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ABSTRACT: To explore the mechanism of Flt3 receptor-interacting lectin (FRIL) maintains quiescence of hematopoietic stem cells (HSCs) in vitro.
Cord blood CD34+ cells were cultured in suspension medium supplemented with or without FRIL and FL. Cells were collected at different time points and the expression of some cell cycle regulators, especially those involved in G0/G1 phase regulation were detected on mRNA and protein level.
The expressions of G0/G1 phase related cyclins or CDKs were undetectable in the newly isolated CD34+ cells, expressions of Cyclin D3, CDK6 and P27 were the lowest in FRIL cultured group after 3d's culture (FRIL group: 483 +/- 63, 553 +/- 39, 0.312 +/- 0.030; FL group: 2437 +/- 52, 3209 +/- 98, 0.787 +/- 0.024; BLANK: 914 +/- 105, 1497 +/- 55, 0.616 +/- 0.029, respectively), but the expression of P53 was the highest in FRIL group (FRIL group: 4.476 +/- 0.159; FL group: 0.581 +/- 0.099, BLANK: 2.167 +/- 0.114). The expression of positive regulators of cell cycle in FRIL group were the same as that of FL group and blank group or lower.
FRIL preserves HSCs effectively in vitro through the mechanisms of down-regulation of cyclin D3 and CDK6 and activation of P53. P27 is mostly involved in the differentiation of HSCs.
Zhonghua xue ye xue za zhi = Zhonghua xueyexue zazhi 02/2007; 28(1):37-40.
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ABSTRACT: Cell cycle progression is tightly regulated in hematopoietic stem cells. The cycle state decides cells' fates, which includes self-renewal, proliferation and differentiation. Proper cell cycle regulation is a pivotal element for the maintenance of hematopoiesis homeostasis. HTm4 is a newly identified specific cell cycle regulator of the hematopoietic cell. Through interacting with KAP-CDK2 complex, it arrests cells in G(0)/G(1) phase. K562 is a human chronic myelogenous leukemia cell; it could be induced to megakaryoblast by phorbol 12-myristate 13-acetate (PMA). Such differentiation must be associated with cell cycle change. To further clarify HTm4's function in hematopoietic cell cycle regulation, K562 cells were treated with PMA. Cell cycle change was analysed using flow cytometric system. And during the induction process gene expression of HTm4 as well as CycleE and CDK2, which are responsible for G(1) to S transition, were analysed using semi-quantitative RT-PCR. The C-terminal domain of HTm4 protein has been shown to be important for HTm4's binding with KAP-CDK2 complex. To determine its impact on HTm4's function, HTm4 and C-terminal truncated HTm4 (HTm4-ct) were transfected into K562 cells using Tet-Off regulation expression system. Their influence on cell cycle was observed. The results showed that PMA induced both expansion and differentiation of K562 cells as measured by cell number count and NBT staining respectively. During PMA treatment, G(0)/G(1) cell proportion and HTm4 expression displayed coordinated change, which suggested that HTm4 might drive K562 cells out of cell cycle but was not involved in the quiescence maintenance. Additionally, transfection of HTm4 caused G(0)/G(1) arrest in K562 cells, while transfection of HTm4-ct did not. It is therefore suggested that the C-terminal domain is important for the function of HTm4 in cell cycle regulation.
Sheng li xue bao: [Acta physiologica Sinica] 05/2005; 57(2):188-92.
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Lian-Xu Zhao,
Jie Zhang,
Feng Cao,
Ling Meng, Dong-Mei Wang,
Yan-Hua Li,
Xue Nan,
Wen-Cang Jiao,
Min Zheng,
Xiao-Hu Xu,
Xue-Tao Pei
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ABSTRACT: Multipotential mesenchymal stem cells (MSCs) are ideal seed cells for recruiting the loss of neural cells due to their strong proliferative capacity, easy acquisition, and considerable tolerance of genetic modifications. After transduction of brain-derived neurotrophic factor (BDNF) gene via recombinant retroviral vectors into the human MSCs, nearly 100% of cells expressed BDNF (which were therefore transformed into BNDF-MSCs) as detected by immunocytochemistry, and the quantity of BDNF in the culture medium was increased by approximately 20,000-fold. In spite of the genomic integration of an exogenous gene, BDNF-MSCs did not present any structural aberration in the chromosomes. All-trans-retinoic acid (RA) induction caused the BDNF-MSCs to differentiate into neural cells with significantly increased expressions of such neural-specific proteins as nestin, NeuN, O4, and glial fibrillary acidic protein (GFAP). The voltage-dependent K+/Ca2+ currents were recorded from the induced BDNF-MSCs using patch-clamp technique. Compared with the MSCs induced by both RA and BDNF, BDNF-MSCs survived in significantly greater number in the induction medium, and also more cells were induced into neuron-like cells (NeuN, P < 0.01) and oligodendrocyte-like cells (O4, P < 0.05). We suppose that, once engrafted into human central nervous system, the BDNF-MSCs would not only recruit the neuronal losses, but also provide, by way of paracrine, large quantities of BDNF that effectively perform the functions of neuroprotection and neuroregeneration, promoting the activation of endogenous neural stem/progenitor cells and their chemotactic migration. On the other hand, the BDNF-MSCs that can survive in the host environment and differentiate subsequently into functional mature cells may also serve as specifically targeting vectors for ex vivo gene therapy.
