雪旺氏细胞的发育、存活及其调控机制

雪旺氏细胞（schwann cells,SC)是周围神经系统的胶质细胞，在神经再生过程中起到至关重要的作用。本阐述SC的发育，存活及其相关的调控因子。了解了SC及其前体的生物学特性。轴突源性Neuregulin和SC自分泌调控的信号对其存活的调控。以及SC凋亡的调控。以便在体外模拟体内环境大量扩增SC，解决目前组织工程神经修复中的难点。     

实验性胃癌大鼠脾脏免疫杀伤细胞活性的研究

分别检测了正常大鼠与胃癌大鼠(各15例)外周血淋巴细胞(PBL)及脾细胞(SC)的NK与LAK细胞活性。结果发现,胃癌大鼠的NK与LAK细胞活性均低于正常者,尤以SC更为显著,提示胃癌大鼠脾脏内存在某些抑制因子,能明显地抑制SC的NK活性及其对rIL-2刺激的反应性。     

细胞Ca^2＋信号对基因转录的调节

细胞Ｃａ２ ＋ 信号系统是介导胞外刺激引起核内反应的几个主要信号转导途径之一,对细胞的存活及凋亡起到至关重要的作用。本文对细胞Ｃａ２ ＋ 信号的形成和调控、细胞Ｃａ２＋ 信号的表现形式及其对基因转录的调节机制进行综述     

睾丸支持细胞促进体外培养神经元生长的研究

目的　探讨睾丸支持细胞 (SC)对体外培养神经元生长发育的促进作用。　方法　将SCs制备成饲养层和SCs条件培养液 (SCM)后与神经元共培养 ,观察培养细胞的存活数和突起数 ,并应用图像分析仪观察细胞的面积。　结果　SCs饲养层及SCM培养神经元的存活数、突起数和胞体面积明显高于对照组 (P <0 0 1)。　结论SCs对体外培养的神经元具有显著的促生长作用。     

B细胞在骨髓发育中的凋亡与调控

近年来对细胞凋亡及其调控的广泛研究 ,促进了对B细胞发育及调节机制的理解。我们运用一系列转基因及基因剔除的鼠模型 ,研究了B细胞在各分化阶段的凋亡状况 ,发现一些基因具有调节B细胞发育、影响B细胞存活的功能。实验证明这些基因能通过影响Bcl 2家族蛋白的表达而决定细胞凋亡的阈值。有关领域的深入研究 ,将有助于理解人类淋巴系统肿瘤及自身免疫性疾病的发生机制 ,并为探索治疗这些疾病的新方法提供重要依据     

PKCθ的结构和功能及其在免疫相关疾病中的研究进展

PKCθ是一种不依赖Ca2+激活的nPKC亚型之一,主要在T细胞、骨骼肌细胞和造血系统中表达。它是抗原刺激T细胞后唯一转位于免疫突触的PKC亚型,通过参与胞内信号转导进而调控T细胞的活化和存活以及肿瘤的发生和发展。此外,PKCθ在不同的组织中发挥不同的生理作用。PKCθ参与骨骼肌内胰岛素信号通路的调控,与胰岛素抵抗相关联;PKCθ与血小板的激活和血栓形成密切相关。本文对近年来PKCθ及其在相关疾病中的最新研究作一综述。     

新闻点击

蛋白质在癌症发展中扮演的角色;新的基因调控机制;2个与恶性乳腺癌相关的主要基因;与细胞生长和癌症有关的结构;可以抑制白血病细胞存活的新物质;乳腺癌研究的重大进展;[编者按]     

人类bcl-2基因在小鼠NIH/3T3细胞中的作用观察

本实验探讨了人类ｂｃｌ－２基因对小鼠ＮＩＨ／３Ｔ３细胞增殖和存活能力的影响。结果表明，人类ｂｃｌ－２基因转染对正常培养条件下的细胞的增殖和存活能力无明显影响，但能增加细胞对血清撤退和ｓｔａｕｒｏｓｐｏｒｉｎｅ（ＳＴＳ）两种致凋亡因素的抵抗作用。这一研究丰富了ｂｃｌ－２基因调控细胞凋亡的资料，并为深入研究奠定了基础     

T细胞亚群和免疫耐受

无论采取什么样的方法,我们在耐受诱导研究中的最终目标大部分是建立在对T细胞的调控上,涉及到TCR、共刺激分子、T细胞生长因子及某些T细胞亚群的诱导增生等方面.这些靶T细胞的活化、无能、凋亡或存活均与耐受状态的建立存在某种关联.本文将对近年来T细胞亚群与免疫耐受关系的研究作一综述.     

