心肌干细胞移植心肌梗死区12周后的心电生理稳定性及室颤阈值改善效应

背景：课题组前期研究证实心肌干细胞治疗心肌梗死后短中期(6周)能明显改善心电生理学稳定性和室颤阈值。 目的：观察心肌干细胞对心力衰竭大鼠室颤阈值和心电生理稳定性的长期影响。 方法：开胸结扎20只SD大鼠左前降支冠状动脉,2周后其中10只大鼠局部梗死心肌内注射PKH26荧光标记的由PBS悬浮的心肌干细胞,另10只大鼠局部梗死心肌内注射等量PBS。治疗12周后,再次开胸检测梗死区、梗死边缘区和非梗死区的心电生理特性和室颤阈值。实验结束后,摘取心脏行病理切片,检查PHK26标记的心肌干细胞是否在梗死区内生存并表达连接蛋白43及α-肌动蛋白。 结果与结论：与对照组相比,心肌干细胞移植12周后其梗死区、梗死边缘区和非梗死区的单极电图激动恢复时间、纠正的激动恢复时间差异无显著性意义(P > 0.05);单极电图纠正的激动恢复时间离散度、电刺激所激发的恶性心律失常差异无显著性意义(P > 0.05);室颤阈值方面,实验组梗死区和梗死边缘区与对照组相比差异无显著性意义(P > 0.05),非梗死区与对照组相比差异有显著性意义(P < 0.05)。PHK26标记的心肌干细胞在梗死边缘区内被发现并表达连接蛋白43和α-肌动蛋白。以上结果提示心肌干细胞移植后12周其心电生理的稳定性和室颤阈值的改善效应已逐渐消失,但机制未明。 中国组织工程研究杂志出版内容重点：干细胞;骨髓干细胞;造血干细胞;脂肪干细胞;肿瘤干细胞;胚胎干细胞;脐带脐血干细胞;干细胞诱导;干细胞分化;组织工程全文链接：     

心肌干细胞移植可改进心力衰竭大鼠室颤阈值和电生理的稳定性

背景：心肌干细胞移植后是否引起或加重心肌梗死患者的心律失常是治疗的关键问题。 目的：观察心肌干细胞对心力衰竭大鼠室颤阈值和电生理稳定性的影响。 方法：开胸结扎20只SD大鼠左前降支冠状动脉,2周后选取其中的10只局部梗死心肌内注射PKH26荧光标记的由PBS悬浮的心肌干细胞,另10只局部梗死心肌内注射等量PBS。治疗6周后,再次开胸检测梗死边缘区的心电生理特性和室颤阈值。实验结束后,摘取心脏行病理切片,检查PHK26标记的心肌干细胞是否在梗死区内生存并表达连接蛋白43及α-肌动蛋白。 结果与结论：与对照组相比,心肌干细胞移植组单极电图激动恢复时间及纠正的激动恢复时间明显缩短,电刺激所激发的恶性心律失常明显减少,室颤阈值明显提高。PHK26标记的心肌干细胞在梗死边缘区内被发现并表达连接蛋白43和α-肌动蛋白。提示心肌干细胞移植能改善心力衰竭大鼠心电生理的稳定性和提高室颤阈值;心肌干细胞可在体内表达心肌细胞和连接蛋白的标记。     

