Cancer models in preclinical research: A chronicle review of advancement in effective cancer research

Cancer is a major stress for public well‐being and is the most dreadful disease. The models used in the discovery of cancer treatment are continuously changing and extending toward advanced preclinical studies. Cancer models are either naturally existing or artificially prepared experimental systems that show similar features with human tumors though the heterogeneous nature of the tumor is very familiar. The choice of the most fitting model to best reflect the given tumor system is one of the real difficulties for cancer examination. Therefore, vast studies have been conducted on the cancer models for developing a better understanding of cancer invasion, progression, and early detection. These models give an insight into cancer etiology, molecular basis, host tumor interaction, the role of microenvironment, and tumor heterogeneity in tumor metastasis. These models are also used to predict novel cancer markers, targeted therapies, and are extremely helpful in drug development. In this review, the potential of cancer models to be used as a platform for drug screening and therapeutic discoveries are highlighted. Although none of the cancer models is regarded as ideal because each is associated with essential caveats that restraint its application yet by bridging the gap between preliminary cancer research and translational medicine. However, they promise a brighter future for cancer treatment.     

Genotoxicity of 1‐methylpyrene and 1‐hydroxymethylpyrene in chinese hamster V79‐derived cells expressing both human CYP2E1 and SULT1A1

1‐Methylpyrene (1‐MP) is a widespread pollutant that is carcinogenic in animals following metabolic activation. Previous studies have shown that benzylic hydroxylation of 1‐MP, catalyzed by multiple CYP isoforms, gives rise to 1‐hydroxymethylpyrene (1‐HMP), which becomes bioreactive following further metabolism by various sulfotransferase (SULT) isoforms. However, the mutagenic and chromosome damaging effects of 1‐MP and 1‐HMP in mammalian cells have not been investigated. In this study a Chinese hamster V79‐derived cell line expressing both human CYP2E1 and human SULT1A1 was used to investigate the ability of 1‐MP and 1‐HMP to induce cytotoxicity (using the CCK‐8 assay), micronuclei and Hprt gene mutations. The role of each enzyme was investigated through co‐exposure in the presence of an enzyme inhibitor. We found that at concentrations of 0.5–4 μM and 5–20 μM, under conditions where no reduction in cell viability/growth occurred, 1‐HMP and 1‐MP induced micronuclei in V79‐hCYP2E1‐hSULT1A1 cells in a concentration‐dependent manner; however, both compounds were inactive in V79 cells. Similarly, they both caused an increase in Hprt mutant frequency in V79‐hCYP2E1‐hSULT1A1 cells in these concentration ranges, with 1‐MP impairing cell viability/growth at 10 μM and above in the mutagenicity assay. The compounds were again both inactive in V79 cells. The effects of 1‐HMP in V79‐hCYP2E1‐hSULT1A1 cells were blocked or reduced by addition of pentachlorophenol (PCP), a SULT1 inhibitor; the genotoxicity of 1‐MP was significantly reduced by either 1‐aminobenotrazole, a CYP2E1 inhibitor, or PCP. The results suggest that human CYP2E1 and SULT1A1 cooperate to activate 1‐MP and cause genotoxicity in mammalian cells. Environ. Mol. Mutagen. 56:404–411, 2015. © 2014 Wiley Periodicals, Inc.     

Magnetic resonance elastography‐derived stiffness of the kidneys and its correlation with water perfusion

