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Taxol is one of the most important chemotherapeutic drugs against cancer. Taxol has been mainly extracted from the bark of yews for a long time. However, methods for the extraction of taxol from the bark of Taxus species were inefficient and environmentally costly. As a result of the high ecological toll exacted on trees with the potential for Pacific yew extinction, investigators began to look for other methods of taxol production. Recently, increasing efforts have been made to develop alternative means of taxol production, such as using complete chemical synthesis, semi-synthesis, Taxus spp. plant cell culture and microbe fermentation. Using microbe fermentation in the production of taxol would be a very prospective method for obtaining a large amount of taxol. Therefore, it is necessary to understand the molecular basis and genetic regulation mechanisms of taxol biosynthesis by endophytic fungi, which may be helpful to construct the genetic engineering strain with high taxol output. In this paper, the taxol biosynthesis pathway from Taxus cells and the advantages of taxol biosynthesis by endophytic fungi were discussed. The study on the isolation and biodiversity of taxol-producing endophytic fungi and the taxol biosynthesis related genes are also discussed.
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Endófitos , Fungos , Microbiologia Industrial , Microrganismos Geneticamente Modificados , Neoplasias , Tratamento Farmacológico , Paclitaxel , Taxus , QuímicaRESUMO
BACKGROUND:Bone marrow mesenchyme stem cells are important non-hematopoietic stem cells in the bone marrow, which can stimulate angiogenesis. While, Slit can also stimulate angiogenesis, as many studies have proved. OBJECTIVE:To review the biological functions, clinical application and effects of bone marrow mesenchymal stem cells and Slit2 on promoting angiogenesis. METHODS:A computer-based online research of CNKI and PubMed databases was performed to col ect articles published between 1980 and 2014 with the keywords“MSCs”and“Slit2”in Chinese and English. There were 436 articles after the initial survey. Final y, 65 articles were included according inclusion and exclusion criteria. RESULTS AND CONCLUSION:Both bone marrow mesenchymal stem cells and Slit2 play an important role in promoting angiogenesis, but the relevance of bone marrow mesenchymal stem cells and Slit2 is stil controversial. If assuming that bone marrow mesenchymal stem cells secrete Slit2, more researches should be done to reveal whether bone marrow mesenchymal stem cells promoting angiogenesis is relevant to Slit2 and through which signaling pathway Slit2/Robo functions to adjust bone marrow mesenchymal stem cells thus to promote angiogenesis. If relevant, the transplantation of the Slit2 and bone marrow mesenchymal stem cells wil be a promising treatment of cerebral infarction and other central nervous injuries.
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BACKGROUND: Transplantation of bone marrow mesenchymal stem cells (MSCs) has been used in the field of repair of nerve injury. Brain stereotactic transplantation and transvascular transplantation are two transplantation methods. OBJECTIVE: We infused MSCs into rat peripheral cerebral infarct focus, in order to investigate the improvement of rat neurological dysfunction by forelimb use asymmetry test and postural reflex test.DESIGN: A randomized controlled animal experiment. SETTING: Department of Neurology, First Hospital of Jilin University.MATERIALS: This study was performed at the Key Laboratory of Zoonosis, Ministry of Education, Institute of Zoonosis, Jilin University between October 2006 and April 2007. Healthy male Wistar rats of clean grade, weighing 250-280 g, were provided by the Laboratory Animal Center of Jilin University. The protocol was performed in accordance with ethical guidelines for the use and care of animals.METHODS: MSCs from healthy adult volunteers were in vitro cultured and proliferated by density gradient separation and adherence screening method. Their immunophenotypes were identified by a flow cytometer. The Wistar rats were randomized into 5 groups with 10 rats in each: normal control group, sham-operated group, model group, serum-free DMEM-treated group (DMEM group) and MSCs -treated group (MSCs group). Rat models of cerebral ischemia/reperfusion were developed by occluding rat right middle cerebral artery following suture occlusion method modified by Longa et al. Rats in the normal control group were untouched. In the sham-operated group, operation was not ended till cervical interior and exterior arteries were exposed and sutured, and the other disposals were the same as those in the model group. At ischemia 90 minutes reperfusion 1 hour, a stereotaxic apparatus was used to take rat right peripheral cerebral ischemic region as transplantation site: 3 mm lateral to, 1mm caudal to and 4 mm posterior to Bregma. Rats in the MSCs group were slowly injected 5 μL BrdU-labeled MSCs (4×1011 L-1) serum-free medium. Rats in the DMEM group were injected 5 μL serum-free medium. After perfusion, inserted needle was retained for 5 minutes and then slowly withdrawn in order to avoid the back flow of liquid from needle pole. The survival of MSCs in rats was detected by immunohistochemical technique, and rat behavioral changes of observed on days1, 3, 7 and 28 after transplantation by forelimb use asymmetry test and postural reflex test.MAIN OUTCOME MEASURES: ① The immunophenotype of MSCs were identified by a flow cytometer. ② The survival of transplanted MSCs in the rat brain. ③ Rat behavioral changes. RESULTS: All the 50 rats were included in the final analysis. ① High purity of MSCs were harvested in the experiment. Flow cytometer detection showed that both CD44 and CD29 were positive, while CD34, CD45 and CD31 were negative. ② MSCs transplanted into the brains of rats in the MSCs group gathered in the peripheral cerebral ischemic region and survived. ③ Behavioral scores of rats in the MSCs group were significantly lower than those in the other groups (P < 0.05). They were gradually decreased with time after transplantation, and reached the valley value on day 7 after transplantation (P < 0.01). CONCLUSION: Neurological function of rats recovers in all the groups except normal control group. But the recovery differs in different groups, and neurological function of rats in the MSCs group recovers better than that in other groups.
