成体肝脏干细胞及应用进展

成体肝脏具有极强的再生能力,当肝脏受到严重的损伤或成熟肝细胞增生受到抑制时,肝内干细胞将被活化.成体肝脏干细胞具有维持自我更新的能力,对肝脏损伤或疾病产生反应并进行修复,与急性肝损伤、肝硬化、肝细胞性肝癌等疾病的发生与发展密切相关.     

成体肝脏干细胞及应用进展

成体肝脏具有极强的再生能力,当肝脏受到严重的损伤或成熟肝细胞增生受到抑制时,肝内干细胞将被活化.成体肝脏干细胞具有维持自我更新的能力,对肝脏损伤或疾病产生反应并进行修复,与急性肝损伤、肝硬化、肝细胞性肝癌等疾病的发生与发展密切相关.     

肝卵圆细胞分化调控机制的研究进展

肝卵圆细胞是存在于肝脏中的一类肝干细胞，目前已证实了它在人及多种动物中存在。卵圆细胞来源并定位于肝内的胆管系统中，具有多向分化潜能，正常时处于静止状态，只有当肝脏发生严重损伤且肝细胞再生障碍时才受到激活并大量增殖，可分化为肝细胞和胆管细胞，以修复重建肝脏组织，恢复生化功能。随着研究的深入，卵圆细胞必将在移植、生物人工肝、各种终末期肝病的治疗等方面开辟新的途径。     

内源性细胞介导肝脏再生的研究进展

肝脏再生是一个古老又神奇的命题,复杂的细胞和分子机制调控肝脏再生的启动、维持和终止。肝内不同区域的肝细胞再生能力不同,而且其多倍性特征也在肝脏再生和肝脏稳态中扮演了重要角色。肝细胞、胆管细胞、肝祖细胞以及间充质干细胞都可以作为肝脏再生的细胞来源,不同类型和程度的损伤诱导了最适合再生的细胞类型,阐明新生肝细胞的来源具有重要的再生医学价值。深入研究肝脏再生有助于解决如何加速肝再生,逆转肝纤维化,利用再生医学寻找肝衰竭的新疗法,扩展肝切除术特别是老年人肝切除术的适应范围和平衡肝脏移植供体受体的基本生存需要等一系列临床问题。现我们结合最新的研究,对肝再生的内源性细胞来源这一主题进行综述。     

肝干细胞在肝再生及肝脏疾病中的研究进展

正肝脏具有强大的再生能力,虽然肝再生并不完全依赖于肝干细胞,但当发生肝炎、肝外伤、肝硬化及肝癌等肝损伤时,肝干细胞便会被激活~([1]),受损后的残存肝组织通过再生,可迅速恢复至原有体积和重量,最终实现肝组织结构的重建及肝功能恢复~([2])。通常情况下肝再生是由成熟肝细胞分裂增殖完成,但当成熟肝细胞增殖能力下降或受抑制时,肝干细胞可分化发育为成熟肝细胞。干细胞是存在于胚胎和成体中的一类具有自我更新能力和多向分化潜能的特殊细胞,     

肝干细胞及其应用的研究进展

<正>肝干细胞(hepatic stem cell,HSC)是一类具有同时向肝细胞及胆管细胞分化和增殖以及自我更新潜能的原始细胞,当肝实质损伤尤其是肝脏大部分切除后,HSC会发生分化和高效增殖,参与到肝脏的再生和修复过程中,为机体细胞的更新提供潜在的无限细胞来源。相对于手术而言,HSC治疗具有损伤小、并发症少的优势,为终末期肝病的治疗提供了崭新的思路[1]。本文就HSC的研究和治疗进展进行综述。1 HSC的分类目前认为,HSC按照其来源可分为肝源性和非肝源性两种。肝源性HSC来源于前肠内胚层,     

肝干细胞来源、定向分化及其转化机制

本文综述了近年来胚胎、造血、肝内祖细胞和小肝细胞样祖细胞、骨髓、间充质来源干细胞定向向肝细胞分化的研究进展,并阐述了干细胞转化为肝细胞的机制是融合还是转化.对此深入研究可望为肝干细胞移植和基因治疗带来希望,进而为临床肝移植面临的供肝短缺提供可选择的补充治疗方法.     

