[Comparative Study of the Two High-Efficient Strategies for in vitro Generation of Human Umbilical Cord Blood-derived Natural Killer Cells].

OBJECTIVE: To explore the similarities and variations of biological phenotype and cytotoxicity of human umbilical cord blood natural killer cells (hUC- NK) after human umbilical cord blood-derived mononuclear cells (hUC-MNC) activated and expanded by two in vitro high-efficient strategies. METHODS: Umbilical cord blood mononuclear cells (MNC) from healthy donor were enriched by Ficoll-based density gradient centrifugation. Then, the phenotype, subpopulations, cell viability and cytotoxicity of NK cells derived from Miltenyi medium (denoted as M-NK) and X-VIVO 15 (denoted as X-NK) were compared using a "3IL" strategy. RESULTS: After a 14-day's culture, the contents of CD3-CD56+ NK cells were elevated from 4.25%±0.04% (d 0) to 71%±0.18% (M-NK) and 75.2%±1.1% (X-NK) respectively. Compared with X-NK group, the proportion of CD3+CD4+ T cells and CD3+CD56+ NKT cells in M-NK group decreased significantly. The percentages of CD16+, NKG2D+, NKp44+, CD25+ NK cells in X-NK group was higher than those in the M-NK group, while the total number of expanded NK cells in X-NK group was half of that in M-NK group. There were no significant differences between X-NK and M-NK groups in cell proliferation and cell cycle, except for the lower percentage of Annexin V+ apoptotic cells in M-NK group. Compared with X-NK group, the proportion of CD107a+ NK cells in M-NK group were higher under the same effector-target ratio (E∶T) (P<0.05). CONCLUSION: The two strategies were adequate for high-efficient generation of NK cells with high level of activation in vitro, however, there are differences in biological phenotypes and tumor cytotoxicity.

Structural transition and interconversion between the 2D self-assembled structures of pentacene.

The 2D self-assemblies and structural transitions of pentacene on a Cd(0001) surface have been investigated with low temperature scanning tunneling microscopy (STM). With increasing coverage, pentacene molecules show a structural evolution from the initial disordered gas-like phase through the porous network phase to the herringbone phase, and finally to the brickwall phase at the full monolayer. In particular, orientational frustration and cooperative rotation of pentacene molecules take place in the herringbone phase. Furthermore, successive STM scanning leads to structural interconversions between the porous network phase, herringbone phase, and brickwall phase, indicating the metastability of the 2D assembled structures of pentacene on Cd(0001). These structural transitions and interconversion can be attributed to the interplay between the repulsive electrostatic forces resulting from the charge transfer from the substrate to pentacene and the attractive effects originating from dipole-dipole interactions and intermolecular van der Waals forces.

Spontaneous chiral resolution of pentahelicene molecules on Cd(0001).

Chiral resolution is of fundamental importance to conglomerate or racemate crystallization. Here we demonstrate that the spontaneous chiral resolution of pentahelicene racemates occurred in the monolayer domains. When deposited on a Cd(0001) surface, pentahelicene molecules crystallize into a commensurate (6 × 6)R0° structure built mainly from homochiral trimers. Spontaneous chirality separation takes place in the form of opposite mirror domains, where 2D enantiomorphism is not expressed by the oblique adlattice, but by the supramolecular chirality of the pentahelicene trimers. Furthermore, annealing the sample or extreme close-packing lead to the presence of lattice handedness through the formation of a porous network structure or an edge-on phase. These results provide valuable insight for 2D conglomerate crystallization and stereochemical recognition.

[Role of DNMT3a in Hydroquinone-Induced Hematopoietic Stem Cell Toxicity].

