作用及对心功能的影响。方法　复制兔心肌梗死动物模型 ,3d后将体外分离扩增的自体骨髓基质细胞用荧光标记物DAPI标记后移植到梗死周围缺血区心肌 (细胞移植组 ,n =8) ,对照组注射等量培养基 (n =6 )。 4W后 ,先进行心脏超声检查分别测定对照组和细胞移植组左室射血分数 (EF)和短轴缩短率 (FS) ,然后采集移植区心肌标本 ,用荧光示踪方法观察移植细胞在缺血坏死区心肌存活的情况 ,用CD31单克隆抗体免疫组化染色法测定毛细血管密度。结果　细胞移植组心肌组织和小血管内壁均可见蓝色荧光的DAPI标记的移植细胞 ;细胞移植组心肌毛细血管密度显著高于对照组 [(16 3 0 0± 2 5 85 )vs (96 0 0± 16 6 1) ,P <0 0 5 ];细胞移植组EF较对照组增高 [(0 5 0± 0 0 3)vs(0 4 6± 0 0 3) ,P <0 0 5 ],短轴缩短率FS也高于对照组[(2 7 0 2± 1 2 7)vs (2 3 85± 1 6 9) ,P <0 0 5 ]。结论　体外扩增的骨髓基质细胞可在缺心肌内存活 ,并能促进缺血组织血管新生、改善心功能。     

自体内皮祖细胞移植修复兔动脉内皮损伤

目的观察不同数量的内皮祖细胞移植对内膜球囊损伤血管修复的影响。方法密度梯度离心法分离兔外周血单个核细胞,以EGM-2培养基培养7天,获得兔外周血内皮祖细胞。分高细胞数量移植组(5×105个细胞)和低细胞数量移植组(2×105个细胞),将相应数量的内皮祖细胞重悬于100μL生理盐水中移植至兔内膜球囊损伤血管局部,对照组仅注入100μL生理盐水。同时用CM-DiI标记内皮祖细胞移植,进行细胞示踪。4周后,处死动物,荧光显微镜下观察CM-DiI标记细胞的分布,并测量各组内膜损伤血管再生内皮覆盖率和新生内膜增生程度。结果荧光显微镜下发现荧光标记的内皮祖细胞分布在血管的中膜层、新生内膜层和内膜表面。内皮祖细胞移植可显著促进内膜损伤血管的再内皮化,以高细胞数量移植组为著,同时内皮祖细胞移植也大大减少了新生内膜的形成。结论内皮祖细胞移植可修复内膜球囊损伤血管,高细胞数量移植有更显著的效果。     

PKH26荧光示踪剂在小鼠骨髓单个核细胞肝内迁移过程中标记作用的研究

目的 探讨PKH26荧光示踪剂在小鼠骨髓单个核细胞肝内迁移过程中的标记作用。方法以红色荧光染料PKH26标记从小鼠骨髓中分离出的骨髓单个核细胞，从小鼠的尾静脉注入CCIA—AAF造成肝损伤的同种异体的小鼠体内，移植2周后取肝组织，通过荧光显微镜观察实验组小鼠骨髓干细胞向肝脏迁移的情况。结果受体组小鼠的肝小叶中央静脉及汇管区均可见新生的PKH26标记阳性的肝细胞。结论PKH26可用于标记向急性肝损伤小鼠肝脏迁移的骨髓单个核细胞。     