吡格列酮联合骨髓间充质干细胞移植治疗改善大鼠心肌梗死后的心功能

背景：前期研究发现骨髓间充质干细胞移植能够改善心肌梗死大鼠的心功能,但整体效果并不太理想。 目的：拟采用PPAR-γ激动剂吡格列酮联合骨髓间充质干细胞移植治疗以进一步改善心肌梗死大鼠的心功能并探讨相关机制。 方法：开胸结扎20只SD大鼠左前降支冠状动脉并随机分为2组：骨髓间充质干细胞组和骨髓间充质干细胞+吡格列酮组。2周后在局部梗死心肌内注射PKH26标记的由PBS悬浮的骨髓间充质干细胞,联合治疗组在注射骨髓间充质干细胞后予以吡格列酮3 mg/(kg•d)连续灌胃2周。细胞移植后2周进行超声心动图检测,免疫荧光染色、Western blot、qRT-PCR检测左心室心肌组织不同区域PPAR-γ、TGF-β1/SMAD通路相关因子和Cx43的表达情况。 结果与结论：两组大鼠基础心功能参数无明显差异性。细胞移植2周后,骨髓间充质干细胞+吡格列酮组左室舒张末径、左室收缩末径明显减小,左室射血分数明显增高;左心室心肌组织不同区域PPAR-γ和Cx43的表达量显著增加;TGF-β1、SMAD2、SMAD3在梗死区和梗死边缘区表达明显下降。以上结果提示PPAR-γ激动剂吡格列酮干预能够增强骨髓间充质干细胞移植对心功能的改善作用,其机制可能与PPAR-γ抑制TGF-β1/SMAD通路进而提高Cx43的表达有关。  中国组织工程研究杂志出版内容重点：干细胞;骨髓干细胞;造血干细胞;脂肪干细胞;肿瘤干细胞;胚胎干细胞;脐带脐血干细胞;干细胞诱导;干细胞分化;组织工程     

透明质酸水凝胶包裹骨髓间充质干细胞改善心肌梗死大鼠的心功能(Ⅲ)

背景：作者前期的研究结果显示透明质酸水凝胶包裹骨髓间充质干细胞显著改善大鼠心肌梗死后心功能。目的：探索透明质酸水凝胶及骨髓间充质干细胞促进心肌修复的分子机制。方法：分离培养雄性SD大鼠骨髓间充质干细胞，然后用透明质酸水凝胶包裹骨髓间充质干细胞在培养皿中进行体外三维培养。结扎雌性SD大鼠左冠状动脉前降支制作心肌梗死模型，1周后行超声检测，将符合条件的大鼠随机分为4组：(1)PBS组(n=12)；(2)透明质酸组(n=12)；(3)骨髓间充质干细胞组(n=15)；(4)骨髓间充质干细胞+透明质酸组(n=15)。造模1周后将模型鼠行二次开胸，按照分组将PBS、透明质酸水凝胶、骨髓间充质干细胞、透明质酸水凝胶包裹骨髓间充质干细胞注射到梗死边缘区及梗死区。移植后1 d、1周、2周，Western blot检测梗死区域及周边的基质金属蛋白酶2、血管内皮生长因子、胸腺素β4以及c-Kit的蛋白表达水平，移植后2周免疫荧光检测移植细胞的分化情况。结果与结论：(1)在移植后1周时，骨髓间充质干细胞组的基质金属蛋白酶2及血管内皮生长因子蛋白表达水平明显高于其他3组(P <0.05)；在移植后2周时，...     

外源性硫化氢预处理骨髓间充质干细胞移植治疗大鼠心肌梗死

背景：骨髓间充质干细胞移植可促进心肌修复,治疗心肌梗死,但移植后细胞存活率低等原因制约了其应用与发展。 目的：探讨硫化氢预处理对骨髓间充质干细胞移植治疗心肌梗死效果的影响。 方法：从(100±20) g SD大鼠中分离培养骨髓间充质干细胞,第4代时按实验分组处理,移植前2 h给予DAPI标记。将50只体质量(200±20) g雄性SD大鼠分为心肌梗死组和假手术组,心肌梗死组结扎冠状动脉前降支建立心肌梗死模型,假手术组只穿线不结扎,每组10只。模型建立24 h后,分组在梗死心肌周围选择4个点,分别注射生理盐水、骨髓间充质干细胞、硫化氢预处理骨髓间充质干细胞及硫化氢。细胞移植4周后用超声心动图检测心功能指标,Masson染色测定梗死交界区胶原。 结果与结论：生理盐水组大鼠心肌纤维化严重,梗死区域无心肌组织再生;外源性硫化氢处理后的骨髓间充质干细胞移植组比单用硫化氢或者骨髓间充质干细胞组心肌纤维化程度轻,胶原组织中可见较多心肌细胞再生。硫化氢预处理骨髓间充质干细胞组左室射血分数、左室短轴缩短率显著高于硫化氢组及骨髓间充质干细胞组(P < 0.05)。提示硫化氢预处理骨髓间充质干细胞可提高移植后的细胞存活率,改善梗死后心功能,其作用优于单用硫化氢或者骨髓间充质干细胞。中国组织工程研究杂志出版内容重点：干细胞;骨髓干细胞;造血干细胞;脂肪干细胞;肿瘤干细胞;胚胎干细胞;脐带脐血干细胞;干细胞诱导;干细胞分化;组织工程全文链接：     

