骨髓干细胞移植治疗Duchenne型肌营养不良鼠的实验研究

目的　研究骨髓干细胞移植治疗Duchenne型肌营养不良鼠 (mdx鼠 )的效果。方法　取 4～ 5周龄昆明鼠骨髓干细胞 ,体外培养 3d ,静脉移植到 7Gyγ射线预处理 7～ 8周龄mdx鼠体内。临床监测受体鼠移植物抗宿主病 (GVHD)表现 ,并对移植 12周mdx鼠的运动功能、肌电生理、dystrophin蛋白表达情况进行检测。 结果　 5只 7Gy剂量放疗mdx鼠 ,静脉移植 4 8× 10 6骨髓干细胞 ,3个月后 ,肌电图指标有了部分改善 ;10 %肌纤维表达了dystrophin蛋白。结论　静脉移植同种非同系鼠骨髓干细胞治疗mdx鼠有效 ,显示骨髓干细胞移植治疗DMD有着理想的前景。     

Duchenne 型肌营养不良模型鼠骨髓移植后的行为学观察

目的确立Duchenne型肌营养不良模型鼠(mdx鼠)骨髓移植前的有效放疗剂量，观察不同数量、不同成分的骨髓细胞对受体mdx鼠造血功能的重建和保护作用。方法用不同数量的体外培养6～8周C57BL/6雄鼠的骨髓细胞、骨髓基质细胞、骨髓悬浮细胞，经鼠尾静脉注射给不同剂量放疗后的mdx鼠，观察受体鼠的存活率及行为学改变。结果10只mdx鼠移植前3天12Gyγ射线照射，在移植后7天内全部死亡，且注射细胞数较多者，存活时间相对较长，而8Gyγ射线照射的6只mdx鼠，移植后30天5例存活，1例死亡。结论本实验条件下，移植前8Gyγ射线放疗较合理，在有效剂量放疗破坏受体骨髓造血系统后，移植同系鼠的骨髓细胞、基质细胞、悬浮细胞，mdx鼠均能耐受并存活，且以移植细胞数量为1×10     

成肌细胞治疗DMD模型-mdx鼠体内骨骼肌细胞dystrophin/utrophin蛋白的表达

目的 研究成肌细胞移植入放疗的mdx鼠后dystrophin/utrophin的表达变化.方法 培养大鼠L6骨骼肌成肌细胞株(L6 SkM),进行肌内注射于Duchenne型模型鼠-mdx鼠.移植后1个月、2个月、3个月分别取实验鼠的四肢骨骼肌,运用免疫荧光法、Western blot检测dystrophin及utrophin的表达情况.另分别取5只正常C57BL/6鼠和mdx鼠作阳性和阴性对照.结果 成肌细胞移植后1、2和3个月后mdx鼠的dystrophin表达随移植时间延长增多,而utrophin的表达随移植时间延长下降.结论 成肌细胞移植后dystrophin表达对utrophin有一定的抑制作用,两者存在互补关系.     

不同放疗剂量对肌营养不良鼠骨髓干细胞移植的影响

目的　使用不同剂量γ射线对Duchenne型肌营养不良鼠 (mdx鼠 )照射 ,研究骨髓干细胞移植后mdx鼠缺失蛋白表达的情况。方法　将 18只 7～ 8周mdx鼠随机平均分为A、B、C 3组 ,依次给予 7Gy、7.5Gy、8Gyγ射线预处理 ;3天后行骨髓干细胞移植。移植骨髓干细胞取自 4～ 5周的C5 7BL/6鼠 ,体外培养 3d ,按 1 2× 10 7个细胞 /每只剂量移植给 3组预处理后的mdx鼠。连续观察受体鼠的移植物抗宿主病 (GVHD)程度 ;移植 12周后 ,检测受体鼠体内抗肌萎缩蛋白表达情况。结果　C组GVHD反应较明显 ;A、B、C 3组的股骨肌肌纤维dystrophin蛋白表达率分别为 8%、9%和 13 %。各组间缺失蛋白表达率有显著差异。结论　对 7～ 8周mdx鼠 ,给予不同剂量的γ射线预处理 ,骨髓干细胞移植后 ,8Gyγ射线表达最多 ,7Gy射线照射表达量最少 ;但 8Gyγ射线照射GVHD反应较明显。     