大鼠成体干细胞食管下段移植的实验研究

目的研究成体干细胞注射至食管下段的可行性，探索利用成体干细胞[骨骼肌卫星细胞（SC）和骨髓间充质干细胞（MSC）]移植治疗胃食管反流病（GERD）的新方法。方法选取体质量160～240g的Wistar大鼠，雌雄各半，不同实验组分别于体外培养并扩增骨骼肌SC或MSC，5-溴-2-脱氧尿嘧啶核苷（BrdU）标记后，经腹腔将大鼠自体骨骼肌SC悬液植入食管下段肌层；MSC悬液植入同种异体大鼠食管下段肌层。1周和4周后分批处死动物，取食管下段组织并使用组织学方法评价植入细胞生长分化情况。结果BrdU的细胞标记率接近100％。接受干细胞移植的大鼠生长良好。干细胞移植后第1周和第4周，SC组和MSC组大鼠食管下段均可见大量分化为骨骼肌细胞的BrdU阳性细胞，SC组第4周较第1周BrdU阳性细胞核数显著增多（P〈0．01）。MSC组第4周较第1周BrdU阳性细胞核计数增多，但差异无统计学意义（P〉0．05）。SC组与MSC组比较，第1周BrdU阳性细胞核数差异无统计学意义（P〉0．05），第4周SC组较MSC组显著增多（P〈0．05）。注射局部未见炎症反应，与对照组病理学分析无差异。结论成体干细胞移植至大鼠食管下段安全、可行，能在食管下段长期存活并分化为骨骼肌。骨骼肌SC或MSC移植可能成为治疗GERD的新方法。     

小鼠骨髓基质细胞成内皮细胞分化及其缺血区存活能力研究

目的探讨体外培养的骨髓基质细胞的部分生物学特性、成内皮细胞分化能力及在缺血区存活能力。方法2005年1月至11月,第三军医大学新桥医院全军心血管内科中心分离5~6周龄的小鼠胫骨、股骨,预冷的DMEM/F12培养基冲洗出骨髓,密度梯度离心分离出骨髓单核细胞,接种后12~16d形成单层贴壁的成纤维样细胞。体外诱导分化鉴定分离的细胞。建立下肢缺血模型,荧光标记的体外扩增的骨髓基质细胞被移植入缺血组织,移植后1周,荧光显微镜及HE染色,检查荧光强弱分布与HE染色密度的时空关系。结果体外传代培养的基质细胞诱导后分泌NO,移植1周在缺血区检测到大量荧光阳性细胞存活。结论在本实验条件下,体外培养的骨髓基质细胞生长稳定,传代后的细胞增殖较快,表现出较早期细胞特点,在体外能分化为血管内皮细胞,可望用作缺血性心脏病的细胞治疗的供体细胞。     

小鼠骨髓基质细胞成内皮细胞分化及其缺血区存活能力研究

目的 探讨体外培养的骨髓基质细胞的部分生物学特性、成内皮细胞分化能力及在缺血区存活能力？方法 2005年1月至11月，第三军医大学新桥医院全军心血管内科中心分离5～6周龄的小鼠胫骨、股骨，预冷的DMEM／F12培养基冲洗出骨髓，密度梯度离心分离出骨髓单核细胞，接种后12～16d形成单层贴壁的成纤维样细胞：体外诱导分化鉴定分离的细胞：建立下肢缺血模型，荧光标记的体外扩增的骨髓基质细胞被移植入缺血组织，移植后1周，荧光显微镜及HE染色，检查荧光强弱分布与HE染色密度的时空关系。结果 体外传代培养的基质细胞诱导后分泌NO，移植1周在缺血区检测到大量荧光阳性细胞存活。结论在本实验条件下，体外培养的骨髓基质细胞生长稳定，传代后的细胞增殖较快，表现出较早期细胞特点，在体外能分化为血管内皮细胞，可望用作缺血性心脏病的细胞治疗的供体细胞。     

血运重建对骨髓间充质干细胞移植后凋亡影响的实验研究

目的 研究血运重建与兔骨髓间充质干细胞移植后凋亡之间的关系.方法 无菌条件下采集兔骨髓间充质干细胞,用荧光标记.直接结扎法建立兔心肌梗死模型,实验动物随机分两组:①1 h后开放阻断的冠脉,将干细胞移植于兔心肌梗死区(20只).②不开放冠脉,1 h后将干细胞移植于兔心肌梗死区(20只).心梗后1 h在心梗区域注人MSCs.2周后用荧光显微镜观察移值细胞是否存活,利用TUNEL法检测植入细胞的凋亡率.结果 移植2周后,用荧光显微镜观察梗死区组织,可见DAPI标记带蓝色荧光的供体细胞核,形态呈椭圆形类似心肌细胞核,并与心肌纤维排列方向一致,证明移植细胞已存活.利用TUNEL法检测,两组移植细胞均出现细胞凋亡,差异无统计学意义.结论干细胞移植入心肌组织后的凋亡与植入区血运重建有关.     