肿瘤坏死因子对肠上皮细胞分泌片的影响

目的：研究TNF-α对Caco-2细胞表达SC的影响。方法：采用免疫组化、ELISA、Western blot、Real-time PCR方法检测肠上皮细胞表达SC的变化。结果：与无TNF-α刺激比较,用不同浓度TNF-α刺激后SC阳性细胞、培养上清液中游离SC、Caco-2细胞SC蛋白和SC基因的表达明显增加（P〈0.01）。结论：TNF-α上调Caco-2细胞内SC的表达。     

Efficient Generation of Schwann Cells from Human Embryonic Stem Cell-Derived Neurospheres

Schwann cells (SC), the glial cells of peripheral nerves, are involved in many diseases including Charcot Marie Tooth and neurofibromatosis, and play a pivotal role in peripheral nerve regeneration. Although it is possible to obtain human SC from nerve biopsies, they are difficult to maintain and expand in culture. Here we describe an efficient system for directing the differentiation of human embryonic stem cells (hESC) into cells with the morphological and molecular characteristics of SC. Neurospheres were generated from hESC using stromal cell induction and grown under conditions supportive of SC differentiation. After 8 weeks, hESC-derived SC expressed characteristic markers GFAP, S100, HNK1, P75, MBP and PMP-22, and were observed in close association with hESC-derived neurites. ~60% of the cells were double-immunostained for the SC markers GFAP/S100. RT-PCR analysis confirmed the expression of GFAP, S100, P75, PMP-22 and MBP and demonstrated expression of the SC markers P0, KROX20 and PLP in the cultures. Expression of CAD19 was observed in 2 and 4 week cultures and then was down-regulated, consistent with its expression in SC precursor, but not mature stages. Co-culture of hESC-derived SC with rat, chick or hESC-derived axons in compartmentalized microfluidic chambers resulted in tight association of the SC with axons. Apparent wrapping of the axons by SC was occasionally observed, suggestive of myelination. Our method for generating SC from hESC makes available a virtually unlimited source of human SC for studies of their role in nerve regeneration and modeling of disease.     

The role of microstructured and interconnected pore channels in a collagen-based nerve guide on axonal regeneration in peripheral nerves

The use of bioengineered nerve guides as alternatives for autologous nerve transplantation (ANT) is a promising strategy for the repair of peripheral nerve defects. In the present investigation, we present a collagen-based micro-structured nerve guide (Perimaix) for the repair of 2 cm rat sciatic nerve defects. Perimaix is an open-porous biodegradable nerve guide containing continuous, longitudinally orientated channels for orientated nerve growth. The effects of these nerve guides on axon regeneration by six weeks after implantation have been compared with those of ANT. Investigation of the regenerated sciatic nerve indicated that Perimaix strongly supported directed axon regeneration. When seeded with cultivated rat Schwann cells (SC), the Perimaix nerve guide was found to be almost as supportive of axon regeneration as ANT. The use of SC from transgenic green-fluorescent-protein (GFP) rats allowed us to detect the viability of donor SC at 1 week and 6 weeks after transplantation. The GFP-positive SC were aligned in a columnar fashion within the longitudinally orientated micro-channels. This cellular arrangement was not only observed prior to implantation, but also at one week and 6 weeks after implantation. It may be concluded that Perimaix nerve guides hold great promise for the repair of peripheral nerve defects.     

Evidence for endothelial nitric oxide as a negative regulator of Schwann cell dedifferentiation after peripheral nerve injury

The loss of intimate contact with axons triggers Schwann cells (SCs) to switch from a myelin-producing phenotype to a dedifferentiated, proliferating non-myelin-forming state after nerve injury. SC dedifferentiation is required for effective nerve regeneration. Negative regulators of SC dedifferentiation are promising targets to accelerate function recovery in acquired peripheral neuropathies. We recently reported that nitric oxide (NO) synthesized by endothelial NO synthase (eNOS) slows down functional recovery and axon regeneration after XIIth nerve crushing. This harmful action could be effected by a NO-delaying action on SC dedifferentiation. Adenoviral vectors directing the expression of a dominant negative mutant for eNOS (AVV-TeNOS) or the enhanced green fluorescent protein (AVV-eGFP) were individually injected into the distal stump just after XIIth nerve crushing. Growth-associated protein 43 (GAP-43), strongly over-expressed in dedifferentiated SCs and regenerating axons, was up-regulated in AVV-TeNOS-transduced nerves relative to AVV-eGFP-treated nerves. AVV-TeNOS increased the number of GAP-43-positive cells and bands of Bungner but did not alter the number of Hoechst-positive nuclei relative to AVV-eGFP. These results signal endothelial NO as a negative regulator of the SC dedifferentiation process, but not of SC proliferation rate, after nerve injury. Vascular-derived factors should be taken into account as feasible extrinsic regulators of SC plasticity.     

