Cell transplantation for heart failure,and tissue engineering of cardiovascular structures

The emergence of selective cell transplantation and tissue engineering has opened up new alternatives for the treatment of heart failure. These involve the use of stem and progenitor cells, as well as new biodegradable polymer scaffolds. The last two decades have seen a dramatic increase in our knowledge of how to fabricate a wide array of tissues, including cardiovascular structures. This article reviews current trends in selective cell transplantation and tissue engineering, and summarises recent achievements and remaining questions in constructing functional cardiac tissue.     

推拿手法对家兔骨骼肌失神经支配后成肌调节因子Myf-5、Myogenin表达的影响

目的观察推拿手法对家兔失神经支配骨骼肌干预后肌湿重、成肌调节因子中生肌因子5(Myogenic factor 5,Myf-5)、肌细胞生成素(Myogenin)表达的影响。方法普通级新西兰雄性家兔随机分为正常对照组、模型对照组、神经生长因子(nerve growth factor,NGF)治疗组和手法治疗组,每组30只。每组再随机分为2周、3周、1个月、2个月和4个月五个亚组,每组6只。模型对照组、NGF治疗组及手法治疗组家兔建立腓肠肌失神经支配模型,NGF治疗组给予肌注注射用鼠神经生长因子,手法干预组进行推拿干预,模型对照组及正常对照组不进行其他操作。分别干预后处死取材,称量腓肠肌肌湿重,计算术侧与健侧的腓肠肌肌湿重比值;检测腓肠肌组织Myf-5 mRNA、Myogenin mRNA表达水平。结果 (1)腓肠肌肌湿重比:NGF治疗组在2周(0.79±0.03)%、3周(0.70±0.06)%、1个月(0.58±0.04)%、2个月(0.44±0.05)%,手法治疗组在2周(0.72±0.05)%、3周(0.55±0.04)%、1个月(0.55±0.09)%、2个月(0.49±0.03)%、4个月(0.50±0.03)%高于模型对照组同期[2周(0.53±0.01)%、3周(0.41±0.03)%、1个月(0.40±0.03)%、2个月(0.38±0.05)%、4个月(0.38±0.05)%,P0.05]。手法治疗组在2周(0.72±0.05)%、3周(0.55±0.04)%低于NGF治疗组[2周(0.79±0.03)%、3周(0.70±0.06)%],4个月(0.50±0.03)%时则高于NGF治疗组(0.42±0.02)%(P0.05)。(2)腓肠肌Myf-5 mRNA表达:NGF治疗组在2周(18.50±1.79)、3周(12.52±0.58)、1个月(5.30±1.76)、2个月(2.82±0.23),手法治疗组在2周(20.48±2.20)低于模型对照组同期[2周(40.91±10.31)、3周(25.25±1.27)、1个月(13.91±1.40)、2个月(8.83±0.86),P0.05],手法治疗组在1个月(16.50±1.17)、2个月(12.20±0.84)、4个月(5.32±0.60)高于模型对照组[1个月(13.91±1.40)、2个月(8.83±0.86)、4个月(3.82±0.54),P0.05]。手法治疗组在3周(37.21±9.10)、1个月(16.50±1.17)、2个月(12.20±0.84)、4个月(5.32±0.60)时高于NGF治疗组[3周(12.52±0.58)、1个月(5.30±1.76)、2个月(2.82±0.23)、4个月(3.88±0.57),P0.05]。(3)腓肠肌Myogenin mRNA表达:NGF治疗组在2周(94.31±23.87)、3周(165.95±29.58)、1个月(156.59±64.76)、4个月(4.05±0.51),手法治疗组在4个月(5.74±1.35)低于模型对照组同期[2周(185.92±48.71)、3周(359.21±116.88)、1个月(597.50±146.66)、4个月(63.13±12.24),P0.05],手法治疗组在2个月(1026.75±132.63)高于模型对照组(168.84±31.85),P0.05]。手法治疗组在2周(209.80±91.25)、3周(482.37±97.95)、1个月(667.73±97.95)、2个月(1026.75±132.63)均高于NGF治疗组[2周(94.31±23.87)、3周(165.95±29.58)、1个月(156.59±64.76)、2个月(140.63±40.18),P0.05]。结论推拿手法可能通过改善成肌调节因子Myf-5、Myogenin表达来延缓失神经支配后骨骼肌的萎缩,远期疗效较NGF良好。     

前庭诱发肌源性电位临床研究现状与展望

 前庭诱发肌源性电位与前庭功能的关系逐步被发现并应用于临床检查,并在一部分前庭功能障碍疾病,如梅尼埃病、良性阵发性位置性眩晕、前庭神经炎等病中发挥了协助诊断及评估病情的作用。本文主要概述前庭诱发肌源性电位的历史、原理、方法及其临床应用。     