OBJECTIVE: To investigate the regulatory effect and mechanism of DNA methyltransferase 3A (DNMT3a) in hydroquinone-induced hematopoietic stem cell toxicity. METHODS: Cells (HSPC-1) were divided into 4 groups, that is A: normal HSPC-1; B: HQ-intervented HSPC-1; C: group B + pcDNA3 empty vector; D: group B + pcDNA3- DNMT3a. RT-qPCR and Western blot were used to detect the expression levels of DNMT3a and PARP-1 mRNA and protein, respectively. Cell morphology was observe; Cell viability and apoptosis rate of HSPC-1 were detected by MTT and flow cytometry, respectively. RESULTS: Compared with group A, the expression levels of DNMT3a mRNA and protein in HSPC-1 of group B were decreased, while PARP-1 mRNA and protein were increased (P<0.05); there was no significant difference in the above indexes between group C and group B; compared with group B, the expression levels of DNMT3a mRNA and protein showed increased, while PARP-1 mRNA and protein were decreased significantly in cells of group D transfected with DNMT3a (P<0.05). Cells in each group were transfected with DNMT3a and cultured for 24 h, HSPC-1 in group A showed high density growth and mononuclear fusion growth, while the number of HSPC-1 in group B and C decreased and grew slowly. Compared with group B and C, the cell growth rate of group D was accelerated. The MTT analysis showed that cell viability of HSPC-1 in group B were lower than that of group A at 24 h, 48 h and 72 h (P<0.05); after transfected with DNMT3a, the cell viability of HSPC-1 in group D were higher than that of group B at 24 h, 48 h and 72 h (P<0.05). The apoptosis rate of cells in group B was significantly higher than that of group A (P<0.001), while the apoptosis rate in group D was lower than that of group B (P<0.001). CONCLUSION: DNMT3a may be involved in the damage of hematopoietic stem cells induced by hydroquinone, which may be related to the regulation of PARP-1 activity by hydroquinone-inhibited DNMT3a.

[Effect of Decitabine on Regulatory T Cells Relative Content in Peripheral Blood and Bone Marrow of Patients with Myelodysplastic Syndrome/Acute Myeloid Leukemia].

OBJECTIVE: To investigate regulatory T cells (Tregs) relative content in peripheral blood and bone marrow of patients with myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML) treated with or without decitabine (DAC), analyze the immunomodulatory of Tregs in pathogenesis and remission of MDS and AML, as well as effect of DAC on Tregs. METHODS: From October 2018 to February 2019, 15 patients with MDS and 49 patients with AML (newly diagnosed, treated with DAC or other chemotherapy regimens) were enrolled in this study, and 14 cases with iron deficiency or megaloblastic anemia while without malignant tumor and autoimmune disease as controls. The Tregs relative contents in bone marrow and peripheral blood were analyzed by flow cytometry, meanwhile clinical data of the objects were collected. RESULTS: In peripheral blood and bone marrow of the patients with MDS and AML, the Tregs relative contents at newly diagnosed were higher than those of the control group (P=0.05, P=0.043). The Tregs relative content of AML patients in DAC regimen treatment group was significantly lower than that in the newly diagnosed group and non-DAC chemotherapy group (P<0.05). In DAC regimen treatment group, the Tregs relative contents was significantly lower in remission group than in non-remission group (P<0.05). There was no difference between DAC regimen treatment group and control group in Tregs relative content. CONCLUSION: DAC may increase the body's anti-tumor immunity by consuming Tregs content, enhance the body's immune function to identify and kill tumor cells, thereby promote the patients' reliefs.

Homochiral to heterochiral transition in a pentahelicene monolayer on Bi(111).

We report the nucleation and two dimensional (2D) crystallization of the helical aromatic hydrocarbon pentahelicene ([5]H) on the semimetallic Bi(111) surface studied via low-temperature scanning tunneling microscopy. Individual homochiral dimers and heterochiral trimers appear on the substrate at a low coverage. With an increase in the coverage, a chiral phase transition takes place from the 2D conglomerate of [5]H dimers to the 2D racemate of [5]H trimers. The heterochiral [5]H trimers reveal a wavy arrangement due to the swing of 5[H] trimer rows after every second or third trimers. The swing mechanism of the trimer rows can be attributed to the steric repulsion between the adjacent trimers with same handedness.