Stiffness plays an important role in diagnosing renal fibrosis. However, kidney stiffness is altered by perfusion changes in many kidney diseases. Therefore, the aim of the current study is to determine the correlation of kidney stiffness with water intake. We hypothesize that kidney stiffness will increase with 1 L of water intake due to increased water perfusion to the kidneys. Additionally, stiffness of the kidneys will correlate with apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values before and after water intake. A 3 T MRI scanner was used to perform magnetic resonance elastography and diffusion tensor imaging of the kidneys on 24 healthy subjects (age range: 22‐66 years) before and after water intake of 1 L. A 3D T1‐weighted bladder scan was also performed to measure bladder volume before and after water intake. A paired t‐test was performed to evaluate the effect of water intake on the stiffness of kidneys, in addition to bladder volume. A Spearman correlation test was performed to determine the association between stiffness, bladder volume, ADC and FA values of both kidneys before and after water intake. The results show a significant increase in stiffness in different regions of the kidney (ie, percentage increase ranged from 3.6% to 7.5%) and bladder volume after water intake (all P < 0.05). A moderate significant negative correlation was observed between change in kidney stiffness and bladder volume (concordance correlation coefficient = ‐0.468, P < 0.05). No significant correlation was observed between stiffness and ADC or FA values before and after water intake in both kidneys (P > 0.05). Water intake caused a significant increase in the stiffness of the kidneys. The negative correlation between the change in kidney stiffness and bladder volume, before and after water intake, indicates higher perfusion pressure in the kidneys, leading to increased stiffness.     

Intravoxel water diffusion heterogeneity imaging of human high‐grade gliomas

This study aimed to determine the potential value of intravoxel water diffusion heterogeneity imaging for brain tumor characterization and evaluation of high‐grade gliomas, by comparing an established heterogeneity index (α value) measured in human high‐grade gliomas to those of normal appearing white and grey matter landmarks. Twenty patients with high‐grade gliomas prospectively underwent diffusion‐weighted magnetic resonance imaging using multiple b‐values. The stretched‐exponential model was used to generate α and distributed diffusion coefficient (DDC) maps. The α values and DDCs of the tumor and contralateral anatomic landmarks were measured in each patient. Differences between α values of tumors and landmark tissues were assessed using paired t‐tests. Correlation between tumor α and tumor DDC was assessed using Pearson's correlation coefficient. Mean α of tumors was significantly lower than that of contralateral frontal white matter (p = 0.0249), basal ganglia (p < 0.0001), cortical grey matter (p < 0.0001), and centrum semiovale (p = 0.0497). Correlation between tumor α and tumor DDC was strongly negative (Pearson correlation coefficient, ?0.8493; p < 0.0001). The heterogeneity index α of human high‐grade gliomas is significantly different from those of normal brain structures, which potentially offers a new method for evaluating brain tumors. The observed negative correlation between tumor α and tumor DDC requires further investigation. Copyright © 2009 John Wiley & Sons, Ltd.     

High‐resolution MRI analysis of breast cancer xenograft on the chick chorioallantoic membrane

The chick chorioallantoic membrane (CAM) model has been successfully used to study angiogenesis, cancer progression and its pharmacological treatment, tumor pharmacokinetics, and properties of novel nanomaterials. MRI is an attractive technique for non‐invasive and longitudinal monitoring of physiological processes and tumor growth. This study proposes an age‐adapted cooling regime for immobilization of the chick embryo, enabling high‐resolution MRI of the embryo and the CAM tumor xenograft. 64 chick embryos were enrolled in this study. The novel immobilization and imaging protocol was optimized in 29 embryos. From d7 to d18 immobilization of the embryo up to 90 min was achieved by cooling at 4 °C pre‐imaging, with cooling times adapted to age. Its application to tumor growth monitoring was evaluated in 15 embryos after xenotransplantation of human MDA‐MB‐231 breast cancer cells on CAM. Tumor volumes were monitored from d4 to d9 after grafting (d11 to d16 after incubation) applying a T₂‐weighted multislice RARE sequence. At d9 after grafting, the tumors were collected and compared with the MRI‐derived data by histology and weight measurements. Additional imaging methods comprising DWI, T₂ mapping, and the bio‐distribution of contrast agents were tested at d9 after grafting in 20 further embryos. With the adaptive cooling regime, motion artifacts could be completely avoided for up to 90 min scan time, enabling high‐resolution in ovo imaging. Excellent anatomical details could be obtained in the embryo and tumors. Tumor volumes could be quantified over time. The results prove the feasibility of high‐resolution MRI for longitudinal tumor and organ growth monitoring. The suggested method is promising for future applications such as testing tailored and/or targeted treatment strategies, longitudinal monitoring of tumor development, analysis of therapeutic efficacies of drugs, or assessment of tumor pharmacokinetics. The method provides an alternative to animal experimentation. Copyright © 2015 John Wiley & Sons, Ltd.     

