间充质干细胞分化为肝样细胞的研究进展

肝炎后肝硬化等慢性进展性肝病、急性肝功能衰竭、肝脏代谢性疾病及肝脏恶性肿瘤等终末期肝病的发病率日益上升,美国贝塞斯达回忆宣布肝移植是目前治疗终末期肝病最有效的方法,但由于肝源有限、移植后的免疫排斥反应以及高额费用等限制了这种治疗方法的开展。近年来,随着对干细胞研究的深入,发现间充质干细胞(MSCs)具有向肝样细胞分化的潜能,且安全性、可行性及疗效均显示了较好的应用前景,为终末期肝病的治疗提供了新的途径。本文就MSCs不同组织来源分化特点、体内外分化为肝样细胞研究、分化后的肝样细胞的生物学特性及MSCs分化为肝样细胞的机制、MSCs应用的一些问题作一概述。     

人肝细胞L02诱导MSCs分化为肝样细胞的观察

目的 探讨骨髓间充质干细胞(MSCs)在与肝细胞L02在体外共培养条件下诱导分化为肝细胞的可行性.方法 密度梯度离心联合贴壁筛选法获取MSCs.将接种于盖玻片上的MSCs和人肝细胞L02共置于培养皿中.在2、4、6、8 d时分别用免疫细胞化学检测AFP、细胞角蛋白(CK18),同时检测染色体核型.结果 成功分离培养出MSCs,其表型为CD29阳性,CD34阴性.共培养的MSCs可在2～8 d时,形态变为三角形、多角型或类圆形.第2天时,共培养细胞AFP表现为强阳性表达,以后减弱,第8天AFP的阳性表达很少.第2、4天检测出CK18均为阴性表达,第6、8天CK18为阳性表达.阳性对照组细胞CK18有较强的阳性表达,AFP弱阳性表达.阴性对照组均为阴性表达.共培养细胞染色体核型无融合现象.结论 人肝细胞L02能够诱导MSCs分化为肝样细胞.     

肝病患者血清诱导人骨髓间充质干细胞表达甲胎蛋白和白蛋白的实验研究

近年研究发现骨髓间充质干细胞（MSCs）具有高度可塑性,在特定环境下除分化为中胚层的组织细胞外,还可跨越胚层界限分化为外胚层及内胚层组织细胞.肝细胞生长因子（HGF）、表皮细胞生长因子（EGF）等有诱导骨髓MSCs向肝细胞分化的作用,为肝脏干细胞提供了一种新来源.本研究采用密度梯度离心、贴壁培养和消化时间控制相结合的方法纯化人骨髓MSCs,并用肝病患者血清诱导培养,探讨肝病患者血清对其分化作用.     

两种细胞因子诱导人骨髓多能成体祖细胞向肝样细胞分化的作用

本实验用免疫磁性分离（MACS）方法分选骨髓间充质干细胞（MSCs）亚群MAPCs，用成纤维细胞生长因子-4（FGF-4）及肝细胞生长因子（HGF）诱导其向肝细胞方向分化，并采用不同方法鉴定了细胞分化能力。     

人骨髓间充质干细胞体外分化为肝细胞样细胞

目的 探讨人骨髓间充质干细胞(MSCs)的体外培养及特异性诱导为肝细胞样细胞的能力。方法 骨髓标本来源于健康志愿者的胸骨,年龄2～35岁,采用淋巴细胞分离液(密度1.077)分离人MSCs,并分别采用HGF、FGF4、HGF FGF4以及无生长因子四种处理因素体外诱导第三代人MSC向肝细胞样细胞分化。通过流式细胞术分析鉴定.MSCs的纯度,于诱导培养的0、7、14、21、28天时留取细胞检测CK18、AFP和白蛋白的表达情况,同时进行糖原染色验证细胞功能。结果 用淋巴细胞分离液分离出的人MSCs纯度可达90％,采用HGF、FGF4及HGF FGF4三种处理因素均可在体外诱导人MSCs特异分化为具有肝细胞样细胞表型和功能的细胞。结论 人MSCs能在体外扩增并定向诱导为肝细胞样细胞。     