骨髓移植治疗Duchenne型肌营养不良症模型鼠后dystrophin相关蛋白表达

目的观察骨髓移植治疗Duchenne型肌营养不良症(DMD)模型鼠—mdx鼠后，β-dystroglycan和α-sarcoglycan在肌膜上的表达情况。方法以正常C57鼠作为供体，以mdx鼠作为受体进行骨髓移植，在移植后2、4、6个月分别进行mdx鼠骨骼肌的β-dystroglycan和α-sarcoglycan免疫荧光染色，计算阳性细胞的荧光积分光密度，与C57鼠及未移植的mdx鼠进行比较。结果在骨髓移植后2、4、6个月mdx鼠骨骼肌肌膜上β-dystroglycan和α-sarcoglycan的表达量均有随时间的延长逐渐增加的趋势．至移植后6个月时，二者的表达量明显高于未治疗的mdx鼠。结论骨髓移植可使mdx鼠的dystrophin相关蛋白在病损骨骼肌细胞膜上表达增加．其对维持肌膜的稳定性、促进肌肉的恢复有重要意义。     

骨髓移植治疗Duchenne型肌营养不良症中骨髓细胞体内分布的实验研究

目的　探讨骨髓移植治疗肌营养不良症的早期骨髓细胞在体内的分布规律。方法　采用1 2 5I和99m Tc分别标记C5 7鼠的骨髓细胞和红细胞,将其静脉移植入放疗后的m dx鼠体内示踪,于4、12、2 4 h计算各器官内细胞特异性分布指数。用免疫荧光法对宿主骨骼肌的dystrophin检测。结果　骨髓细胞在移植后4 h以内随血流在体内均匀分布。在12 h时其在骨髓中的特异性分布指数明显增加(P<0 .0 5 ) ,而2 4 h时在病损骨骼肌中的特异性分布指数较正常骨骼肌明显增加(P<0 .0 5 ) ,并在2个月后宿主骨骼肌中表达了dystrophin。结论　骨髓移植后骨髓细胞有回巢现象和对病损骨骼肌有趋化现象,有利于靶器官的组织修复。该研究为骨髓移植后骨髓细胞早期能够定居在病损骨骼肌中并发挥修复功能提供了有力的实验依据。     

肌营养不良症模型鼠骨骼肌的组织病理学研究

目的　比较肌营养不良症模型 (mdx)鼠、C57鼠和Duchenne型肌营养不良症 (DMD)患者骨骼肌的组织病理学改变 ,以及dystrophin在肌细胞膜上的分布。方法　取mdx鼠、C57鼠和DMD患者骨骼肌作常规HE染色 ,比较其组织学改变 ;同时对mdx鼠、C57鼠骨骼肌作dystrophin的免疫组化染色 ,比较dystrophin在肌细胞膜上的分布。结果　mdx鼠骨骼肌肌纤维大小不等 ,轮廓变圆 ,肌间隙增宽 ,少量脂肪、结缔组织增生 ,细胞核中心移位增多 ,部分肌纤维变性坏死 ,而DMD患者骨骼肌的改变和mdx鼠基本一致。mdx鼠肌细胞膜缺乏完整环行棕色条带 ,而C57鼠则呈一完整环行棕色条带 ,提示mdx鼠dystrophin蛋白缺乏。结论　mdx鼠有类似于DMD患者的骨骼肌组织病理学改变     

Micro-dsytrophin基因修饰的骨髓间充质干细胞移植后mdx鼠腓肠肌病理改变及micro-dystrophin的表达

目的探讨自体骨髓间充质干细胞(mMSCs)携带micro-dystrophin基因在移植鼠体内分化为有功能肌细胞的可能性。方法采用脂质体介导micro-dystrophin基因转染mdx小鼠mMSCs,通过尾静脉注射移植治疗mdx鼠,在移植后不同时间点对腓肠肌进行HE染色、计数核中心移位纤维(CNF)比例,并用免疫荧光法检测micro-dystrophin的表达。结果移植后各时间点腓肠肌病理改变较对照组有所改善,CNF比例下降,差异有统计学意义,部分肌细胞膜能表达micro-dystrophin蛋白,并随移植时间延长micro-dystrophin阳性肌纤维比例增加,分别达到3%(8周时)、6%(12周时)和8%(16周时)。结论自体mMSCs可携带外源性micro-dys-trophin基因在受体鼠体内分化为micro-dystrophin阳性肌细胞。     

