title: Real-time assessment of encapsulated neonatal porcine islets prior to clinical xenotransplantation.
abstract: BACKGROUND
  Porcine islet transplantation is emerging as an attractive option for the treatment of patients with type 1 diabetes, with the possibility of providing islets of higher and more consistent quality and in larger volumes than available from human pancreata. The use of encapsulated neonatal porcine islets (ENPI) is appealing because it can address islet supply limitations while reducing the need for anti-rejection therapy. Pre-transplant characterization of ENPI viability and potency is an essential component of the production process. We applied the validated assay for oxygen consumption rate normalized for DNA content (OCR/DNA) to characterize ENPI viability.
  
  
  METHODS
  ENPI of low viscosity and high m alginate were prepared according to standard methods and characterized at various culture time points up to 5 weeks.
  
  
  RESULTS
  The OCR/DNA (nmol/min·mgDNA ± SEM) of ENPI (235 ± 10, n = 9) was comparable to that of free NPI (255 ± 14, n = 13). After encapsulation, NPI OCR/DNA was sustained over a culture period of up to 5 weeks. The average OCR/DNA of ENPI cultured longer than 9 days was higher than that of freshly encapsulated NPI.
  
  
  CONCLUSIONS
  This is the first characterization of ENPI by a validated and more sensitive method for product viability. The NPI encapsulation process does not compromise viability as measured by OCR/DNA, and ENPI can be cultured for up to 5 weeks with maintenance of viability. ENPI meet or exceed current adult porcine islet product release criteria (established at the University of Minnesota) for preclinical xenotransplantation in terms of OCR/DNA.
authors.affiliation: Department of Surgery, Schulze Diabetes Institute, University of Minnesota, Minneapolis, MN, USA.
authors.forename: Jennifer P
authors.initials: JP
authors.lastname: Kitzmann
authors.forename: Lee
authors.initials: L
authors.lastname: Law
authors.forename: Avik
authors.initials: A
authors.lastname: Shome
authors.forename: Marija
authors.initials: M
authors.lastname: Muzina
authors.forename: Robert B
authors.initials: RB
authors.lastname: Elliott
authors.forename: Kate R
authors.initials: KR
authors.lastname: Mueller
authors.forename: Henk-Jan
authors.initials: HJ
authors.lastname: Schuurman
authors.forename: Klearchos K
authors.initials: KK
authors.lastname: Papas
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001681:Biological Assay; D003922:Diabetes Mellitus, Type 1 / Q000601:surgery*; D006801:Humans; D007515:Islets of Langerhans / Q000276:immunology* / Q000601:surgery; D016381:Islets of Langerhans Transplantation / Q000379:methods; D010101:Oxygen Consumption / Q000502:physiology; D013552:Swine; D014183:Transplantation, Heterologous / Q000276:immunology*