人工脑膜复合大鼠骨髓间充质干细胞修复心肌梗死

背景：干细胞移植治疗心肌梗死拥有广泛的应用前景,寻求理想的细胞类型和有效的移植方式是提高干细胞治疗效果的关键因素。 目的：探讨人工脑膜复合骨髓间充质干细胞修复心肌梗死的安全性及作用。 方法：采用全骨髓贴壁筛选法分离培养骨髓间充质干细胞,取培养良好的第3代骨髓间充质干细胞经DAPI标记后接种于人工脑膜制备细胞人工脑膜复合物。构建SD大鼠心肌梗死模型,60只大鼠随机数字表法均分为假手术组、心肌梗死组、人工脑膜组、细胞脑膜复合物组。移植4 周后检测心功能参数,Western blot检测心肌组织缝隙连接蛋白43的表达,计算心肌梗死后生存率。 结果与结论：构建心肌梗死模型并移植后4周,细胞脑膜复合物组心脏组织冰冻切片于荧光显微镜下可观察到心肌内少量核蓝染的细胞,表明骨髓间充质干细胞得以存活;细胞脑膜复合物组与心肌梗死组和人工脑膜组相比,左心室功能明显改善,Cx43蛋白的表达上调,生存率增加(P < 0.05)。说明人工脑膜复合骨髓间充质干细胞移植可提高心肌梗死大鼠心脏功能及生存率。     

糖尿病与正常大鼠骨髓间充质干细胞移植治疗心肌梗死的比较

背景：目前国内外在干细胞移植治疗心肌梗死的研究中,大多采用正常或者年轻的骨髓间充质干细胞作为移植细胞来源。 目的：比较糖尿病和正常大鼠骨髓间充质干细胞移植治疗心肌梗死的疗效差别。 方法：无菌条件下获取正常大鼠及糖尿病大鼠的骨髓间充质干细胞,建立大鼠心肌梗死模型并随机分为3组,分别于心肌梗死病灶区注射100 μL含有105-106个F2代正常大鼠或糖尿病大鼠来源骨髓间充质干细胞的细胞混悬液,空白对照组注射100 μL含体积分数20%胎牛血清的DMEM。移植后1个月行苏木精-伊红染色检测各组梗死区域心肌组织形态的变化;通过免疫组化方法检测Bcl-2的表达。 结果与结论：通过对细胞形态观察及流式细胞术鉴定,大鼠股骨骨髓贴壁培养可获取纯度较高的骨髓间充质干细胞,绘制细胞生长曲线结果显示正常大鼠骨髓间充质干细胞较糖尿病大鼠骨髓间充质干细胞生长快。移植后1个月,正常大鼠干细胞移植组梗死区域心肌组织形态较糖尿病大鼠干细胞移植组及空白对照组明显改善,梗死区域心肌组织Bcl-2的表达也高于其他2组。证实正常大鼠来源骨髓间充质干细胞较糖尿病大鼠骨髓间充质干细胞生长明显加快,且糖尿病使骨髓干细胞移植治疗心肌梗死的疗效降低。     

大鼠骨髓间充质干细胞的PKH26标记和示踪☆

背景：骨髓间充质干细胞标记是体内迁移分化研究的重要环节。 目的：对大鼠骨髓间充质干细胞进行PKH26标记,探讨PKH26标记对骨髓间充质干细胞的生长特征、分化的影响及体内示踪情况。 方法：培养扩增大鼠骨髓间充质干细胞,第2代细胞按PKH26标记程序进行细胞标记,观察标记组和未标记组细胞的增殖、周期和凋亡情况,对标记组细胞行成骨成脂体外诱导分化。尾静脉移植PKH26标记细胞,6周后荧光显微镜观察骨髓间充质干细胞在子宫内膜的分布情况。 结果与结论：PKH26标记对细胞增殖、凋亡和周期无明显影响,不影响成骨成脂诱导分化。子宫内膜组织中PKH26标记阳性的细胞分布于腺上皮和间质细胞。PKH26标记技术可用于示踪骨髓间充质迁移转归和干细胞移植方面的实验研究。      

