title: Surgical protocol involving the infusion of paramagnetic microparticles for preferential incorporation within porcine islets.
abstract: BACKGROUND
  Despite significant advances, widespread applicability of islet cell transplantation remains elusive. Refinement of current islet isolation protocols may improve transplant outcomes. Islet purification by magnetic separation has shown early promise. However, surgical protocols must be optimized to maximize the incorporation of paramagnetic microparticles (MP) within a greater number of islets. This study explores the impact of MP concentration and infusion method on optimizing MP incorporation within islets.
  
  
  METHODS
  Five porcine pancreata were procured from donors after cardiac death. Splenic lobes were isolated and infused with varying concentrations of MP (8, 16, and 32 × 10(8) MP/L of cold preservation solution) and using one of two delivery techniques (hanging bag versus hand-syringe). After procurement and infusion, pancreata were stored at 0°C to 4°C during transportation (less than 1 hour), fixed in 10% buffered formalin, and examined by standard magnetic resonance imaging (MRI) and histopathology.
  
  
  RESULTS
  T2*-weighted MRI showed homogeneous distribution of MP in all experimental splenic lobes. In addition, histologic analysis confirmed that MP were primarily located within the microvasculature of islets (82% to 85%), with few MP present in acinar tissue (15% to 18%), with an average of five to seven MP per islet (within a 5-μm thick section). The highest MP incorporation was achieved at a concentration of 16 × 10(8) MP/L using the hand-syringe technique.
  
  
  CONCLUSIONS
  This preliminary study suggests that optimization of a surgical protocol, MP concentrations, and applied infusion pressures may enable more uniform distribution of MP in the porcine pancreas and better control of MP incorporation within islets. These results may have implications in maximizing the efficacy of islet purification by magnetic separation.
authors.affiliation: Schulze Diabetes Institute, University of Minnesota, Minneapolis, Minnesota 55455, USA.
authors.forename: M D
authors.initials: MD
authors.lastname: Rizzari
authors.forename: T M
authors.initials: TM
authors.lastname: Suszynski
authors.forename: L S
authors.initials: LS
authors.lastname: Kidder
authors.forename: S A
authors.initials: SA
authors.lastname: Stein
authors.forename: T D
authors.initials: TD
authors.lastname: O'Brien
authors.forename: V S K
authors.initials: VS
authors.lastname: Sajja
authors.forename: W E
authors.initials: WE
authors.lastname: Scott
authors.forename: V A
authors.initials: VA
authors.lastname: Kirchner
authors.forename: B P
authors.initials: BP
authors.lastname: Weegman
authors.forename: E S
authors.initials: ES
authors.lastname: Avgoustiniatos
authors.forename: P W
authors.initials: PW
authors.lastname: Todd
authors.forename: D J
authors.initials: DJ
authors.lastname: Kennedy
authors.forename: B E
authors.initials: BE
authors.lastname: Hammer
authors.forename: D E R
authors.initials: DE
authors.lastname: Sutherland
authors.forename: B J
authors.initials: BJ
authors.lastname: Hering
authors.forename: K K
authors.initials: KK
authors.lastname: Papas
mesh_terms: D000818:Animals; D007515:Islets of Langerhans / Q000473:pathology; D016381:Islets of Langerhans Transplantation / Q000379:methods*; D008279:Magnetic Resonance Imaging; D008863:Microspheres; D013552:Swine