mdx小鼠骨骼肌组织成肌、成脂、成骨基因的特异性表达**

背景：干细胞移植是治疗肌营养不良症的有效方法之一,但移植的干细胞在病理骨骼肌中成肌表达较低。 目的：通过比较mdx小鼠和C57小鼠的骨骼肌形态及成肌、成脂、成骨基因表达的差异,探讨mdx小鼠骨骼肌病理改变的可能机制。 方法：取mdx小鼠与C57小鼠的骨骼肌组织行冰冻切片,苏木精-伊红染色和Vonkossa染色观察两种小鼠肌肉组织的形态特征;提取mdx小鼠和C57小鼠骨骼肌组织总RNA,real-time PCR检测成肌、成脂、成骨相关基因的表达。 结果与结论：mdx小鼠骨骼肌有肌纤维坏死和再生,伴有轻度脂肪、纤维结缔组织增生,Vonkossa染色可见钙结节沉积,而C57小鼠的骨骼肌细胞形态清晰,核位于细胞周边。与C57小鼠比较,mdx小鼠肌肉组织成骨、成脂基因表达有不同程度的上调(P < 0.05),而成肌基因表达下调(P < 0.05)。dystrophin基因缺失及成肌基因表达下调、成骨和成脂基因上调是造成mdx小鼠肌肉组织变性坏死的原因。     

Duchenne型肌营养不良症模型小鼠神经肌肉接头特征研究

目的观察Duchenne型肌营养不良症模型小鼠骨骼肌肌膜抗肌萎缩蛋白(dystrophin)表达变化和神经肌肉接头形态,分析其可能机制。方法 C57BL/6和mdx小鼠各8只,HE染色观察肌细胞组织学形态,免疫荧光染色检测腓肠肌肌膜dystrophin蛋白表达变化和神经肌肉接头形态。结果C57BL/6小鼠腓肠肌肌细胞大小基本一致,呈多角形,胞核位于细胞周边、极少数位于肌纤维中心;肌膜均匀表达dystrophin蛋白;神经肌肉接头形态完好。Mdx小鼠腓肠肌肌细胞大小不一致,呈圆形,部分胞核趋中心化;仅少量或个别肌细胞表达dystrophin蛋白;mdx种鼠突触后膜乙酰胆碱受体断裂成小片段,突触前膜神经末梢突起增多、变细,而mdx幼鼠神经肌肉接头形态与C57BL/6小鼠基本一致;mdx小鼠神经肌肉接头数目明显减少,突触前膜和突触后膜横截面积明显减小,肌细胞间神经轴突明显变细。结论Mdx小鼠骨骼肌肌膜dystrophin蛋白缺失并非导致神经肌肉接头改变的直接因素,可能与病情进展有关。     

Localization and characterization of dystrophin in muscle biopsy specimens from Duchenne muscular dystrophy and various neuromuscular disorders

Dystrophin, surmised to be the causative protein of Duchenne muscular dystrophy (DMD), was studied for its intracellular localization and characterization by immunostaining and Western blotting using antidystrophin antibodies. In normal controls and in patients with various neuromuscular diseases other than DMD and Becker's muscular dystrophy (BMD), dystrophin was detected homogeneously on the entire surface membrane of the muscle fibers, whereas it was absent in DMD patients and partially observed in BMD cases. The density of dystrophin was low in BMD and female DMD patients. In mouse skeletal and cardiac muscles, too, dystrophin localized in the muscle surface membrane, and its presence in the brain was also suggested. However, dystrophin was not detected in mdx mice. These data suggest that myofiber necrosis in DMD patients and mdx mice is likely to be the result of plasma membrane instability.     

Myogenic stem cells from the bone marrow: a therapeutic alternative for muscular dystrophy?

Differentiated muscle fibres can be formed by transplanted haematopoietic stem cells in models of acute or chronic muscle regeneration, including the dystrophin-deficient mdx mouse. Muscle-forming activity can be found in adult, foetal and embryonic haematopoietic tissues. The blood-to-muscle transition may be due to transdifferentiation of haematopoietic progenitors in response to local signals provided by the regenerating muscle. These signals are only poorly provided by the muscle of the mdx mouse, since transplantation into these mice of normal C57Bl/6 bone marrow gives rise only to a minimal number of muscle fibres expressing the normal dystrophin protein (<1%) throughout the animal life span. Expansion and active recruitment to myogenic differentiation of transplanted haematopoietic cells are therefore critical factors for a future use of bone marrow transplantation in cell/gene therapy of muscular dystrophy.     

