title: Young porcine endocrine pancreatic islets cultured in fibrin and alginate gels show improved resistance towards human monocytes.
abstract: OBJECTIVE
  To investigate the protective function of alginate and fibrin gels used to embed porcine endocrine pancreatic islets towards human monocytes.
  
  
  METHODS
  Groups of 200 islet equivalents from young pigs were embedded in either a fibrin or in an alginate gel, and as a control seeded in tissue culture polystyrene (TCPS) well plates. The islet cultures were incubated with 2×10(5) human monocytes for 24h. In addition, both islets and monocytes were separately cultured in TCPS, fibrin and alginate. Islet morphology, viability and function were investigated as well as the secretion of cytokines TNFα, IL-6, and IL-1β.
  
  
  RESULTS
  When freely-floating in TCPS, non-encapsulated islets were surrounded by monocytes and started to disperse after 24h. In fibrin, monocytes could be found in close proximity to embedded islets, indicating monocyte migration through the gel. In contrast, after 24h, few monocytes were found close to islets in alginate. Immunofluorescence staining and manual counting showed that integrin expression was higher in fibrin-embedded islet cultures. A TUNEL assay revealed elevated numbers of apoptotic cells for islets in TCPS wells compared to fibrin and alginate cultures. Insulin secretion was higher with islets embedded in fibrin and alginate when compared to non-encapsulated islets. TNFα, IL-6 and IL-1β were found in high concentrations in the media of co-cultures and monocyte mono-culture in fibrin.
  
  
  CONCLUSIONS
  Both alginate and fibrin provide key structural support and offer some protection for the islets towards human monocytes. Fibrin itself triggers the cytokine secretion from monocytes.
authors.affiliation: Laboratoire de bio-ingénierie et de biophysique de l'Université de Sherbrooke, Department of Chemical and Biotechnological Engineering, Université de Sherbrooke, 2500, boulevard de l'Université, J1K 2R1 Sherbrooke, Québec, Canada; Research Centre on Aging, Institut universitaire de gériatrie de Sherbrooke, 1036, rue Belvédère Sud, J1H 4C4 Sherbrooke, Québec, Canada.
authors.forename: C
authors.initials: C
authors.lastname: Kuehn
authors.affiliation: Research Centre on Aging, Institut universitaire de gériatrie de Sherbrooke, 1036, rue Belvédère Sud, J1H 4C4 Sherbrooke, Québec, Canada.
authors.forename: T
authors.initials: T
authors.lastname: Fülöp
authors.affiliation: Department of Surgery and Biomedical Engineering, University of California, Irvine, 333 City Boulevard West, Suite 700, Orange, 92868 CA, United States.
authors.forename: J R T
authors.initials: JR
authors.lastname: Lakey
authors.affiliation: Laboratoire de bio-ingénierie et de biophysique de l'Université de Sherbrooke, Department of Chemical and Biotechnological Engineering, Université de Sherbrooke, 2500, boulevard de l'Université, J1K 2R1 Sherbrooke, Québec, Canada; Research Centre on Aging, Institut universitaire de gériatrie de Sherbrooke, 1036, rue Belvédère Sud, J1H 4C4 Sherbrooke, Québec, Canada. Electronic address: Patrick.Vermette@USherbrooke.ca.
authors.forename: P
authors.initials: P
authors.lastname: Vermette
mesh_terms: D000464:Alginates / Q000737:chemistry / Q000494:pharmacology; D000818:Animals; D018929:Cell Culture Techniques / Q000379:methods*; D002465:Cell Movement / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D018920:Coculture Techniques; D057899:Cytophagocytosis / Q000187:drug effects; D019610:Cytoprotection / Q000187:drug effects; D005260:Female; D005337:Fibrin / Q000737:chemistry / Q000494:pharmacology; D005782:Gels; D020723:Glucuronic Acid / Q000737:chemistry / Q000494:pharmacology; D006603:Hexuronic Acids / Q000737:chemistry / Q000494:pharmacology; D006801:Humans; D007515:Islets of Langerhans / Q000166:cytology* / Q000187:drug effects / Q000502:physiology*; D008297:Male; D009000:Monocytes / Q000502:physiology*; D013552:Swine; D054457:Tissue Scaffolds / Q000737:chemistry
chemical_list: D000464:Alginates; D005782:Gels; D006603:Hexuronic Acids; D020723:Glucuronic Acid; D005337:Fibrin
keywords: Alginate; Encapsulation; Fibrin; Fibrine; Human monocytes; Immune protection; Islet transplantation; Monocytes humains; Protection immunitaire; Transplantation d’îlots