Evidence for fusion between cardiac and skeletal muscle cells

Cardiomyoplasty with skeletal myoblasts may benefit cardiac function after infarction. Recent reports indicate that adult stem cells can fuse with other cell types. Because myoblasts are "fusigenic" cells by nature, we hypothesized they might be particularly likely to fuse with cardiomyocytes. To test this, neonatal rat cardiomyocytes labeled with LacZ and green fluorescent protein (GFP) were cocultured with unlabeled C2C12 myoblasts. After 3 days, we observed a small population of skeletal myotubes that expressed LacZ and GFP, indicating cell fusion. To test whether such fusion occurred in vivo, LacZ-expressing C2C12 myoblasts were grafted into normal nude mouse hearts. At 2 weeks after grafting, cells at the graft-host interface expressed both LacZ and cardiac-specific myosin light chain 2v (MLC2v). To test more definitively whether fusion between skeletal and cardiac muscle could occur, we used a Cre/lox reporter system that activated LacZ only upon cell fusion. When neonatal cardiomyocytes from -myosin heavy chain promoter (-MHC)-Cre mice were cocultured with myoblasts from floxed-lacZ reporter mice, LacZ was activated in a subset of cells, indicating cell fusion occurred in vitro. Finally, we grafted the floxed-lacZ myoblasts into normal hearts of -MHC-Cre+ and -MHC-Cre- mice (n=5 each). Hearts analyzed at 4 days and 1 week after transplantation demonstrated activation of LacZ when the skeletal muscle cells were implanted into hearts of -MHC-Cre+ mice, but not after implantation into -MHC-Cre- mice. These data indicate that skeletal muscle cell grafting gives rise to a subpopulation of skeletal-cardiac hybrid cells with a currently unknown phenotype. The full text of this article is available online at http://circres.ahajournals.org.     

IGF-1 receptor mediates differentiation of primary cultures of mouse skeletal myoblasts

Studies involving immortalized myoblasts suggested that insulin-like growth factors (IGFs) promote differentiation of skeletal muscle, but gene targeting experiments in mice did not provide support for this hypothesis. To address this discrepancy, we examined differentiation of primary cultures of mouse myoblasts. Differentiation was normally unaffected by addition of IGFs to the differentiation medium. However, when we interrupted IGF-mediated signaling, by incubating myoblasts with suramin or with a monoclonal antibody to the IGF-I receptor, differentiation was inhibited. Inhibition was reversed by exogenous IGF-I or IGF-II, but not by insulin. Differentiation was enhanced in myoblasts that were incubated with an inhibitor of the mitogen-activated protein kinase signaling pathway (PD098059) and such cells were responsive to exogenous IGF-I. Our results demonstrate that IGF action contributes to the differentiation of non-immortalized mouse myoblasts and that these cells represent a model system that can be experimentally manipulated to study the molecular events involved in skeletal muscle differentiation.     

Expression of human factor IX in mice after injection of genetically modified myoblasts.

Hemophilia B is an X chromosome-linked recessive bleeding disorder. To develop a somatic gene therapy for this disease, we have examined whether mouse skeletal myoblasts can serve as efficient vehicles for systemic delivery of recombinant factor IX. When mouse myoblasts (C2C12) transduced with a Moloney murine leukemia virus-based vector containing the bacterial beta-galactosidase gene were injected into mouse skeletal muscles, they fused with the existing and regenerating myofibers and continued to express beta-galactosidase. C2C12 myoblasts that were infected with recombinant retroviruses containing a human factor IX cDNA secreted biologically active human factor IX cDNA secreted biologically active human factor IX into the culture medium at a rate of 2.6 micrograms per 10(6) cells per day. Myotubes derived from these cells in culture continued to express human factor IX (0.68 micrograms/day from myotubes derived from 10(6) C2C12 cells). After injection of the transduced C2C12 myoblasts into skeletal muscles of mice, the systemic level of recombinant human factor IX was found to be as high as approximately 1 microgram/ml of serum. These results provide the rationale for using skeletal myoblasts as an efficient gene delivery vehicle in the somatic gene therapy for hemophilia B.     