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Objective To explore the effect of mesenchymal stem cells(MSCs) on nervous function in rats with focal cerebral ischemia.Methods The MSCs were cultivated,purified,and proliferated in vitro by density gradient and adherence to plastic dishes method.The models of Wistar rats were prepared after middle cerebral artery occlusion(MCAO) of right lasted 90 min and reperfusion 1 h.Wistar rats were randomly divided into normal control group(A,n=10),sham operation group(B,n=10),no-handle group after cerebral ischemia/reperfusion (C,n=10),free-serm DMEM transplantation group after cerebral ischemia/reperfusion(D,n=10),MSCs transplantation group after cerebral ischemia/reperfusion(E,n=10).After identified by flow cytometry,5 ?L 5-bromo-2-deoxyuridine(BrdU) labeled MSCs(4?105? ?L-1) and 5 ?L serum-free DMEM were respectively injected intracerebraly into ischemic boundary zone of right in D and E groups.Immunohistochemical method was used to detect the expression and survival of BrdU-labeled MSCs in vivo.Nervous function behavioral tests were performed on 1st,3th,7th and 28th day after transplantation by forelimb use asymmetry test and postural reflex test.Results MSCs were successfully purified and proliferated in vitro.The MSCs expressed CD29,CD44,but didn't expressed CD34,CD45,CD31 identified by flow cytometry.transplanted MSCs survived and were localized to the ischemic boundary zone.Behavioral tests of every group were improved with time prolonged.However,MSCs transplantation group was significantly better than any other groups(P
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BACKGROUND: Vascular endothelial growth factor (VEGF) can accelerate neovascularization and, as a multifunctional cytokine, performs critical functions via its receptors in angiogenesis.OBJECTIVE: To investigate the expression of VEGF and its receptor FLT-1 and FLK-1 mRNA during the early stage of acute focal cerebral brain ischemia, and examine the relationship between the timing and location of their expressions.DESIGN: Randomized controlled study.SETTING: Department of Neurology of the First Hospital Affiliated to Jilin University and Teaching and Research Section of Pathology, Bethune Medical College of Jilin University.MATERIALS: This study was carried out between June 2001 and April 2002. Totally 130 adult SD rats were selected, with male and female in half, and randomly divided into normal control group (n=10), sham operation group (n=10), and cerebral ischemia group (n=110). The rats in cerebral ischemia group were further divided equally into 11 subgroups and examined at 0, 1, 2, 3, 6, 24, 48 hours and 1, 2, 3, 4 weeks after cerebral ischemia model establishment, respectively.METHODS: Permanent middle cerebral artery occlusion (MCAO) model was established in rats in cerebral ischemia group by ligation of the left common carotid artery, while the rats in the sham operation group received no artery ligation but with identical other treatments. The rats in the control group did not have any treatment. Reverse transcriptional (RT) PCR was used to detect the expression of VEGF and its receptor mRNA at different time points after ischemic model establishment, and neovascularization in the rats'brain was observed.MAIN OUTCOME MEASURES: ① Expression of VEGF and its receptor mRNA and ② neovascularization in the brain tissue at different time points of cerebral ischemia.RESULTS: Data of the 130 mice were statistically analyzed without losses.At 3, 6, 24, and 48 hours of ischemia, the number of cells positive for VEGF expression was 31.13±2.21, 43.11±2.43, 85.41±2.75 and 98.66±1.76 in each vision filed in the surrounding ischemic region, greater than the numbers in the central ischemic region at the corresponding time points (13.32±1.31, 19.40±3.22, 47.63±2.45, 57.32±3.35 in each vision field, respectively, P ＜ 0.05). VEGF mRNA expression gradually decreased since 48 hours after model establishment till recovering the control level by 2weeks. The expression of VEGF receptor FLT-1 mRNA, determined by the number of positive cells in each vision field at 3, 6, 24, and 48 hour after the ischemia in each vision field for FLK-1 mRNA at these time points in the peripheral ischemic regions, higher than those in the central ischemic regions (P ＜ 0.05), which recovered the control level 3 weeks after the ischemia (P ＜ 0.05). At 48 hours and 1 week after the ischemia, the number of microvessels in each vision field was 47.2±2.11 and 199.2±3.45 in the peripheral ischemic region, significantly higher than the number in the central ischemic region (29.4±2.37 and 76.6±4.62, P ＜ 0.05).CONCLUSION: VEGF and its receptors FLT-1 and FLK-1 mRNA are expressed in the neurons, glial cells and endothelial cells during the early stage of acute focal cerebral ischemia, and the expressions are significantly enhanced in response to ischemia, exhibiting temporal and spatial expression patterns.