Genome-wide DNA methylation analysis identifies potent CpG signature for temzolomide response in non-G-CIMP glioblastomas with unmethylated MGMT promoter: MGMT-dependent roles of GPR81.

PURPOSES: To identify potent DNA methylation candidates that could predict response to temozolomide (TMZ) in glioblastomas (GBMs) that do not have glioma-CpGs island methylator phenotype (G-CIMP) but have an unmethylated promoter of O-6-methylguanine-DNA methyltransferase (unMGMT). METHODS: The discovery-validation approach was planned incorporating a series of G-CIMP-/unMGMT GBM cohorts with DNA methylation microarray data and clinical information, to construct multi-CpG prediction models. Different bioinformatic and experimental analyses were performed for biological exploration. RESULTS: By analyzing discovery sets with radiotherapy (RT) plus TMZ versus RT alone, we identified a panel of 64 TMZ efficacy-related CpGs, from which a 10-CpG risk signature was further constructed. Both the 64-CpG panel and the 10-CpG risk signature were validated showing significant correlations with overall survival of G-CIMP-/unMGMT GBMs when treated with RT/TMZ, rather than RT alone. The 10-CpG risk signature was further observed for aiding TMZ choice by distinguishing differential outcomes to RT/TMZ versus RT within each risk subgroup. Functional studies on GPR81, the gene harboring one of the 10 CpGs, indicated its distinct impacts on TMZ resistance in GBM cells, which may be dependent on the status of MGMT expression. CONCLUSIONS: The 64 TMZ efficacy-related CpGs and in particular the 10-CpG risk signature may serve as promising predictive biomarker candidates for guiding optimal usage of TMZ in G-CIMP-/unMGMT GBMs.

Differentiation of Rat Bone Marrow Mesenchymal Stem Cells Into Neuron-Like Cells In Vitro and Co-Cultured with Biological Scaffold as Transplantation Carrier.

BACKGROUND Autograft and allograft transplantation are used to prompt the regeneration of axons after nerve injury. However, the poor self-regeneration caused by the glial scar and growth inhibitory factors after neuronal necrosis limit the efficacy of these methods. The purpose of this study was to develop a new chitosan porous scaffold for cell seeding. MATERIAL AND METHODS The bone marrow mesenchymal stem cells (BMSCs) and tissue-engineered biomaterial scaffold compound were constructed and co-cultured in vitro with the differentiated BMSCs of Wistar rats and chitosan scaffold in a 3D environment. The purity of the third-generation BMSCs culture was identified using flow cytometry and assessment of induced neuronal differentiation. The scaffolds were prepared by the freeze-drying method. The internal structure of scaffolds and the change of cells' growth and morphology were observed under a scanning electron microscope. The proliferation of cells was detected with the MTT method. RESULTS On day 5 there was a significant difference in the absorbance value of the experimental group (0.549±0.0256) and the control group (0.487±0.0357) (P>0.05); but on day 7 there was no significant difference in the proliferation of the experimental group (0.751±0.011) and the control group and (0.78±0.017) (P>0.05). CONCLUSIONS Tissue engineering technology can provide a carrier for cells seeding and is expected to become an effective method for the regeneration and repair of nerve cells. Our study showed that chitosan porous scaffolds can be used for such purposes.

Chitosan-collagen porous scaffold and bone marrow mesenchymal stem cell transplantation for ischemic stroke.

In this study, we successfully constructed a composite of bone marrow mesenchymal stem cells and a chitosan-collagen scaffold in vitro, transplanted either the composite or bone marrow mesenchymal stem cells alone into the ischemic area in animal models, and compared their effects. At 14 days after co-transplantation of bone marrow mesenchymal stem cells and the hitosan-collagen scaffold, neurological function recovered noticeably. Vascular endothelial growth factor expression and nestin-labeled neural precursor cells were detected in the ischemic area, surrounding tissue, hippocampal dentate gyrus and subventricular zone. Simultaneously, a high level of expression of glial fibrillary acidic protein and a low level of expression of neuron-specific enolase were visible in BrdU-labeled bone marrow mesenchymal stem cells. These findings suggest that transplantation of a composite of bone marrow mesenchymal stem cells and a chitosan-collagen scaffold has a neuroprotective effect following ischemic stroke.