肝卵圆细胞在肝硬化组织中介导肝脏再生的研究进展

肝脏依靠肝细胞的自我更新和肝卵圆细胞(HOC)的增殖分化两大途径参与肝损伤的修复。HOC是一类具有多向分化潜能的肝干细胞,在肝脏再生中扮演重要角色。肝硬化肝细胞再生能力低下,HOC参与肝脏损伤的修复和重建,其活化,增殖及分化等与肝硬化微环境密切相关。因此,深入研究HOC在肝硬化中介导肝脏再生的机制及细胞移植的优势,将为治疗终末期肝硬化提供新策略。笔者就HOC的特征、其在肝硬化微环境下的作用、以及肝硬化微环境对HOC介导肝脏再生的调控等研究进展进行综述。     

肝干细胞来源、定向分化及其转化机制

本文综述了近年来胚胎、造血、肝内祖细胞和小肝细胞样祖细胞、骨髓、间充质来源干细胞定向向肝细胞分化的研究进展,并阐述了干细胞转化为肝细胞的机制是融合还是转化.对此深入研究可望为肝干细胞移植和基因治疗带来希望,进而为临床肝移植面临的供肝短缺提供可选择的补充治疗方法.     

胎盘源性干细胞在肝脏疾病中的研究进展

人类胎盘源性干细胞(hPDSCs)是干细胞的混合群.再生医学已将其用于某些功能衰竭和损伤器官的细胞再生、抗细胞凋亡、抗炎,抗肿瘤和细胞功能恢复研究.目前已有许多实验研究证明:胎盘间充质干细胞(PDMSCs)可以在体外分化为肝细胞样细胞,并于体内外促进干细胞增生和抗肝细胞凋亡,在动物肝损伤模型抑制肝纤维化.本文就胎盘干细胞的来源、分类、生物学特性以及胎盘干细胞在肝脏疾病中的治疗研究做一综述,以便为进一步探讨胎盘源性干细胞在肝脏疾病治疗中的应用提供新的思路.     

ALPPS一期术后肝内干/祖细胞的变化及其与肝再生的关系

目的:探讨肝内干/祖细胞在联合肝脏分割和门静脉结扎二步肝切除术(ALPPS)一期手术后肝再生中的作用。方法:将72只SD大鼠随机均分为ALPPS组、门静脉结扎(PVL)组和假手术组,分别行ALPPS一期手术、单纯PVL和假手术。分别在术后1、2、3、7 d检测各组血清转氨酶、炎症因子水平与肝右中叶肝再生率(HRR),并检测肝脏组织中细胞增殖指标Ki-67与肝内卵圆细胞(干/祖细胞)标志物OV-6表达水平。结果:与假手术组比较,ALPPS组与PVL组术后1~2 d的转氨酶与炎症因子水平均明显升高,且在ALPPS组的升高水平均大于PVL组(均P0.05);ALPPS组与PVL组术后肝右中叶HRR及肝组织Ki-67阳性率明显升高,但ALPPS组在术后3、7 d的HRR明显高于PVL组,术后2、3 d的Ki-67阳性率明显高于PVL组(均P0.05);ALPPS组与PVL组术后肝组织均有明显OV-6表达,但ALPPS组术后2、3 d的OV-6表达水平明显高于PVL组(均P0.05)。结论:ALPPS一期手术诱导的肝再生明显优于PVL,机制可能为ALPPS术后较高的炎症状态使激活肝内干/祖细胞的动员和活化,从而促进快速肝再生有关。     