Quantification of normal dystrophin mRNA following myoblast transplantation in mdx mice

A mutagenesis RT-PCR method was used to detect normal dystrophin mRNA following the injection of normal myoblasts in mdx mice using two immunosuppressors. A specific sequence of the dystrophin mRNA (257 bp) was amplified by RT-PCR from the muscle total RNA. Maell digestion of the amplified products allowed us to distinguish the normal messenger of dystrophin from the dystrophic one and to establish the percentage of normal and of dystrophic (mdx) dystrophin mRNA. Normal dystrophin mRNA was detected using this technique in mdx muscles transplanted with histocompatible normal myoblasts. For this type of transplantation, no significant difference in the percentage of normal dystrophin mRNA was observed between immunosuppressed mice and those not immunosuppressed. No normal dystrophin mRNA was, however, observed in mdx mice following histoincompatible normal myoblast transplantation without immunosuppression. When such transplantations were done in mice immunosuppressed with cyclosporine or FK-506, normal dystrophin mRNA accounted for 31% and 36% of the total dystrophin mRNA, respectively. In fact, one animal immunosuppressed with FK-506 expressed as much as 57% of normal dystrophin mRNA. These results thus show that FK-506 makes it possible to restore dystrophin expression to a level comparable to that observed in DMD carriers that are usually asymptomatic. © 1995 John Wiley & Sons, Inc.     

Dystrophin immunostaining and freeze-fracture studies of muscles of patients with early stage amyotrophic lateral sclerosis and Duchenne muscular dystrophy

We used polyclonal antibodies against dystrophin for the immunohistochemical localization of this protein in human skeletal muscle. Dystrophin was localized in the sarcolemma of the myofibers in 8 infantile and 11 adult normal control muscles and in 10 early stage patient muscles with amyotrophic lateral sclerosis (ALS). The protein was absent or markedly decreased in 8 early stage patients with Duchenne muscular dystrophy (DMD). Moreover the densities of sarcolemmal plasma membrane assemblies, orthogonal arrays and their pits were estimated by freeze-fracture electron microscopy studies in the same number of muscle samples in each disease and control case. The group median densities of orthogonal arrays and their pits in the ALS group and adult control group were 4.8 with a midrange of 1.1-13.5 (25-75%) and 7.5 with a midrange of 2.3-12.9, respectively (P greater than 0.1, Wilcoxon rank-sum test), whereas those of the DMD group and child control group were 0 with a midrange of 0-1.1 and 10.8 with a midrange of 5.4-16.7 respectively (P less than 0.01). The skeletal muscles of mdx mice and their controls were also investigated by the same techniques. In mdx mice, the absence or marked deficiency of dystrophin was also noted; however, the decrease of orthogonal arrays was not as severe as in DMD, which might relate to the milder clinical features in mdx mice as compared with those in DMD.     

Invited Review. The potential for gene therapy in duchenne muscular dystrophy and other genetic muscle diseases

Dystrophin cDNAs have been introduced into skeletal muscle fibers of dystrophin-deficient mice (mdx) through direct DNA injection in plasmid expression vectors and by replication-defective recombinant adenovirus vectors. The introduced genes appear to protect those muscle fibers from necrosis in which they become expressed. By direct injection of dystrophin cDNA in plasmid expression vector, only 1–2% of adult mdx muscle fibers of the injected muscle expressed dystrophin. On the other hand, by recombinant adenovirus injection into very young mdx muscle, a better efficiency has been reported. We have discussed several putative and proven factors that may contribute to the thus far demonstrated relatively low efficiency of dystrophin gene transfer. These include poor uptake of gene constructs by muscle fibers, degradation of the injected DNA, and poor access of gene constructs to the nuclear compartment. Neutralization or elimination of these factors could improve the efficiency of gene transfer so that it might, in the future, qualify as an effective therapy for DMD and some other genetic diseases of muscle.© 1993 John Wiley & Sons, Inc.     

Distribution of dystrophin, nebulin and Ricinus communis I (RCA-I)-binding glycoprotein in tissues of normal and mdx mice

Dystrophin, the protein product of the Duchenne muscular dystrophy (DMD) gene locus, appeared as an immunoreactive triplet of polypeptides in striated muscle tissues from normal mice on Western blot analysis. In smooth muscle tissues, an immunoreactive doublet of corresponding molecular weight was detected. No dystrophin was found in normal mouse brain, not even after enrichment for the Triton X-100 insoluble fraction. Dystrophin was absent from all corresponding tissues from the mdx mutant mouse strain which is known to lack dystrophin. The possibility that these immunoreactive bands represent isoforms is discussed. We have also investigated two other high molecular weight proteins which show secondary abnormalities in DMD muscle, namely nebulin and the 370 kDa Ricinus communis I lectin (RCA I)-binding glycoprotein. Nebulin levels were reduced in skeletal muscle from 6-week-old mdx mice but not in oesophagus from the same animals. By contrast, the RCA I-binding 370 kDa glycoprotein which is greatly reduced in DMD skeletal muscle was present in normal amounts in mdx skeletal muscle. These findings show, for the first time, that mdx myopathy differs from DMD myopathy not only morphologically, but also in its secondary biochemical abnormalities.