Development of a Prognostic Model to Identify the Suitable Definitive Radiation Therapy Candidates in de Novo Metastatic Nasopharyngeal Carcinoma: A Real-World Study.

PURPOSE: We aimed to develop an accurate prognostic model to identify suitable candidates for definitive radiation therapy (DRT) in addition to palliative chemotherapy (PCT) among patients with de novo metastatic nasopharyngeal carcinoma (mNPC). METHODS AND MATERIALS: Patients with de novo mNPC who received first-line PCT with or without DRT were included. Overall survival for patients who received PCT alone versus PCT plus DRT was estimated using inverse probability of treatment weighting-adjusted survival analyses. We developed and validated a prognostic model to predict survival and stratify risks in de novo mNPC. A model-based trees approach was applied to estimate stratified treatment effects using prognostic scores obtained from the prognostic model and to identify suitable DRT candidates. Dominance analysis was used to determine the relative importance of each predictor of receiving DRT. RESULTS: A total of 460 patients were enrolled; 244 received PCT plus DRT and 216 received PCT alone. The 6-month conditional landmark, inverse probability of treatment weighting-adjusted Cox regression analysis showed that PCT plus DRT was associated with a significant survival benefit (hazard ratio: 0.516; 95% confidence interval, 0.403-0.660; P < .001). A prognostic model based on 5 independent prognostic factors, including serum lactate dehydrogenase, number of metastatic sites, presence of liver metastasis, posttreatment Epstein-Barr virus DNA level, and response of metastases to chemotherapy was developed and subsequently validated. Prognostic scores obtained from the prognostic model were used for risk stratification and efficacy estimation. High-risk patients identified using the proposed model would not benefit from additional DRT, whereas low-risk patients experienced significant survival benefits. Socioeconomic factors, including insurance status and education level, played an important role in receipt of DRT. CONCLUSIONS: Additional DRT after PCT was associated with increased overall survival in patients with de novo mNPC, especially low-risk patients identified with a newly developed prognostic model.

Proposed a self-absorption internal standard model to detect element concentrations of complex constituent material with a single emission line of element in laser plasmas.

Laser induced plasmas (LIPs) method is a highly regarded approach to evaluate the chemical composition of materials. But the strong self-absorption of the radiation seriously affects its accuracy. Meanwhile, the model based on self-absorption phenomenon makes its application very difficult. In this work, a self-absorption internal standard (SAIS) model is proposed for detection of the multi-element concentrations of complex constituent material with a single emission line of the element in laser plasmas. A typical LIPs experiment system is set up to generate plasmas, and the soil is selected as a test sample. The average electron temperature (0.975 eV) and electron density (1.44×1018 cm-3) are determined by the Boltzmann plot and emission lines Stark broadening, respectively. The plasmas are diagnosed as in local thermodynamic equilibrium condition. The emission lines selected to calculate the concentration of sample contain a wide set of kt values (0.575×10-30∼37.2×10-30 m3). Then, the concentrations of some elements are calculated by the model using single emission line of each element. It is found that the concentrations of the five elements (Ti, Fe, Mg, Al, Si) calculated by SAIS model are relatively consistent with the results of the traditional chemical testing methods. This indicated that the SAIS model is an effective and neat method for multi-element concentrations detection of complex constituent materials.

Electrical and thermal properties of silver nanowire fabricated on a flexible substrate by two-beam laser direct writing for designing a thermometer.

Accurate knowledge of electrical conductivity and thermal conductivity temperature dependence plays a crucial role in the design of a thermometer. Here, by using a two-beam laser direct writing system, an individual silver nanowire (AgNW) with well-defined dimensions is fabricated on a polyethylene terephthalate (PET) substrate. The temperature dependence of the resistivity of the fabricated AgNW is measured ranging from 10 to 300 K, and fitted with the Bloch-Grüneisen formula. The residual resistivity ((1.62 ± 0.20) × 10-7 Ω m) of the AgNW is larger than that of the bulk material (1 × 10-11 Ω m). The electron-phonon coupling constant of the AgNW is (1.08 ± 0.13) × 10-7 Ω m, which is larger than that of the bulk silver (5.24 × 10-8 Ω m). Moreover, the Debye temperature of the AgNW is 199.30 K and is lower than that of the bulk silver (235 K). The Lorenz number of the fabricated AgNW is found to decrease as the temperature increases. Besides, the Lorenz number (2.66 × 10-7 W Ω K-2) is larger than the Sommerfeld value (2.44 × 10-8 W Ω K-2) at room temperature. The measurement results allow one to design a thermometer in the temperature range 40-300 K. The flexibility of the AgNW is also excellent, and the resistance increase of the AgNW is only 2.58% when the AgNW bending about 1000 times with a bending radius of 1 mm.