Influence of neural and humoral beta–adrenoceptor stimulation on dynamic myogenic microvascular reactivity in cat skeletal muscle

Analysis of myogenic microvascular reactivity in terms of its recently described prominent dynamic component was performed before and during graded sympathetic stimulation and catecholamine infusion. Phenoxybenzamine and propranolol were used to differentiate between α– and β–adrenoceptor effects. The study first confirmed previous findings of a β–adrenergic inhibitory component in the neural control of microvascular resistance which attenuated the a–adrenergic constriction. The results concerning the interaction between adrenergic and myogenic control mechanisms corroborated the conclusion that the sympathoadrenal system, via its β–adrenergic link, exerts effective inhibitory action on myogenic excitatory reactions. As regards the neural control, its –adrenergic component seemed to quite precisely compensate for the reinforcing effect on the myogenic constrictor response which results from increased vascular tone per se (in this case caused by a–adrenergic constriction), interpreted as a physical ‘gain’ effect inherent in the inverse fourth power relationship between radius and resistance. The latter complicating factor, which implies non–linearity in integrated peripheral resistance control, was thus revealed only after β–blockade, but not on the vascular bed with intact adrenoceptors, where a given transmural pressure stimulus evoked an almost equally large myogenic constrictor response irrespective of the prevailing level of vascular tone. The β–inhibitory action of blood–borne noradrenaline was similar to the neural one, whereas that of adrenaline was more effective, causing decline of myogenic reactivity below control.     

Methods for isolation and characterization of intracerebral arterioles in the C57/BL6 wild-type mouse

Vascular control mechanisms have been studied extensively in mice. However, an in vitro characterization of penetrating intracerebral arterioles has not been reported. We describe methods for isolation and cannulation for mouse intracerebral arterioles. This technique allows analysis of mouse cerebral arteriolar physiology and pharmacology without the confounding influences of the surrounding brain elements. Penetrating intracerebral arterioles from adult C57/BL6 wild-type (WT) mice were isolated at 4 °C, transferred to an inverted microscope and cannulated at both ends using a dual glass micropipette system, wherein intraluminal flow (0.2 μl/min) and pressure (60 mmHg) were maintained. The arterioles developed spontaneous tone when the chamber was warmed to 37 °C, with the resulting diameter reaching 68.4±0.9% of passive diameter (29.8±1.1 μm). After the development of spontaneous tone, incremental changes in luminal pressure from 20 to 140 mmHg induced myogenic responses. Acidosis (pH 6.8) and alkalosis (pH 7.6) caused dilation (20.0±1.4%) and constriction (17.2±1.4%), respectively. Extraluminal adenosine (ADO (10 μM); 24.3±3.6%) and sodium nitroprusside (SNP (10 μM); 28.6±4.1%) and intraluminal adenosine 5′-triphosphate (ATP (10 μM); 20.0±3.9%) resulted in vasodilation similar in magnitude to that observed in rat arterioles. This information provides a foundation for elucidating cerebral vascular control mechanisms in genetically engineered mice.     

A novel monoclonal antibody identifies all avian embryonic myogenic cells and adult smooth muscle cells

A novel monoclonal antibody, designated GIIF3, recognized prospective and differentiated smooth muscle cells in avian species studied – guinea fowl, chicken and quail. The GIIF3 antigen appeared in the myocardial, and the myotomal cells of the embryos at Hamburger-Hamilton stages 10 and 14, respectively. The expression of the GIIF3 molecule in the vascular smooth muscle cells emerged in the ventral wall of the dorsal aorta at Hamburger-Hamilton stage 16. The visceral smooth muscle cells started to produce the GIIF3 molecule from Hamburger-Hamilton stage 28 onwards. In both cardiac and skeletal muscles the GIIF3 expression gradually diminished, and it was lost by the end of the embryonic period, unlike in the differentiated vascular and visceral smooth muscle cells. In the latter cells the GIIF3 immunoreactive product showed a fine granular pattern that accumulated in the central region of the cytoplasm; it also occurred in the nucleus. A heavily stained discontinuous layer was associated with the cell membrane. The immunoblotting of the GIIF3 antibody recognized protein bands at 50 and 42 kDa in lysates of adult avian gizzard. A detailed comparative immunohistochemical study was made by smooth muscle markers, which confirmed the results of the immunoblotting, namely, that the GIIF3 monoclonal antibody recognized an avian myogenic cell specific molecule. During smooth muscle cell differentiation the GIIF3 molecule appeared as early as the α-smooth muscle actin, and in adult birds continued to be expressed; therefore the GIIF3 molecule could be regarded as a novel avian smooth muscle specific marker. Accepted: 27 April 2001     