MRI活体示踪心肌梗死大鼠骨髓间充质干细胞的移植

背景：干细胞移植的疗效和安全性评估均需要对体内干细胞的存活、分布、迁徙、增殖及分化进行连续监测。 目的：观察MRI示踪超顺磁性氧化铁标记的骨髓间充质干细胞在缺血心肌组织的分布、迁徙情况。 方法：直接贴壁法分离和培养大鼠骨髓间充质干细胞,获得的细胞进行免疫鉴定。以新型超顺磁性氧化铁标记骨髓间充质干细胞,体外MRI成像确定其体内示踪的可行性。标记后锥虫蓝拒染试验、MTT比色试验分别检测标记细胞的活力、增殖情况。60只SD大鼠随机分为3组,制备大鼠心肌梗死模型2周后再次开胸移植含标记骨髓间充质干细胞的PBS混合液、含未标记骨髓间充质干细胞的PBS混合液和等量PBS。于移植后第1天、第3周行MRI检查,动态观察移植细胞的分布、迁徙,并根据MRI图像定位选择性行CD90免疫组化检查。 结果与结论：骨髓间充质干细胞标记后,普鲁士蓝染色见胞浆内蓝色铁颗粒,标记效率为99%,标记细胞与未标记细胞间锥虫蓝拒染率、MTT吸光度差异无显著性意义。体外MRI可检测到标记细胞,并在T2WI及T2W/FFE序列上呈低信号。细胞移植1 d后,在T2WI及T2W/FFE序列上可见标记细胞在梗死心肌边缘呈类圆形低信号;移植3周后,移植区域信号边界模糊,范围扩大,对比度降低。CD90免疫组化检测证实移植细胞可由梗死边缘向梗死区域迁徙。结果可见新型超顺磁性氧化铁可成功对大鼠骨髓间充质干细胞进行标记,细胞标记后可被MRI检测。     

胎儿脐血间充质干细胞治疗大鼠急性心肌梗死

背景：胎儿脐血间充质干细胞对病变心肌有修复和再生能力,胎儿脐血间充质干细胞移植是治疗心肌梗死的一种新途径。 目的：探讨胎儿脐血间充质干细胞移植治疗大鼠心肌梗死的效果。 方法：选取32只大鼠结扎左冠状动脉前降支制作心肌梗死动物模型,随机等分为移植组和梗死组,从胎儿脐血中分离培养脐血间充质干细胞,制备脐血间充质干细胞悬液,对移植组大鼠进行脐血间充质干细胞移植。 结果与结论：胎儿脐血间充质干细胞在体外可以被成功分离培养;与梗死组相比,移植组大鼠心肌梗死边缘区的微血管密度、左室收缩末压、左室内压最大上升和下降速率显著增加(P < 0.05),左室舒张末压显著下降(P < 0.05),心电图情况稍有好转。表明胎儿脐血间充质干细胞治疗心肌梗死大鼠可以促进心肌血管再生,改善心脏功能。中国组织工程研究杂志出版内容重点：干细胞;骨髓干细胞;造血干细胞;脂肪干细胞;肿瘤干细胞;胚胎干细胞;脐带脐血干细胞;干细胞诱导;干细胞分化;组织工程     

九种心脏起搏器临床应用结果分析

本文报告我院1974年至1986年7月使用九种心脏起搏器于70例病人进行150次人工心脏起搏的情况,重点是分析117个国产埋藏式起搏器的质量与临床应用结果。 已使用完毕的67个埋藏式起搏器的平均使用寿命为18.06±10.65个月。其中66个为国产起搏器,其使用寿命以YCP—Ⅱ型最长(19.17±12.35个月),但YCP—Ⅱ、YCP—Ⅰ、GXB—2M及AXB—3型共四种国产起搏器间的平均使用寿命无显著差别(p>0.05)。起搏器失效率为53.7％,其中以YCP—Ⅰ型最高,但无统计学意义(x~2值=4.256,p>0.05)。全组共发生30次起搏器故障,占20.4％(不含电源提前耗竭)。 经分析发现,目前国产埋藏式起搏器存在的主要问题是使用寿命短(平均约18个月)、体积大、重而厚、并发症多、故障率高。其原因关键是能源电池问题。因此,在讨论中强调指出:改进电池性能,研先和采用可靠性高、使用寿命长、体积小的锂碘电池或微型锂电池,不仅是起搏器临床应用的当务之急,而且是生物医学工程学工作者面临的重要课题。     

