The effects of polymorphisms on human gene targeting

DNA mismatches that occur between vector homology arms and chromosomal target sequences reduce gene targeting frequencies in several species; however, this has not been reported in human cells. Here we demonstrate that even a single mismatched base pair can significantly decrease human gene targeting frequencies. In addition, we show that homology arm polymorphisms can be used to direct allele-specific targeting or to improve unfavorable vector designs that introduce deletions.

Phylogenetic distinction of iNOS and IDO function in mesenchymal stem cell-mediated immunosuppression in mammalian species

Mammalian mesenchymal stem cells (MSCs) have been shown to be strongly immunosuppressive in both animal disease models and human clinical trials. We have reported that the key molecule mediating immunosuppression by MSCs is species dependent: indoleamine 2,3-dioxygenase (IDO) in human and inducible nitric oxide synthase (iNOS) in mouse. In the present study, we isolated MSCs from several mammalian species, each of a different genus, and investigated the involvement of IDO and iNOS during MSC-mediated immunosuppression. The characterization of MSCs from different species was by adherence to tissue culture plastic, morphology, specific marker expression, and differentiation potential. On the basis of the inducibility of IDO and iNOS by inflammatory cytokines in MSCs, the tested mammalian species fall into two distinct groups: IDO utilizers and iNOS utilizers. MSCs from monkey, pig, and human employ IDO to suppress immune responses, whereas MSCs from mouse, rat, rabbit, and hamster utilize iNOS. Interestingly, based on the limited number of species tested, the iNOS-utilizing species all belong to the phylogenetic clade, Glires. Although the evolutionary significance of this divergence is not known, we believe that this study provides critical guidance for choosing appropriate animal models for preclinical studies of MSCs.

Lack of genotoxicity due to foamy virus vector integration in human iPSCs

Integrating vectors can lead to the dysregulation of nearby chromosomal genes, with important consequences for clinical trials and cellular engineering. This includes the retroviral and lentiviral vectors commonly used for deriving induced pluripotent stem cells (iPSCs). We previously used integrating foamy virus (FV) vectors expressing OCT4, SOX2, MYC, and KLF4 to reprogram osteogenesis imperfecta mesenchymal stem cells (MSCs). Here we have studied the effects of 10 FV vector proviruses on neighboring gene expression in four iPSC lines and their corresponding iPSC-derived mesenchymal stem cells (iMSCs). Gene expression profiles in these iPSC lines showed that none of the 38 genes within 300 kb up- or downstream of integrated proviruses had a significant difference in mRNA levels, including 5 genes with proviruses in their transcription units. In the iMSCs derived from these iPSCs, the same type of analysis showed a single dysregulated transcript out of 46 genes found near proviruses. This frequency of dysregulation was similar to that of genes lacking nearby proviruses, so it may have been due to interclonal variation and/or measurement inaccuracies. While the number of integration sites examined in this paper is limited, our results suggest that integrated FV proviruses do not impact the expression of chromosomal genes in pluripotent human stem cells or their differentiated derivatives. This interpretation is consistent with previous reports that FV vectors have minimal genotoxicity, even when integrating near or within genes.

Mesenchymal stem cells: a double-edged sword in regulating immune responses

Mesenchymal stem cells (MSCs) have been employed successfully to treat various immune disorders in animal models and clinical settings. Our previous studies have shown that MSCs can become highly immunosuppressive upon stimulation by inflammatory cytokines, an effect exerted through the concerted action of chemokines and nitric oxide (NO). Here, we show that MSCs can also enhance immune responses. This immune-promoting effect occurred when proinflammatory cytokines were inadequate to elicit sufficient NO production. When inducible nitric oxide synthase (iNOS) production was inhibited or genetically ablated, MSCs strongly enhance T-cell proliferation in vitro and the delayed-type hypersensitivity response in vivo. Furthermore, iNOS^−/− MSCs significantly inhibited melanoma growth. It is likely that in the absence of NO, chemokines act to promote immune responses. Indeed, in CCR5^−/−CXCR3^−/− mice, the immune-promoting effect of iNOS^−/− MSCs is greatly diminished. Thus, NO acts as a switch in MSC-mediated immunomodulation. More importantly, the dual effect on immune reactions was also observed in human MSCs, in which indoleamine 2,3-dioxygenase (IDO) acts as a switch. This study provides novel information about the pathophysiological roles of MSCs.