Morphogenesis and Three‐Dimensional Movement of the Stomach During the Human Embryonic Period

The stomach develops as the local widening of the foregut after Carnegie stage (CS) 13 that moves in a dramatic and dynamic manner during the embryonic period. Using the magnetic resonance images of 377 human embryos, we present the morphology, morphometry, and three‐dimensional movement of the stomach during CS16 and CS23. The stomach morphology revealed stage‐specific features. The angular incisura and the cardia were formed at CS18. The change in the angular incisura angle was approximately 90° during CS19 and CS20, and was <90° after CS 21. The prominent formations of the fundus and the pylorus differentiate at around CS20. Morphometry of the stomach revealed that the stomach gradually becomes “deflected” during development. The stomach may appear to move to the left laterally and caudally due to its deflection and differential growth. The track of the reference points in the stomach may reflect the visual three‐dimensional movement. The movement of point M, representing the movement of the greater curvature, was different from that of points C (cardia) and P (pyloric antrum). The P and C were located just around the midsagittal plane in all the stages observed. Point M moved in the caudal‐left lateral direction until CS22. Moreover, the vector CP does not rotate around the dorsoventral axis, as widely believed, but around the transverse axis. The plane CPM rotated mainly around the longitudinal axis. The data obtained will be useful for prenatal diagnosis in the near future. Microsc. Res. Tech, 297:791–797, 2014. © 2013 Wiley Periodicals, Inc.     

Double labelling of human umbilical cord mesenchymal stem cells with Gd‐DTPA and PKH26 and the influence on biological characteristics of hUCMSCs

The aim of this study was to determine whether double labelling of human umbilical cord mesenchymal stem cells (hUCMSCs) with gadolinium‐diethylene triamine penta‐acetic acid (Gd‐DTPA) and PKH26 influences their biological characteristics. A tissue adherence technique was used to separate and purify the hUCMSCs and flow cytometry was performed to detect the surface markers expressed on them. Gd‐DTPA and PKH26 were used to label the stem cells and MRI and fluorescence microscopy were used to detect the double‐labelled hUCMSCs. A MTT assay was used to delineate the growth curve. Transmission electron microscopy (TEM) and atomic force microscopy were used to demonstrate the ultrastructural features of the hUCMSCs. Flow cytometry showed that hUCMSCs highly expressed CD29, CD90, CD44 and CD105. No expression of CD31, CD34 and CD45 was detected. Very low expression of HLA‐DR and CD40 was detected. Atomic force microscopy showed these cells were long, spindle shaped, and the cytoplasm and nucleus had clear boundaries. After double labelling, TEM showed Gd particles aggregated in the cytoplasm in a cluster pattern. The proliferation activity, cell cycle, apoptosis and differentiation of the stem cells were not influenced by double labelling. Thus a tissue adherence technique is helpful to separate and purify hUCMSCs effectively; and Gd‐DTPA and PKH26 are promising tracers in the investigation of migration and distribution of hUCMSCs in vivo.     

Evaluating the feasibility of creatine‐weighted CEST MRI in human brain at 7 T using a Z‐spectral fitting approach