Survival impact of waiting time for radical radiotherapy in nasopharyngeal carcinoma: A large institution-based cohort study from an endemic area.

BACKGROUND: Whether the waiting time for radical radiotherapy (WRT) detrimentally impacts nasopharyngeal carcinoma (NPC) prognosis is unclear. We estimated the influence of WRT on overall survival (OS) and disease-specific survival (DSS) of NPC. PATIENTS AND METHODS: Patients were identified from prospectively maintained database. WRT was calculated from histological diagnosis to initiation of radiotherapy (RT). Survival analysis was estimated using Weibull parametric model and propensity score analysis (PSA). Recursive partitioning analysis (RPA) identified optimal WRT threshold via conditional inference trees to estimate the greatest survival differences based on randomly selected training and validation sets, and this process was repeated 1000 times to ensure threshold robustness. Sensitivity analysis estimated effects of potential unmeasured confounders. RESULTS: A total of 9896 patients were included. In multivariate analysis, WRT of 31-60°d, of 61-90°d and of greater than 90°d independently increased mortality risk compared to less than 30°d. Upon RPA, ranges of 30-35°d with the peak of 30°d were confirmed with 89% of simulations validating optimal thresholds. In threshold-based groups, adjusted hazard ratios (HRs) for WRT of greater than 30°d by both Weibull model and PSA were significantly higher than for WRT of less than 30°d [OS: HR = 1.13, 95% confidence interval (CI) 1.04-1.23, P = 0.003; DSS: HR = 1.15, 95% CI 1.05-1.26, P = 0.002]. Sensitivity analysis revealed robustness of results. CONCLUSIONS: WRT independently affects survival. Increasing WRT beyond 30°d was most consistently detrimental to survival. WRT of NPC should be as short as reasonably achievable (ASARA).

Establishment and maintenance of three Chinese human embryonic stem cell lines.

To establish a potential resource for cell therapy and a developmental model for human diseases, we had isolated three Chinese human embryonic stem cell lines from the inner cell mass of human blastocysts in 2002. All the three cell lines were grown on mouse embryonic fibroblasts as feeder cells; one of these cell lines, chHES-3, has maintained its normal karyotype even after being cultured in vitro for more than 100 passages, after the standardization of mouse feeder preparation. Each hES cell line has been completely characterized. All the three cell lines expressed hES-specific markers and pluripotency-related genes. These cells maintained their normal karyotype during long-term culture and displayed a high telomerase activity. When differentiated in vivo and in vitro, the derivatives representing the three germ layers could be observed. Human leukocyte antigen, ABO blood type, and DNA fingerprinting were also performed to provide a unique identity to each cell line. By establishing these hES cell lines, we provide an appropriate in vitro model to study human development and regeneration. All the three cell lines can be obtained for research purposes by placing a request at our website at www.hescbank.cn.

Expression profiling of nuclear receptors in human and mouse embryonic stem cells.

Nuclear receptors (NRs) regulate gene expression in essential biological processes including differentiation and development. Here we report the systematic profiling of NRs in human and mouse embryonic stem cell (ESC) lines and during their early differentiation into embryoid bodies. Expression of the 48 human and mouse NRs was assessed by quantitative real-time PCR. In general, expression of NRs between the two human cell lines was highly concordant, whereas in contrast, expression of NRs between human and mouse ESCs differed significantly. In particular, a number of NRs that have been implicated previously as crucial regulators of mouse ESC biology, including ERRbeta, DAX-1, and LRH-1, exhibited diametric patterns of expression, suggesting they may have distinct species-specific functions. Taken together, these results highlight the complexity of the transcriptional hierarchy that exists between species and governs early development. These data should provide a unique resource for further exploration of the species-specific roles of NRs in ESC self-renewal and differentiation.

A comparison of murine smooth muscle cells generated from embryonic versus induced pluripotent stem cells.