Structure transition of a C60 monolayer on the Bi(111) surface.

The interfacial structures of C60 molecules adsorbed on solid surfaces are essential for a wide range of scientific and technological processes in carbon-based nanodevices. Here, we report structural transitions of the C60 monolayer on the Bi(111) surface studied via low-temperature scanning tunneling microscopy (STM). With an increase in temperature, the structure of the C60 monolayer transforms from local-order structures to a (√93 × âˆš93) R20° superstructure, and then to a (11 × 11) R0° superstructure. Moreover, the individual C60 molecules in different superstructures have different orientations. C60 molecules adopt the 6 : 6 C-C bond and 5 : 6 C-C bond facing-up, mixed orientations, and hexagon facing-up in the local-order structure, (√93 × âˆš93) R20°, and (11 × 11) R0° superstructure, respectively. These results shed important light on the growth mechanism of C60 molecules on solid surfaces.

[Effects of Human Amniotic Mesenchymal Stem Cells on Acute Graft-Versus-Host Disease in Xenotransplantation].

OBJECTIVE: To investigate the effects of human amniotic mesenchymal stem cell（AMSC） on acute graft-versus-host disease (aGVHD) in xenotransplatation. METHODS: NPG mice were injected with human PBMNC via tail vein to establish a xenografted aGVHD model. The mice in the experimental group were divided into PBMNC infusion group and PBMNC+AMSC co-infusion group, the general condition, survival time and manifestations of aGVHD were observed, the body weight and blood routine indicators were detected, the pathological changes of aGVHD target organs (lung, liver, spleen, small intestine) were observed by HE staining, and the levels of human T cells in peripheral blood, tissues and organs of mice was detected by flow cytometry. RESULTS: The manifestations of aGVHD (lassitude hunchback, shrub, weight reduction, etc.) and the pathological damage of the target organs (lung, liver, spleen, intestine) in PBMNC+AMSC co-infusion group were lighter than those in PBMNC infusion group. Moreover, the PBMNC and AMSC co-infusion significantly reduced the implantion proportion of human T lymphocytes (CD3+, CD45+) in mice and increased the ratio of CD4+/CD8+. CONCLUSION: Infusion of human-derived AMSC can attenuate the manifestations of aGVHD in mouse xenografts to a certain level, and improve the pathological damage of receptor target organs.

Effect of co­culture with amniotic epithelial cells on the biological characteristics of amniotic mesenchymal stem cells.

The aim of the present study was to investigate the effect of co­culture with amniotic epithelial cells (AECs) on the biological characteristics of amniotic mesenchymal stem cells (AMSCs), to compare the expression of C­X­C motif chemokine receptor 4 (CXCR4) in co­cultured AMSCs and to investigate the roles of the stromal cell­derived factor­1 (SDF­1)/CXCR4 axis in the homing and migration of AMSCs. AMSCs were isolated from human amniotic membranes, purified and then differentiated into osteoblasts and adipocytes in vitro, which was verified by von Kossa Staining and Oil Red O staining. Cell viability was measured by Cell Counting kit­8 and trypan blue assays at 24, 48 and 72 h, the expression of CXCR4 was analyzed by immunofluorescence­based flow cytometry and reverse transcription­quantitative polymerase chain reaction, and the migration ability of AMSCs in vitro was observed by a migration assay. The results demonstrated that cell viability (at 48 and 72 h) and survival (at 24, 48 and 72 h) in the co­culture and serum groups were higher compared with the serum­free group. Furthermore, CXCR4 mRNA and protein expression, and migration along the SDF­1 gradient, in the co­culture and serum­free groups were higher compared with the serum group. Overall, the results indicated that AMSCs co­cultured with AECs exhibited enhanced proliferation activity and survival rate. In conclusion, the present study demonstrated that co­culture of AMSCs with AECs upregulated CXCR4 on the surface of AMSCs and enhanced the migration ability of AMSCs in vitro. This result may improve the directional migration and homing ability of AMSCs, as well as provide a theoretical basis for the application of AMSCs in clinical practice as a novel strategy to increase the success of hematopoietic stem cell transplantation.