The current study aims to evaluate the feasibility of creatine (Cr) chemical exchange saturation transfer (CEST)‐weighted MRI at 7 T in the human brain by optimizing the saturation pulse parameters and computing contrast using a Z‐spectral fitting approach. The Cr‐weighted (Cr‐w) CEST contrast was computed from phantoms data. Simulations were carried out to obtain the optimum saturation parameters for Cr‐w CEST with lower contribution from other brain metabolites. CEST‐w images were acquired from the brains of four human subjects at different saturation parameters. The Cr‐w CEST contrast was computed using both asymmetry analysis and Z‐spectra fitting approaches (models 1 and 2, respectively) based on Lorentzian functions. For broad magnetization transfer (MT) effect, Gaussian and Super‐Lorentzian line shapes were also evaluated. In the phantom study, the Cr‐w CEST contrast showed a linear dependence on concentration in physiological range and a nonlinear dependence on saturation parameters. The in vivo Cr‐w CEST map generated using asymmetry analysis from the brain represents mixed contrast with contribution from other metabolites as well and relayed nuclear Overhauser effect (rNOE). Simulations provided an estimate for the optimum range of saturation parameters to be used for acquiring brain CEST data. The optimum saturation parameters for Cr‐w CEST to be used for brain data were around B_1rms = 1.45 μT and duration = 2 seconds. The Z‐spectral fitting approach enabled computation of individual components. This also resulted in mitigating the contribution from MT and rNOE to Cr‐w CEST contrast, which is a major source of underestimation in asymmetry analysis. The proposed modified z‐spectra fitting approach (model 2) is more stable to noise compared with model 1. Cr‐w CEST contrast obtained using fitting was 6.98 ± 0.31% in gray matter and 5.45 ± 0.16% in white matter. Optimal saturation parameters reduced the contribution from other CEST effects to Cr‐w CEST contrast, and the proposed Z‐spectral fitting approach enabled computation of individual components in Z‐spectra of the brain. Therefore, it is feasible to compute Cr‐w CEST contrast with a lower contribution from other CEST and rNOE.     

Comparison of hyperpolarized 3He MRI rat lung volume measurement with micro‐computed tomography

In this study, the upper‐limit volume (gas plus partial tissue volume) as well as absolute volume (gas only) of lungs measured with hyperpolarized ³He‐MR imaging is compared with that determined by micro‐computed tomography (CT) under similar ventilation conditions in normal rats. Five Brown Norway rats (210–259 g) were ventilated with O₂, alternately with ³He, using a computer‐controlled ventilator, and 3D density‐weighted images of the lungs were acquired during a breath hold after six wash‐in breaths of ³He. The rats were then transferred to a micro‐CT scanner, and a similar experimental setup was used to obtain images of the lungs during a breath hold of air with an airway pressure equal to that of the MR imaging breath hold. The upper‐limit and absolute volumes obtained from ³He‐MR and micro‐CT methods were not significantly different (p > 0.05). The good agreement between the lung volumes measured with the two imaging methods suggests that ³He‐MR imaging can be used for quantitative analysis of lung volume changes in longitudinal studies without the exposure to the ionizing radiation which accompanies micro‐CT imaging. Copyright © 2010 John Wiley & Sons, Ltd.     

Anatomy and three‐dimensional reconstructions of the brain of a bottlenose dolphin (Tursiops truncatus) from magnetic resonance images

Cetacean (dolphin, whale, and porpoise) brains are among the least studied mammalian brains because of the formidability of collecting and histologically preparing such relatively rare and large specimens. Magnetic resonance imaging offers a means of observing the internal structure of the brain when traditional histological procedures are not practical. Furthermore, internal structures can be analyzed in their precise anatomic positions, which is difficult to accomplish after the spatial distortions often accompanying histological processing. In this study, images of the brain of an adult bottlenose dolphin, Tursiops truncatus, were scanned in the coronal plane at 148 antero‐posterior levels. From these scans a computer‐generated three‐dimensional model was constructed using the programs VoxelView and VoxelMath (Vital Images, Inc.). This model, wherein details of internal and external morphology are represented in three‐dimensional space, was then resectioned in orthogonal planes to produce corresponding series of virtual sections in the horizontal and sagittal planes. Sections in all three planes display the sizes and positions of major neuroanatomical features such as the arrangement of cortical lobes and subcortical structures such as the inferior and superior colliculi, and demonstrate the utility of MRI for neuroanatomical investigations of dolphin brains. Anat Rec 264:397–414, 2001. © 2001 Wiley‐Liss, Inc.     

