title: Insulin-producing cells generated from dedifferentiated human pancreatic beta cells expanded in vitro.
abstract: BACKGROUND
  Expansion of beta cells from the limited number of adult human islet donors is an attractive prospect for increasing cell availability for cell therapy of diabetes. However, attempts at expanding human islet cells in tissue culture result in loss of beta-cell phenotype. Using a lineage-tracing approach we provided evidence for massive proliferation of beta-cell-derived (BCD) cells within these cultures. Expansion involves dedifferentiation resembling epithelial-mesenchymal transition (EMT). Epigenetic analyses indicate that key beta-cell genes maintain open chromatin structure in expanded BCD cells, although they are not transcribed. Here we investigated whether BCD cells can be redifferentiated into beta-like cells.
  
  
  RESULTS
  Redifferentiation conditions were screened by following activation of an insulin-DsRed2 reporter gene. Redifferentiated cells were characterized for gene expression, insulin content and secretion assays, and presence of secretory vesicles by electron microscopy. BCD cells were induced to redifferentiate by a combination of soluble factors. The redifferentiated cells expressed beta-cell genes, stored insulin in typical secretory vesicles, and released it in response to glucose. The redifferentiation process involved mesenchymal-epithelial transition, as judged by changes in gene expression. Moreover, inhibition of the EMT effector SLUG (SNAI2) using shRNA resulted in stimulation of redifferentiation. Lineage-traced cells also gave rise at a low rate to cells expressing other islet hormones, suggesting transition of BCD cells through an islet progenitor-like stage during redifferentiation.
  
  
  CONCLUSIONS
  These findings demonstrate for the first time that expanded dedifferentiated beta cells can be induced to redifferentiate in culture. The findings suggest that ex-vivo expansion of adult human islet cells is a promising approach for generation of insulin-producing cells for transplantation, as well as basic research, toxicology studies, and drug screening.
authors: Department of Human Molecular Genetics and Biochemistry, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.
authors: Holger A
authors: HA
authors: Russ
authors: Elad
authors: E
authors: Sintov
authors: Leeat
authors: L
authors: Anker-Kitai
authors: Orr
authors: O
authors: Friedman
authors: Ayelet
authors: A
authors: Lenz
authors: Ginat
authors: G
authors: Toren
authors: Chen
authors: C
authors: Farhy
authors: Metsada
authors: M
authors: Pasmanik-Chor
authors: Varda
authors: V
authors: Oron-Karni
authors: Philippe
authors: P
authors: Ravassard
authors: Shimon
authors: S
authors: Efrat
mesh_terms: D002454:Cell Differentiation / Q000235:genetics / Q000502:physiology*; D049109:Cell Proliferation; D002478:Cells, Cultured; D006801:Humans; D050417:Insulin-Secreting Cells / Q000166:cytology* / Q000378:metabolism*; D034741:RNA, Small Interfering; D000071250:Snail Family Transcription Factors; D046509:Tissue Culture Techniques; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D034741:RNA, Small Interfering; C000604407:SNAI1 protein, human; C000604408:SNAI2 protein, human; D000071250:Snail Family Transcription Factors; D014157:Transcription Factors