title: Islet isolation under cGMP conditions: replacing the coil.
abstract: BACKGROUND
  Clinical islet transplantation is increasingly regulated, with isolation standards defined under current good manufacturing practices (cGMPs). cGMP requires validation of equipment cleaning and sterilization. The automated process for islet isolation requires rapid thermal exchange during processing, manipulating a metal coil containing cellular product into and out of chilled/heated waterbaths. We recognize challenges of validating cleaning and sterilization of this coil and propose replacement with a disposable blood warming system. Our specific aims were to assess the system's ability to accommodate flow rates utilized during various phases of pancreatic digestion and to assess its efficiency of heat exchange and temperature control.
  
  
  METHODS
  In a pancreas digestion circuit, heat exchange occurred via the coil in a digital water bath, or Warmflo blood warming bag in a digital warming unit. Temperature within the digestion chamber was assessed using an inserted thermocouple. Time to achieve 37 degrees C was measured for set heating element temperatures 38.5 degrees C to 41 degrees C. Circuit temperature maintenance characteristics were also recorded.
  
  
  RESULTS
  The Warmflo bloodbag easily accommodated flows of 150 and 300 mL/min. At all set temperatures, the bag resulted in shorter or equivalent time to 37 degrees C than the coil. Maintenance of 37 degrees C was also equivalent. We have utilized this system for four human islet isolations with mean time to 37 degrees C of 5.5 minutes, without difference in digestion quality.
  
  
  CONCLUSIONS
  Use of a disposable blood warming system in place of the coil during islet isolation provides adequate flow characteristics, heat exchange, and temperature control and may facilitate evolution of islet isolation toward cGMP compliance.
authors.affiliation: Department of Surgery, The University of Chicago, Chicago, Illinois 60637, USA. mgarfink@surgery.bsd.uchicago.edu
authors.forename: M R
authors.initials: MR
authors.lastname: Garfinkel
authors.forename: M
authors.initials: M
authors.lastname: Connors
authors.forename: D
authors.initials: D
authors.lastname: Ostrega
authors.forename: J
authors.initials: J
authors.lastname: Jarosz
authors.forename: L
authors.initials: L
authors.lastname: Philipson
authors.forename: J M
authors.initials: JM
authors.lastname: Millis
mesh_terms: D018929:Cell Culture Techniques / Q000379:methods; D002469:Cell Separation / Q000379:methods; D006152:Cyclic GMP / Q000494:pharmacology*; D006801:Humans; D007515:Islets of Langerhans / Q000166:cytology* / Q000187:drug effects; D016381:Islets of Langerhans Transplantation / Q000502:physiology; D013696:Temperature; D013816:Thermodynamics
chemical_list: D006152:Cyclic GMP