The effect of bone marrow‐ and adipose tissue‐derived mesenchymal stem cell transplantation on myocardial remodelling in the rat model of ischaemic heart failure

This study aimed to investigate the effect of bone marrow‐ and adipose tissue‐derived mesenchymal stem cell (BM‐MSC and AD‐MSC respectively) transplantation on left ventricular function and infarct area (IA) in the rat model of ischaemic heart failure. In anaesthetized Wistar rats, the left coronary artery (LCA) was occluded for 40 min with subsequent reperfusion for 7 days. Seven days following surgery, the animals with LCA occlusion/reperfusion were randomized into three groups: (i) Controls received intramyocardial injection of vehicle at three different locations within the peri‐infarct zone, (ii) BM‐MSC: cells were injected in the same way as in previous group (10⁶), (iii) AD‐MSC: using the same protocol as used in the BM‐MSC group. In addition there was also a sham‐treated group that had no injection. Two weeks following MSC transplantation, the hearts were isolated and perfused according to the Langendorff method followed by 30‐min global ischaemia and 90‐min reperfusion. After this IA was determined histologically. During Langendorff perfusion initial and postischaemic LV functions were the same in all groups although LV pressure at the 10th minute of reperfusion was higher in the AD‐MSC group compared to controls. However, LV pressure during 30‐min global ischaemia was significantly higher in BM‐MSC as compared to controls and AD‐MSC. The sham treated animals showed the same results as those seen with BM‐MSC. Thus, BM‐MSC transplantation, in contrast to transplantation of AD‐MSC, resulted in better preservation of the LV ability to contract during ischaemia. Furthermore, IA was significantly smaller in BM‐MSC group as compared to the controls and the AD‐MSC groups. Thus this study has demonstrated that treatment with BM‐MSC both ameliorates LV function and reduces histological scar size.     

Effects of targeting the VEGF and PDGF pathways in diffuse orthotopic glioma models

Currently available compounds that interfere with VEGF-A signalling effectively inhibit angiogenesis in gliomas, but influence diffuse infiltrative growth to a much lesser extent. Development of a functional tumour vascular bed not only involves VEGF-A but also requires platelet-derived growth factor receptor-β (PDGFRβ), which induces maturation of tumour blood vessels. Therefore, we tested whether combined inhibition of VEGFR and PDGFRβ increases therapeutic benefit in the orthotopic glioma xenograft models E98 and E473, both displaying the diffuse infiltrative growth that is characteristically observed in most human gliomas. We used bevacizumab and vandetanib as VEGF(R) inhibitors, and sunitinib to additionally target PDGFRβ. We show that combination therapy of sunitinib and vandetanib does not improve therapeutic efficacy compared to treatment with sunitinib, vandetanib or bevacizumab alone. Furthermore, all compounds induced reduction of vessel leakage in compact E98 tumour areas, resulting in decreased detectability of these mostly infiltrative xenografts in Gd-DTPA-enhanced MRI scans. These data show that inhibition of VEGF signalling cannot be optimized by additional PDGFR inhibition and support the concept that diffuse infiltrative areas in gliomas are resistant to anti-angiogenic therapy.     

In vivo detection and automatic analysis of GABA in the mouse brain with MEGA‐PRESS at 9.4 T

The goals of this study were to develop an acquisition protocol and the analysis tools for Meshcher–Garwood point‐resolved spectroscopy (MEGA‐PRESS) in mouse brain at 9.4 T, to allow the in vivo detection of γ‐aminobutyric acid (GABA) and to examine whether isoflurane alters GABA levels in the thalamus during anesthesia. We implemented the MEGA‐PRESS sequence on a Bruker 94/20 system with ParaVision 6.0.1, and magnetic resonance spectra were acquired from nine male wild‐type C57BL/6 J mice at the thalamus. Four individual scans were obtained for each mouse in a 2‐h time course whilst the mouse was anesthetized with isoflurane. We developed an automated analysis program with improved correction for frequency and phase drift compared with the standard creatine (Cr) fitting‐based method and provided automatic quantification. During MEGA‐PRESS acquisition, a single voxel with a size of 5 × 3 × 3 mm³ was placed at the thalamus to evaluate GABA to Cr (GABA/Cr) ratios during anesthesia. Detection and quantitative analysis of thalamic GABA levels were successfully achieved. We noticed a significant decrease in GABA/Cr during the 2‐h anesthesia (by linear regression analysis: slope < 0, p < 0.0001). In summary, our findings demonstrate that MEGA‐PRESS is a feasible technique to measure in vivo GABA levels in the mouse brain at 9.4 T.     

