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BACKGROUND:It is not fuly understood that whetherp53 inhibitor can directly intervene in the viability of bone marrow mesenchymal stem cels and the possible mechanism. OBJECTIVE:To investigate the effect of p53 inhibitor, PFT-α, on the aging process of bone marrow mesenchymal stem cels in late-phase amplification and to discover the key target to delay the replicative senescence of human bone marrow mesenchymal stem cels. METHODS:The expression levels ofp53,p21, andp15 mRNA in human bone marrow mesenchymal stem cels in both early and late-phase amplification were detected by quantitative PCR assay. Then, human bone marrow mesenchymal stem cels in late-phase amplification were respectively treated with 20 μmol/L PFT-α or an equivalent amount of dimethyl sulfoxide for 2 weeks. The positive rate of aging cels was determined by SA-β-Gal staining. The apoptosis was detected by TUNEL staining. Human bone marrow mesenchymal stem cels were treated with 300 μmol/L H2O2 for 30 minutes, and then celular anti-oxidative stress capacity was detected by cel counting kit-8 assay. RESULTS AND CONCLUSION:The quantitative PCR assay showed that the mRNA expression level ofp15, p21 andp53 in human bone marrow mesenchymal stem cels in late-phase amplification was significantly increased (1.45±0.23), (1.51±0.14) and (1.78±0.14) times as much as that in early phase amplification (P < 0.05). The positive rate of aging cels in PFT-α group was significantly lower than that in the dimethyl sulfoxide group[(41±5)%vs. (63±7)%,P < 0.05)]. However, there was no significant difference in apoptosis rate between PFT-α group and dimethyl sulfoxide group. After treatment with H2O2, the absorbance value in the PFT-α group was(1.27±0.13) times as much as that in the dimethyl sulfoxide group (P < 0.001). The above results demonstrate that the activation ofp53 signaling pathway may be an important factor of causing aging of human bone marrow mesenchymal stem cels. Application ofp53 inhibitor PFT-αcan enhance the anti-oxidative stress capacity of human bone marrow mesenchymal stem cels in late phrase amplification.
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BACKGROUND:Cationic liposome-mediated celltransfection is reliable and repeatable. However the transfection efficiency is often low. OBJECTIVE:To study the optimized methods for gene transfection mediated by liposome into N2a cells (mouse neuroblastma cells). METHODS:Using traditional adherent method and improved suspension method, 500 ng recombinant plasmid pcDNA3-GFP carrying green fluorescence protein was transfected into N2a cells in 24-wel culture plate, which was mediated by 1.5μL Lipofectamine?LTX Reagent. The expression of green fluorescent protein was observed by inverted fluorescence microscope, and the transfection efficiencies at different transfection ways were calculated. By using improved suspension transfection method, 500 ng plasmid DNA was transfected with different doses of Lipofectamine?LTX Reagent (1.0, 1.5, 2.0, 2.5μL). The optimal ratio of liposome and DNA was explored. RESULTS AND CONCLUSION:The transfection efficiency of suspension transfection method was significantly higher than that of the tranditional adherent method (P<0.01) when using 1.5μL liposome/500 ng DNA. The transfection efficiency of the 1.0, 1.5, 2.0, 2.5μL Lipofectamine?LTX on 500 ng plasmid DNA was respectively (76.60±3.85)%, (80.00±4.17)%, (88.00±5.89)%, (54.96±4.23)%. It showed the 500 ng DNA and 2.0μL liposome achieve the highest transfection efficiency.
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Objective To observe how exogenous estrogen influences the distribution and the expression of NOS positive neurons in the supraoptic nuclei of hypothalamus in the overiectomized female rats. Methods The 2-3-month-old female rats(n=40) were selected as the healthy and nulli-copulatory experimental animals. Rats were divided into following groups: normal control group(n=10), ovariectomized control group(n=10), and two experimental groups that have been injected with estrogen for post-operative 40 days(n=10) and for post-operative 70 days(n=10). Finally, all the animals were infused and the brains were removed. Immunohistochemical (SABC) method was adopted to count the number of NOS poitive neurons and observed the NOS poitive neuronal morphology under the light microscope. The image analysis system was used to test the average gray value of immunoreactivity in NOS positive neurons. Results In the ovariectomized control group, the density of NOS positive neurons in supraoptic nucleus was significantly increased and their shapes were bigger than that of the normal control group(P<0.05). The density and the form of the NOS positive neurons in supraoptic nucleons had no apparent difference between the estrogen for post-operative 40 days group and the ovariectomizeed control group(P>0.05).In the group after estrogen-injection 2 months compared with the normal control group, and the ovariectomized control group, both of the NOS positive neurons' density and the size become significantly decreased, and the staining of cells was lesser in the group injected with estrogen for post-operation 70 days. Conclusion The present results suggest that exogenous estrogen may influence the distribution and the expression of NOS positive neurons in supraoptic nucleus of hypothalamus of ovariectomized female rats.
