Prevention of beta cell dysfunction and apoptosis by adenoviral gene transfer of rat insulin-like growth factor 1

Background Islet β-cells are almost completely destroyed when patients with type 1 diabete are diagnosed. To date, insulin substitute therapy is still one of the main treatments. The cure of type 1 diabetes requires β-cell regeneration from islet cell precursors and prevention of recurring autoimmunity. Therefore, β-cell regeneration and proliferation emerge as a new research focus on therapy for type 1 diabetes. Islet β-cell regeneration and development are controlled by many growth factors, especially insulin-like growth factor-1 （IGF-1）. Methods Recombinant adenovirus encoding rat IGF-1 （rlGF-1） was constructed and transduced into rat β-cells, RINm5F cells. Western blotting analysis and ELISA were used to detect rlGF-1 protein. Streptozotocin （STZ） was used to induce RINm5F cell destruction. The level of nitric oxide （NO） was detected in cell culture supernatants by the Griess reaction. Islet cell function was evaluated by glucose-stimulated insulin production. Flow cytometry analysis was further used to investigate the apoptosis of RINm5F cells. Thiaoollyl blue viability assay was applied to determine cell viability. Results The recombined adenovirus-rlGF-1 was successfully constructed and the titer was 4.0×10^8 pfu/ml. The rlGF-1 protein was effectively expressed in the RINm5F cells and cell culture supernatants, rlGF-1 expression remarkably inhibited STZ-induced islet cell apoptosis and significantly decreased the level of NO. Furthermore, IGF-1 expression also significantly protected insulin secretion and cell proliferation in a time-dependent manner. Conclusions Our study suggests that locally produced rlGF-I from RINm5F cells may be beneficial in maintaining β-cell function, protecting β-cells from the destruction of apoptosis factors and promoting β-cell survival and proliferation. IGF-1 might be considered as a candidate gene in gene therapy for type 1 diabetes. In addition, it appears that the apoptosis induced by STZ may be NO-dependent.     

Effect of RGD-modified silk material on the adhesion and proliferation of bone marrow-derived mesenchymal stem cells

In order to investigate the effect ofArg-Gly-Asp （RGD） peptide-modified silk biomaterial on the adhesion and proliferation of bone marrow-derived mesenchymal stem cells （MSCs）, MSCs of third generation were seeded onto the surface of RGD-decorated silk （silk-RGD group）, silk alone （silk group） or tissue culture plate （TCP group）. After incubation for 4 or 12 h, MSCs were examined quantitatively by using precipitation method for cell attachment. The cell proliferation, which was defined as cell density, was compared among the three groups after culture for 1, 2, 3, and 4 days. Cell skeleton, which was labeled fluorescently, was observed under laser confocal microscope after 24 h of culture. The results showed that cell adhesion rate in silk-RGD group was higher than in silk group （P〈0.05）, but similar to that in TCP group after incubation for 4 or 12 h （P〉0.05）. There were no sig- nificant differences in the cell proliferation among the three groups at different time points （P〉0.05 for all）. Laser confocal microscopy revealed that in silk-RGD group, MSCs, strongly fluorescently stained, spread fully, with stress fibers clearly seen, while in silk group, actin filaments were sparsely aligned and less stress fibers were found. It was concluded that RGD peptide could improve the ad- hesion of MSCs to the silk scaffold, but had no impact on the proliferation of the cells.     

血清放射免疫胰岛素和真胰岛素测定对胰岛β细胞功能评价

Objective:To study the changes of true insulin(TI) and immunoreactive insulin (IRI) in subjectswith NGT, IGT and DM, to study the difference betwee true insulin and immunoreactive insulin in evaluating β-cell function and insulin sensitivity. Methods: The levels of serum IRI and TI were determined in 54 cases with typeⅡ diabetes mellitus(Group DM),43 cases with impaired glucose tolerance (Group IGT) and 75 cases with normalglucose tolerance (Group NGT). Then every group was subdivided into obese and non-obese subgroups according tobody mass index. IRI was determined by RIA. TI was determined by ELISA using monoclonal antibody with no sig-nificant cross-reaction between insulin and proinsulin. The insulin resistance index (Homa-IR), pancreatic β-cell     

PDX1和BTC共表达的骨髓间充质干细胞移植治疗大鼠糖尿病的实验研究

目的 观察共表达PDX-1和BTC基因的大鼠骨髓间充质干细胞(MSCs)植入1型糖尿病大鼠肾包膜下对糖尿病的治疗作用。方法 分离纯化SD大鼠MSCs,将pTRE2hyg-PDX1,pTRE2hyg-BTC 和pTet-On共同转染MSCs,诱导MSCs分化为胰岛样细胞(pancreatic islet-like cells PILCs),并移植到糖尿病大鼠肾包膜下, 进行血糖、糖耐量实验、胰岛素的监测并作组织学分析。结果 PDX-1和BTC共表达的MSCs置于基础分化培养基7天后,形成分泌胰岛素的PILCs,移植组在移植PILCs后,血糖水平明显降低,体内胰岛素水平明显上升,腹腔糖耐量试验接近正常水平,与假手术组的差异有统计学意义（P<0.05）。移植组大鼠肾组织中检测到胰岛素的分泌。结论 通过基因工程技术可促使MSCs分化为胰岛样细胞,移植PILCs后能够有效改善糖尿病大鼠功能,缓解糖尿病症状,是一种糖尿病基因治疗的新途径。     