[The effect of TNF-alpha on TAZ expression and osteogenic potential of mesenchymal stem cells from myeloma patients].

OBJECTIVE: To explore the relationship between TNF-alpha, transcriptional co-activator with PDZ-binding motif (TAZ) and bone disease of multiple myeloma. METHODS: The biological characteristics, especially the osteogenic potential of marrow MSCs from myeloma patients and normal subjects were studied. Real-time RT-PCR and Western-blot were employed to detect mRNA and protein expression of TAZ in MSCs. The concentration of TNF-alpha in the marrow plasma was detected using ELISA method. CD138(+) myeloma cells were cocultured with normal MSCs with or without anti-human TNF-alpha monoclonal antibody in the Transwell system. Real-time RT-PCR was employed to detect the mRNA expressions of ALP, Cbfa1 and TAZ in MSCs two weeks later. von Kossa staining was used to detect the mineral deposition. TNF-alpha was added into the culture media of normal marrow MSCs and real-time RT-PCR and Western-blot were employed to detect mRNA and protein expression of TAZ in MSCs one week later. RESULTS: Real-time RT-PCR revealed that the mRNA of osteogenic markers was decreased in comparison with that of normal controls after cultured in the osteogenic medium. von Kossa staining showed weakened mineral deposition in MSCs from multiple myeloma patients compared with that in normal subjects after osteogenic differentiation for two weeks. The mRNA and protein levels of TAZ in the MSCs from myeloma patients were decreased. TNF-alpha concentration in the marrow plasma of myeloma patients was higher than that in the normal controls [(355.4 +/- 49.1) vs. (92.3 +/- 17.2) pg/ml]. CD138(+) myeloma cells inhibited mRNA expressions of ALP, Cbfal1 and TAZ in MSCs, which could be partially reversed by anti-human TNF-alpha monoclonal antibody. CONCLUSION: The osteogenic potential of MSCs from myeloma patients is significantly decreased in comparison with that in normal subjects, which may play an important role in the pathology of myeloma bone disease. TAZ expression inhibited by TNF-alpha may play an important role in this inhibition effect.

[Effect of total body irradiation on cellular senescence related indexes of bone marrow mesenchymal stem cells].

The aim of this study was to explore the changes in cellular senescence related indexes of bone marrow mesenchymal stem cells (BMMSCs) after total body irradiation (TBI). At different time points after 4 Gy irradiation, BMMSCs were isolated from male C57BL/6 mice and cultured. Morphology, senescence-associated beta-galactosidase (SA-beta-gal) staining and cell cycle analysis were used to evaluate the changes in BMMSCs at cellular level while real-time RT-PCR was used to detect the alterations in senescence related gene expression including p16INK4a, p21Cip1/Waf1, p53 and TGF-beta1. The results showed that within 4 weeks after exposure to 4 Gy TBI, the morphology of BMMSCs and the expression level of SA-beta-gal were not significantly changed, the cellular senescence-related cell cycle arrest was not occurred and the senescence related gene expression level was not increased. It is concluded that at the early stage after 4 Gy TBI, the related molecular level of cellular senescence in BMMSCs is not changed.

[Reduction of bone marrow mesenchymal stem/progenitor cells pool and alteration of their osteogenesis potential caused by total body irradiation].