Adaptation of human left ventricular volumes to the onset of supine exercise

Summary The purpose of this study was to measure the changes and rates of adaptation of left ventricular volumes at the onset of exercise. Eight asymptomatic subjects, in whom intramyocardial markers had been implanted 3–6 years previously during aortocoronary bypass surgery, exercised in the supine position at a constant workload of 73.6 W for 5 min. Six also exercised first at 16.4 W, and then against a workload which progressively increased by 8.2 W every 15s. Cardiac volumes were measured by computer assisted analysis of the motion of the implanted markers. In the constant workload test, cardiac output increased rapidly from 5.7±1 min^–1 to 10.3±1.9 1 min^–1 by 2 min and then increased more slowly to 10.8±2.0 1 min^–1 by 5 min. The cardiac output increase was mainly due to an increase in heart rate from 68±12 beats min^–1 to 120±16 beats min^–1 with minimal changes in stroke volume. The time constant for the early increase in cardiac output was 45 s and for heart rate, 35 s. With progressively increasing workloads, there was an almost linear increase of heart rate and cardiac output, but these increased at a slower rate than during the early phase of the constant load exercise test. In conclusion: (i) rapid changes in cardiac output during supine exercise were produced by changes in heart rate; (ii) changes in stroke volume provided minor adjustments to cardiac output; (iii) the end-diastolic volume was almost constant.     

心房纤维性颤动形成机制的研究和探讨——(Ⅰ)高密度心脏电活动测量系统的研制

首先介绍了心房纤维性颤动形成机制的研究历史及背景，然后着重介绍了我们研制的研究心房纤维性颤动形成机制所必需的一种测量仪器——高密度心脏电活动测量系统。这种最新研制的仪器为我们进一步深入地研究心房纤维性颤动的形成机制提供了坚实的物质基础。     

心房纤维性颤动形成机制的研究和探讨——(I)高密度心脏电活动测量系统的研制

首先介绍了心房纤维性颤动形成机制的研究历史及背景,然后着重介绍了我们研制的研究心房纤维性颤动形成机制所必需的一种测量仪器——高密度心脏电活动测量系统。这种最新研制的仪器为我们进一步深入地研究心房纤维性颤动的形成机制提供了坚实的物质基础。     

Oxidative and proteolytic profiles of the right and left heart in a model of cancer-induced cardiac cachexia

Cardiac cachexia is a syndrome that has received increased attention in recent years. Although an association between proteolysis and cardiac cachexia has been proposed, the direct influence of oxidative stress on the process has not been demonstrated. In the present study, the right (RH) and left (LH) hearts (atrium and ventricle of each side of the heart) were collected from rats at the 5th and 10th days after phosphate buffer (control) orWalker-256 solid tumour implantation. Immediately after sacrifice, cachexia was determined in tumour-bearing animals by the formula: [(inicial body weight − final body weight + tumour weight + weight gain of control group)/(initial body weight + body mass gain of control group)] × 100%; RH and LH were stored until use. Oxidative stress and proteolysis were determined in each collected sample. In addition, heart samples were collected from a separate set of animals to determine the thickness of the left and right ventricles. Cachexia values increased over time after tumour implantation from 6.85% at the 5th day to 17.76% at the 10th day. There was no significant difference in LH wet weight and ventricle thickness compared with the control, where as RH wet weight (0.109 ± 0.09 g at the 5th day and 0.093 ± 0.09 g at the 10th day) and thickness (420 ± 16 μm at the 5th day and 279 ± 08 μm at the 10th day) were significantly decreased at both time points when compared with control values (0.153 ± 0.06 g and 607 ± 21 μm, respectively). tert-Butyl-stimulated chemiluminescence analysis revealed a significant increase in the LH and decrease in the RH oxidative stress profiles. Carbonylated proteins increased in the LH (140%, p < 0.05) and RH (100%, p < 0.05) at the 5th day, and significantly decreased in both sides on the 10th day compared to controls. Chemotrypsin-like, caspase-like, and calpain-like activities were evaluated by chemiluminescence, and only calpain-like activity was found to increase at the 5th day in the RH. In the LH, all proteolytic activities systems were decreased when compared with controls. Together, these results demonstrate that oxidative stress appears to play a different role in mass modulation on the LH and RH. The proteolytic systems evaluated herein also appear to have different effects on the responses developed during cardiac cachexia in the two sides of the heart.     

