Project description:The decreasing numbers of Donation after Brain Death (DBD) donors necessitates the comprehensive evaluation of Donation after Cardiac Death Donors (DCD) as a source of pancreata. The aim of this study was to characterize pancreata and islets from DCD and DBD donors with respect to markers of cellular stress that may indicate compromised islet quality. Immunohistochemical staining of pre-isolation pancreas biopsies found increased numbers of caspase 3 positive islets in DBD, while markers of oxidative stress (nitrotyrosine, CML, and HNE) were elevated in DCD. Assessment of islet quality by standard (yield, morphology, fluorescence microscopy, and glucose stimulated insulin secretion) and novel methods (flow cytometry, HPLC quantification of ATP) did not reveal significant differences. However, the post culture loss of DCD islets was increased compared to DBD, and DCD islets showed delayed functional potency when transplanted into diabetic NOD.scid mice. Microarray analysis of cultured islets showed increased expression of multiple stress pathway related genes in DCD compared to DBD. Together these data indicate that the current standard donor management, pancreas recovery and preservation practices are insufficient to quench the oxidative stress injury suffered by DCD islets which leads to loss in culture and may complicate their use in clinical transplant. Keywords: cell type comparison
Project description:We have sequenced miRNA libraries from human embryonic, neural and foetal mesenchymal stem cells. We report that the majority of miRNA genes encode mature isomers that vary in size by one or more bases at the 3’ and/or 5’ end of the miRNA. Northern blotting for individual miRNAs showed that the proportions of isomiRs expressed by a single miRNA gene often differ between cell and tissue types. IsomiRs were readily co-immunoprecipitated with Argonaute proteins in vivo and were active in luciferase assays, indicating that they are functional. Bioinformatics analysis predicts substantial differences in targeting between miRNAs with minor 5’ differences and in support of this we report that a 5’ isomiR-9-1 gained the ability to inhibit the expression of DNMT3B and NCAM2 but lost the ability to inhibit CDH1 in vitro. This result was confirmed by the use of isomiR-specific sponges. Our analysis of the miRGator database indicates that a small percentage of human miRNA genes express isomiRs as the dominant transcript in certain cell types and analysis of miRBase shows that 5’ isomiRs have replaced canonical miRNAs many times during evolution. This strongly indicates that isomiRs are of functional importance and have contributed to the evolution of miRNA genes
Project description:Gene expression profiling of immortalized human mesenchymal stem cells with hTERT/E6/E7 transfected MSCs. hTERT may change gene expression in MSCs. Goal was to determine the gene expressions of immortalized MSCs.