肝脏干细胞调控机制的研究进展

肝脏干细胞在正常肝脏中处于静息状态 ,但当肝脏受到严重损伤和或肝细胞的再生能力受到抑制时 ,肝脏干细胞便活化、增殖并分化为成熟肝细胞及胆管细胞以发挥代偿作用。尽管目前对肝脏干细胞的来源及肝组织内的准确定位还不明确 ,但众多研究己证实肝内肯定存在肝脏干细胞 ,其活化后的子代细胞为卵圆细胞 ,卵圆细胞具备多向分化潜能 ,体内外实验证实其可以分化为肝细胞、胆管细胞、胰腺及肠型上皮 ,1999年Ｐｅｔｅｒｓｏｎ研究证实骨髓细胞可以转化为肝细胞 ,其他学者对骨髓干细胞的体内移植及体外培养的研究中也证实了Ｐｅｔｅｒｓｏｎ的观点…     

间充质干细胞治疗肝脏疾病的研究进展

间充质干细胞(MSCs)可应用于治疗急性肝衰竭、终末期肝病和遗传代谢性肝病,旁分泌机制是其治疗肝病的重要机制。MSCs还可以通过调节免疫功能减轻炎症反应、抗肝细胞凋亡、抗肝纤维化、促进内源性肝干细胞分化和刺激内源性肝细胞增殖、促进血管增生等修复肝组织。进一步阐明MSCs的治疗机制,合理设计随机双盲对照临床试验,明确干细胞移植可能的副作用,是其广泛应用于临床的前提。     

骨髓间充质干细胞分化为心肌细胞的研究进展

骨髓间充质干细胞（MSCs）在不同的诱导条件下可向心肌细胞（CM）分化,但目前对于MSCs心肌化过程中的信号分子、具体途径及基因调控等均不太明确。本文对MSCs向心肌细胞分化的实验条件及目前研究可能包含的分子机制作一综述。     

MSCs分化为功能性肝细胞的研究进展

间充质干细胞(mesenchymal stemcells,MSCs)来源于中胚层间充质,广泛存在于骨髓、脐带组织、脐血、外周血、脂肪等组织中.在特定条件下,可以分化为骨、脂肪、神经细胞及肝细胞等多种细胞,进而作为一种替代器官移植的新的治疗方法.近年来,肝硬化等终末期肝病的发病率日益上升,成为影响人类健康的重大疾病之一.肝源紧张、免疫排斥限制了肝移植的临床应用,然而众多研究证实MSCs对肝纤维化、肝硬化等肝病的治疗作用可能与其分化为功能性肝细胞有关,但具体机制尚不十分清楚.本文就MSCs的分化能力及其分化的调控、分子机制和不同来源干细胞对肝纤维化的治疗作用作一综述.     

间充质干细胞在糖尿病细胞疗法中的研究现状

间充质干细胞(mesenchymal stem cells,MSCs)是一类具有自我更新和多向分化潜能的细胞,在细胞替代治疗中有极其重要的作用.MSCs来源广泛,几乎所有的成体和胚胎组织中都有MSCs [1].目前研究较多的是骨髓、脂肪、滑膜、脐带血、胎肝、羊膜等来源的MSCs.MSCs最重要的特性是多能性,能分化成多种不同的细胞谱系,如骨、脂肪、软骨等间质细胞谱系,以及神经元、肝细胞和内皮细胞等内胚层和神经外胚层细胞[2-3].MSCs同样具有分化为胰岛内分泌细胞的可塑性,已经证实来源于各组织中的MSCs可以分化为有功能的胰岛素分泌细胞.本文就MSCs分化为胰岛样细胞的方法 和分化机制做一综述.     