An effect comparison between Furlow double opposing Z-plasty and two-flap palatoplasty on velopharyngeal closure

The aim of this study was to compare velopharyngeal closure between patients who underwent Furlow palatoplasty and two-flap palatoplasty. A retrospective review of 88 patients with incomplete palate cleft was performed. 48 patients (17 males; 31 females) aged 2-28 years received Furlow palatoplasty. 40 patients (17 males; 23 females) aged 2-21 years received two-flap palatoplasty. Velopharyngeal function was categorized as adequate, marginal or inadequate. Complications associated with the operation were documented. Statistically significant differences were not found amongst sex distribution, age at operation, follow-up time, and preoperative speech intelligibility. After primary repairs using Furlow and two-flap palatoplasty, the surgeon's incidence of postoperative palatal fistula was 0%. The complications were not significantly different between the two groups. The authors achieved the lowest reported incidence of postoperative palatal fistulas in primary Furlow palatoplasty. The outcomes of the velopharyngeal closure were better in patients who received Furlow palatoplasty (P<0.05). Furlow palatoplasty was more effective than two-flap palatoplasty in obtaining perfect velopharyngeal closure. A probable explanation may be that Furlow palatoplasty can reposition and overlap the divergent palatal muscle and lengthen the soft palate.

Pineal parenchymal tumours: minimum apparent diffusion coefficient in prediction of tumour grading

Retrospective assessment was performed of the minimum apparent diffusion coefficient (minADC) together with quantitative assessment of the histopathological features of resected tumour tissue and the Ki-67 labelling index (LI) for predicting pineal parenchymal tumour (PPT) grade. Magnetic resonance images of tumours from 26 male and female patients (mean age 27.7 years) with pathologically confirmed PPTs, comprising 10 pineocytomas (PCs), seven pineal parenchymal tumours of intermediate differentiation (PPTIDs) and nine pineoblastomas (PBs), were reviewed retrospectively. Using ADC maps derived from isotropic diffusion-weighted images, the minADC value of each tumour was determined postoperatively from several regions of interest defined in the tumour, excluding cystic, necrotic, haemorrhagic or calcified components. Surgical intervention was undertaken in all cases. The Ki-67 LI was measured in surgical specimens. Mean minADC and Ki-67 LI showed significant differences among PCs, PPTIDs and PBs, and minADC was negatively correlated with Ki-67 LI. It is concluded that the minADC of PPTs provide useful additional information when predicting tumour grading.

Clinical observation of 73 nasopharyngeal carcinoma patients treated by helical tomotherapy: the China experience

The preliminary short-term clinical outcome of 73 nasopharyngeal carcinoma (NPC) patients treated with helical tomotherapy at our cancer institute has been evaluated. Between September 2007 and September 2009, 73 newly diagnosed NPC patients were treated with helical tomotherapy. The distributions of clinical stages according to the UICC 2002 Staging System were: 6, 27, 24, and 16 for Stage I, IIa-b, III, and IVa-b, respectively. The prescription dose was 70-74 Gy/33F to planning gross tumor volume containing the primary tumor and positive lymph nodes, with 60-62.7 Gy/33F to high risk planning target volume, while delivering 52-56 Gy/33F to low risk planning target volume. Twenty-four patients were treated with radiation therapy as single modality, 25 with concurrent cisplatin-based chemotherapy with or without anti-EGFR monoclonal antibody therapy, and 24 with concurrent anti-EGFR monoclonal antibody therapy. Setup errors were analyzed. Side-effects were evaluated with the established RTOG/EORTC criteria. Average beam-on-time was 468.8 sec/F (396.7-696.1 sec). The setup errors in the lateral, longitudinal and vertical directions were 0.00 ± 1.79 mm, -0.55± 2.17 mm and 0.38 ± 1.43 mm, corresponding to 3.80 mm, 4.20 mm, and 2.46 mm as the CTV-PTV margin in these directions. The grade 0, 1, 2 and 3 acute skin toxicity was 2.7%, 76.7%, 13.8% and 6.8%; the grade 0, 1, 2 and 3 acute mucositis was 1.4%, 32.9%, 60.2% and 5.5%; and the grade 0, 1, 2 and 3 acute xerostomia was 4.0%, 45.3%, 50.7% and 0, respectively. Only 5 patients suffered from grade 3 or 4 leucopenia. Xerostomia resolved with passing of time and no grade 2 or more xerostomia was noted one year after radiation therapy. Concurrent chemotherapy significantly increased incidence of severe acute toxicities. One month after radiation therapy the remission rates of primary tumor and positive lymph nodes were 91.8% and 98.1%, respectively. The median follow-up was 14.8 months. The one-year relapse-free survival, distant metastasis-free survival and overall survival was 95.6%, 97.2% and 94.8%, respectively. In conclusion, the incidence of severe acute toxicities and late xerostomia was relatively infrequent for NPC patients treated with helical tomotherapy. The long-term clinical outcome for these patients is under investigation.