Muscle-derived stem cells for musculoskeletal tissue regeneration and repair

Muscle recently has been identified as a good source of adult stem cells that can differentiate into cells of different lineages. The most well-known muscle progenitor cells are satellite cells, which not only contribute to the replenishment of the myogenic cell pool but also can become osteoblasts, adipocytes and chondrocytes. Other populations of stem cells that appear to be distinct from satellite cells also have been discovered recently. Muscle-derived stem cells (MDSCs) can be divided into two major categories based on these cells' varied abilities to differentiate into myogenic lineages. Interestingly, MDSCs that can differentiate readily into myogenic cells are usually CD45-. In contrast, MDSCs with less myogenic potential are CD45+. Various lines of evidence suggest that different populations of MDSCs are closely related. Furthermore, MDSCs appear to be closely related to endothelial cells or pericytes of the capillaries surrounding myofibers. When used in tissue engineering applications, MDSCs--particularly those genetically engineered to express growth factors--have been demonstrated to possess great potential for the regeneration and repair of muscle, bone and cartilage. Further research is necessary to delineate the relationship between different populations of MDSCs and between MDSCs and other adult stem cells, to investigate their developmental origin, and to determine the regulatory pathways and factors that control stem cell self-renewal, proliferation and differentiation. This knowledge could greatly enhance the usefulness of muscle-derived stem cells, as well as other adult stem cells, for tissue repair and regeneration applications.     

NON-DYSTROPHIC, MYOGENIC MYOPATHIES WITH ONSET IN INFANCY OR CHILDHOOD

ABSTRACT. Some "congenital stationary muscle diseases" and some myopathies with known metabolic or endocrine background are reviewed. The clinical picture is described as well as the histological picture in the muscle, the diagnostic and differential diagnostic considerations and procedures, and–when available–the treatment.     

The effect of alkaline pH and transmural pressure on arterial constriction and membrane potential of hypertensive cerebral arteries

These studies were undertaken to examine the effect of alkalosis to modify pressure-induced activation of isolated cerebral arteries from spontaneously hypertensive rats (SHR) and their normotensive Wistar-Kyoto (WKY) controls. At pH 7.4 andPCO₂ of 34 torr elevation of transmural pressure from 0–140 mm Hg resulted in myogenic activation preceeded by membrane depolarization in both SHR and WKY. The degree of developed myogenic tone in SHR was elevated above WKY. Aklalosis (pH 7.4–7.7) depolarized and activated SHR cerebral arteries to a greater extent than WKY. Furthermore, both the electrical and mechanical responses to elevation in transmural pressure were exaggerated in SHR compared to WKY at pH 7.7 (PCO₂ constant at 34 torr).Manipulation ofPCO₂ at constant pH of 7.4 had similar effects on pressure-induced myogenic tone in both SHR and WKY. Thus, cerebral arteries from both SHR and WKY depolarize and develop myogenic tone in response to increasing transmural pressure. This response is augmented in SHR, but to a much greater extent upon elevation of extracellular pH, whilePCO₂ is maintained within normal limits. The implications of these findings are discussed.D. R. Harder is an Established Investigator of the American Heart Association and a Research Career Scientist of the Veterans Administration. This study supported by NIH grants 33833 and 31871 and the Veterans Adminstration.     

A cellular mechanism for myogenic regulation of cat cerebral arteries

Autoregulation of cerebral blood flow is accomplished through integration of metabolic, neurogenic and myogenic mechanisms. Myogenic mechanisms involve activation of cerebral arterial muscle cells as transmural pressure increases, providing a means through which vessel caliber can be regulated to maintain blood flow constant. The cellular mechanisms involved in this myogenic response may involve changes in the electrical potential across the plasma membrane. When isolated cat middle cerebral arteries are cannulated and prepared in a manner allowing manipulation of transmural pressure, the muscle cell membrane depolarizes as pressure increases. The degree of membrane depolarization in response to an elevated pressure is dependent upon extracellular Ca²⁺ ([Ca]₀), increasing as [Ca]₀ is elevated and markedly decreasing as [Ca]₀ is reduced to low levels. When these arterial preparations are maintained at a physiological pressure of around 100 mm Hg, spontaneous action potentials can be recorded which increase in frequency upon further elevation in pressure. Vessels exhibiting such electrical activity can be observed to decrease in diameter as pressure is increased. Such finding suggest a membrane electrical mechanism for myogenic autoregulation of cerebral arteries.