Experimental Neurology 12/2004; 190(2):396-406. · 4.70 Impact Factor
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ABSTRACT: Ex vivo maintainance of human stem cells is crucial for many clinical applications. Current culture conditions provide some level support but cytokines induce most quiescent stem cells to proliferate and differentiate. Better control of primitive cells is needed to extend the time and range of manipulation of such cells. A recently identified plant lectin Flt3 receptor-interacting lectin (FRIL) present may a special ability to preserve primitive CB progenitors for extended periods in culture without exogenous cytokines. But the mechanisms of FRIL preserving quiescent primitive cells are still unknown. Recently a novel protein HTm4 and its alternatively spliced variant HTm4S, which serve as hematopoietic cell cycle regulators, have been identified. In this report we studied the effect of FRIL on the in vitro maintenance of quiescent human cord blood stem cells and the expression of the novel hematopoietic cell cycle regulator HTm4 and HTm4S in progenitor cells cultured in FRIL. We analyzed the proliferation and the HPP-CFC proportion of CD34(+) cells treated with FRIL. The human HTm4 and HTm4S mRNA expression was detected by semi-quantitative RT-PCR, and the cell cycle status of CB CD34(+) cells was analyzed by FACS. The results showed that incubation of CD34(+) cells in FRIL resulted in a low proliferation of progenitor cells and fewer cycling cells, but FRIL selectively maintained a higher number of primitive cells with proliferative potential in suspension culture. CB CD34(+) cells cultured in FRIL showed significant diversity in the expression of HTm4 and HTm4S during 0~14 d. On d 0, HTm4 was detected at high level, downregulated on d 1, but upregulated during d 3 to d 14, and reaching the highest level on d 7. But the expression levels of HTm4S changed little in the cells cultured in FRIL except the obviously increased expression on d 7. Exogenous expression showed that HTm4 was localized around the karyon while HTm4S scatted in the cytoplasm, respectively, which may be responsible for their difference in function. Thus, FRIL can preserve quiescent primitive CD34(+), and FRIL's ability to preserve quiescent primitive cells in a reversible manner may significantly expand the time and range of ex vivo manipulations of human stem cells for clinical applications. In other words, HTm4 and HTm4S may play a crucial role in the cell cycle modulation of CD34(+) progenitor cells maintained with FRIL in vitro.
Sheng li xue bao: [Acta physiologica Sinica] 07/2004; 56(3):306-12.
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ABSTRACT: To identify genes that differentially expressed in Lin(-)CD(34)(-) and Lin(-)CD(34)(+) cells.
With Lin(-)CD(34)(-) cells as tester and Lin(-)CD(34)(+) cells as driver, cDNA subtractive library for Lin(-)CD(34)(-) cells was constructed using suppression subtractive hybridization technique. Part of clones in the library were sequenced and the homologue analysis was conducted against the DNA database in GenBank.
593 clones containing an average of 300 - 500 bp insert were identified. Of them, 53 randomly selected ESTs were sequenced. Homologue analysis revealed that 37 ESTs represented 10 known genes, and the other 16 ESTs represented 4 novel sequences.
Part of specifically expressed genes in Lin(-)CD(34)(-) cells were identified, which maybe related to Lin(-)CD(34)(-) cells' specific characteristics.
Zhonghua xue ye xue za zhi = Zhonghua xueyexue zazhi 09/2003; 24(8):423-5.
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ABSTRACT: The purpose of this study was to transplant neonatal rat with human cord blood Lin(-) cells to test the possibility of this xenograft model. The Lin(-) cells were purified from human cord blood (CB) using negative selection strategy based on different lineage-specific antigens. The Lin(-) cells were injected into the liver of neonatal rats using a microinjector at an average of 5 x 10(5) cells for each. Peripheral blood (PB) and spleen were collected at 2,4 and 8 weeks after injection. Flow cytometry was performed to detect human cells in the rat PB, PCR was used to detect human cells in PB as well as spleen. The results showed that a definite proportion of human cells existed in peripheral blood of chimeric rat and the human specific beta2 microglobulin gene fragments were detected in spleen genomic DNA of chimeric rat. It is concluded that human/rat chimera model can be developed with neonatal rats. Human/rat xenograft model may provide a useful and convenient method for human hematopoietic stem cell assay in vivo.
Zhongguo shi yan xue ye xue za zhi / Zhongguo bing li sheng li xue hui = Journal of experimental hematology / Chinese Association of Pathophysiology 07/2003; 11(3):297-300.