肝硬化门脉高压症治疗的新途径——干细胞移植研究进展

肝干细胞是多源性的,可分为肝源性肝干细胞和非肝源性肝干细胞两大类。多种成体组织来源的干细胞可在受者(包括鼠和人)肝脏内分化为肝细胞和胆管上皮细胞,为成体干细胞移植治疗肝硬化门脉高压提供了新思路。在临床应用中,肝干细胞移植具有移植技术简单、价格相对低廉,免疫源性小、易于低温保存,具有广泛的扩展性,体外基因转染率高,并能稳定高效地表达外源基因等优点;但肝内干细胞移植是否会引起肝脏肿瘤等问题尚未明确。     

No evidence of hematopoietic stem cell mobilization in patients submitted to hepatectomy or in patients with acute on chronic liver failure

BACKGROUND: Liver regeneration is a heterogeneous phenomenon involving the proliferation of different cell lineages in response to injury. Under a strong positive selection pressure bone marrow derived stem cells may be involved in this process, by making a contribution to both parenchymal restoration and endothelial cell replacement. We investigate bone marrow stem cell migration to the liver in patients undergoing hepatectomy or with acute on chronic liver failure. METHODS: We enrolled 6 patients submitted to hepatectomy, 6 patients to cholecystectomy and 8 patients with acute decompensation of liver cirrhosis. Mobilization of CD34+ cells was evaluated by cytofluorimetry on peripheral blood samples at different time points; baseline, 1, 3, 7, 15 and 30 days after surgery and at admission, 1, 7 and discharge among patients with acute on chronic liver failure. 10 healthy subjects undergoing blood donation were also enrolled to evaluated the basal value of CD34+ cells. RESULTS: White blood cell counts remained in the normal range (4.1-9.8 x 10(9)/L) in all groups throughout the follow-up. In all patients of Groups 1, 2 and 3, circulating CD34+ failed to show statistically significant differences both as the absolute number and as the percentage at any time point compared to healthy controls. CONCLUSIONS: Bone marrow derived cell mobilization can not be detected after hepatectomy or during an acute decompensation on a cirrhotic liver. Under these circumstances liver regeneration can probably call upon mature hepatocytes and endogenous progenitor cells. The involvement of extrahepatic progenitors if any, is a rare and limited phenomenon.     

肝脏类器官构建及其对小鼠部分肝切除术后肝再生的作用#br#

目的 观察肝脏类器官对小鼠部分肝切除术后肝再生的作用。方法 体外构建肝脏类器官，通过形态学、PCR和免疫荧光对类器官进行初步鉴定。C57BL/6小鼠随机等分为对照组和治疗组，每组18只。对照组进行肝左叶、中叶切除术+肝包膜注射200 μL PBS；治疗组进行肝左叶、中叶切除术+肝包膜移植200 μL类器官悬液。建模成功后分别于术后第1、4、7天收集标本。通过血清生化检测、免疫组化和Western blotting评估肝脏类器官对小鼠肝部分切除术后肝再生的作用。结果 类器官体外培养3 d，从直径20 μm的囊性结构扩增到约125 μm的细胞团（P＜0.05），直径扩增近6 倍。肝脏干细胞标志基因EPCAM、SOX9和CK19明显上调（P＜0.05），传代前后基因保持稳定。免疫荧光显示CK8、Desmin、AFP和PCNA呈阳性。HE显示术后第4天，治疗组肝细胞形态大小基本恢复正常，形态较清晰，无炎症细胞浸润，无脂肪或气球样变。对照组小鼠肝细胞核仁染色加深，仍有炎性细胞浸润，部分区域存在肝细胞坏死区。免疫组化Ki67和Western blotting对增殖水平进行检测，结果显示治疗组增殖能力是对照组的3 倍。肝功能检测发现治疗组在术后第4天ALT、AST、TBIL和DBIL明显下降，ALB合成增加（P＜0.05）。结论 具有肝脏干细胞属性和增殖能力的肝脏类器官，能通过保护肝细胞、改善部分肝切除术后小鼠肝功能，发挥促进肝再生作用。     