Value of Diffusion-Weighted Imaging in Grading Tumours Localized in the Fourth Ventricle Region by Visual and Quantitative Assessments

This study investigated visual and quantitative assessment of diffusion-weighted imaging (DWI) for grading tumours localized in the fourth ventricle region. Patients were diagnosed histopathologically and classified into two groups: those with high-grade (World Health Organization [WHO] grades III and IV) and those with low-grade tumours (benign, WHO grades I and II). DWI signal intensity was described using a five-point scale. Minimum apparent diffusion coefficient (ADC) values were obtained from areas with the lowest signal. The mean signal intensity was significantly higher in high-grade than in low-grade tumours. The mean minimum ADC value was significantly lower in high-grade than low-grade tumours. Marked hyperintensity had sensitivity, specificity, positive predictive value and negative predictive value of 89.7%, 100%, 100% and 94.2%, respectively, when used as a diagnostic tool for high-grade tumours compared with 96.6%, 97.9%, 96.6% and 97.9%, respectively, when using a minimum ADC of 0.9 × 10−3 mm2/s as a diagnostic marker. It was concluded that DWI is helpful in predicting the grades of tumours in the fourth ventricle region.

Mouse mandible contains distinctive mesenchymal stem cells

Although human orofacial bone-marrow-derived mesenchymal stem cells showed differentiation traits distinctly different from those of mesenchymal stem cells (MSCs) derived from long bone marrow (BMMSCs), mouse MSCs derived from orofacial bone have not been isolated due to technical difficulties, which in turn precludes the use of mouse models to study and cure orofacial diseases. In this study, we developed techniques to isolate and expand mouse orofacial bone/bone-marrow-derived MSCs (OMSCs) from mandibles and verified their MSC characteristics by single-colony formation, multi-lineage differentiation, and in vivo tissue regeneration. Activated T-lymphocytes impaired OMSCs via the Fas/Fas ligand pathway, as occurs in BMMSCs. Furthermore, we found that OMSCs are distinct from BMMSCs with respect to regulating T-lymphocyte survival and proliferation. Analysis of our data suggests that OMSCs are a unique population of MSCs and play an important role in systemic immunity.

ABBREVIATIONS

BMMSC, bone marrow mesenchymal stem cell; HA/TCP, hydroxyapatite/tricalcium phosphate; OMSC, orofacial mesenchymal stem cell; OVX, ovariectomized.

Generation of mammalian cell lines with gene knock-down for human MCHR2

Appetite regulating neuropeptide melanin-concentrating hormone (MCH) has been implicated in obesity. It functions through its two receptors MCHR1 and MCHR2. While MCH and MCHR1 have been studied more extensively, the function of MCHR2 remains largely unknown, due to the lack of suitable in vitro and in vivo models. To create an in vitro system of genetic knock-down of MCHR2 in mammalian cells, we constructed four small hairpin RNAs (shRNAs) against human MCHR2 in eukaryotic expression vector, and transfected the plasmids into CHO cells that stably express human MCHR2. Using the empty vector or a negative shRNA control plasmid, we show that MCHR2-shRNAs suppressed 45.8% - 66.4% of MCHR2 expression at both mRNA and protein levels. As the result, in cells carrying the MCHR2-shRNAs, binding of MCHR2 to MCH was decreased by 39.4% - 78.7% accompanied by a similar decrease in affinity of the receptor to ligand by 40.9% - 81.9%. These cells still respond to MCH treatment, but intracellular Ca2+ release as the downstream signaling event was also decreased by 114.8% - 822.4%. Together, this study generated a set of shRNAs and cell lines as valuable reagents for further study on MCHR2 functions. These results will ultimately help to advance our knowledge about appetite regulating neuropeptide receptors.