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AIM: To investigate the process of human bone marrow stromal cells (hBMSCs) differentiation into neural-like cells and to determine the role of 26S proteasome in neuronal differentiation. METHODS: Purified hBMSCs were treated with β-mercaptoethanol (β-ME) for 1 day and retinoic acid (RA) for 3 days, followed by growth factor (10 μg/L bFGF or 20 μg/L NGF) for another 3 days. Immunofluorescence was performed to detect the expression of nestin (a neural precursor cells marker), Tuj1 (a premature neuronal marker), and neurofilament (NF, a mature neuronal marker) at all stages of induced differentiation. Immunostaining and RT-PCR were used to analyze the expression of 26S proteasome during neuronal differentiation of hBMSCs. To further confirm the role of 26S proteasome in hBMSCs differentiation, cells were treated with β-ME/RA and then followed by protesome inhibitor MG132 and growth factor. Immunostaining was performed to detect NF-positive cells. RESULTS: Quantification results showed that the untreated cells were almost never positive for nestin, Tuj1 and NF. After treated with β-ME/RA, the numbers of nestin-positive cells (34.41%±1.27%) and Tuj1-positive cells (27.79%±1.27%) were increased. Notably, the numbers of NF-positive cells were significantly increased to 56.72%±2.4% after induction with β-ME/RA/GF. Immunofluorescence analysis showed that undifferentiated hBMSCs cells were weakly stained by antibody against 26S proteasome, but the numbers of cells with high-intensity of 26S proteasome were increased after treated with β-ME/RA. The RT-PCR result of 26S proteasome further confirmed that the mRNA level of the cells differentiated by β-ME/RA (1.33), as well as by β-ME/RA/GF (1.77), was significantly increased compared to the undifferentiated cells. Moreover, hBMSCs incubated with protesome inhibitor MG132 significantly decreased the numbers of NF-positive cells (37.59%±1.52%). CONCLUSION: After induction with β-ME/RA/GF, hBMSCs can be differentiated into neural-like cells, which is concomitant with the increase in 26S proteasome expression. Inhibitor of 26S protesome prevents hBMSCs differentiation, suggesting that 26S proteasome may be involved in the differentiation of hBMSCs into neural-like cells.
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BACKGROUND:As a kind of stressor, exercise-induced fatigue surely can lead to the material and functional changes of certain nerve nucleus within brain.It is still uncertain on what kind of nucleus closely relate to exer-cise-induced fatigue and what materials induce the functional or/and structural changes of tired central nerve.OBJECTIVE:To study the relationship between nitric oxide synthase (NOS) in ventromedial hypothalamic nucleus(VMH),dorsomedial hypothalamic nucleus(DMH) and exercise-induced fatigue.DESIGN:Randomized controlled study.MATERIALS:The experiment was completed in the Department of Human Anatomy of North University of China and Shanxi Medical University during October 2003 to January 2004.Twenty male Wister rats of clean class were selected.INTERVENTIONS:The rats were randomly divided into experimental group and control group with each of 10 rats.The rats in experimental group were made exercise-induced fatigue animal model by doing heavy load swimming until they were exhausted for 4 consecutive weeks. After the model was built,ABC immunohistochemical method was used to observe the expression of neuronal NOS (nNOS) in neurons of VMH ,and DMH and image analysis and statistic process were conducted.MAIN OUTCOME MEASURES:Number of nNOS positive cells in per unit visual field; Area and gray of positive substance.RESULTS:The number of nNOS positive cells in VMH of fatigue group was (25.25±7.35)/visual field which was much greater than that of control group (9.70±3.20)/visual field(P＜ 0.001).The area of nNOS positive substance was (3 867.75±1 940.41)μm2/visual field which was greater than that of control group(750.13±579.88)μm2/visual field(P ＜ 0.001). The number of nNOS positive cells in DMH of fatigue group was (30.25±7.87) /visual field which was much greater than that of control group (14.00±4.99) /visual field. And the area of nNOS positive substance was (4 512.06±1 243.93) μm2/visual field that was much greater than that of control group(782.46±711.46)μm2/visual field(P ＜ 0.001).CONCLUSION:The nNOS positive neurons in VMH and DMH neurons are closely related to the occurrence of central exercise-induced fatigue.Nitric oxide may play an important role in regulation of VMH and DMH to stress caused by fatigue.