To investigate the effect of irradiation on the quantity and osteogenesis potential of BMMSCs and to explore the response of them in the irradiation stress and its contribution to long-term effects of radiation-induced bone and hematologic injury, a total body irradiation (TBI) murine model was adopted. The number of CFU-F and cell cycle profile of BMMSCs were analyzed at different time points before and after TBI. Osteogenic differentiation was evaluated by Von Kossa staining, expressions of osteogenesis-related genes and transcriptional coactivator with PDZ-binding motif (TAZ) were detected by real-time RT-PCR. The results showed that the number of CFU-F decreased greatly at day 28 after TBI. At day 3 after TBI, more cells entered cell cycle and the osteogenesis potential was greatly enhanced followed by recovery of cell cycle distribution and significant defect in osteoblast differentiation respectively, meanwhile the expression of TAZ was changed. It is concluded that TBI results in the reduction of bone marrow mesenchymal stem/progenitor cell pool and alters the osteogenesis potential of BMMSCs, which is related to the change of TAZ expression.

[Isolation and identification of chronic myelogenous leukemia bone marrow mesenchymal stem cells and their functional characteristics].

OBJECTIVE: To isolate and culture bone marrow mesenchymal stem cells (MSCs) from chronic myelogenous leukemia (CML) patients and examine their functional characteristics. METHODS: Bone marrow was extracted from the anterior superior iliac spines of 21 patients with CML. MSCs were isolated and cultured. Single colony derived MSCs were harvested by limiting dilution. The cell cycle and immunophenotype of the expanded clonal MSCs were detected by fluorescence-activated cell sorter (FACS). Different agents were used to induce the MSCs to differentiate into osteocyte, adipocyte and neural cells. Von Kossa staining, oil-red staining, and Western blotting was used to examine the ability of differentiation. PCR was used to detect the expression of BCR/ABL gene. The ultrastructure of the CML derived MSCs was observed with electron microscopy. Sixteen BALB/c nude mice were randomly divided into 2 equal groups to be inoculated with HL60 cancer cells and CML derived MSCs to observe the tumorigenicity. MSCs were cultured in soft agar for 2 weeks to observe the clone growth. RESULTS: Fibroblast-like, positive in CD29, CD44, and CD105, and negative in CD116, CD34, CD48, and HLA-DR, the CML derived MSCs could differentiate into osteocyte, adipocyte and neural cells. CML derived MSCs showed normal karyotype and ultrastructure, they did not express BCR/ABL gene. After 2 weeks' culture no clone was formed from the MSCs. Four weeks after tumors were shown in 6 of the 8 mice inoculated with HL60 cells, and no tumor was seen in the mice inoculated with MSCs. CONCLUSION: Able to differentiate into different types of cell and without tumorigenicity, MSCs from the bone marrow of CML patients have the potentiality in clinical application.

[Flk1+ mesenchymal stem cells ameliorate carbon tetrachloride-induced liver fibrosis in mice].

Fibrosis is the common end stage of most liver diseases. Unfortunately, there is no effective treatment available currently. This study was designed to evaluate the effect of Flk1+ mesenchymal stem cells (MSC) from murine bone marrow (Flk1 + MSC) on fibrosis formation induced by carbon tetrachloride (CCl4). In this study Flk1+ MSC were isolated from bone marrow of male BALB/c mice. A CCl4 induced hepatic fibrosis model was used. Flk1+ MSC were systemically infused immediately or one week after the female mice were challenged with CCl4. Fibrosis index and donor cell engraftment were assessed two or five weeks after CCl4 challenge. We found that Flk1+ MSC transplantation immediately, but not one week after exposure to CCl4, significantly reduced CCl4-induced liver damage and collagen deposition. In addition, levels of hepatic hydroxyproline and serum fibrosis markers (HA, P-III-P) in mice receiving immediate Flk1+ MSC transplantation after CCl4 challenge were significantly lower compared to those of control mice. More importantly, histological examination suggested that hepatic damage recovery was much better in these immediately Flk1+ MSC-treated mice. Immunofluorescence, PCR, and fluorescence in situ hybridization (FISH) analysis revealed that donor cells engrafted into host liver, had epithelium-like morphology and expressed albumin (ALB), although at low frequency. In conclusion Flk1+ MSC might initiate endogenous hepatic tissue regeneration, engraft into host liver in response to CCl4 injury, and ameliorate its fibrogenic effects.