title: An effective method to release human islets from surrounding acinar cells with agitation in high osmolality solution.
abstract: BACKGROUND
  Islet purification is mainly performed by the density gradient method. However, purification of the embedded islets that are surrounded by exocrine tissue should be difficult, because their density is similar to exocrine tissue. In this study, we performed chart review to assess the relationship between the ratio of embedded islets and efficacy of purification. Then, we tested several conditions of a new method to free the islets from surrounded exocrine tissues using high osmolality solution with gentle agitation.
  
  
  METHODS
  First, we performed chart review of our human islet isolation. Second, embedded islet-enriched human islet fractions (embedded islets >50%) were suspended in University of Wisconsin (UW) solution (UW group, 320 mOsm/kg/H(2)0) or osmolality-adjusted UW solution (400, 500, and 600 mOsm/kg/H(2)0; 400 group, 500 group, and 600 group, respectively). Each tube was gently shaken at 4°C. The tissue samples were taken before shaking and after 15, 30, and 60 minutes. Islet yield, percentage of embedded islets, and viabilities were assessed.
  
  
  RESULTS
  The chart review revealed that high ratio of embedded islets deteriorated the efficacy of islet purification. The islet yield in all groups except for the 600 group did not change at 15 minutes, but it decreased in all groups at 60 minutes. The average percentage of embedded islets before shaking was 62.6%. Although percentage of embedded islets were decreasing in all groups, it was < 20% at 15 minutes in the 500 and 600 groups whereas it was >44% in the UW group, which indicated that higher osmolality would have a greater effect. Viability was >95% in all groups at 30 minutes.
  
  
  CONCLUSIONS
  The embedded islets deteriorated the efficacy of islet purification. Gentle agitation of embedded islets in high osmolality (500 mOsm/kg/H(2)O, 15 minutes) could release islets from surrounded exocrine tissue.
authors.affiliation: Baylor Research Institute, Dallas, Texas, USA.
authors.forename: M
authors.initials: M
authors.lastname: Shimoda
authors.forename: T
authors.initials: T
authors.lastname: Itoh
authors.forename: K
authors.initials: K
authors.lastname: Sugimoto
authors.forename: M
authors.initials: M
authors.lastname: Takita
authors.forename: D
authors.initials: D
authors.lastname: Chujo
authors.forename: S
authors.initials: S
authors.lastname: Iwahashi
authors.forename: J A
authors.initials: JA
authors.lastname: SoRelle
authors.forename: B
authors.initials: B
authors.lastname: Naziruddin
authors.forename: M F
authors.initials: MF
authors.lastname: Levy
authors.forename: P A
authors.initials: PA
authors.lastname: Grayburn
authors.forename: S
authors.initials: S
authors.lastname: Matsumoto
mesh_terms: D061354:Acinar Cells / Q000166:cytology*; D000241:Adenosine / Q000494:pharmacology; D000493:Allopurinol / Q000494:pharmacology; D018929:Cell Culture Techniques / Q000379:methods*; D002469:Cell Separation / Q000379:methods; D002470:Cell Survival; D017690:Cell Transplantation; D002478:Cells, Cultured; D005260:Female; D005978:Glutathione / Q000494:pharmacology; D006801:Humans; D007328:Insulin / Q000494:pharmacology; D007515:Islets of Langerhans / Q000166:cytology*; D016381:Islets of Langerhans Transplantation / Q000379:methods*; D008297:Male; D008875:Middle Aged; D019188:Organ Preservation Solutions / Q000494:pharmacology; D009994:Osmolar Concentration; D011887:Raffinose / Q000494:pharmacology; D012996:Solutions; D013997:Time Factors
chemical_list: D007328:Insulin; D019188:Organ Preservation Solutions; D012996:Solutions; C055206:University of Wisconsin-lactobionate solution; D000493:Allopurinol; D005978:Glutathione; D000241:Adenosine; D011887:Raffinose