小鼠成体骨骼肌卫星细胞提取及纯化方法的改进

目的建立一种快速高效的小鼠成体骨骼肌卫星细胞的提取、纯化的实验方法。方法通过布比卡因预处理激活肌卫星细胞,48小时后,以混合酶一步消化法及改良纯化法从成年骨骼肌中分离高纯度卫星细胞,并与普通差速贴壁法、反复差速贴壁法及Percoll非连续密度梯度离心法等纯化方法相比较。结果通过改良提取、纯化法所得到的骨骼肌卫星细胞纯度可达到(82.53±3.16)%,明显高于普通差速贴壁法、反复差速贴壁法及Percoll非连续密度梯度离心法(P<0.05),并具有很好的增殖及分化能力。结论通过采用改良成体骨骼肌卫星细胞提取及纯化法,能快速高效地获取高纯度肌卫星细胞。     

Mesenchymal stem cells: isolation, characterisation and in vivo fluorescent dye tracking

Cell therapies have been used to regenerate the heart by direct myocardial delivery, by coronary infusion and by surface attached scaffolds. Multipotent mesenchymal stem cells (MSC) with capacity to differentiate into cardiomyocytes and other cell lines have been predominantly trialled in rodents. However, large animal models are increasingly needed to translate basic research into new, safe regenerative therapies. Understanding the mode of action of cell therapies in the mammalian heart has been limited by cell tracking capability. This study examined the ability to track the fate of allogeneic MSC in sheep using various fluorescent dyes. MSC isolated from sheep bone marrow were grown in culture following extraction and flow cytometric characterisation. After labelling with fluorescent tracking dyes (e.g. CFSE and DiI) cells were tested for in vitro and in vivo signal up to six weeks. Labelling effect on cell division and differentiation was studied. Several dyes lost fluorescence and slowed cell division. However, the thiol reactive dye CM-DiI showed detectable in vivo fluorescence in labelled MSC six weeks after injection into sheep skeletal muscle and two weeks after implantation of an MSC coated biomaterial scaffold. CM-DiI labelled MSC differentiated in vitro showed label retention over four weeks. The fluorescent membrane dye CM-DiI tracks implanted sheep MSC and provides an alternative to traditional cell markers such as gene modified GFP.     

Myoblasts transplanted into rat infarcted myocardium are functionally isolated from their host

Survival and differentiation of myogenic cells grafted into infarcted myocardium have raised the hope that cell transplantation becomes a new therapy for cardiovascular diseases. The approach was further supported by transplantation of skeletal myoblasts, which was shown to improve cardiac performance in several animal species. Despite the success of myoblast transplantation and its recent trial in human, the mechanism responsible for the functional improvement remains unclear. Here, we used intracellular recordings coupled to video and fluorescence microscopy to establish whether myoblasts, genetically labeled with enhanced GFP and transplanted into rat infarcted myocardium, retain excitable and contractile properties, and participate actively to cardiac function. Our results indicate that grafted myoblasts differentiate into peculiar hyperexcitable myotubes with a contractile activity fully independent of neighboring cardiomyocytes. We conclude that mechanisms other than electromechanical coupling between grafted and host cells are involved in the improvement of cardiac function.     

The actin regulator N-WASp is required for muscle-cell fusion in mice

A fundamental aspect of skeletal myogenesis involves extensive rounds of cell fusion, in which individual myoblasts are incorporated into growing muscle fibers. Here we demonstrate that N-WASp, a ubiquitous nucleation-promoting factor of branched microfilament arrays, is an essential contributor to skeletal muscle-cell fusion in developing mouse embryos. Analysis both in vivo and in primary satellite-cell cultures, shows that disruption of N-WASp function does not interfere with the program of skeletal myogenic differentiation, and does not affect myoblast motility, morphogenesis and attachment capacity. N-WASp-deficient myoblasts, however, fail to fuse. Furthermore, our analysis suggests that myoblast fusion requires N-WASp activity in both partners of a fusing myoblast pair. These findings reveal a specific role for N-WASp during mammalian myogenesis. WASp-family elements appear therefore to act as universal mediators of the myogenic cell-cell fusion mechanism underlying formation of functional muscle fibers, in both vertebrate and invertebrate species.     