Smooth muscle cell (SMC) differentiation and dedifferentiation play a critical role in the pathogenesis of cardiovascular diseases. The lack of a good and simple in vitro SMC differentiation system has hampered the progress of SMC field for years. The generation of such an in vitro system would be invaluable for exploring molecular mechanisms of SMC differentiation and dedifferentiation. Recently, the establishment of induced pluripotent stem (iPS) cells has offered a novel therapeutic strategy to generate patient-specific stem cell lines. Here we have investigated whether iPS cells are able to differentiate into SMCs in vitro. Mouse iPS cell (O9 and TT025) monolayers were treated with 10(-5) mol/L all-trans retinoid acid (RA). After 8 days of RA treatment, we found that >40% of the O9 iPS cells expressed the SMC-markers including SMalpha-actin and SM myosin heavy chain. Also, we documented that iPS-derived SMCs acquired SMC functional characteristics including contraction and calcium influx in response to stimuli. Moreover, our results indicated that there were differences in SMC-specific gene expression patterns between SMCs derived from O9 and TT025 iPS as well as normal embryonic stem cells. These differences might be due to disparity in the current iPS technology. Taken together, our data have established a simple iPS-SMC system to generate SMCs in vitro, which has tremendous potential to generate individualized SMCs for vascular tissue engineering and personalized drug screening.

Rad GTPase deficiency leads to cardiac hypertrophy.

BACKGROUND: Rad (Ras associated with diabetes) GTPase is the prototypic member of a subfamily of Ras-related small G proteins. The aim of the present study was to define whether Rad plays an important role in mediating cardiac hypertrophy. METHODS AND RESULTS: We document for the first time that levels of Rad mRNA and protein were decreased significantly in human failing hearts (n=10) compared with normal hearts (n=3; P<0.01). Similarly, Rad expression was decreased significantly in cardiac hypertrophy induced by pressure overload and in cultured cardiomyocytes with hypertrophy induced by 10 micromol/L phenylephrine. Gain and loss of Rad function in cardiomyocytes significantly inhibited and increased phenylephrine-induced hypertrophy, respectively. In addition, activation of calcium-calmodulin-dependent kinase II (CaMKII), a strong inducer of cardiac hypertrophy, was significantly inhibited by Rad overexpression. Conversely, downregulation of CaMKIIdelta by RNA interference technology attenuated the phenylephrine-induced hypertrophic response in cardiomyocytes in which Rad was also knocked down. To further elucidate the potential role of Rad in vivo, we generated Rad-deficient mice and demonstrated that they were more susceptible to cardiac hypertrophy associated with increased CaMKII phosphorylation than wild-type littermate controls. CONCLUSIONS: The present data document for the first time that Rad is a novel mediator that inhibits cardiac hypertrophy through the CaMKII pathway. The present study will have significant implications for understanding the mechanisms of cardiac hypertrophy and setting the basis for the development of new strategies for treatment of cardiac hypertrophy.

Transplantation of human undifferentiated embryonic stem cells into a myocardial infarction rat model.

Human embryonic stem (hES) cells hold great therapeutic potential for cell transplantation. To date, it remains uncertain whether undifferentiated hES cells can differentiate into cardiac lineage in vivo during myocardial infarction. Here we provide the first report that undifferentiated hES cells can survive in rat hearts during myocardial infarction without the formation of teratoma using undifferentiated green fluorescent protein (GFP)-transgenic hES cells. Using a laser-capture microscope to dissect the GFP-positive cell area from the hES-injected hearts, we documented the expression of human cardiac-specific genes, including GATA-4, Nkx-2.5, and cardiac troponin I. Taken together, our results demonstrate that undifferentiated hES cells can be driven to the cardiac lineage under the local injured environment in the heart, which may provide a potential method for regenerating de novo myocardium to treat myocardial infarction.

Genetic engineering of human embryonic stem cells with lentiviral vectors.

Human embryonic stem (hES) cells present a valuable source of cells with a vast therapeutic potential. However, the low efficiency of directed differentiation of hES cells remains a major obstacle in their uses for regenerative medicine. While differentiation may be controlled by the genetic manipulation, effective and efficient gene transfer into hES cells has been an elusive goal. Here, we show stable and efficient genetic manipulations of hES cells using lentiviral vectors. This method resulted in the establishment of stable gene expression without loss of pluripotency in hES cells. In addition, lentiviral vectors were effective in conveying the expression of an U6 promoter-driven small interfering RNA (siRNA), which was effective in silencing its specific target. Taken together, our results suggest that lentiviral gene delivery holds great promise for hES cell research and application.