肝癌干细胞标志物研究的进展

肝癌是常见的恶性肿瘤,其目前的治疗手段是以手术为主的综合治疗,但是术后易复发、转移,预后较差。肿瘤干细胞学说认为只有杀灭肝癌干细胞才能从根本上治愈肝癌,因此分离和鉴定肝癌干细胞成为研究的热点。笔者就目前的肝癌干细胞表面标志物研究进展进行综述。     

A Distinct Subpopulation of Bone Marrow Mesenchymal Stem Cells,Muse Cells,Directly Commit to the Replacement of Liver Components

Genotyping graft livers by short tandem repeats after human living‐donor liver transplantation (n = 20) revealed the presence of recipient or chimeric genotype cases in hepatocytes (6 of 17, 35.3%), sinusoidal cells (18 of 18, 100%), cholangiocytes (15 of 17, 88.2%) and cells in the periportal areas (7 of 8, 87.5%), suggesting extrahepatic cell involvement in liver regeneration. Regarding extrahepatic origin, bone marrow mesenchymal stem cells (BM‐MSCs) have been suggested to contribute to liver regeneration but compose a heterogeneous population. We focused on a more specific subpopulation (1–2% of BM‐MSCs), called multilineage‐differentiating stress‐enduring (Muse) cells, for their ability to differentiate into liver‐lineage cells and repair tissue. We generated a physical partial hepatectomy model in immunodeficient mice and injected green fluorescent protein (GFP)‐labeled human BM‐MSC Muse cells intravenously (n = 20). Immunohistochemistry, fluorescence in situ hybridization and species‐specific polymerase chain reaction revealed that they integrated into regenerating areas and expressed liver progenitor markers during the early phase and then differentiated spontaneously into major liver components, including hepatocytes (≈74.3% of GFP‐positive integrated Muse cells), cholangiocytes (≈17.7%), sinusoidal endothelial cells (≈2.0%), and Kupffer cells (≈6.0%). In contrast, the remaining cells in the BM‐MSCs were not detected in the liver for up to 4 weeks. These results suggest that Muse cells are the predominant population of BM‐MSCs that are capable of replacing major liver components during liver regeneration.     

Liver regeneration is an angiogenesis- associated phenomenon

OBJECTIVE: To investigate whether liver regeneration is an angiogenesis-associated phenomenon.SUMMARY BACKGROUND DATA: Angiogenesis is predominantly known for its pivotal role in tumor growth. However, angiogenesis could also play a role in physiologic processes involving tissue repair, such as liver regeneration. METHODS: Mice subjected to 70% partial hepatectomy were treated with human angiostatin (100 mg/kg body weight). Regeneration-induced hepatic angiogenesis was determined by assessing intrahepatic microvascular density using CD31 staining of frozen liver sections. Liver regeneration was evaluated by assessing wet liver weights and BrdU incorporation in DNA at regular intervals after partial hepatectomy. Possible direct effects of angiostatin on hepatocytes were studied by assessment of liver enzymes (ASAT, ALAT, bilirubin, lactate dehydrogenase), MTT assay (cytotoxicity), aminophenol production (metabolic function), and TUNEL (apoptosis). RESULTS: In a regenerating liver, microvascular density increased by 38%. Angiostatin significantly inhibited this response by 60%. In addition, angiostatin inhibited liver regeneration by 50.4% and 24.9% on postoperative days 7 and 14, respectively. In control mice liver weights regained normalcy in 8 days, whereas those in angiostatin-treated mice normalized after 21 days. In angiostatin-treated mice, the maximal BrdU incorporation was decreased and delayed. Direct adverse effects of angiostatin on cultured and in vivo hepatocytes were not observed. Angiostatin neither induced necrosis on hematoxylin and eosin staining nor affected serum levels of liver enzymes. CONCLUSIONS: Liver regeneration is accompanied by intrahepatic angiogenesis. Antiangiogenic treatment using angiostatin inhibits both phenomena. The authors conclude that liver regeneration is, at least in part, an angiogenesis-dependent phenomenon.     