体外诱导小鼠胎肝间充质干细胞向胰岛B样细胞分化的研究

目的:体外分离和定向诱导小鼠胎肝间充质干细胞向胰岛B样细胞分化.方法:无菌条件下从正常C57BL/6J胎鼠肝中分离出间充质干细胞,体外培养传3代后用高浓度葡萄糖培养基以及碱性纤维生长因子(basic fibroblast growth factor,bFGF)和尼克酰胺诱导分化,观察胎肝间充质干细胞诱导前后形态变化;用RT-PCR检测细胞诱导前后胰十二指肠同源异型基因盒1(pancreatic duodenal homeobox-1,PDX-1)、胰岛素原1(proinsulin-1,INS-1)、葡萄糖转运子2(glucose transporter-2,GLUT-2)表达情况;胰岛素免疫细胞化学染色鉴定诱导后细胞胰岛素的表达;在形成胰岛样细胞簇后,用双硫腙做胰岛B细胞特异性染色.结果:RT-PCR显示诱导5 d后PDX-1、INS-1、GLUT-2均有表达,而诱导前的细胞则没有检测到表达;胰岛素免疫细胞化学表明细胞簇内的细胞胰岛素染色强阳性;细胞簇双硫腙染色阳性(每个T-25培养瓶有80～120个).结论:从胎肝中分离出的间充质干细胞在体外可以定向诱导分化为胰岛B样细胞.     

间质干细胞移植治疗1型糖尿病

1型糖尿病是由胰岛β细胞的自身免疫性破坏所致。补充胰岛素是1型糖尿病最基本的治疗,胰岛移植是治愈的根本。然而胰岛移植受供体缺乏的限制。来源于间质母细胞(MSCs)的胰岛生成细胞(IPCs)则成为一种新的有吸引力的选择。一方面,在体外,来源于胰腺、骨髓、脂肪组织、脐带血及组织的MSCs通过基因修饰能够分化成为IPCs。另一方面,MSCs可以作为人类胰岛素基因表达的载体。此外,MSCs的血管生成作用也能被用于糖尿病的治疗。总之,应用MSCs治疗1型糖尿病具有广阔前景。     

骨髓间充质干细胞体外可定向诱导为内皮细胞

目的:探讨大鼠骨髓间充质干细胞(MSCs)的体外培养方法和向血管内皮细胞分化的能力。方法:利用淋巴细胞分离液分离出MSCs,体外扩增,激光共聚焦显微镜检测表面抗原表达,以含VEGF、bFGF的诱导分化培养液定向诱导传代使细胞向血管内皮细胞分化,免疫荧光及免疫组化检测内皮细胞特异性标志物鉴定。结果:MSCs在体外传代扩增后激光共聚焦显微镜检测结果显示CD44、CD90表达阳性,CD31、CD45为阴性,分化后的细胞具有内皮细胞的形态学特征可表达CD31及Ⅷ因子。结论:骨髓间充质干细胞可在体外诱导向内皮细胞方向分化。     

小鼠骨髓间充质干细胞的体外培养和鉴定

目的建立一种实用高效的小鼠骨髓间充质干细胞(mesenchymal stem cells,MSCs)的体外分离培养方法,并进行初步表型鉴定。方法采取贴壁细胞分离法分离和培养MSCs。倒置显微镜观察原代及传代细胞的形态及生长过程,使用免疫细胞化学方法进行MSCs的初步表型鉴定。结果 MSCs贴壁生长,形态均一,呈成纤维缓胞样,生长状态良好。免疫细胞化学检测CD44、CD105、CD34阳性率分别为94.3%、82.3%、3.3%。结论采用贴壁培养法可分离培养出高纯度的MSCs。     

BrdU体外标记大鼠骨髓间充质干细胞的研究

OBJECTIVE: To study the optimal dosage and timing for bromodeoxyuridine (BrdU) labeling of rat bone marrow-derived mesenchymal stem cells (MSCs) in vitro. METHODS: Bone marrow-derived MSCs of SD rats were cultured in vitro routinely and the sixth passage was taken for identification of specific surface antigens by flow cytometry. Before reaching cell confluence, the purified MSCs were incubated with BrdU at different concentrations (5, 10, and 15 micromol/L) for different incubating time (3, 12, 24, 36, 48, and 72 h) with 10 micromol/L BrdU, to identify the optimal BrdU concentration and incubating time for cell labeling. Immunohistochemistry was performed to calculate the labeling index (LI). RESULT: Flow cytometry showed that MSCs expressed CD29 and CD44 but not CD11b or CD45. Incubation of the MSCs with BrdU at 10 micromol/L and for an optimal length of 48 h appeared to achieve the highest LI, both of which exceeded 98%, with the labeling identifiable in five consecutive passages. CONCLUSIONS: The continually passaged cells are MSCs, the incubation of which with 10 micromol/L BrdU for 48 h may achieve a LI over 98% without producing obvious cell damages. The results suggest that BrdU labeling provides a feasible means for a dynamic in vivo observation of the survival, growth and differentiation of the implanted MSCs.     