The wrist is not the brain: Estimation of sleep by clinical and consumer wearable actigraphy devices is impacted by multiple patient‐ and device‐specific factors

Clinical actigraphy devices provide adequate estimates of some sleep measures across large groups. In practice, providers are asked to apply clinical or consumer wearable data to individual patient assessments. Inter‐individual variability in device performance will impact such patient‐specific interpretation. We assessed two devices, clinical and consumer, to determine the magnitude and predictors of this individual‐level variability. One hundred and two patients (55 [53.9%] female; 56.4 [±16.3] years old) undergoing polysomnography wore Jawbone UP3 and/or Actiwatch2. Device total sleep time, sleep efficiency, wake after sleep onset and sleep latency were compared with polysomnography. Demographics, sleep architecture and clinical measures were compared to device performance. Actiwatch overestimated total sleep time by 27.2 min (95% confidence limits [CL], 138.3 min over to 84.0 under), overestimated sleep efficiency by 6.8% (95% CL, 34.1% over to 20.5% under), overestimated sleep onset latency by 2.6 min (95% CL, 63.3 over to 58.2 under) and underestimated wake after sleep onset by 50.7 min (95% CL, 162.5 under to 61.2 over). Jawbone overestimated total sleep time by 59.1 min (95% CL, 208.6 min over to 90.5 under) and overestimated sleep efficiency by 14.9% (95% CL, 52.6% over to 22.7% under). In multivariate models, age, sleep onset latency, wake after sleep onset, % N1 and apnea–hypopnea index explained only some of the variance in device performance. Gender also affected performance. Actiwatch and Jawbone mis‐estimate sleep measures with very wide confidence limits and accuracy varies with multiple patient‐level characteristics. Given these large individual inaccuracies, data from these devices must be applied only with extreme caution in clinical practice.     

Atorvastatin promotes the expansion of myeloid‐derived suppressor cells and attenuates murine colitis

Statins, widely prescribed as cholesterol‐lowering drugs, have recently been extensively studied for their pleiotropic effects on immune systems, especially their beneficial effects on autoimmune and inflammatory disorders. However, the mechanism of statin‐induced immunosuppression is far from understood. Here, we found that atorvastatin promoted the expansion of myeloid‐derived suppressor cells (MDSCs) both in vitro and in vivo. Atorvastatin‐derived MDSCs suppressed T‐cell responses by nitric oxide production. Addition of mevalonate, a downstream metabolite of 3‐hydroxy‐3‐methylglutaryl coenzyme A reductase, almost completely abrogated the effect of atorvastatin on MDSCs, indicating that the mevalonate pathway was involved. Along with the amelioration of dextran sodium sulphate (DSS) ‐induced murine acute and chronic colitis, we observed a higher MDSC level both in spleen and intestine tissue compared with that from DSS control mice. More importantly, transfer of atorvastatin‐derived MDSCs attenuated DSS acute colitis and T‐cell transfer of chronic colitis. Hence, our data suggest that the expansion of MDSCs induced by statins may exert a beneficial effect on autoimmune diseases. In summary, our study provides a novel potential mechanism for statins‐based treatment in inflammatory bowel disease and perhaps other autoimmune diseases.     