Green fluorescent protein is a stable morphological marker for schwann cell transplants in bioengineered nerve conduits

Bioengineered systems incorporate cultured cells to mimic the substituted tissue. A labeling method is necessary to monitor the survival of transplanted cells within the host. This labeling method must be compatible with the histochemical methods used for morphological analysis. This study assessed (1) The in vitro characteristics of Schwann cells (SCs) labeled with green fluorescent protein (GFP), (2) the in vivo effect of transplanted GFP-SCs in a model of peripheral nerve injury, and (3) the compatibility of GFP-SCs with immunofluorescence histochemical techniques. SCs were retrovirally labeled with GFP and their growth characteristics were compared with those of nontransduced SCs (ntSCs). GFP-SCs were seeded in a resorbable nerve conduit for grafting into a 1-cm gap in rat sciatic nerve. Grafts were harvested after 2 weeks and immunofluorescent staining was performed to measure axonal and SC regeneration distances and to identify GFP-SCs. Results of GFP-SC vitality assays did not vary significantly from those of ntSC assays. GFP-SCs were readily located ex vivo and stimulated significantly better axonal and SC regeneration distances in comparison with empty conduits. These findings show that GFP labeling does not have a deleterious effect on SCs and that it is a useful labeling method for the study of bioengineered systems.     

Addition of fibronectin to alginate matrix improves peripheral nerve regeneration in tissue-engineered conduits

Schwann cell (SC) transplantation has been proposed to encourage peripheral nerve regeneration, but an optimal SC-carrying matrix would be needed. The aim of this study was to characterize how the addition of fibronectin to alginate would affect the outcome of nerve regeneration promoted by Schwann cells embedded in this matrix. Genetically labeled rat SCs were obtained by lacZ gene transduction. SCs were suspended in alginate hydrogel matrix with/without addition of liquid fibronectin, and their viability and growth in the different types of matrices were assessed in vitro by AlamarBlue assay. In vivo assessment of SC transplantation in the matrix was carried out with poly-3-hydroxybutyrate (PHB) conduits to bridge a sciatic nerve gap. The grafted conduits were harvested at 2, 3, and 6 weeks and assessed for the presence of labeled SCs in relation to regrowing axons. The amount and rate of axonal regeneration were assessed by quantitative immunohistochemistry. Addition of fibronectin to alginate hydrogel improved SC viability and growth profile in vitro. X-Gal staining confirmed that SCs transplanted in PHB conduits were viable throughout the time course, and that the labeled SCs were clearly associated with regenerating axons. The regeneration rate was enhanced when liquid fibronectin was added to the alginate matrix. Furthermore, the presence of SCs also enhanced regeneration and there was an additive effect when both SCs and fibronectin were combined with alginate. In conclusion, the addition of fibronectin to alginate hydrogel matrix contributed to improve nerve regeneration, supporting SC viability and augmenting their effect on axonal growth when transplanted in a bioengineered nerve conduit.     

The effects of FGF-2 gene therapy combined with voluntary exercise on axonal regeneration across peripheral nerve gaps

Studies were conducted to determine the possibility that voluntary exercise could enhance regenerative effects of gene therapy via Schwann cells (SC) over-expressing FGF-2. Sedentary or exercise rehabilitation conditions were therefore provided shortly after reconstructing 10 mm sciatic nerve gaps in rats with silicone grafts. Exercise for 7 days elevated mRNA levels of regeneration associated proteins (GAP-43 and synapsin I) in lumbar spinal cord and dorsal root ganglia of SC transplanted, in contrast to non-cellular reconstructed rats. FGF-2 gene therapy followed by 25–27 days of exercise did enhance regeneration of myelinated axons in comparison to sedentary animals. Four weeks after surgery mRNA levels of regeneration associated proteins were significantly higher in lumbar spinal cord of running compared to sedentary SC transplanted animals. Our results suggest that voluntary exercise could reinforce the beneficial effects of SC transplantation and FGF-2 gene therapy in peripheral nerve reconstruction approaches.     