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ABSTRACT: Bone marrow mesenchymal stem cells (MSCs) are multipotent tissue stem cells that can be induced in vitro to differentiate into a variety of cells such as osteoblasts, chondrocytes and adipocytes. MSCs are useful vehicles for both cell and gene therapy for a variety of diseases. Here, we injected human MSCs with enhanced green fluorescent protein (EGFP) into the striatum of Parkinson disease (PD) rat and examined their survival, migration, differentiation, and the behavior changes in PD rats, which will provide a theoretical foundation and technical method for clinic PD therapy by stem cells. The results showed that human bone marrow MSCs can survive in rat brain for a long time (exceeding 70 d). MSCs were found in multiple areas of the rat brain including the striatum, the corpus callosum, contralateral cortex and even the brain vascular wall. Immunocytochemical staining suggested that implanted cells expressed human neurofilament (NF), neuron-specific enolase (NSE) and glial fibrillary acid protein (GFAP). At the same time, remission in abnormal behavior of the PD rats appeared. Rotation scores decreased gradually from 8.86+/-2.09 r/min pre-transplantation to 4.87+/-2.06 r/min 90 d post-transplantation (statistic result showed P<0.05).
Sheng li xue bao: [Acta physiologica Sinica] 04/2003; 55(2):153-9.
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ABSTRACT: To evaluated the feasibility of preventing infection after high dose chemotherapy and radiotherapy using the granulocytes derived from differentiated from hematopoietic stem/progenitor cells ex vivo, human CD34-positive cells were isolated from umbilical cord blood by using a high-gradient magnetic cell sorting system (MACS), and the cells committedly differentiated with hematopoietic cytokines (SCF + IL-3 + IL-6 + G-CSF) in a liquid culture system. The expanded cell number, ratio of the viable cells, chromosome and phenotype of the differentiated cells and safety analysis of expanded cells were detected by using cell count, trypan blue exclusion test, karyotype analysis, flow cytometry and tumorigenic model of nude mice, respectively. The results showed that the combination of cytokines increased cell number by (1006.4 +/- 103.2) folds and flow cytometric analysis showed myeloid marker CD11b expressed in the about 60% cells. The growth peak of differentiated cells was at 14 days of culture and decreased at about 33 days. No abnormality was found in the karyotype analysis of expanded cells. No tumor was found in the nude mice injected with expanded cells after 35 days and the expanded cells had the ability of phagocytizing bacteria. It is concluded that the cells, differentiated from CD34(+) cells, expanded ex vivo possess the function of granulocyte and it was safe for clinical trial.
Zhongguo shi yan xue ye xue za zhi / Zhongguo bing li sheng li xue hui = Journal of experimental hematology / Chinese Association of Pathophysiology 01/2003; 10(6):492-5.
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ABSTRACT: To investigate the expression of telomerase in cord blood hematopoietic stem/progenitor cells during their committed differentiation in vitro and provide an index of monitoring the proliferating potential of the hematopoietic stem/progenitor cells and security for clinical application. Human CD34 positive cells were isolated from umbilical cord blood by using magnetic cell sorting system (MACS), and were induced to differentiation with hematopoietic growth factors (SCF + IL3 + IL6 + GCSF and SCF + IL3 + IL6 + EPO) in a liquid culture system. The telomerase activity and the cytalytic subunit of telomerase (hTERT) of the cells were analysed during different periods of culture by using TRAP-PCR, TRAP-ELISA, Western blot and RT-PCR techniques, respectively. The results showed that a peak of cell growth was achieved on day 14 - 21 during induction of differentiation in vitro. Total cell number could increase 1006.4 +/- 103.2 times and could not increase there after. Telomerase activity and hTERT expression were low in freshly isolated cord blood CD34(+) cells and increased after about 7 days of culture in addition of cytokine combinations of SCF + IL3 + IL6 + GCSF and SCF + IL3 + IL6 + EPO, respectively. The telomerase activity and hTERT decreased after 14 days of culture and were not detected after 28 days of culture. It was concluded that the hematopoietic stem/progenitor cells can be expanded in large number in vitro and do not have the character of immortality and the telomerase activity could be a useful index in hematopoiesis regulation.
Zhongguo shi yan xue ye xue za zhi / Zhongguo bing li sheng li xue hui = Journal of experimental hematology / Chinese Association of Pathophysiology 09/2002; 10(4):281-4.
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ABSTRACT: To identify differentially expressed genes between fetal mesenchymal stem cell (MSC) and adult MSC, especially specified genes expressed in fetal MSC, a cDNA subtractive library of fetal MSC was constructed using suppression subtractive hybridization (SSH) technique. At first, total RNA was isolated from fetal and adult MSC. Using SMART PCR synthesis method, single-strand and double-strand cDNAs were synthesized. After Rsa I digestion, fetal MSC cDNAs were divided into two groups and ligated to adaptor 1 and adaptor 2 respectively. Results showed that the amplified library contains 890 clones. Analysis of 890 clones with PCR demonstrated that 768 clones were positive. The positive rate is 86.3%. The size of inserted fragments in these positive clones was between 0.2 - 1 kb, with an average of 400 - 600 bp. Conclusion: SSH is a convenient and effective method for screening differentially expressed genes. The constructed cDNA subtractive library of fetal MSC cDNA lays solid foundation for screening and cloning new and specific function related genes of fetal MSC.
Zhongguo shi yan xue ye xue za zhi / Zhongguo bing li sheng li xue hui = Journal of experimental hematology / Chinese Association of Pathophysiology 05/2002; 10(2):89-92.
