110

Naturally pure islets for autotransplantation after total pancreatectomy for chronic pancreatitis

A.N. Balamurugan¹, Sajjad M. Soltani¹, Melena D. Bellin^1,2, Rachel Sutliff¹, Gopalakrishnan Loganathan¹, Klearchos K. Papas¹, Bernhard J. Hering¹, David E.R. Sutherland¹

Departments of ¹Surgery and ²Pediatrics, Schulze Diabetes Institute, University of Minnesota, Minneapolis, MN, United States

The enzymatic digestion step for islet isolation from a chronic pancreatitis (CP) pancreas separates the intact pancreas into acinar cell and islet components. In general, the purity of islets at the digest level will be <10%. In some cases of diseased pancreases, however, after digestion there is a low to very low amount of exocrine tissue, presumably because of the destruction of exocrine tissue by the fibrotic process that occurs from the disease. In these cases, islet purity is naturally greater (>30% islet purity) and high islet purity (up to 98%) is achieved without the need for traditional density gradient purification. In this study we present isolation and clinical outcomes from 34 cases in which islet isolation resulted in naturally pure islets (NPI) with >30% islet purity. Islets were isolated using standard protocols throughout the study period. Patient characteristics, islet isolation, and clinical outcome are summarized in the table. Interestingly, 10 (29%) patients were pediatric, and the genetic mutations of cystic fibrosis transmembrane conductance regulator (CFTR) or cationic trypsinogen genes (PRSS1) were associated with the CP in 14 (41%). Although the average pancreas weight from these CP organs was 50.3±22.8 gms as compared to 94.0±28.5 gms in normal deceased donor (DD) pancreases (n=139), the tissue volumes after digestion were disproportionally small (6.9±5.9 vs 28.6±13.8 mL from DD pancreases), indicating a low acinar cell mass. Mean transplanted islet mass of NPI was 4,082±2,383 IEQ/kg with a purity of 30-98% (mean, 49±21%), and average portal pressures were elevated to 13.2±11.0 mm Hg. The gross morphology (score of 8.7±0.6) and viability (89.6±5.8) of islets isolated from the CP organs were normal. Insulin independence and partial function was achieved in 56% of patients receiving >2000 IEQ/kg. Unpurified autologous islet preparations are routinely transplanted after total pancreatectomy for CP. When the islets are naturally pure, the tissue volume is low and islet loss from gradient purification can be avoided, allowing as many islets as possible to be transplanted without elevating portal pressure to unacceptable levels.