title: Deterioration and variability of highly purified collagenase blends used in clinical islet isolation.
abstract: BACKGROUND
  The quality and stability of enzyme blends used in islet cell processing are critical for successful human islet isolation. A wide variability in enzymatic activity among lots of Liberase HI has been reported. This study examines the interlot and intralot variability of Liberase HI and the over-time deterioration of enzyme quality based on the analysis of islet isolation outcomes.
  
  
  METHODS
  The data of 169 human isolations processed for clinical islet transplantation, using five different lots of Liberase HI, were retrospectively analyzed. Inter- and intralot variables in the islet isolation were assessed over a 15-month period.
  
  
  RESULTS
  The analysis revealed significant interlot differences in the digestion time, prepurification islet counts, percent recovery, viability, and glucose stimulation insulin index. Moreover, a significant decrease in the pre- and postpurification islet yield per pancreas weight (IEQ/g) in isolations processed by two different enzyme lots used over a 15-month period was observed, suggesting a progressive deterioration of enzyme quality.
  
  
  CONCLUSIONS
  Our data demonstrate a significant lot-to-lot related variability in islet isolation outcomes. In addition, the over-time decline in isolation outcomes processed using a single enzyme lot was observed even when the enzyme blends were used within the expiration dating specified by the manufacturer.
authors.affiliation: Cell Transplant Center, Diabetes Research Institute, University of Miami Leonard M. Miller School of Medicine, Miami, FL 33136, USA.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Yamamoto
authors.forename: Camillo
authors.initials: C
authors.lastname: Ricordi
authors.forename: Shari
authors.initials: S
authors.lastname: Messinger
authors.forename: Yasunaru
authors.initials: Y
authors.lastname: Sakuma
authors.forename: Atsushi
authors.initials: A
authors.lastname: Miki
authors.forename: Rayner
authors.initials: R
authors.lastname: Rodriguez
authors.forename: Ross
authors.initials: R
authors.lastname: Haertter
authors.forename: Aisha
authors.initials: A
authors.lastname: Khan
authors.forename: Rodolfo
authors.initials: R
authors.lastname: Alejandro
authors.forename: Hirohito
authors.initials: H
authors.lastname: Ichii
mesh_terms: D000328:Adult; D002469:Cell Separation; D002470:Cell Survival; D017364:Collagenases / Q000737:chemistry / Q000302:isolation & purification / Q000592:standards*; D005260:Female; D005947:Glucose / Q000494:pharmacology; D006801:Humans; D007515:Islets of Langerhans / Q000737:chemistry / Q000187:drug effects / Q000502:physiology*; D016381:Islets of Langerhans Transplantation; D008297:Male; D013820:Thermolysin / Q000737:chemistry / Q000302:isolation & purification / Q000592:standards*; D014019:Tissue Donors; D020858:Tissue and Organ Harvesting; D016896:Treatment Outcome
chemical_list: D017364:Collagenases; C106635:Liberase; D013820:Thermolysin; D005947:Glucose