Human melanoma cells transplanted into zebrafish proliferate, migrate, produce melanin, form masses and stimulate angiogenesis in zebrafish

In this research, we optimized parameters for xenotransplanting WM-266-4, a metastatic melanoma cell line, including zebrafish site and stage for transplantation, number of cells, injection method, and zebrafish incubation temperature. Melanoma cells proliferated, migrated and formed masses in vivo. We transplanted two additional cancer cell lines, SW620, a colorectal cancer cell line, and FG CAS/Crk, a pancreatic cancer cell line and these human cancers also formed masses in zebrafish. We also transplanted CCD-1092Sk, a human fibroblast cell line established from normal foreskin and this cell line migrated, but did not proliferate or form masses. We quantified the number of proliferating melanoma and normal skin fibroblasts by dissociating xenotransplant zebrafish, dispensing an aliquot of CM-DiI labeled human cells from each zebrafish onto a hemocytometer slide and then visually counting the number of fluorescently labeled cancer cells. Since zebrafish are transparent until approximately 30 dpf, the interaction of labeled melanoma cells and zebrafish endothelial cells (EC) can be visualized by whole-mount immunochemical staining. After staining with Phy-V, a mouse anti-zebrafish monoclonal antibody (mAb) that specifically labels activated EC and angioblasts, using immunohistology and 2-photon microscopy, we observed activated zebrafish EC embedded in human melanoma cell masses. The zebrafish model offers a rapid efficient approach for assessing human cancer cells at various stages of tumorigenesis.     

Replicating myoblasts express a muscle-specific phenotype.

During the terminal stage of skeletal myogenesis, myoblasts stop replicating, fuse to form multinucleate fibers, and express the genes that encode the proteins that convey contractile capacity. Because of this dramatic shift in proliferative state, morphology, and gene expression, it has been possible to readily identify and quantitate terminally differentiating myoblasts. In contrast, it is not clear whether the proliferating cells that give rise to postmitotic myoblasts are equally distinct in their phenotype and in fact whether distinct stages in skeletal myogenesis precede the onset of terminal differentiation. To address these questions, monoclonal antibodies and immunofluorescence microscopy were used to determine that replicating myoblasts from newborn rats do express a muscle-specific phenotype. To identify replicating cells, incorporation of 5-bromo-2'-deoxyuridine (BrdUrd) into DNA was assayed by using anti-BrdUrd antibody. The developmentally regulated, muscle-specific, integral membrane protein H36 and the intermediate-filament protein desmin were scored as markers of the myogenic phenotype. The percentage of BrdUrd+ (i.e., proliferative) cells among H36+ and desmin+ myoblasts was equal to the percentage of BrdUrd+ cells in the entire population, indicating that the expression of H36 and desmin is uniformly characteristic of replicating myoblasts. Inhibition of protein synthesis before and during growth in BrdUrd did not alter the frequency of desmin and H36 immunofluorescence in BrdUrd+ cells. Thus, desmin and H36 were present in the replicating myoblasts prior to the onset of growth in BrdUrd. These results were confirmed using H36+ cells selected by flow cytometry: these purified H36+ myoblasts replicate, express desmin, and differentiate. Similar results were obtained with mouse myoblasts. Desmin expression in these mammalian cells differs from that in chicken embryo myoblasts: only a small proportion of replicating chicken embryo myoblasts express desmin. That replicating mammalian myoblasts have a muscle-specific phenotype serves to define a distinct stage in myogenic development and a specific cell in the myogenic lineage. Further, it implies that there is a regulatory event activated during myogenesis that precedes terminal differentiation and that is required for expression of those genes whose products distinguish the replicating myoblast.