On the Passive Cardiac Conductivity

In order to relate the structure of cardiac tissue to its passive electrical conductivity, we created a geometrical model of cardiac tissue on a cellular scale that encompassed myocytes, capillaries, and the interstitial space that surrounds them. A special mesh generator was developed for this model to create realistically shaped myocytes and interstitial space with a controled degree of variation included in each model. In order to derive the effective conductivities, we used a finite element model to compute the currents flowing through the intracellular and extracellular space due to an externally applied electrical field. The product of these computations were the effective conductivity tensors for the intracellular and extracellular spaces. The simulations of bidomain conductivities for healthy tissue resulted in an effective intracellular conductivity of 0.16S/m (longitudinal) and 0.005S/m (transverse) and an effective extracellular conductivity of 0.21S/m (longitudinal) and 0.06S/m (transverse). The latter values are within the range of measured values reported in literature. Furthermore, we anticipate that this method can be used to simulate pathological conditions for which measured data is far more sparse.     

Improvements in the technique of assessing implanted cardiac pacemakers

Over 250 pacemaker patients currently attend pacemaker clinics in three Glasgow hospitals. Since 1968, the pacemaker frontal-plane vector technique has been used at these clinics along with other investigations to detect adverse changes in the pacing function, or in the pacemaker itself. A pacemaker vectorcardiograph, which employs simultaneous measurements on conventional e.c.g. limb Leads, gives direct display on an oscilloscope screen of the pacemaker frontal-plane vector.     

Instantaneous cardiac tachometer with extendable range

There have been various designs presented in the literature which provide heart rate (Roy and Wehnert, 1974; Clark and Meyer, 1969; Cisek, 1972; Czekajewski and Tove, 1965; Caldwellet al., 1970). Virtually all fall into the following two categories: those that perform an average over several beats and those that measure the time interval between beats and display the reciprocal on a beat-to-beat basis. Although the averaging technique certainly has its area of application, other cases exist where it is desirable to update heart rate with each beat. This communication describes a technique that produces a signal proportional to the instantaneous (beat-to-beat) heart rate with an error of 2 beats/min (b.p.m.) over a 4∶1 range of rate. Further, with the addition of a small number of components, the range can be extended to more than five and one half to one with only a small decrease in accuracy. Total component cost including the extendable range feature, but excluding the milliameter, is $6·00.     

Detection of Quiescent Cardiac Phases in Echocardiography Data Using Nonlinear Filtering and Boundary Detection Techniques

We describe an algorithm to detect cardiac quiescence within a heartbeat using nonlinear filtering and boundary detection techniques in echocardiography images. The motivation for detection of these quiescent phases is to provide improved cardiac gating to obtain motion-artifact-free images of the heart at cardiac computed tomography (CT). Currently, cardiac gating is provided through electrocardiography (ECG), which does not provide information about the instantaneous mechanical state of the heart. Our goal is to test if information about the actual mechanical motion of the heart obtained from B-mode echocardiographic data could potentially be used for gating purposes. The nonlinear filtering algorithm presented involves anisotropic diffusion to smoothen the homogeneous regions of the B-mode images while preserving image edges that represent myocardial boundaries. Following this, we detect the boundary of a particular region of interest (ROI) using a thresholding step. The positional changes of this ROI are then observed for quiescent phases over multiple cardiac cycles using the ECG’s R-R interval. In a pilot study, seven subjects were imaged in the apical, four-chamber view, and quiescence of the interventricular septum was primarily observed in the diastolic region of the ECG signal. However, the position and length of quiescence vary across multiple heartbeats for the same individual and for different individuals as well. The center of quiescence for the seven patients ranged from 51 to 84 % and did not show a trend with heart rates, which ranged from 54 to 83 beats per minute. The gating intervals based on such analysis of echocardiographic signals could potentially optimize cardiac CT gating.