Notch signaling: a novel regulating differentiation mechanism of human umbilical cord blood-derived mesenchymal stem cells into insulin-producing cells in vitro

Background Human umbilical cord blood-derived mesenchymal stem cells （UCB-MSCs） could be induced to differentiate into insulin producing cells （IPCs） in vitro, which have good application potential in the cell replacement treatment of type-1 diabetes. However, the mechanisms regulating this differentiation have remained largely unknown. Notch signaling is critical in cell differentiation. This study investigated whether Notch signaling could regulate the IPCs differentiation of human UCB-MSCs. Methods Using an interfering Notch signaling protocol in vitro, we studied the role of Notch signaling in differentiation of human UCB-MSCs into IPCs. In a control group the induction took place without interfering Notch signaling. Results Human UCB-MSCs expressed the genes of Notch receptors （Notch 1 and Notch 2） and ligands （Jagged 1 and Deltalike 1）. Human UCB-MSCs with over-expressing Notch signaling in differentiation resulted in the down-regulation of insulin gene level, proinsulin protein expression, and insulin-positive cells percentage compared with the control group. These results showed that over-expressing Notch signaling inhibited IPCs differentiation. Conversely, when Notch signaling was attenuated by receptor inhibitor, the induced cells increased on average by 3.06-fold （n=-4, P 〈0.001） in insulin gene level, 2.60-fold （n=-3, P 〈0.02） in proinsulin protein expression, and 1.62-fold （n=-6, P 〈0.001） in the rate of IPCs compared with the control group. Notch signaling inhibition significantly promoted IPCs differentiation with about 40% of human UCB-MSCs that converted to IPCs, but these IPCs were not responsive to glucose challenge very well both in vitro and in vivo. Hence, further research has to be carried out in the future. Conclusions Notch signaling may be an important mechanism regulating IPCs differentiation of human LICB-MSCs in vitro and Notch signaling inhibition may be an efficient way to increase the number of IPCs, which may resolve the shortage of islet of cell replacement treatment of type-1 diabetes.     

间充质干细胞的培养特性及其相关细胞因子表达

目的:探讨体外培养间充质干细胞的方法及其生物学特性,并检测与其抑制T淋巴细胞增殖活性减轻GVHD机制的细胞因子的表达。方法:通过密度梯度离心及贴壁筛选法分离、纯化及培养间充质干细胞,观察其生物学特性,并进行免疫细胞化学染色观察间充质干细胞是否表达TGF-β1、HGF。结果:采用贴壁筛选法培养间充质干细胞原代经7天贴壁后变为梭形,经14~17天可长满瓶底,传代后3~4天即可长满,免疫分型示CD29+,CD44+,CD34-,CD45-,免疫细胞化学染色显示高度表达TGF-β1及HGF。结论:密度剃度离心结合贴壁筛选法培养间充质干细胞可获得纯度较高,生物学特性稳定的间充质干细胞;间充质干细胞可能通过TGF-β1与HGF两种细胞因子抑制T淋巴细胞增殖减轻移植后GVHD。     

慢性粒细胞性白血病骨髓间充质干细胞的分离纯化及其功能特性的研究

目的 分离、纯化慢性粒细胞性白血病（CML）患者骨髓间充质干细胞（MSC）,并对MSC进行功能、特性鉴定。方法 获取CML患者的骨髓MSC,应用极限稀释法获取单克隆来源的MSC,并在低血清培养液中培养和扩增;流式细胞术检测MSC免疫表型和细胞周期;通过油红O染色、Von Kossa染色和Western印迹检测MSC向脂肪、骨和神经细胞的分化。电镜检测CML患者骨髓MSC的超微结构;通过软琼脂培养法和裸鼠接种,确定CML来源的MSC是否存在致瘤性。结果 MSC在相应的诱导条件下可以向骨、脂肪和神经细胞分化。CML来源的MSC在倒置显微镜下为梭形,表达CD29、CD44、CDl05,而CDllb,CD31、CD34、CD45、HLA—DR均为阴性。CML来源的MSCBCR／ABL融合基因阴性,不具备体内和体外致瘤性。结论CML患者骨髓中存在具有多向分化能力的MSC,该细胞群体不具备体外和体内致瘤性,表现为正常MSC的生物学特征。