Three layer functional model and energy exchange concept of aging process

Relying on a certain degree of abstraction, we can propose that no particular distinction exists between animate or living matter and inanimate matter. While focusing attention on some specifics, the dividing line between the two can be drawn. The most apparent distinction is in the level of structural and functional organization with the dissimilar streams of ‘energy flow’ between the observed entity and the surrounding environment. In essence, living matter is created from inanimate matter which is organized to contain internal intense energy processes and maintain lower intensity energy exchange processes with the environment. Taking internal and external energy processes into account, we contend in this paper that living matter can be referred to as matter of dissipative structure, with this structure assumed to be a common quality of all living creatures and living matter in general. Interruption of internal energy conversion processes and terminating the controlled energy exchange with the environment leads to degeneration of dissipative structure and reduction of the same to inanimate matter, (gas, liquid and/or solid inanimate substances), and ultimately what can be called ‘death.’ This concept of what we call dissipative nature can be extended from living organisms to social groups of animals, to mankind. An analogy based on the organization of matter provides a basis for a functional model of living entities. The models relies on the parallels among the three central structures of any cell (nucleus, cytoplasm and outer membrane) and the human body (central organs, body fluids along with the connective tissues, and external skin integument). This three-part structural organization may be observed almost universally in nature. It can be observed from the atomic structure to the planetary and intergalactic organizations. This similarity is corroborated by the membrane theory applied to living organisms. According to the energy nature of living matter and the proposed functional model, the decreased integrity of a human body's external envelope membrane is a first cause of the structural degradation and aging of the entire organism. The aging process than progresses externally to internally, as in single cell organisms, suggesting that much of the efforts towards the restoration and maintenance of the mechanisms responsible for structural development should be focused accordingly, on the membrane, i.e., the skin. Numerous reports indicate that all parts of the human body, like: bones, blood with blood vessels, muscles, skin, and so on, have some ability for restoration. Therefore, actual revival of not only aging tissue of the human body's membrane, but the entire human body enclosed within, with all internal organs, might be expected. We assess several aging theories within the context of our model and provide suggestions on how to activate the body's own anti-aging mechanisms and increase longevity. This paper presents some analogies and some distinctions that exist between the living dissipative structure matter and inanimate matter, discusses the aging process and proposes certain aging reversal solutions.     

Unusual responses of nocturnal pineal melatonin synthesis and secretion to swimming: Attempts to define mechanisms

Abstract: The effect of swimming at night on rat pineal melatonin synthesis was compared with that of light exposure at night. Rats were forced to swim at 0030 hr (lights out at 2000 hr) and sacrificed by decapitation 15 and 30 min later, immediately after swimming. Other groups of animals were exposed to white light (650μW/cm²) for 15 and 30 min at same time. Swimming caused a rapid and highly significant drop in the melatonin content in the pineal gland; however, the activity of N-acetyltransferase (NAT), the supposed rate limiting enzyme in the melatonin production, was not changed. Despite the drop in pineal melatonin levels, serum concentrations of the indole remained elevated in the rats that swam. In contrast, melatonin levels in the pineal and serum of light exposed rats fell precipitously, accompanied by a significant suppression of NAT activity. Since we anticipated that the strenuous exercise associated with swimming may induce release of artrial natriuretic peptide (ANP) from the heart, which in turn could cause the release of pineal melatonin, in a second study we injected physiological saline intravenously to stretch the cardiac muscle and release ANP. Three milliliters of normal saline was injected during the day into the jugular vein of anesthetized rats that were pretreated with isoproterenol to stimulate pineal melatonin production. Animals were killed 15 min after the saline injection, and pineal NAT activity and pineal melatonin levels were measured. The saline injections caused no alteration in the elevated levels of either NAT or melatonin. These data suggest that the disparity in pineal NAT activity (which was high) and pineal melatonin (which was low), in animals swum at night, may not be caused by ANP which is released during strenuous exercise such as swimming.     

The immunoneuroendocrine role of melatonin

Abstract: A tight, physiological link between the pineal gland and the immune system is emerging from a series of experimental studies. This link might reflect the evolutionary connection between self-recognition and reproduction. Pinealectomy or other experimental methods which inhibit melatonin synthesis and secretion induce a state of immunodepression which is counteracted by melatonin. In general, melatonin seems to have an immunoenhancing effect that is particularly apparent in immunodepressive states. The negative effect of acute stress or immunosuppressive pharmacological treatments on various immune parameters are counteracted by melatonin. It seems important to note that one of the main targets of melatonin is the thymus, i.e., the central organ of the immune system. The clinical use of melatonin as an immunotherapeutic agent seems promising in primary and secondary immunodeficiencies as well as in cancer immunotherapy. The immunoenhancing action of melatonin seems to be mediated by T-helper cell-derived opioid peptides as well as by lymphokines and, perhaps, by pituitary hormones. Melatonin-induced-immuno-opioids (MHO) and lymphokines imply the presence of specific binding sites or melatonin receptors on cells of the immune system. On the other hand, lymphokines such as -γ-interferon and interleukin-2 as well as thymic hormones can modulate the synthesis of melatonin in the pineal gland. The pineal gland might thus be viewed as the crux of a sophisticated immunoneuroendocrine network which functions as an unconscious, diffuse sensory organ.     