Proliferative feeder cells support prolonged expansion of human embryonic stem cells.

Long-term proliferation of human embryonic stem (hES) cells is currently achieved by co-culturing with mitotically inactive primary mouse embryonic fibroblasts (mEFs), which serve as feeder cells. This study explores the possibility that proliferative mEFs can be used as feeder cells to maintain the prolonged expansion of hES cells. All undifferentiated hES cell clumps were re-plated on six different densities of proliferative mEFs. hES colonies cultured on 1 x 10(5) - 5 x 10(5) proliferative mEFs amplified over 130 days of continuous culture and remained undifferentiated, as did those cultured on mitotically inactive mEFs. This suggests that certain densities of proliferative mEFs can maintain the propagation of hES cells, which may be helpful for identifying the cytokines and adhesion molecules that are required for their self-renewal.

In vitro hematopoietic differentiation of human embryonic stem cells induced by co-culture with human bone marrow stromal cells and low dose cytokines.

Human embryonic stem (hES) cells randomly differentiate into multiple cell types during embryoid body (EB) development and limited studies have focused on directed hematopoietic differentiation. Here, we report that the treatment of hES cells during EBs development with a combination of low dose hematopoietic cytokines, including stem cell factor (SCF), Flt-3 ligand, vascular endothelial growth factor (VEGF) and human bone marrow stromal cells (hBMSCs), generated cell clusters that contained 8.81% KDR-positive hemangioblasts, 9.94% CD34-positive hematopoietic stem cells and 25.7% CD45-positive mature hematopoietic cells, and expressed hematopoietic genes such as KDR, stem cell leukemia (scl) and runt-related transcription factor 1 (Runx1). We provide the first evidence for the role of the cytokine-hBMSCs combination in promoting hematopoietic differentiation of hES cells, and thus provide the potential for generation of hematopoietic cells, as well as for understanding early developmental events that govern the initiation of hematopoiesis in humans.

[Preliminary proteome analysis of mouse embryonic fibroblast conditioned medium].

OBJECTIVE: To perform the proteome analysis of conditioned medium prepared from mouse embryonic fibroblast feeder layers by 2-dimensional (2D) electrophoresis and mass spectrometry and to find out the possible differentiation-inhibitory factor in conditioned medium. METHODS: Feeder layers were prepared by 60Co gamma-irradiation on mouse embryonic fibroblast. Insulin-transferrin-sodium selenite supplemented medium was used to culture the feeder layers for 24 hours. The condioned medium prepared from mouse embryonic fibroblast feeder layers were made into powder by lyophilization, the redissolved solution was applied to Sephadex G-50 gel filtration chromatography, and then cold acetone was used to precipitate the proteins in the eluted solution. The protein samples were applied to 2D electrophoresis. The 2D images were analyzed by 2D image analysis software. Selected protein spots were digested by trypsin, analyzed by mass spectrometry, and then searched against the NCBInr batabase using Mascot MS/MS Ions Search. RESULTS: The protein samples extracted from mouse embryonic fibroblast feeder layers conditioned medium could be used for 2D electrophoresis. On 2D images, there were (221+/-67) spots. Most of the proteins were located in the region of MW 20 approximately 70 kD, pI 4 approximately 8. Using mass spectrometry, we preliminarily identified 13 spots: 3 keratins, 3 transferrins, 1 trypsin precursor, 2 unknown proteins (3 spots), 1 connexin 46, 1 beta-galactoside binding protein, and 1 secreted protein, acidic and rich in cysteine. CONCLUSION: Conditioned medium prepared from mouse embryonic fibroblast feeder layers contain beta-galactoside binding protein and secreted protein, acidic and rich in cysteine.

[Differentiation from human embryonic stem cells to hematopoietic cells and endothelial cells].

