title: Acute Ischemia Induced by High-Density Culture Increases Cytokine Expression and Diminishes the Function and Viability of Highly Purified Human Islets of Langerhans.
abstract: Encapsulation devices have the potential to enable cell-based insulin replacement therapies (such as human islet or stem cell-derived β cell transplantation) without immunosuppression. However, reasonably sized encapsulation devices promote ischemia due to high β cell densities creating prohibitively large diffusional distances for nutrients. It is hypothesized that even acute ischemic exposure will compromise the therapeutic potential of cell-based insulin replacement. In this study, the acute effects of high-density ischemia were investigated in human islets to develop a detailed profile of early ischemia induced changes and targets for intervention.
  
  
  
  Human islets were exposed in a pairwise model simulating high-density encapsulation to normoxic or ischemic culture for 12 hours, after which viability and function were measured. RNA sequencing was conducted to assess transcriptome-wide changes in gene expression.
  
  
  
  Islet viability after acute ischemic exposure was reduced compared to normoxic culture conditions (P < 0.01). Insulin secretion was also diminished, with ischemic β cells losing their insulin secretory response to stimulatory glucose levels (P < 0.01). RNA sequencing revealed 657 differentially expressed genes following ischemia, with many that are associated with increased inflammatory and hypoxia-response signaling and decreased nutrient transport and metabolism.
  
  
  
  In order for cell-based insulin replacement to be applied as a treatment for type 1 diabetes, oxygen and nutrient delivery to β cells will need to be maintained. We demonstrate that even brief ischemic exposure such as would be experienced in encapsulation devices damages islet viability and β cell function and leads to increased inflammatory signaling.
authors.affiliation: 1 Department of Surgery, University of Arizona, Tucson, AZ. 2 Department of Physiological Sciences GIDP, University of Arizona, Tucson, AZ. 3 School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, AZ. 4 Department of Physiology, University of Arizona, Tucson, AZ. 5 Sanofi-Aventis Group, Tucson, AZ. 6 Icagen, Inc., Tucson, AZ. 7 Department of Surgery, SUNY Upstate Medical University, Syracuse, NY.
authors.forename: Kate E
authors.initials: KE
authors.lastname: Smith
authors.forename: Amy C
authors.initials: AC
authors.lastname: Kelly
authors.forename: Catherine G
authors.initials: CG
authors.lastname: Min
authors.forename: Craig S
authors.initials: CS
authors.lastname: Weber
authors.forename: Fiona M
authors.initials: FM
authors.lastname: McCarthy
authors.forename: Leah V
authors.initials: LV
authors.lastname: Steyn
authors.forename: Vasudeo
authors.initials: V
authors.lastname: Badarinarayana
authors.forename: J Brett
authors.initials: JB
authors.lastname: Stanton
authors.forename: Jennifer P
authors.initials: JP
authors.lastname: Kitzmann
authors.forename: Peter
authors.initials: P
authors.lastname: Strop
authors.forename: Angelika C
authors.initials: AC
authors.lastname: Gruessner
authors.forename: Ronald M
authors.initials: RM
authors.lastname: Lynch
authors.forename: Sean W
authors.initials: SW
authors.lastname: Limesand
authors.forename: Klearchos K
authors.initials: KK
authors.lastname: Papas
mesh_terms: D000328:Adult; D015687:Cell Hypoxia; D002470:Cell Survival; D016207:Cytokines / Q000235:genetics / Q000378:metabolism*; D005260:Female; D020869:Gene Expression Profiling; D006801:Humans; D018836:Inflammation Mediators / Q000378:metabolism*; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D050417:Insulin-Secreting Cells / Q000378:metabolism* / Q000473:pathology; D007515:Islets of Langerhans / Q000378:metabolism* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D015398:Signal Transduction; D013997:Time Factors; D046509:Tissue Culture Techniques; D014022:Tissue Survival; D015854:Up-Regulation
chemical_list: D016207:Cytokines; D018836:Inflammation Mediators; D007328:Insulin