Melatonin and photoperiodic time measurement: Seasonal breeding in the sheep

Abstract: Well-established circadian physiology supports the view that photoperiodic time measurement utilizes the coincidence between the presence of light and a photosensitive phase of a 'biological clock' to alter reproductive status—the so-called external coincidence model of seasonal breeding. In this review, we examine the mechanism whereby photoperiod interacts with presumed suprachiasmatic nuclei activity to allow endogenous melatonin to normally synchronize reproductive activity to the optimal time of year. The Romney Marsh sheep is particularly explored as an experimental model. It is suggested that the on/off activity of seasonal reproduction may be a robust mechanism able to be predictably manipulated by the judicious use of the light/dark cycle and exogenous melatonin, but firmly based on circadian principles.     

Response of rat pineal melatonin to calcium, magnesium, and lithium is circadian stage dependent

Abstract: Herein we documented the response of pineal melatonin production to electrolytes known to be effective on pineal function in view of a possible circadian stage dependence. We studied the release of melatonin by perifused rat pineal glands at 2 different circadian stages corresponding to the middle of the light and dark periods, i.e., respectively, 7 and 19 HALO (Hours After Light Onset, L:D = 12:12). The initial efflux rates were, as expected, much higher in the perifusates of glands removed from rats sacrificed during the dark phase than of those removed during the light phase. After 3 hr of perifusion, melatonin release reached similar levels which were found constant up to the 8th hr of perifusion, whatever the circadian stage. Perifusion of the glands with physiological concentrations for the rat of calcium (5.2 mmol/1) and magnesium (1.34 mmol/1) resulted in a stimulatory effect on the pineal glands removed from rats sacrificed in the middle of the dark period (19 HALO), whereas no effects were observed on the pineal glands removed from rats sacrificed during the light (7 HALO). Lithium (0.28 and 0.55 mmol/1) was ineffective on melatonin release in pineal glands removed 7 and 19 HALO. Our results show differences in the initial efflux rates of melatonin and in the response of perifused pineal glands to calcium and magnesium according to the circadian stage.     

Changes in connexin43, the gap junction protein of astrocytes, during development of the rat pineal gland

Abstract: The abundance of gap junctions between rat pineal astrocytes formed by connexin43 (Cx43) was studied during development. Levels and distribution of Cx43 were measured by immunoblotting and indirect immunofluorescence, respectively. The amount of Cx43 in cells located within the gland was low until about the 7th postnatal day and increased to adult values between the 14th and 21st days postpartum. Although astrocytes, recognized by their vimentin immunoreactivity, were scarce before birth, they were abundant by the 7th postnatal day suggesting that the low levels of Cx43 found at this age corresponded to a low expression of this protein. Localization of the immunoreactivity to Cx43 and vimentin showed a close correlation, indicating that mature or immature pineal astrocytes form gap junctions made of Cx43. Since Cx43 levels attained their adult values at about the time the innervation and the functional state of the gland reached maturity (2–3 weeks after birth), it is proposed that astrocyte gap junctions are involved in the function of the adult rat pineal gland.     

Conservative management of perforated duodenal diverticulum： A case report and review of the literature

Duodenal diverticula are a relatively common condition. They are asymptomatic, unless they become complicated, with perforation being the rarest but most severe complication. Surgical treatment is the most frequently performed approach. We report the case of a patient with a perforated duodenal diverticulum, which was diagnosed early and treated conservatively with antibiotics and percutaneous drainage of secondary retroperitoneal abscesses. We suggest this method could be an acceptable option for the management of similar cases, provided that the patient is in good general condition and without septic signs.     

Language of CTO interventions – Focus on hardware

The knowledge of variety of chronic total occlusion (CTO) hardware and the ability to use them represents the key to success of any CTO interventions. However, the multiplicity of CTO hardware and their physical character and the terminology used by experts create confusion in the mind of an average interventional cardiologist, particularly a beginner in this field. This knowledge is available but is scattered. We aim to classify and compare the currently used devices based on their properties focusing on how physical character of each device can be utilized in a specific situation, thus clarifying and simplifying the technical discourse.