Embryonic stem cells are pluripotent and their differentiation in vitro can serve as an experimental model to explore the molecular mechanisms of early embryonic development. To investigate the effect of stromal cell conditioned medium combined with cytokines (sccm + cys) on the differentiation from human embryonic stem cells to hematopoietic cells and endothelial cells, the mouse fibroblast feeder cells to make human embryonic stem cells grown into embryonic bodies (EBs) were initially deleted. After culture for 3 days, EB cells were trypsinized into single cells and induced for 8 days by sccm + cys. Then, the differentiated cells were cultured in the semisolid medium containing 0.9% methylcellulose and cytokines to study the colony forming and self-renewal ability of cells. Immunocytochemical staining was used to check the surface markers of the colony cells. During the induction, mRNA expression of flk-1, BMI-1, scl, and Zeta-globin genes was tested by RT-PCR. Surface markers, such as flk-1, CD34 were tested by the flow cytometry. The results demonstrated that: (1) cell clusters containing 20-30 cells were formed after culture for 8 - 14 days in the semisolid medium, replanting these cells resulted in similar cell cluster forming. In addition, CD45 positive in big cell colonies were also found in the semisolid medium; (2) attached cell colonies appeared after culture for 8 days in the semisolid medium and VIII factor, UEA and KDR could be detected as negative by immunocytochemical staining; (3) on the 4(th) day of induction, mRNAs of flk-1, BMI-1, scl and Zeta-globin were all expressed. On the 8(th) day of induction, all of the above genes except Zeta-globin were expressed, while ES cell and EB cells which served as controls did not express scl and Zeta-globin genes; (4) on the 8(th) day of induction, the proportions of flk-1(+) cells and CD34(+) cells among all the inducing population were 9.8% and 16.8%, respectively, while the corresponding positive populations were 0.36% and 1.16% in spontaneously differentiated 11(th) day's EB, and 0.04% and 0.16%, respectively, in ES cells. If is concluded that embryonic stem cells can differentiate into hematopoietic cells and endothelial cells in combinant culture system of this study.

Derivation of adipocytes from human embryonic stem cells.

Human embryonic stem (hES) cells are undifferentiated and pluripotent cells that hold great therapeutic potential, but are hampered by our limited knowledge to promote specific cell differentiation. Here we provide the first report of the directed differentiation of hES cells into adipocytes. Embryoid bodies (EBs) derived from hES cells are shown to respond to factors that promote adipogenesis. Differentiated cells were observed that displayed the key features of adipocytes, i.e., expression of specific molecular markers, such as peroxisome proliferator-activated receptor gamma2 (PPARgamma2), adipocyte fatty acid binding protein (aP2) and adiponectin, the secretion of leptin, and the accumulation of lipid droplets in cytoplasm. Taken together, our results demonstrate that adipocytes derived from hES cells in vitro can provide a novel model system to study human adipogenesis and obesity.

Newly expressed proteins of mouse embryonic fibroblasts irradiated to be inactive.

It has been found that post-radiation mouse embryonic fibroblasts can well maintain the pluripotency in human embryonic stem cells. However, the molecular mechanism remains unclear. In the present study, the new protein expression profile of post-radiation mouse embryonic fibroblasts was analyzed by immobilized pH gradient 2-dimensional polyacrylamide gel electrophoresis. Image analysis following silver staining revealed (969+/-57) vs. (1085+/-107) spots from post-radiation mouse embryonic fibroblasts and pre-radiation ones, respectively. Some newly expressed proteins, which were only abundantly present after irradiation, were subjected to peptide mass fingerprint analysis and identified using MALDI-TOF-MS, SWISS-PROT database, and RT-PCR. Several of those proteins were preliminarily identified to participate in cytokine secretion, cell signal transduction, transcriptional regulation, and apoptosis, etc., which suggested that inactive post-radiation mouse embryonic fibroblasts expressed some new proteins that may underlie the molecular mechanisms to maintain the pluripotency in human embryonic stem cells.

[Isolation culture and identification of human neural stem cells from human embryos].

OBJECTIVE: To obtain and culture the human neural stem cells from the aborted human embryos. METHODS: The neural stem cells were isolated and purified by the specific proliferous culture system of neural stem cells, and the molecular maker and multi-potency of the obtained neural stem cells were identified. RESULTS: Human neural stem cells, which were isolated from 8 - 10 month old aborted human embryos, could express nestin ( a kind of specified antigen of the neural stem cell), and it could be differentiate into neurons and glials. CONCLUSION: Neural stem cells can exist in human embryos, and it can be expanded in vitro.