[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.

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 × √93) 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 × √93) R20°, and (11 × 11) R0° superstructure, respectively. These results shed important light on the growth mechanism of C₆₀ molecules on solid surfaces.

With the increase in temperature, the structure of the C₆₀ monolayer on the Bi(111) substrate transforms from local-order structures to a (√93 × √93) R20° superstructure, and then to a (11 × 11) R0° superstructure.

Effect of co‑culture 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 co‑culture with amniotic epithelial cells (AECs) on the biological characteristics of amniotic mesenchymal stem cells (AMSCs), to compare the expression of C‑X‑C motif chemokine receptor 4 (CXCR4) in co‑cultured AMSCs and to investigate the roles of the stromal cell‑derived factor‑1 (SDF‑1)/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 kit‑8 and trypan blue assays at 24, 48 and 72 h, the expression of CXCR4 was analyzed by immunofluorescence‑based flow cytometry and reverse transcription‑quantitative 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 co‑culture and serum groups were higher compared with the serum‑free group. Furthermore, CXCR4 mRNA and protein expression, and migration along the SDF‑1 gradient, in the co‑culture and serum‑free groups were higher compared with the serum group. Overall, the results indicated that AMSCs co‑cultured with AECs exhibited enhanced proliferation activity and survival rate. In conclusion, the present study demonstrated that co‑culture 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.

Changes in Rat Adipocyte and Liver Glucose Metabolism Following Repeated Restraint Stress

Rats exposed to repeated restraint weigh less than controls even 8 weeks after stress. Stress-induced weight loss is lean tissue, but the post-stress difference in weight between control and restrained rats is lean and fat mass. Whole-body glucose clearance is enhanced 1 day after stress, but adipocyte glucose utilization is inhibited and muscle glucose transport is unchanged. The studies described here demonstrated that glucose transport was increased in both restrained and pair-fed rats, but that glycogen synthesis was increased only in restrained rats, which may account for the improved whole-body glucose clearance. Adipocyte glucose transport was inhibited and adipose plasma membrane β-adrenergic receptor number was increased 1 day post-stress in restrained rats when weight loss was lean tissue, but were not different from control rats 5 days post-stress, when both fat and lean tissue were reduced. Thus, repeated restraint induces reversible changes in adipocyte metabolism that may represent a transition from the catabolic state of stress to a new energetic equilibrium in rats that maintain a reduced body weight for an extended period of time.

A nonlocal shell model for mode transformation in single-walled carbon nanotubes

A second-order strain gradient nonlocal shell model is established to study the mode transformation in single-walled carbon nanotubes (SWCNTs). Nonlocal length is calibrated carefully for SWCNTs in reference to molecular dynamics (MD) simulations through analysis of nonlocal length effects on the frequencies of the radial breathing mode (RBM) and circumferential flexural modes (CFMs) and its effects on mode transformation. All analyses show that only a negative second-order nonlocal shell model is appropriate to SWCNTs. Nonlocal length is evidently related to vibration modes and the radius-to-thickness ratio. It is found that a nonlocal length is approximately 0.1 nm in an average sense when RBM frequency is concerned. A nonlocal length of 0.122-0.259 nm is indicated for the mode transformation in a selected group of armchair SWCNTs. 2:1 and 1:1 internal resonances are found for the same SWCNT based on different models, which implies that the internal resonance mechanism depends on the model employed. Furthermore, it is shown that an effective thickness of approximately 0.1 nm is more appropriate to SWCNTs than 0.066 nm.

[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.

[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.

The dynamic change of plasma endothelin-1 during the perioperative period in patients with rheumatic valvular disease and secondary pulmonary hypertension

The arterial plasma endothelin-1 concentration was substantially more elevated in 15 patients with rheumatic valvular disease and secondary pulmonary hypertension than in healthy volunteers (3.66 +/- 2.20 versus 1.17 +/- 0.38 pg/ml, mean +/- standard deviation; p < 0.01). The preoperative plasma endothelin-1 level was highly correlated with the pulmonary hemodynamics: pulmonary artery systolic pressure (r = 0.94, p < 0.001), pulmonary artery mean pressure (r = 0.86, p < 0.001), pulmonary capillary wedge pressure (r = 0.82, p < 0.001), and pulmonary vascular resistance (r = 0.63, p < 0.02). After valve replacement, the plasma endothelin-1 concentration declined substantially and the pulmonary hemodynamics improved markedly. Two weeks after the operation, the plasma endothelin-1 level in patients (1.26 +/- 0.45 pg/ml, mean +/- standard deviation) was not statistically different from that in the healthy volunteers. The plasma endothelin-1 concentration continuously increased during the course of cardiopulmonary bypass and peaked after cessation of bypass. The peak plasma endothelin-1 level (13.49 +/- 4.60 pg/ml, mean +/- standard deviation) positively correlated with the bypass time (r = 0.64, p < 0.02) and negatively correlated with the urine volume during bypass (r = -0.69, p < 0.01). We conclude that (1) increased plasma endothelin-1 might be implicated in the pathogenesis of secondary pulmonary hypertension caused by rheumatic valvular disease and (2) markedly elevated plasma endothelin-1 concentrations might be associated with the mechanism of cardiac or renal dysfunction after prolonged cardiopulmonary bypass.

[Hamartoma of the lung: an analysis of 24 cases]

Hamartoma is one of the most common benign tumors in the lung, and most of the lung hamartomas are located in the parenchyma. This report reviews 24 cases with this kind of tumor. The male-female ratio was 1.4:1 and the mean age 46.4 years. Sixteen patients of the 24 were asymptomatic, while in the remainder cases chest pain or distress, cough, short breath or hemoptysis were presented. Lung hamartoma is usually composed of cartilage, fat, smooth muscle and respiratory epithelium. X-ray findings of the parenchymal type in these cases were characterized by a round or oval sharply outlined mass, but only one with a mass in the shape of a dumbbell. 33% cases showed calcification. In 19 cases the mass was < 3.0 cm diameter (79%) and in 17 it was located in the superficial edge of the lung. The diagnosis was confirmed in only 6 cases preoperatively. The other cases were misdiagnosed as lung cancer, tuberculoma, metastatic tumors of the lung, etc. Enucleation or wedge resection is desirable for this kind of tumor.