经血源性子宫内膜干细胞及其修复外周神经损伤的应用前景

外周神经损伤带给患者长期病痛的同时严重影响了患者的生活质量,目前临床上除显微外科手术外,移植施万细胞(SC)也成为有效的治疗方法。然而SC移植的先天不足限制了其在临床上的大规模使用,因此,干细胞治疗神经损伤逐渐成为近年来的研究热点。而近来发现的经血源性子宫内膜干细胞(Men ESCs)凭借其丰富的来源,无创伤的分离方式以及较高的增殖活性和分化潜能等方面的优势获得广泛关注,并在成骨、心肌、肝脏、子宫内膜及中风等疾病的治疗过程中显示了良好的效果。因此,我们在明确外周神经损伤发生机制的基础上,着重阐明Men ESCs的生物学特性及其在治疗外周神经损伤的机制,以期为Men ESCs在外周神经损伤的治疗提供借鉴。     

A synthetic oxygen carrier in fibrin matrices promotes sciatic nerve regeneration in rats

Tissue-engineering nerve conduits have been studied for a long time in bridging large nerve defects. However, the low oxygen availability within the nerve conduits, which results in death of migratory Schwann cells (SC) or loss of the newly formed tissue’s function, is still an obstacle for axonal regeneration. Thus, it was hypothesized that an oxygen-enriched conduit would enhance axonal regeneration and functional recovery in vivo. To address this issue, perfluorotributylamine (PFTBA) enriched fibrin hydrogel was prepared and injected into collagen–chitosan conduits. The conduit containing PFTBA-enriched fibrin hydrogel was then used to bridge a 12-mm sciatic nerve defect in rats. The control rats were bridged with collagen–chitosan conduits filled with fibrin matrices without PFTBA. It was found that axonal regeneration and functional recovery in the combined PFTBA group were significantly higher than those in the control group without PFTBA. Further investigations showed that the mRNA and protein levels of S-100, brain-derived neurotrophic factor and nerve growth factor were enhanced by PFTBA at 1 and 3 weeks after surgery. However, the mRNA and protein levels of vascular endothelial growth factor were in a similar range between the combined PFTBA group and the control group without PFTBA. In addition, immunohistochemical results showed that the morphological appearances of regenerated nerve and survival of SC were enhanced by PFTBA at 4 and 12 weeks after surgery. In conclusion, PFTBA-enriched nerve conduit is capable of enhancing axonal regeneration, which provides a new avenue for achieving better functional recovery in the treatment of nerve defect.     

Effects of cerebrolysin on rat Schwann cells in vitro

Although the peripheral nervous system (PNS) is capable of regeneration, these processes are limited. As a potential means to augment PNS regeneration, the effects of cerebrolysin (CL), a proteolytic peptide fraction, were tested in vitro on Schwann cell (SC) proliferation, stress resistance, phagocytic and cluster-forming capacity. Primary SC/fibrocyte co-cultures were prepared from dorsal root ganglia of 5–7-day-old rats. SCs were subjected to mechanical stress by media change and metabolic stress by serum glucose deprivation (SGD). Cell survival was assessed using MTT test. SC proliferation was determined by counting BrdU-labeled cells. SC clustering was studied by ImageJ analysis of S100 immunostaining. Wallerian degeneration (WD) was evaluated by measuring acetylcholine-esterase staining within sciatic nerves in vitro. It was found that CL caused no effect on MTT turnover in the tested doses. CL inhibited SC proliferation in a dose-dependent manner. Media change and additional SGD stress inhibited SC clustering. CL enhanced the reorganization of SC clusters and was able to counteract SGD-induced cluster defects. Moreover, CL accelerated WD in vitro. CL was able to enhance the functions of SCs that are relevant to nerve regeneration. Thus, our findings suggest that CL may be suitable for therapeutic usage to enhance PNS regeneration/reconstruction.     

雪旺细胞和层粘蛋白对脊髓前角运动神经元损伤的保护作用

选３０只成年Ｗｉｓｔａｒ大鼠，坐骨神经切断后，分别应用体外培养的雪旺细胞，层粘蛋白和生理盐水于神经侧断端，４周后，观察损伤侧腰４、５节段脊髓前角运动神经元的存活率，神经元酸性磷酸酶和胆碱脂酶活性变化。结果：生理盐水组脊髓前角运动神经元存活率为５９％，酸性磷酸酶活性明显增强，胆碱脂酶活性明显降低；雪旺细胞组和层粘蛋白组脊髓前角运动神经元存活率分别为８２．３％和８１．１％，酸性磷酸酶和胆碱脂酶活性较对