Statistical analysis of the accuracy of water content‐based electrical properties tomography

Water content‐based electrical properties tomography (wEPT) can retrieve electrical properties (EPs) from water content maps, thereby eliminating the need for B₁ field measurement in the traditional magnetic resonance electrical properties tomography method. The wEPT is performed by conventional MR scanning, such as T₁ ‐weighted spin‐echo imaging, and thus can be directly applied to clinical settings. However, the random noise propagation involved in wEPT causes inaccuracy in EP mapping. To guarantee the EP estimates desired for clinical practice, this study statically investigates the noise‐specific uncertainty of wEPT through probability density function models. We calculated the probability distribution of EP maps with different noise levels and examined the effects of scan parameters on reconstruction accuracy with various flip angles (FAs) and repetition time (TR) settings. The theoretical derivation was validated by Monte Carlo simulations and human imaging experiment at 3 T. Results showed that a serious deviation could occur in tissues with large conductivity value at a low signal‐to‐noise ratio and quantitatively demonstrate that such deviation could be mitigated by increased FAs or TRs. This study provided useful information for the setup of scan parameters, evaluation of accuracy of the wEPT under specific SNR levels, and promote its clinical applications.     

Fetal BM‐derived mesenchymal stem cells promote the expansion of human Th17 cells,but inhibit the production of Th1 cells

Th type 17 (Th17) cells have been identified as a proinflammatory T‐cell subset. Here, we investigated the regulation of human Th17 cells by fetal BM‐derived mesenchymal stem cells (FBM‐MSC). We cocultured FBM‐MSC with human PBMC or CD4⁺ T cells from healthy donors. FBM‐MSC significantly suppressed the proliferation of CD4⁺ T cells stimulated by PHA and recombinant IL‐2. Significantly higher levels of IL‐17 were observed in FBM‐MSC cocultured with either PBMC or CD4⁺ T cells than that in PBMC cultured alone or CD4⁺ T cells cultured alone. Flow cytometry analysis showed that the percentage of Th17 cells in coculture of FBM‐MSC and CD4⁺ T cells was significantly higher than that in CD4⁺ T‐cell cultured alone. FBM‐MSC did not express IL‐17 protein. Consistent with the augmentation of Th17 cells, significantly higher levels of IL‐6 and IL‐1 were observed in coculture of FBM‐MSC and CD4⁺ T cells than that in CD4⁺ T‐cell culture, while the levels of IL‐23 were similar between FBM‐MSC + PBMC coculture and PBMC alone, or FBM‐MSC + CD4⁺ T‐cell and CD4⁺ T‐cell alone. The presence of FBM‐MSC decreased the percentage of Th1 cells, but minimally affected the expansion of CD4⁺CD25⁺ T cells. In conclusion, our data demonstrate for the first time that FBM‐MSC promote the expansion of Th17 cells and decrease IFN‐γ‐producing Th1 cells. These data suggest that IL‐6 and IL‐1, instead of IL‐23, may be partly involved in the expansion of Th17 cells.     

A semi‐LASER,single‐voxel spectroscopic sequence with a minimal echo time of 20.1 ms in the human brain at 3 T

An optimized semi‐LASER sequence that is capable of acquiring artefact‐free data with an echo time (TE) of 20.1 ms on a standard clinical 3 T MR system was developed. Simulations were performed to determine the optimal TEs that minimize the expected Cramér‐Rao lower bound (CRLB) as proxy for quantification accuracy of metabolites. Optimized RF pulses, crusher gradients and phase cycling were used to achieve the shortest TE in a semi‐LASER sequence to date on a clinical system. Synthetic spectra were simulated using the density matrix formalism for TEs spanning from 20.1 to 220.1 ms. These simulations were used to calculate the expected CRLB for each of the 18 metabolites typically considered in ¹H MRS. High quality spectra were obtained in six healthy volunteers in the prefrontal cortex, which is known for spurious echoes due to its proximity to the paranasal sinuses, and in the parietal‐occipital cortex. Spectral transients were sufficient in quality to enable phase and frequency alignment prior to summation over all repetitions. Automated high‐quality water suppression was obtained for all voxels without manual adjustment. The shortest TE minimized the CRLB for all brain metabolites except glycine due to its overlap with myo‐inositol at this TE. It is also demonstrated that the CRLBs increase rapidly with TE for certain coupled metabolites.