肝内胆管癌的大体类型与细胞来源的关系

肝内胆管癌是原发性肝癌的一个重要组成部分,其发生发展的机制复杂.从细胞层面来分析,目前已被发现可能的来源有胆管上皮细胞、肝干细胞、肝细胞.从大体类型来分析,可将其分为以下三类:肿块型、管壁浸润型、腔内型.临床研究表明,不同类型的肝内胆管癌不仅形态学上有差异,患者的临床表现、治疗及预后差异也较大.因此,为探求肝内胆管癌的大体类型与细胞来源的关系,进一步研究清楚其相关发生机制及预后影响因素,笔者特就两者关系进行综述.     

慢性肝损伤时肝内干细胞的增殖

目的：采用免疫组织化学的方法研究慢性肝损伤时肝干细胞在肝脏内的分布和增值,初步探讨肝脏的损伤修复与肿瘤发生的细胞生物学机制。方法：3,-me-DAB喂食大鼠四周,建立应激模型刺激大鼠肝内干细胞的迅速增殖,取材、固定制成石蜡切片,ABC法检测肝干细胞特异性的表面标记蛋白CD34、C-11、CK19、OV6和神经前体细胞的特异性表面标记Nestin在大鼠肝脏内的表达。结果：大鼠肝实质结构改变显著,汇管区内结缔组织细胞大量增生,浸润周围肝组织形成假小叶。靠近界板处断续的排列着卵圆样细胞分别表达CD34、CK19、OV6和Nestin,阳性细胞的形态和分布特点相似,而且具有典型的干细胞的特点。此外,肝实质内可见大量的单个核样干细胞分别表达OV6、CD34、Nestin和CK19。这些细胞类似造血系统来源的单核细胞分布在肝索、肝血窦、肝内血管、增生的小叶间胆管和胆管之间,多见于汇管区的结缔组织内。结论：3’-me-DAB作用后,肝内存在着多种干细胞,而且具有空间分布的规律性。增生的干细胞在损伤应激下继续增殖分化为肝实质细胞,参与肝脏的组织修复,同时成为引发肝脏肿瘤的可能原因之一,具体机制还需要进一步的深入研究。     

Limited contribution of cells of intact extrahepatic tissue origin to hepatocyte regeneration in transplanted rat liver

BACKGROUND: It is now well established that various adult somatic tissues harbor multipotent stem cells that can differentiate into a broad variety of cell types of all three germ layer origins. It remains controversial, however, whether they are a reservoir of cells utilized for emergent tissue repair or simply a vestige of evolution and, if the former is the case, to what extent they can potentially contribute to reconstitution of a specific organ. To get an insight in such a direction, we examined the extent of contribution of naive intact cells of extrahepatic origin to hepatocyte reconstitution in the transplanted liver with or without injury in the rat. METHODS: Liver from wild-type donor rats was transplanted to green fluorescent protein (GFP)-transgenic rats, and GFP-positive hepatocytes were examined with or without liver injury. RESULTS: The proportion of GFP-positive hepatocytes in the transplanted noninjured liver linearly increased by 0.0048% per week, that is, approximately 5 x 10(3) hepatocytes of extrahepatic origin were generated per day. Liver injury induced by treatment with 2-acetylaminofluorene and CCl4 or the additional application of hepatocyte growth factor did not further increase the percentage of GFP-positive hepatocytes. CONCLUSION: The present results indicate that cells derived from nonmanipulated extrahepatic tissues appreciably contribute, though limitedly, to hepatocyte reconstitution in the liver of the rat.