Unknown,Transcriptomics,Genomics,Proteomics

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Transcription profiling of human islets after in vitro expansion.

ABSTRACT: Pancreatic islet transplantation as a cure for type 1 diabetes (T1D) cannot be scaled up due to a scarcity of human pancreas donors. In vitro expansion of beta cells from mature human pancreatic islets provides an alternative source of insulin-producing cells. The exact nature of the expanded cells produced by diverse expansion protocols, and their potential for differentiation into functional beta cells, remain elusive. We performed a large-scale meta-analysis of gene expression in human pancreatic islet cells, which were processed using three different previously described protocols for expansion and attempted re-differentiation. All three expansion protocols induced dramatic changes in the expression profiles of pancreatic islets; many of these changes are shared among the three protocols. Attempts at re-differentiation of expanded cells induce a limited number of gene expression changes. Nevertheless, these fail to restore a pancreatic islet-like gene expression pattern. Comparison with a collection of public microarray datasets confirmed that expanded cells are highly comparable to mesenchymal stem cells. Genes induced in expanded cells are also enriched for targets of transcription factors important for pluripotency induction. The present data increases our understanding of the active pathways in expanded and re-differentiated islets. Knowledge of the mesenchymal stem cell potential may help development of drug therapeutics to restore beta cell mass in T1D patients. Experiment Overall Design: In this study, we have tested three different protocols to expand human pancreatic islets in monolayer and after attempted maneuvers to re-differentiate the expanded cells back to islets. We have characterized the resulting cells in detail by performing microarray analyses with fresh pancreatic islets, expanded islet cells and re-differentiated cells. Genes modified by either of three protocols have 70 to 80% overlap with the genes changed by the other two protocols. Although there are promising changes in the right direction, none of the three protocols could achieve a return to a functional islet state. The expanded cells highly resemble Mesenchymal Stem Cells (MSC), and similar gene regulatory networks seem to be active in both cell types. On the other hand, the expanded islet cells are different from MSC in that they seem to retain activity of some islet gene modules. The current results highlight the importance of designing new strategies that take into account the MSC potential of expanded cells.

ORGANISM(S): Homo sapiens

SUBMITTER: Burak Kutlu

PROVIDER: E-GEOD-15543 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Meta-analysis of gene expression in human pancreatic islets after in vitro expansion.

Kutlu B B Kayali A G AG Jung S S Parnaud G G Baxter D D Glusman G G Goodman N N Behie L A LA Hayek A A Hood L L

Physiological genomics 20090721 1

Pancreatic islet transplantation as a potential cure for type 1 diabetes (T1D) cannot be scaled up due to a scarcity of human pancreas donors. In vitro expansion of beta-cells from mature human pancreatic islets provides an alternative source of insulin-producing cells. The exact nature of the expanded cells produced by diverse expansion protocols and their potential for differentiation into functional beta-cells remain elusive. We performed a large-scale meta-analysis of gene expression in huma ...[more]

PMID: 19622797

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Project description:β cell proliferation rates decline with age and adult β cells have limited self-duplicating activity for regeneration, which predisposes to diabetes. Here we show that, among MYC family members, Mycl was expressed preferentially in proliferating immature endocrine cells. Genetic ablation of Mycl caused a modest reduction in cell proliferation of pancreatic endocrine cells in neonatal mice. By contrast, systemic expression of Mycl in mice stimulated proliferation in pancreatic islet cells and resulted in expansion of pancreatic islets without forming tumors in other organs. Single-cell RNA sequencing and genetic tracing experiments revealed that the expression of Mycl provoked transcription signatures associated with immature proliferating endocrine cells and stimulated self-duplication in adult hormone-expressing cells. The expanded hormone-expressing cells ceased proliferation but persisted after withdrawal of Mycl expression. Remarkably, a subset of the expanded α cells gave rise to insulin-producing cells after the withdrawal. Moreover, transient Mycl expression in vivo was sufficient to normalize increased blood glucose levels in diabetic mice evoked by chemical ablation of β cells. In vitro expression of Mycl similarly provoked active replication without inducing apoptosis in adult hormone-expressing islet cells, even those from aged mice. Furthermore, the expanded islet cells functioned in diabetic mice after transplantation. Finally, we show that MYCL stimulated self-duplication of human adult cadaveric islet cells. Collectively, these results demonstrate that sole induction of Mycl expands adult β cells both in vivo and in vitro. Moreover, islet cell-specific reprogramming via transient Mycl transduction elicits endogenous expansion of insulin-producing cells in adult pancreas through both self-duplication of β cells and transdifferentiation ofα cells into insulin-producing cells, which may provide a regenerative strategy of β cells.

Project description:Increased fat intake is associated with obesity and insulin resistance. In some individuals, a failure of pancreatic b-cells to increase insulin production in response to the high demands of obesity leads to diabetes. We sought to determine whether the impaired b- cell adaptation in obesity is associated with differential expression of genes involved in b-cell expansion and intermediary metabolism. Two strains of inbred mice prone to obesity, C57Bl/6J and AKR/J, were fed regular rodent chow or high-fat diet, after which islet morphology, secretory function and gene expression were assessed. AKR/J had lower blood glucose and higher insulin levels compared with C57Bl/6J mice on regular rodent chow or high fat diet. Insulin secretion was 3.2 fold higher in AKR/J than C57Bl/6J mice following intraperitoneal glucose injection. Likewise, glucose-stimulated insulin secretion from isolated islets was higher in AKR/J. Additionally, islet mass was 1.4 fold greater in AKR/J compared with C57Bl/6J. To elucidate the factors associated with the differences in insulin, we analyzed the gene expression profiles in pancreatic islets in AKR/J and C57Bl/6J mice. Of 14,000 genes examined, 220 were up-regulated and 286 were down-regulated in islets from diet-induced obese AKR/J mice compared with C57Bl/6J mice. Key genes involved in islet signaling and metabolism, e.g. glucagon like peptide-1 receptor, sterol Co-A desaturase 1 & 2 and fatty acid desaturase 2 were upregulated in obese AKR/J mice. The expression of multiple extracellular matrix proteins was also increased in AKR/J mice, suggesting a role in modulation of islet mass. Functional analyses of differentially regulated genes hold promise for elucidating factors linking obesity to alterations in islet function. Experiment Overall Design: Microarray analyses were performed on quadruplicate RNA samples of pancreatic islets from AKR and Bl6 mice placed on high-fat diet for 3 months. Pancreases from two mice were combined to yield one sample of islet RNA. All protocols were conducted as described in the Affymetrix GeneChips Expression Analysis Technical Manual (Affymetrix, Santa Clara, CA) using 5 Î¼g total RNA and GeneChip Mouse Expression Arrays MOE 430 (Affymetrix).

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Transcription profiling of human islets after in vitro expansion.

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Meta-analysis of gene expression in human pancreatic islets after in vitro expansion.

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