In compliance with federal regulations, islet isolations were performed from deceased donors (research/clinical) (n=94), split pancreas digestion (n=5), and chronic pancreatitis (n=150) pancreases. On arrival at the laboratory, the pancreas was trimmed, cannulated, and distended with tissue dissociation enzymes of various combinations. After ductal perfusion of the enzymes, the pancreas was digested using a modified Ricordi’s semi-automated method (31 (link)). The digested tissue was then purified by continuous iodixanol (OptiPrep™, Axis-Shield, Oslo, Norway) density gradient on a COBE-2991 cell processor.
Clinical pancreases were accepted following standard organ acceptance criteria and the Edmonton pancreas donor scoring algorithm was applied to each donor (32 (link)). In clinical allograft isolations, our University of Minnesota isolation protocol (17 (link)) was used for all isolations performed with EC-A (n=13) and EC-F (n=19). For clinical isolations performed with the NEM, 2 were performed with this protocol while the remaining 8 isolations were performed with the Clinical Islet Transplantation (CIT) Consortium islet isolation protocol. In all cases of allotransplantation, the liberated islets were first cultured in CMRL-1066 supplemented medium (Mediatech, Inc, Manassas, VA) for 36–72h before being transplanted.
Autologous islet isolations were performed following total pancreatectomy as described (33 (link)–35 (link)). The isolated islets were transplanted immediately after isolation.
Split pancreas digestions (n=5) were performed on research pancreases to study the potency of the NEM compared to EC-F (Table-1C). Each pancreas was split into two lobes, head/body and body/tail, and each portion was digested with either intact collagenase and ChNP (NEM) or intact collagenase and thermolysin (EC-F). Digestions were performed sequentially and each lobe received alternating enzyme treatments to reduce intra-pancreatic variability.