Novel 12-bp deletion in the coding region of the bovine NPM1 gene affects growth traits

The nucleophosmin 1 gene (NPM1) encodes a multifunctional nucleolar phosphoprotein that plays a crucial role in the control of various aspects of cell growth and homeostasis. In this study, the coding region of the NPM1 gene was screened in 1035 individuals of 4 Chinese cattle breeds by DNA sequencing and polyacrylamide gel electrophoresis. A novel 12-bp deletion mutation was identified in the coding region of the NPM1 gene. The PCR products of primer NPM1-P2 exhibited 3 genotypes and 2 alleles: 178 bp (denoted as W) and 166 bp (denoted as D). Genotype DD and allele D were predominant in the studied populations. Association analysis with growth traits in the Nanyang breed (N = 265) showed that the animals with genotype DD had significantly greater birth weight, body weight, body length, and heart girth than those with genotype WD (P < 0.01 or P < 0.05) at birth and after 6 months and 12 months, but not at 18 and 24 months of age. Results of this study suggest that the NPM1 gene is a candidate gene for growth traits in cattle.

A review of nanoparticle functionality and toxicity on the central nervous system

Although nanoparticles have tremendous potential for a host of applications, their adverse effects on living cells have raised serious concerns recently for their use in the healthcare and consumer sectors. As regards the central nervous system (CNS), research data on nanoparticle interaction with neurons has provided evidence of both negative and positive effects. Maximal application dosage of nanoparticles in materials to provide applications such as antibacterial and antiviral functions is approximately 0.1-1.0 wt%. This concentration can be converted into a liquid phase release rate (leaching rate) depending upon the host or base materials used. For example, nanoparticulate silver (Ag) or copper oxide (CuO)-filled epoxy resin demonstrates much reduced release of the metal ions (Ag(+) or Cu(2+)) into their surrounding environment unless they are mechanically removed or aggravated. Subsequent to leaching effects and entry into living systems, nanoparticles can also cross through many other barriers, such as skin and the blood-brain barrier (BBB), and may also reach bodily organs. In such cases, their concentration or dosage in body fluids is considered to be well below the maximum drug toxicity test limit (10(-5) g ml(-1)) as determined in artificial cerebrospinal solution. As this is a rapidly evolving area and the use of such materials will continue to mature, so will their exposure to members of society. Hence, neurologists have equal interests in nanoparticle effects (positive functionality and negative toxicity) on human neuronal cells within the CNS, where the current research in this field will be highlighted and reviewed.

A review of nanoparticle functionality and toxicity on the central nervous system

Although nanoparticles have tremendous potential for a host of applications, their adverse effects on living cells have raised serious concerns recently for their use in the healthcare and consumer sectors. As regards the central nervous system (CNS), research data on nanoparticle interaction with neurons has provided evidence of both negative and positive effects. Maximal application dosage of nanoparticles in materials to provide applications such as antibacterial and antiviral functions is approximately 0.1-1.0 wt%. This concentration can be converted into a liquid phase release rate (leaching rate) depending upon the host or base materials used. For example, nanoparticulate silver (Ag) or copper oxide (CuO)-filled epoxy resin demonstrates much reduced release of the metal ions (Ag(+) or Cu(2+)) into their surrounding environment unless they are mechanically removed or aggravated. Subsequent to leaching effects and entry into living systems, nanoparticles can also cross through many other barriers, such as skin and the blood-brain barrier (BBB), and may also reach bodily organs. In such cases, their concentration or dosage in body fluids is considered to be well below the maximum drug toxicity test limit (10(-5) g ml(-1)) as determined in artificial cerebrospinal solution. As this is a rapidly evolving area and the use of such materials will continue to mature, so will their exposure to members of society. Hence, neurologists have equal interests in nanoparticle effects (positive functionality and negative toxicity) on human neuronal cells within the CNS, where the current research in this field will be highlighted and reviewed.

A novel single-nucleotide polymorphism of the visfatin gene and its associations with performance traits in the chicken

Visfatin is a peptide that is predominantly expressed in visceral adipose tissue and is hypothesized to be related to obesity and insulin resistance. In this study, a novel silent single-nucleotide polymorphism (SNP) was found in exon 7 of the chicken visfatin gene (also known as PBEF1) by single-stranded conformation polymorphism (SSCP) and DNA sequencing. In total, 836 chickens forming an F2 resource population of Gushi chicken crossed with Anka broiler were genotyped by XbaI forced RFLP, and the associations of this polymorphism with chicken growth, carcass characteristics, and meat quality were analyzed. Significant associations were found between the polymorphism and 4-week body weight (BW4), 6-week body weight (BW6), 4-week body slanting length (BSL4), fat bandwidth (FBW), breast muscle water loss rate (BWLR) and breast muscle fiber density (BFD) (P < 0.05), as well as 4-week breastbone length (BBL4) (P < 0.01). These observations suggested that the polymorphism in exon7 of the visfatin gene had significant effects on the early growth traits of chicken.